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Institute of Dentistry,
Faculty of Medicine,
University of Helsinki, Finland
CONDITION OF TEETH AND PERIODONTIUM
IN THE HOME-DWELLING ELDERLY
- With Special Reference to Level of Education
Päivi Siukosaari
ACADEMIC DISSERTATION
To be presented, with the permission of the Faculty of Medicine, University of
Helsinki, for public examination in main auditorium of the Institute of Dentistry,
Mannerheimintie 172, Helsinki, on 10th of May 2013, at 12 noon.
Helsinki 2013
Supervised by
Professor Timo Närhi DDS, PhD
Department of Prosthetic Dentistry
University of Turku
FINLAND
and
Professor emerita Anja Ainamo DDS, PhD
Department of Prosthetic Dentistry and Stomatognathic
Physiology
University of Helsinki, FINLAND
Reviewed by
Professor James Newton
University of Aberdeen, UNITED KINGDOM
and
Professor Liisa Suominen DDS, PhD
Faculty of Health Sciences
University of Eastern Finland, Kuopio, FINLAND
Opponent
Professor Cees de Baat
Radboud University
Nijmegen , THE NETHERLANDS
ISBN 978-952-10-8776-9 (nid.)
ISBN 978-952-10-8777-6 (PDF)
Unigrafia Oy
Helsinki 2013
CONTENTS
List of original publications
6
Abstract
7
Abbreviations
9
1. Introduction
10
2. Review of the literature
12
2.1 Gerontology, geriatrics, and geriatric dentistry
12
2.2 The elderly
12
2.2.1 Demographic change
13
2.2.2 Health and medication
14
2.3 Oral health
16
2.3.1 Saliva and biofilm
17
2.3.2 Edentulism and number of teeth
18
2.3.3 Caries
20
2.3.4 Periodontal diseases
22
2.3.5 Oral health behavior
24
2.4 Socioeconomic position
25
2.4.1 Level of education
25
2.4.2 Income
26
2.4.3 Occupation
26
2.4.4 Level of education in Finland
26
2.4.5 SEP and oral health
27
3. Hypothesis and the aim of the study
29
4. Subjects and methods
30
4.1 Study population
30
4.2 Methods
34
4.2.1 Medical examination and interview
34
4.2.2 Questionnaire
34
4.2.3 Oral examinations
35
4.3 Statistical analysis
38
4.4 Ethical aspects
38
5. Results
39
5.1 Attendance
39
5.2 Loss of teeth
41
5.3 Caries
43
5.4 Periodontal diseases
46
6. Discussion
48
6.1. Subjects
48
6.2. Methods
51
6.3. Tooth loss and root caries
53
6.4. Periodontal diseases
56
6.5. Tooth brushing practices
58
6.6. Strengths and weaknesses of the study
60
6.7 Implications for the future
61
7. Conclusions and recommendations
63
Acknowledgements
65
List of references
67
LIST OF ORIGINAL PUBLICATIONS
This thesis is based on the following original publications, which are referred to in
the text by the Roman numerals I –– IV. In addition, some unpublished results are
included.
I
Vehkalahti M, Siukosaari P, Ainamo A, Tilvis R. Factors related to nonattendance in an oral health study on the home-dwelling elderly.
Gerodontology 139:17-24, 1996
II
Närhi TO, Vehkalahti M, Siukosaari P, Ainamo A. Salivary findings, daily
medication and root caries in the elderly. Caries Research 32:5-9, 1998
III
Siukosaari P, Ainamo A, Närhi TO. Level of education and incidence of
caries in the elderly: a five ––year follow-up study. Gerodontology 22: 130136, 2005.
IV
Siukosaari P, Ajwani S, Ainamo A, Närhi T. Periodontal health status in
the elderly with different level of education –– a five-year follow-up study.
Gerodontology 29: e170––e178, 2012
Original publications are reprinted with the permission of the publishers.
ABSTRACT
Siukosaari P. Condition of teeth and periodontium in home-dwelling older people.
––With special reference to level of education. Institute of Dentistry, University of
Helsinki, Finland, 2012.
This study is part of the longitudinal population based Helsinki Aging Study
(HAS). The study population consisted of a random sample of subjects born in
1904, 1909 and 1914 and living in Helsinki, Finland in 1990. Clinical oral and
radiographical status along with an interview on background factors, oral health
behavior and self-perceived need of treatment were obtained from 364 elderly aged
76, 81 and 86 years at the baseline in 1990-91. Of these 196 were dentate and the
171 dentate who had information on their education formed the baseline study
group. Prior to oral examination the participants underwent comprehensive medical
examination. Five years later 113 dentate elderly participated in the follow-up
examinations. Background information for the non-participation analysis was
obtained from the medical HAS records.
To assess any possible non-response bias we evaluated the background factors of
the participants and non-participants. The multicausal analysis revealed that the
strongest factors explaining non-participation were old age (OR=3.6), being
edentulous (OR=2.5), having clinically diagnosed signs of dementia (OR=4.1) and
a deteriorated ability to move easily (OR=5.3).
Caries was common among the participants. At baseline 71% of men and 48% of
women had decayed teeth. Subjects’’ DMFT (Decayed Missing Filled Teeth) index
increased during the follow-up mostly as a result of tooth extractions. Although the
number of teeth and root surfaces (p<0.05) at risk were higher in the high education
groups, no significant differences were found in number of DRS (Decayed Root
Surfaces) (0.6 ± 1.3) and RCI (Root Caries Index) (0.13 ± 0.18) in the different
education groups. The only factor, which could explain the increment in root caries,
was high salivary microbial counts. However, none of the salivary factors examined
were directly associated with the level of education.
Many of these participants were also in need of periodontal treatment. The results
of the study indicated that there are oral health disparities among this elderly
population. The fact that the elderly with higher level of education had more
remaining teeth than the elderly with lower level of education explained the finding
that better educated elderly also had a greater need for periodontal treatment.
During the five year follow-up only slight deteriorating in periodontal health was
found, while the differences between education groups remained, indicating that
good periodontal health is possible to maintain even with advancing age.
The major chronic oral diseases, caries and periodontal disease, share many
common risk factors. While there is much evidence on the prevention of these
diseases, the implementation of this knowledge into successful programs for
specific groups and populations has been modest. This was also seen in the present
study population with high prevalence of caries and periodontal diseases. There is
an urgent need for preventive programs against caries and periodontal disease both
in the community and individual level because a growing proportion of older adults
retain their teeth into old age and the proportion of the older adults in the
population is estimated to continue to grow.
ABBREVIATIONS
CAL
Clinical Attachment Loss
CEJ
Cemento-Enamel Junction
CFU
Colony-Forming Units
CPITN
Community Periodontal Index of Treatment Need
DFRS
Decayed Filled Root Surfaces
DMFT
Decayed Missing Filled Teeth
DRS
Decayed Root Surfaces
DT
Decayed Teeth
HAS
Helsinki Aging Study
LB
Lactobacilli
OR
Odds Ratio
RPD
Removable Partial Denture
RCI
Root Caries Index
SDA
Shortened Dental Arch
SEP
Socioeconomic position
SES
Socioeconomic status
SGH
Salivary Gland Hypofunction
SM
Streptococcus Mutans
SP
Severe Periodontitis
WHO
World Health Organization
1. INTRODUCTION
Demographic changes during the twentieth century have led to an increase in the
number and proportion of the population over 65 years old. In Finland 17% of the
population is over 65––years old (Official Statistics of Finland 2010). The most
rapid growth has been seen in the oldest age groups as life expectancy is steadily
increasing. Today most of the older adults are living independently in their own
homes and are active users of health care services. The number of home dwelling
elderly is expected to continue to increase. The rate of the graying of a population
varies in different parts of the world. Finland is at the moment one of the fastest
aging nations in the western world (Eurostat yearbook 2011).
Oral health in the elderly has been improving since the 1970s along with the
improving general health. In 1990 more than half of the elderly in Finland were
edentulous (Vehkalahti et al. 1991). The decrease in the number of edentulous
inhabitants is already seen among the younger generations, and the mean number of
teeth has been increasing in every adult age cohort. However, with advancing age
maintenance of good oral health becomes challenging. Deterioration of motoric
functions, impaired vision and moreover, declining cognitive status decreases the
ability to maintain proper oral hygiene. Many diseases, and especially their
treatment with multiple medications, change the oral environment increasing the
risk of oral diseases in the remaining dentition.
There is a clear need to have more information on the oral health status of the older
population groups. There is very little information available on oral health,
especially of the home-dwelling elderly in Finland.
The Helsinki Aging Study (HAS) was designed as a comprehensive medical
follow-up investigation representing three different age cohorts living in Helsinki,
the capital of Finland. The oral health component of HAS was intended to cover 10
years providing information on background factors of the various oral diseases
among the elderly. Most of the participants of HAS had lived a major part of their
lives in Helsinki and were a genetically very homogenous elderly population with
different socioeconomic backgrounds. Socioeconomic position has been reported to
be one of the most important factors predicting mortality and accumulation of
diseases in many adult populations (Mackenbach et al. 2003). However, its
influence on oral health in the elderly age groups is not clear due to the effects of
other risk factors. HAS gave an excellent possibility to study the occurrence of oral
diseases in the elderly with different socioeconomic backgrounds.
Socioeconomic position has been evaluated with several indicators, of which level
of education is one of the most frequently used. Therefore, the level of education
was also used in the present thesis. Although oral health in Finland has dramatically
improved in general in the last 20-30 years, oral health inequalities still remain, and
have even widened in some populations (Suominen-Taipale et al. 2008). A
particularly strong association between oral health and education level has been
found in several studies (Aromaa and Koskinen 2000, Koskinen et al. 2006,
Suominen-Taipale et al. 2008). The present study was based on the working
hypotheses that a low level of education increases the prevalence and increment of
tooth loss, caries or periodontal diseases among elderly home dwelling individuals.
Due to the attrition of the study population it was not possible to conduct clinical
examination after ten-year follow-up and the follow-up articles were limited to
contain five-year data. The present thesis contains four separate articles, the first of
which describes the background factors affecting non-attendance in the study. The
prevalence and increment of root caries as well as periodontal diseases are
described in three different publications. Additionally previously unpublished data
is presented.
2. REVIEW OF THE LITERATURE
2.1 Gerontology, geriatrics, and geriatric dentistry
Gerontology (from Greek: , geron, "old man" and -, -logy, "study of")
is the study of the social, psychological and biological aspects of aging and the
aging process itself. The field of gerontology was developed relatively late.
However, the huge increase in the elderly population in the post-industrial Western
nations has led to this becoming one of the most rapidly growing fields of
medicine. It is distinguished from geriatrics, which is the branch of medicine that
studies the diseases of the elderly (Mosby 2008).
Geriatric dentistry or gerodontics is the delivery of oral care to older adults
involving the diagnosis, prevention, and treatment of problems associated with
normal aging and age-related diseases as part of an interdisciplinary team with
other health care professionals (Mosby 2008).
2.2 The elderly
It is difficult to say when a person changes from middle aged to old as old age does
not have the same meaning in all societies. A person can be considered old because
of certain changes in their activities or social roles. Conventionally, a chronological
calendar age of 65 years and older is used when referring to elderly persons (Taylor
P et al. 2009). In Finland, as in many other western countries, this age is equivalent
to the retirement age, and thus commonly used as a cut-off point in national
statistics (Official Statistics of Finland 2010). However, chronological age seldom
correlates with the biological age. Today many retired individuals have been
successful in aging and are fairly healthy and do not perceive themselves as being
old. The previously used threshold of 65 years has often been replaced with 75
years and older as many elderly define their 70's or 80's as the time they begin to
feel elderly and tend to have more physical needs and functional impairments
(Hodgkins 1995). However, the older adults are a very heterogeneous group of
people, and an individual’’s biological age, chronological age, and state of health
have to be taken into consideration separately.
There is a plethora of terms used to describe older adults, seniors, gray panthers or
the aged. Some of these terms can be discriminatory in nature, and there has been
an attempt to define a politically correct word to use when talking about people
aged 65 or 75 and older. Gerontologists have found it useful to define individuals
who are 65-74 as ““the old””, 75-84 old as ““the old old”” and those aged 85 years and
older ““the oldest old”” (Pifer et al. 1986). In this work ““the elderly”” is used to
describe a demographic group, the population aged 75 or older. ““Older adults”” have
also been used where appropriate.
2.2.1 Demographic changes
In the industrialized countries, life expectancy has increased consistently over the
last decades due to improvements in social and living conditions and standards of
health care (Official Statistics of Finland 2010). At the same time there has been a
decline in fertility. This has resulted in a growing number of older adults as well as
a greater proportion of older adults in populations. The rate of the graying of a
population varies in different parts of the world. Finland is at the moment one of the
fastest aging nations in the western world (Eurostat yearbook 2011).
In Finland the proportion of people aged 65 or older increased from 13.5% in 1990
to 17.6% in 2010. At the moment people aged over 65 have outnumbered those
under 16 for the first time ever (Official Statistics of Finland 2010). The older
population is on the threshold of a boom at the moment as the first Baby Boomers
(the very large age cohorts born during a period of rapid population growth and
social change after the Second World War in 1946-1964) reach retirement age in
2010. The population of the 65 and older in 2030 is projected to be twice as large as
in 2010, growing from 0.9 million to 1.8 million and representing more than 26 per
cent of the total Finnish population at the latter date. The imbalance in numbers
between women and men will also continue to increase.
At the same time, the elderly population is getting older, in other words ““the aging
of the aging””. Mortality rates of those aged 85 years or older are decreasing faster
than in any other elderly age group. The fastest growing age group also in Finland
at present is the oldest old (85 years). The national population report has shown
that in 1950 these oldest old constituted about 0.2 % of the total population (n=9
500), by 1994 their proportion was about 1.3% (n= 64 000), and currently 2.1%
(n=114 841). According to the population projection their number will almost
double by 2030 (n=164 500 (4.1%)), and by 2040 when the Baby Boomers begin to
move into this age group, their number has been estimated to be 391 900 (7.3%)
(Official Statistics of Finland 2010).
This increase in the elderly population in western countries will have profound
consequences to the economy, social and health institutions and services. At present
those over 65 years account for one third of the health expenditures in all western
nations. Their oral health care will be a demanding challenge, too.
The use of long-term care services increases with advancing age, although the
majority of the elderly are living at home. Every fifth older adult over the age of 85
years lives in nursing homes or in service housing with 24-hour assistance, as
compared with only one percent of those 65 to 74 years of age (Official Statistics of
Finland 2012). In 2009 5.1% of all inhabitants of Helsinki aged 75 or older lived in
nursing homes and 5.8% in serving housing with 24-hour assistance. In most
countries, older women greatly outnumber older men (Official Statistics of Finland
2010). Elderly men also live with their spouses more often than elderly women. A
total of 70% of elderly men are married whereas 70% of elderly women have
become widowed in their old age. These very old ladies are often very dependent
on the support of their children and the social support of their community (Aromaa
et al. 2004).
2.2.2 Health and medication
With increasing age the prevalence of age-related changes and age-associated
diseases increase. As a consequence of aging decreases in vision, hearing, muscular
strength, bone strength, immunity, and nerve function take place. Muscle mass and
nervous system efficiency decrease, causing slower reflex times and less physical
strength. As the immune system weakens older people become more susceptible to
infections and diseases.
Arthritis and other musculoskeletal disorders, hypertension, heart disease, diabetes,
and respiratory disorders are some of the leading causes of activity limitations
among older people (Lawrence et al., 1998). In a Finnish population based study,
the Health 2000 Survey, 82% of the elderly had at least one chronic condition, and
only one quarter of persons aged 75 or over rated their health as good or fairly
good. Almost every other elderly aged 85 or older reported that their health was
poor or fairly poor (Aromaa et al. 2004). Elderly individuals born in 1910 and
living in eastern Finland had an average of 2.5 (men) and 3.0 (women) diagnosed
chronic diseases (Laukkanen et al. 1997). The prevalence of osteoarthritis and
walking difficulties grew with increasing age. The prevalence of osteoarthritis
increased especially rapidly in men aged 85 or older (Aromaa et al. 2004, KailaKangas 2007).
These conditions were also found in the present study population (the Helsinki
Aging Study). Every third subject suffered from ischemic heart disease, angina
pectoris, and hypertonia. Chronic pulmonary disease was more common in men
(27%) than in women (11%). Musculo-skeletal diseases were found in 40% of the
elderly and were the most common cause for disability for every fourth elderly
subject. Coronary disease as the main reason for disability was found in every sixth
subject (Valvanne 1992). They also had impairments in several mobility categories,
these impairments increased with advancing age (Tilvis et al. 1997).
Dementia is the main condition causing cognitive impairment among the elderly,
and its prevalence increases rapidly with increasing age. The overall prevalence of
dementia doubles for every five-year increase in age after the age of 65 (Lobo et al
2000). In a recent meta-analysis its prevalence in Europe has been estimated to be
one per cent in elderly individuals aged between 65 and 69 years, and 29% of those
aged 90 years or older (Lobo et al. 2000). In Finland, seven per cent of individuals
65 years or older are reported to have severe dementia (Sulkava et al. 1985), while
the prevalence among the 75-year-olds and older is 23% (Rahkonen et al. 2003),
and 38% in 85-year-olds and older (Polvikoski et al 2001). In the Helsinki Aging
Study the overall prevalence was 14% (Juva et al. 1993).
These changes, even though they are not directly involving oral structures, can still
affect oral health due to difficulties in maintaining sufficient level of oral hygiene
or accessing dental practices or sustaining the necessary treatment procedures.
Older people take more medications than any other age group. Several studies have
shown that the number of medications used by the elderly has been growing during
the past decades (Linjakumpu et al. 2002, Jyrkkä et al. 2006). In Finland persons
aged 65 or older using medication has increased from 75% in the 1960s (Klaukka
1988) to 90% in the early 2000s (Linjakumpu et al. 2002, Sulander et al. 2004,
Jyrkkä et al. 2006). In a recent study the number of medication used increased from
6.3 to 7.5 in a five-year follow-up among elderly aged 75 or older in eastern
Finland (Jyrkkä et al. 2006). The prevalence of polypharmacy has also increased up
to 67% in the elderly population (Linjakumpu et al. 2002, Jyrkkä et al. 2006),
although the World Health Organization (WHO) recommendation is three to four
medicines for an elderly person.
2.3. Oral health
Oral health of the elderly has been in the focus of increasing research interest in the
past decades. However, earlier studies have almost solely been targeted to the easily
available institutionalized subjects, although they are the minority of all the elderly.
The oral health of the dependent institutionalized elderly has been reported to be far
poorer than the oral health of community dwelling elderly (Mäkilä 1979, Ekelund
1984, Pajukoski et al. 1999, Peltola et al 2004, Chalmers et al. 2005). There are
only a few studies on the oral health of home living elderly in Finland. Recent
articles by Syrjälä et al (2011, 2012 a,b) and Komulainen et al (2012 a,b) have
reported findings of the population based Geriatric Multidisciplinary Strategy for
Good Care of the Elderly (GeMS) study, conducted in eastern Finland in 20042005.
2.3.1 Saliva and biofilm
Saliva is essential for the maintenance of oral health. Reduction of the flow of
saliva increases the risk for oral disease. It has also an important protective role
against caries. The complaint of a dry mouth (xerostomia) and the objective finding
of salivary gland hypofunction (SGH) are common findings in older individuals,
and can produce transient and permanent oral and systemic problems (Locker et al.
2002, Ship et al. 2002, Makhija et al. 2006). An unstimulated flow rate of 0.1 to 0.2
milliliters per minute and a stimulated flow rate of 0.7 ml/minute or less has been
agreed to indicate hyposalivation (Sreebny 1992, Navazesh 2003, Dawes 2004 and
2008).
Hyposalivation was once considered to be a normal sequela of aging. However,
age-associated changes in salivary composition and flow are minimal in healthy
older adults (Wu and Ship 1993, Närhi 1994, Ghezzi et al. 2000). Salivary flow is
decreased by systemic medications, diseases and head and neck radiotherapy.
Polypharmacy is a major problem in elderly populations, and it is probably a major
contributor to xerostomia and SHG (Ship et al. 2002, Chew et al. 2008). Sreebny
and Schwartz reported that 80 per cent of the most commonly prescribed
medications cause xerostomia, and more than 400 medications are associated with
salivary gland dysfunction as an adverse side effect (Sreebny and Schwartz 1997).
Närhi et al. found a statistically significant difference in unstimulated and
stimulated salivary flow rates between unmedicated persons and those who took
four or more prescribed medications daily in the present study population (the
Helsinki Aging Study) (Närhi et al. 1992).
Estimates of the prevalence of xerostomia in populations range from 16% to 72%
(Osterberg et al. 1984, Locker 1993a, Nederfors et al. 1997, Pajukoski et al. 1997,
Thomson et al. 1999, Bergdahl 2000, Thomson 2005). However, Ship and
colleagues estimated that approximately 30% of the elderly population suffers from
dry mouth and its consequences (Ship et al. 2002). In the present study population
46% of the subjects had noticed subjective symptoms of dry mouth. Continuous
oral dryness was reported by 12% of the subjects (Närhi 1994).
Elderly people are often more prone to have increased amount of oral biofilm for
several reasons. Reduced salivary flow, and hence fewer antimicrobial factors and
slower rate of oral clearance, create a suitable environment for the growth of
numerous microbes. Also inadequate oral hygiene permits large numbers of
bacteria to accumulate on the tooth surfaces (Närhi et al. 1992, de Baat et al. 1993).
The mutans group of streptococci (SM) have a central role in the initiation of caries
and lactobacilli (LB) contribute to tooth decay in advanced caries lesions, perhaps
in combination with other bacteria of the oral biofilm, although the microbial
communities are probably more complex than previously presumed (Krasse 1989,
Tanzer et al. 2001, Preza et al. 2008, Aas et al. 2008, Slots et al. 2011). Yeasts are
aciduric and acidogenic, and they have been associated with root caries lesions
(Beighton et al. 1991, Beighton et al. 1993). High counts of mutans streptococci
and lactobacilli are considered risk factors for root caries (Ellen et al. 1985, Preza et
al. 2008). Abundant growth of salivary microbes has been detected in the old
elderly (Emilson et al. 1988, Klock et al. 1990, Scheinin et al. 1992, Närhi et al.
1993 and 1994). High microbial counts have been also been associated with
decreased salivary flow rate (Brown et al. 1978, Närhi et al. 1994).
2.3.2 Edentulism and number of teeth
Although the oral health of the elderly has improved during the last decades in
Finland and other industrialized countries, edentulism is still prevalent among older
people. There are, however, differences between countries and between
geographical regions within countries, as well as between groups with various
background characteristics (Bourgeois et al 1998).
During the last decades the frequency of tooth loss has decreased in all age groups,
although the rate has been slower in the older age groups (Vehkalahti et al. 1991,
Petersen et al. 2004, Suominen-Taipale et al. 2008). In 1970 23% of all adult Finns
were edentulous (Markkula et al, 1973) and the number of edentulous older adults
( 65) was still growing during the next decade from 54% in 1970 to 67% in 1980
although the total prevalence remained the same (Vehkalahti et al. 1991, Ainamo
1983). In the Health 2000 Survey the prevalence of edentulism was 44% for
subjects aged 65 and older and 56% for older elderly 75+ years of age, while the
total prevalence for all adults had diminished to 13% (Suominen-Taipale et al.
2008). In a study on people aged 60-78 years in two different regions in Finland
37% of the subjects were edentulous (Haikola et al 2008).
In the other European countries the percentage of edentulousness has varied
between 14% and 78% among the elderly (Ambjörnsen 1986, Ahlqwist 1989,
Strayer, 1993, Bourgeois et al. 1998, Petersen et al. 2005b, O’’Sullivan. 2011). In
the US 29% of older adults aged 65-74 years and 40% of 75 and older were
edentulous in 1988-1994, ten years later the prevalence had declined to 24% in the
younger age group and 31% in the older age group (Dye et al. 2007). The
prevalence of edentulousness in Finland has been high compared to the other
countries. The UK has been one of the only nations where the number has been
even greater. This has changed in the latest national data from UK where the
prevalence of edentulism has diminished, although still increasing with age. Only
15% of the people aged 65-74 were edentate compared to 30% of the 75-84 year
olds and 47% of the subjects aged 85 or older. That is a clear reduction when
compared to previous survey in 1998 when 34% of subjects aged 65-74 and 56% of
subjects aged 75 and older were edentate (O’’Sullivan 2011).
The concept of shortened dental arch (SDA) was originally introduced by Käyser
(1981) and has been further documented by the Nijmegen group (Witter et al.
1999). Having 20 or more functioning teeth describes functional dentition, without
the need for prosthetic rehabilitations. In the Finnish Health 2000 Survey only 23%
of the elderly subjects aged 65 or older had 20 or more natural teeth when the WHO
Oral Health Program goal for this age group was 50% by the year 2000. In UK 40%
of dentate adults aged 75 to 84 had 21 or more natural teeth and among adults aged
85 and above only 26% had 21 or more natural teeth (O’’Sullivan 2011). The
average number of teeth for the dentate subjects aged 75 or more was 13.4 in the
Finnish Health 2000 Survey (Suominen-Taipale et al. 2008) This was an
improvement from the Mini Finland Study 20 years before, when elderly had only
11 remaining teeth (Vehkalahti et al. 1991) but less than in Göteborg, Sweden
where 70 year old adults had on average 21 teeth left and 65% had 20 teeth)
(Österberg et al. 2007).
Tooth retention is increasing among the aging population. This has led to increase
in tooth-related diseases and treatments, and this trend will continue in the future,
as there will be still more elderly teeth susceptible to oral disease (Vehkalahti, et al.
1991, Suominen-Taipale et al. 2008).
2.3.3 Caries
The dynamics and progression of dental caries is well established. In conclusion,
the prerequisites for caries development are a susceptible host, acidogenic microorganisms colonizing the tooth surface, and fermentable carbohydrates available in
the diet. Root caries has been called a condition that most concerns
gerodontologists (Mojon et al. 1995, Curzon et al. 2004), although coronal caries,
often around existing restorations, is also an important problem (Mojon et al. 1995,
Fure 2003). Caries, especially root caries, has also been found the most common
reason for tooth extractions in the elderly (Fure and Zickert 1997, Fure 2003,
Richards et al. 2005). Root surface, with its exposed cementum and dentine, is
more vulnerable than enamel to ““the acid attack”” (Stephan curve). The critical pH
for demineralization in dentine is approximately pH 6.0, whereas that for enamel is
around pH 5.5 (Featherstone 1994).
Several factors are associated with root caries development among the elderly.
More root surfaces have been exposed by gingival recession (Budtz-Jorgensen et al.
1996) due to periodontal infection or its treatment and/or vigorous tooth brushing.
Periodontal patients have had increased risk for root caries in several studies
(Ravald et al. 1986, Saotome et al. 2006, Mattila et al. 2010, Fadel et al. 2011).
Increased frequency of intake of fermentable carbohydrates (cariogenic diet)
(Steele et al. 2001), poor oral hygiene (Budtz-Jorgensen et al. 1996, Fure 2004,
Islas-Granillo et al. 2011), presence of removable denture (plaque retention)
(Mojon et al. 1995, Locker 1996, Steele et al. 2001, Nevalainen et al. 2004), and
cognitive status (Avlund et al. 2004) are all known risk factors. Patients with dry
mouth are an easily identified risk group, as they are consistently in the highest risk
category (Curzon and Preston 2004). Studies have supported the multifactorial
nature of root caries, thus attempts to develop caries prediction models have been
difficult to do accurately (Curzon and Preston 2004, Sánchez-García et al. 2011).
The different study designs, diagnostic criteria, reporting methods, indexes used in
clinical examinations and diversity of study populations make it difficult to
estimate the prevalence, and also the increment of root caries. Some of the studies
have reported only root decay while others have reported decayed and filled root
surfaces. The prevalence of root caries in Scandinavia varied between 35-80%
(Kirkegaard et al 1986, Salonen et al 1989, Fure et al. 1990, Fejerskov et al. 1991,
Heegaard et al. 2010, Morse et al. 2002) in dentate subjects aged 60 and older. The
mean number of root surface fillings ranges from 2.1 to 9.2, and the mean number
of active caries lesions varied between 0.9 and 3.5 in these studies. In the USA 49.7
percent of people 75 years or older had root caries affecting at least one tooth
(NHANES III, NCHS 1996). In a review by Fejerskov et al. (1993) the prevalence
of decayed teeth was estimated to be altogether 30-40% in Scandinavia during the
decade prior the present study. A review by Bourgeois and co-workers (Bourgeois
et al. 1998) showed that the decayed teeth (DT) value varied between 0.4-3.2 in the
65-74 year old population in Europe. In a national survey in Finland, the prevalence
of root caries was 32% in men and 27% in women over 70 years. The prevalence
increased with age and it expressed the occurrence of primary root caries only
(Vehkalahti 1987). The total DT was 2.5 in the population aged 65+, and the caries
prevalence 68% in men and 65% in women. In another national health survey
twenty years later DT was only 1.1 at the same age group and the caries prevalence
had declined to 31% in women, but the prevalence in men was still 51% in the
same age group (Suominen-Taipale et al. 2008).
In a five-year follow-up of a group of Swedes aged 55, 65 and 75 years at the
beginning of the study the increment in decayed and filled root surfaces increased
with age from 1.4 in the 60-year-olds to 2.4 and 5.5 in the 70- and 80-year-olds
(Fure et al. 1990). Fure (Fure 2003, Fure 2004) also showed that the incidence of
coronal caries decreased with age, while the incidence of root caries increased. In a
ten-year follow-up of the same group, all the 85-year olds developed new root
caries lesions, and the mean increment in DFRS (decayed and/or filled root
surfaces) increased with age from 5.3 to 8.1 and 14.3 among the 65-, 75- and 85year-olds.
2.3.4 Periodontal diseases
The two most prevalent periodontal diseases are plaque induced gingivitis (a
reversible inflammatory condition of the gingiva without loss of connective tissue
attachment) and chronic periodontitis (the presence of gingival inflammation at
sites where there has been apical migration of the epithelial attachment onto the
root surfaces accompanied by irreversible loss of connective tissue and alveolar
bone) (Armitage 1995).
Chronic periodontitis is also a multifactorial disease, where short periods of tissue
destructions are followed by longer periods of inactivity. The dental biofilm has an
important role in the onset of the disease but a number of host-related factors have
an impact on the presentation and rate of progression of the disease (Heitz-Mayfield
2005). Susceptibility to periodontal diseases varies greatly and is dependent on
host responses to pathogens (Colonna-Romano et al. 2008). Smoking (Beck et al.
1990, Tomar and Asma 2000) and diabetes mellitus (Sandberg et al. 2000,
Soskolne and Klinger 2001) appear to be the most significant factors in modifying
the host’’s response to a biofilm infection (Heitz-Mayfield 2005). However, a recent
study did not find any differences in periodontal status between diabetics and nondiabetics in an older population with a high incidence of periodontitis. The authors
suggested that periodontitis in older subjects might approach similar levels
regardless of whether they have diabetes mellitus or not (Persson et al. 2003).
Already in 1975 Holm-Pedersen (Holm-Pedersen et al. 1975) showed that in the
absence of oral hygiene gingivitis developed more rapidly in the elderly than in
young subjects. However, no difference was observed in the rate of healing (HolmPedersen et al. 1975, Lindhe et al. 1985). It was also observed that plaque formation
was more abundant among the elderly. A decreased host response to plaque
microorganisms with advancing age has been suggested to lead to increased
inflammatory reaction in the gingiva of the elderly (Page 1984). The greater
accumulation of plaque is most likely related to the increased oral surface area
available for plaque retention due to greater amount of gingival recession seen in
the older person. Abdellatif and Burt evaluated the effect of age and oral hygiene
on periodontal disease progression using data from the first National Health and
Nutrition Examination Survey (NHANES I, 1971-1974). Their conclusion was that
the effects of age on periodontal disease progression could be considered negligible
when good oral hygiene is maintained (Abdellatif et al. 1987). Thus, good oral
hygiene is especially important for the dentate elderly, but despite their best
cleaning efforts it is often inadequate (Morris et al. 2001, Artnik, et al. 2008,
Suominen-Taipale et al. 2008).
The prevalence, extent and severity of periodontal disease has been found to
increase with age, although this relationship is thought to be more related to the
cumulative periodontal breakdown over time rather than factors related to the aging
process itself (Albandar et al. 1999, Albandar 2002, Nunn 2003, Stanford et al.
2003, Albandar 2005). In a general review of periodontal diseases affecting older
adults Locker and colleagues found that advanced periodontal disease does affect a
relatively small percentage of adults and is more common in older people (Locker
et al. 1998). The results of the prevalence studies are difficult to compare due to
differences in the age of the subjects included, their general health and study
methods used. Current epidemiological evidence indicates that mild gingival
inflammation is common, many adults have mild to moderate loss of periodontal
attachment at some sites of some teeth and a substantial minority have some
advanced loss, often in relatively few sites (Locker et al. 1998, Sheiham et al.
2002). This was also confirmed in a recent study in the US (NHANES 2009-2010)
where 70.1% of older adults aged 65 and older had periodontal disease. Mild
periodontal disease was found in 5.9%, moderate in 53% and 11.2% of these
elderly had severe periodontal disease (Eke et al. 2012).
In a national study in Finland 70% of people aged 65 and older had periodontal
pockets 4 mm and 31% had pockets 6 mm (Suominen-Taipale et al 2008). In a
recent article by Syrjälä and colleagues analyzed the same subpopulation further:
28% of the participants had one to three teeth with periodontal pockets deeper than
4mm, 15% had four to six and 26% had more than seven. One to three teeth with
deep periodontal pockets ( 6 mm) were found in 23% of the participants and 8%
of the participants had more than 4 teeth with deep periodontal pockets (Syrjälä et
al. 2010),
2.3.5 Oral health behavior
Oral biofilms play a major role in the etiology of periodontal diseases, dental caries,
and other oral diseases. Self-performed and professionally administered control of
oral biofilms, and use of fluoride toothpaste are important in the prevention of these
diseases (Löe 2000, Beikler et al. 2011, Flemmig et al. 2011).
The most common way of removing plaque at home is tooth brushing (Attin et al.
2005). The recommended frequency is brushing teeth twice a day (Löe 2000),
combined with the removal of interdental plaque once a day (Axelsson 1993,
Claydon 2008). Although this concept is widely recognized, only part of the dentate
population follows these recommendations. In industrialized countries 40% to 97%
of elderly subjects report following this recommendation (Davidson et al. 1997,
Kelly et al. 2000, Morris et al. 2001, Christensen et al. 2003, Hugoson et al. 2005,
Suominen-Taipale et al. 2008). Tooth brushing twice a day has become
considerably more common among adult and elderly subjects during recent
decades. In Finland, the change has been particularly noticeable among elderly
women aged 65 and older: twice daily brushing has increased from 45% in 1980 to
69% in 2000, although the change in men was much smaller, from 32% to 39%
(Suominen-Taipale et al. 2008).
Unfortunately effective cleaning of teeth is often difficult. Older people seem to be
generally well informed of the importance of good oral and dental hygiene and their
effect on oral health, but are less aware of the poor results despite their best effort.
There are many reasons for this: diminished motivation, impaired cognition and/or
reduced sight, sense of touch, vision or manual dexterity can often result in an
inadequate level of oral hygiene (Vigild 1988, Ekelund 1989, Murtomaa et al. 1992,
Mojon et al. 1995, Nevalainen et al. 1997, Bellomo et al. 2005,). In the Health 2000
Survey 40% of elderly women and 22% of men had clean teeth, but 14% of women
and 30% of men had an abundant amount of plaque, there was no difference
between different educational groups (Suominen-Taipale et al. 2008).
Age seems to have very little direct influence on the oral health behavior
established early in life (MacEntee et al. 1993).
2.4 Socioeconomic position (SEP)
Socioeconomic position (SEP), socioeconomic status (SES), or social class can be
ascribed at birth, but is often modified by person’’s own achievements, typically
through education, occupation, or income. Social class as such cannot be measured
comprehensively. Instead, indicators are used and they are typically based on
educational attainment, income, wealth, or occupation. Although none of these
indicators is ideal, they all relate to health in diverse ways (Braveman et al. 2005,
Shavers 2007).
2.4.1 Level of education
Level of education is the most frequently used indicator. It has been called the most
basic component of SEP and it has several advantages (Adler et al. 2002). It is
comparatively simple to measure, it can be recorded for everyone regardless of age
and whether working or not, and it is less likely than occupation or income to be
influenced by health (Galobardes et al. 2006). Level of education usually remains
fairly stable after early adulthood. It has a direct effect on other SEP components as
it determines a person’’s employment status and earning potential. There are several
pathways through which education can influence health status indirectly (Braveman
et al. 2005, Shavers 2007). Education reflects general and health-related
knowledge, as well as problem solving skills. Persons with higher education are
more likely to have health-promoting behaviors and lifestyles, and they have also
better access to and use of health care services (Adler et al. 2002). More educated
people are also better able to communicate with their physicians and interact with
the health care system, and make informed choices among treatment options. The
relationship between education and oral health behavior has been reported to be
stronger than the relationship between income and oral health behavior. It has been
suggested that the differences in attitudes, knowledge and traditions are more
important than economic factors in explaining the impact of SEP. However, there
are some limitations to use of education to assess SEP: its meaning changes across
birth cohorts, and the quality of the education is not taken into consideration
(Galobardes et al. 2006).
2.4.2 Income
Income is the indicator of SEP that is directly related to material goods, resources
and conditions of an individual (Lynch 2000). Better income means better
possibilities to pay for health care, higher incomes also provide better nutrition,
housing, schooling and recreation (Adler et al. 2002). However, income is difficult
to measure in studies due to its sensitive nature. Nonresponse for income is often
higher than nonresponse rates for other variables (Turrell 2000). Especially among
the retired other aspects of wealth, as well as other sources of income and the total
income of the family, have an effect of on the amount of the money at their
disposal. Income for older adults may be a less reliable indicator of their true SEP
because income typically follows a curvilinear trajectory with age (Galobardes et
al. 2006).
2.4.3 Occupation
Occupational classifications based on skills, prestige, social influence and/or power
are commonly used for analysis linking social class and health. It reflects a person’’s
place in society, combining the effects of income and intellect (Galobardes et al.
2006). Unfortunately it is difficult to classify people who are not working but not
unemployed, such as retired people and housewives. Although previous occupation
can be used for those who are retired or a husband’’s occupation for a wife’’s to
assign SEP, this may inadequately index current social circumstances (Galobardes
et al. 2006).
2.4.4 Level of education in Finland
The average educational level has significantly improved in Finland during the past
decades. The proportion of adult population with only primary level education has
decreased from 75% in 1970 to 50% in 1990 and further to 33% in 2010.
Concomitantly, in 1970 only 9% of the adult population had the highest level of
education. In 1990 the percentage was 18% and by 2010 it has reached 24%. In
1990 11% of people aged 75 or older and living in Helsinki had received university
degrees, 17% had finished intermediate school and 72% had no degree or no
information on their education (Official Statistics of Finland 2010).
2.4.5 SEP and oral health
SEP is linked to morbidity, mortality, health behavior and also to disparities in oral
health. Despite improvements in the oral health of the overall population during the
past years, disparities remain in some population groups as classified by sex,
income, age, and race or ethnicity. Level of education was strongly and consistently
associated with nearly all indicators of health and functional capacity in the
National Health 2000 study (Aromaa et al. 2004). The association between oral
health status and educational level has been analyzed in a number of
epidemiological studies, however, only a few of them have been conducted on older
adults.
Dental care habits are established early in life and are highly influenced by the level
of education of the mother of the family (Wierzbicka et al. 2002). The relationship
between education and oral health behavior has been shown to be stronger than the
relationship between income and oral health behavior, suggesting that the
differences in attitudes, knowledge and traditions are more important than
economic factors in explaining the impact of socio-economic status (Petersen 1990,
Ronis et al. 1993).
Epidemiological studies show that edentulism is highly associated with socioeconomic status. Individuals with little or no education, of low social class or
income, and living in rural areas are more likely to be edentulous than persons of
high social class, high level of education and income and living in urban area. The
mean number of remaining teeth has also been higher among subjects with higher
SEP (Slade et al 1993, Drury et al. 1999, Palmqvist et al. 2000, Aromaa and
Koskinen 2002, Paulander et al. 2003, Petersen et al. 2005b, Suominen-Taipale et
al 2008, Haikola et al. 2008).
The prevalence of caries is higher in certain subpopulations (Pitts et al. 2011).
Although social disparities have been reported with children and adults, less
attention have been paid to older adults. Children with lower SEP experience higher
rates of dental caries and untreated disease than do their more advantaged peers
(Edelstein 2002). Adults aged 35––44 years with less than a high school education
in the US experience untreated tooth decay nearly three times that of adults with at
least some college education. Adults with lower SEP (measured by educational
attainment and family income) were 6.1 times more likely to have untreated coronal
decay and 7.2 times more likely to have untreated root caries in a large US study
(NHANES III) (Drury et al. 1999). People with less education had fewer sound and
filled teeth and more caries than had the subjects with the most education also in
the National Health 2000 study in Finland: the percentage of subjects with carious
teeth (DT>0) was clearly higher among subjects with a basic education (39%) than
those with higher education (20%) (Suominen-Taipale et al. 2008).
Various symptoms of periodontal diseases have been associated with the level of
education. Gingivitis (Oliver et al. 1998) and attachment loss have been found more
often with subjects of low level of education (Österberg et al. 1986, Oliver et al.
1991 and 1998, Locker and Leake 1993, Burt and Eklund 2005). Several studies
have used the Community Perodontal Index of Treatment Need (CPITN) to assess
periodontal disease (Corbet et al. 2001, Dye and Vargas 2002, Shah and Sundram
2003).
In the National Health 2000 study the association between prevalence of
periodontitis and educational level varied between age groups. In the younger age
group (35-44) men with a basic education more often had periodontitis than men
with a higher education (72% vs. 61%). The association was reversed the in older
age group (55-64); periodontitis was more common in the higher than the basic
education category (71% vs. 86%). The respective figures were 54% vs. 50% and
59% vs. 72% in women. Similar patterns were also seen in prevalence of the severe
form and severity of periodontitis (Suominen-Taipale et al. 2008). The older adults
(65) were further analyzed by Syrjälä and colleagues (2010). The older adults with
higher education had a high need for periodontal treatment whether measured by
gingival bleeding or probing depth.
3. HYPOTHESIS AND GENERAL AIMS
Many epidemiological studies on the elderly have been conducted on the targeted
population. The results of the restricted samples cannot be generalized to the entire
population of old people. This study was designed to evaluate the oral health of the
home-dwelling elderly taking into consideration subjects’’ background factors, state
of health and functional capacity.
This study is based on the working hypothesis that low level of education is
associated with an increasing risk of oral diseases in the elderly
The following specific aims were set:
- to study the background factors related to non-attendance in a cross sectional
population based oral health investigation of the elderly inhabitants of Helsinki
- to study the association of the level of education and salivary findings on the
occurrence and increment of caries among the elderly inhabitants of Helsinki
- to study the association of the level of education on the occurrence and increment
of tooth loss and periodontal diseases among elderly inhabitants of Helsinki
4. SUBJECTS AND METHODS
4.1 Study population
This study forms a part of a comprehensive longitudinal medical and oral health
survey, the Helsinki Aging Study (HAS). HAS is a population-based prospective
birth cohort study, which was designed to study the prognostic significance of
various clinical findings in the elderly population of Helsinki, Finland.
In January 1989, a randomized sample of prospective age cohorts (n=8035), 300
subjects in each age group, born in 1904, 1909 and 1914, were selected for the HAS
from the public register (Valvanne 1992). The sample was representative by gender
and street address. The two oldest age groups were disproportionate to their share in
the general population in order to achieve a sufficient participation rate for these
age groups. From this sample, 795 were located and 651 (82%) participated in the
medical examinations. The medical study was carried out from 1989 to 1990.
(Figure 1)
One year later, participants of the medical study were invited to the baseline clinical
oral examination. Fifty-one subjects had died between initial selection and
participation in the oral component, so 600 were eligible to participate in the oral
examination. An invitation letter introducing the oral study was sent to the subjects
and an appointment for the interview and clinical and radiological oral examination
at the Institute of Dentistry was scheduled by a phone call. If a subject was not
reached after several attempts, one reminder letter was sent, with a short
questionnaire and a pre-paid return envelope.
Subjects at the baseline
Of the 600 invited, 364 subjects (61%) (196 dentate and 168 edentulous) aged 76,
81, and 86 years, were examined in 1990-1991. Of the 364 elderly who underwent
oral examination, 293 were examined at the Dental Clinic in the Institute of
Dentistry, University of Helsinki, and 71, who were unable to come to the Institute
of Dentistry either due to poor general health or due to transportation difficulties,
were examined in their homes, in old people’’s homes, or in hospitals. The
participation rate was 69% for men and 58% for women. The 196 dentate subjects
formed the study population for Study II (Figure 1).
Non-participants at the baseline
Oral health information for 133 subjects who failed to participate in the clinical
examination was obtained by a phone interview (n=67), mail survey (n=61), and
from their own dentists (n=5). However, no information could be obtained for the
remaining 103 subjects; 3 had deceased before the dental examinations started, 50
were institutionalized or too ill to participate, 20 refused to participate and 30 could
not be located or had moved from Helsinki. Of the 364 subjects who took part in
the clinical oral examination 305 subjects, and 124 out of 133 subjects with nonclinical oral data, were home-dwelling. This information was used to evaluate the
factors related to non-response of the home-dwelling subjects in Study I (Figure 1).
Figure 1. Participants at the baseline and follow-up.
Subjects at the follow-up
Five years later all the participants of the clinical oral examination were invited to a
follow-up examination. A letter describing the follow-up study was sent to all the
available subjects (n= 250), and this was followed up by telephone to arrange
appointments for clinical examinations. If a subject could not be reached by phone,
another letter was sent and attempts were again made to contact them by phone. In
total, 113 dentate subjects were examined and 73 dentate home-dwelling subjects
with information of their level of education formed the study group in the follow-up
examination
Information on the level of education was available for 176 dentate elderly who
formed the baseline population for study III. Of these subjects 71 participated in
the follow-up examination 5 years later (Figure 2).
Figure 2. Participants in Study III.
A total of 170 dentate elderly had given information on their level of education and
were eligible for the baseline periodontal examination using CPITN. Of the 170
baseline participants 73 participated in the follow-up examinations and a further 57
subjects met the criteria for follow-up periodontal examination. The remaining 16
subjects could not be included either because they did not have at least one sextant
with two functioning teeth, required antibiotic prophylaxis or were too fragile to
take part in the clinical periodontal examination. A total of 67 subjects were
examined radiographically during both the baseline and follow-up examinations. At
the baseline 18 panoramic radiographs were supplemented with 19 intraoral
radiographs and three panoramic radiographs were repeated. Two panoramic
radiographs were supplemented with two intraoral radiographs and none were
repeated in the follow-up study. These subjects formed the study population for
study IV (Figure 3).
Figure 3. Participants in Study IV
The subjects in different age groups were pooled together for the statistical analyses
as there were no significant differences in clinical parameters between different age
groups at the baseline in Studies III and IV. For the periodontal data analysis the
elderly in the lowest education level (group 4) were merged with group 3 due to the
low number of elderly in group 4 in Study IV.
4.2 Methods
4.2.1 Medical examination and interview
Data from the medical interview and clinical examinations performed a year earlier
were available for this study. Information on subjects’’ housing conditions: at home
or in an institution, alone or with his or her own family, and furthermore, his or her
marital status, level of education, former line of work, self-perceived health level,
presence of clinically diagnosed dementia and memory disturbances, level of
hearing, and ability to move were gathered by the interview. The interview also
included the question: "Do you have any of your own teeth left?" The answers
served to describe the non-participants' dental state. The information on subjects’’
medication was also obtained from the medical examination records.
4.2.2 Questionnaire
Prior to the baseline clinical oral examination the examiners reviewed the
previously mailed and prefilled (by the subject) questionnaires together with the
patients. Any unanswered questions were filled together with the subject. A similar
protocol was also followed in the follow-up examination. This structured
questionnaire was used to obtain information on subjects’’ education, former
occupation, oral health behavior, self perceived oral health and self rated gingival
bleeding, periodontal treatment need and diet.
Level of education
The strategy developed by Helsinki City Statistical Center (Bruun 1954, Järvenpää
1964) based on the highest level of education and number of school years was used
when the subjects were divided into four educational groups.
Level of education group 1 - High school and college/university degree (more than
12 years of education)
Level of education group 2 - Intermediate education (7-11 years of education);
Level of education group 3 - Elementary school and vocational training (4-6 years
of education)
Level of education group 4 - Less than 4 years of education.
The subject’’s last occupation was used in cases where the subject could not recall
the number of school years. Groups 1 and 2 were combined to form the higher
education group and 3 and 4 were combined to form the lower education group.
Information was missing for 6 participants at the baseline.
4.2.3 Oral examination
A comprehensive oral examination carried out for each participant consisted of a
detailed saliva samples, clinical oral examination, full mouth radiological
examination, and a questionnaire. The examinations took an average of two hours
per subject. The baseline examinations were carried out at the University Dental
Clinic by four faculty members. The examiners were calibrated to eliminate interand intra-examiner errors. The clinical examination took place in a dental chair,
using a standard operating light, a dental mirror, a dental explorer, and a WHO
CPITN probe.
The follow-up clinical examination was performed by one of the original examiners
and two other faculty members. They underwent training prior to the follow-up
examinations.
Saliva was collected before the clinical examination in the morning. Unstimulated
saliva secretion rate was measured first by the draining method (Birkhed et al.
1989) and after that stimulated salivary flow rate was measured. The measuring
time was 5 minutes for both measurements and the rate was recorded as ml/min.
Due to impairment in motor or cognitive skills, saliva collections were difficult to
perform for some subjects but they were successfully completed in 167 subjects
Stimulated whole saliva was used to estimate the buffering capacity by using a
Dentobuff-strip method (Orion Diagnostica, Espoo, Finland) for 159 subjects. The
results were classified into three groups by final pH: low 4.0, intermediate = 4.5––
5.5, and high 6.0.
Salivary microbial (mutans streptococci, lactobasilli and yeast) counts were
analyzed using commercial kits and according to the manufacturers’’ instructions.
Counts of salivary mutans streptococci were determined by the Dentocult-SM strip
mutans® method. The results were categorized into four groups ranging from no
growth to 106 colony-forming units per milliliter of saliva (CFUs/ml). Dentocult
LB method® (Orion Diagnostica) was used to assess the counts of salivary
lactobacilli. Growth density was categorized into five groups ranging from no
growth to 106 CFUs/ml of saliva. Salivary yeasts were counted using the Oricult-N
method® (Orion Diagnostica). Yeast counts were placed into four subgroups: 1=no
visible growth, 2=1––20 colonies, 3 = 21––50 colonies, 4= 50 yeast colonies per one
side of the slide (Budtz-Jörgensen, 1976). Counts of SM were estimated for 156
subjects, counts of LB and yeasts were assessed for 161 subjects at the baseline.
During the clinical oral examination, the total number of remaining teeth and the
presence or absence of a removable denture (RPD) was recorded. The subjects were
classified as edentulous if no natural teeth or roots were clinically present in the
mouth. In all other cases the subject was categorized as dentate.
The presence of coronal and root-surface caries were recorded separately. For the
diagnosis of caries lesions WHO recommendations were followed and a DMFT
(Decayed Missing Filled Teeth) index was calculated (WHO 1997). Root surfaces
with gingival recession of 1 mm or more were diagnosed as exposed, and their
status was recorded using the definitions described by DePaola et al. (1989). Frank
cavitations and secondary caries lesions on these surfaces were considered as root
caries (Decayed Root Surfaces, DRS). Root surface status was recorded from 183
participants without any additional cleaning before the examination. Calibration on
19 subjects by 2 examiners resulted in high interexaminer agreement for both
exposed root surfaces (93%) and their status (89%).
Root caries increment was calculated as the difference between the final and
baseline values. Root Caries Index (RCI) was also calculated measuring root caries
experience by relating the DRS to the number of exposed surfaces (Katz 1980).
Periodontal health status was assessed using the Community Periodontal Index of
Treatment Needs (CPITN) (Ainamo et al. 1982). The sextants of dental arches were
given one of five codes. If the sextant was healthy it was given code 0, code 1 if
bleeding on probing was observed, code 2 if supra- and/or sub-gingival calculus
was present, if one or more tooth in the sextant had 4––5 mm pockets, code 3 was
used and code 4 if a pocket was 6 mm or deeper. The periodontal examination
involved recordings on all surfaces of all the teeth. Recordings were made only for
sextants containing at least two functioning natural teeth. The sextants were scored
based on the worst finding, missing sextants were recorded separately and their
number included in the data analysis. In this study, participants with the worst score
of codes 3 or 4 were classified as having periodontal disease.
The radiological examination consisted of a panoramic radiograph supplemented by
intraoral radiographs. The radiographs were exposed at the Department of Oral
Radiology, Institute of Dentistry, University of Helsinki, before the subject’’s oral
examination, following the same protocol both at baseline and follow-up.
Panoramic radiographs were taken with PM 2002 CC-radiograph equipment
(Planmeca Co, Helsinki, Finland). GTU X-ray film (3M) and a Trimax T-16
intensifying screen were used. The quality of the radiographs was evaluated
immediately after processing and intraoral radiographs from poorly visible areas in
the panoramic radiograph were taken with a Siemens Heliodent 70 dental
radiographic unit and Kodak Ultra-speed X-ray film. Automatic processing was
used to develop the films. Two faculty members of the Department of Dental
Radiology studied the radiographs under standardized conditions using Mattson’’s
binoculars and a viewing light of adjustable brightness when necessary. The
presence of calculus and overhanging restorations, number of furcation lesions and
number of teeth with vertical infrabony pockets and horizontal bone loss were also
recorded. The extent of horizontal bone loss and the depth of infrabony pockets
were observed at the site where they were most advanced in relation to the roots of
the teeth.
4.3 Statistical analysis
Statistical analyses were performed with the statistical software program SPSS©
(Version 15.0), the Glim3 computer program and Stat View for Windows program.
In general, non-parametric tests were used for the evaluation of continuous
variables, which followed normal distribution. Parametric tests were used for the
data that were not normally distributed. Associations between two distributions
were evaluated with Mann-Whitney U-test. The unpaired t-test was used to evaluate
differences in mean values between two groups, whereas the paired t-test was used
to study the differences in mean values between baseline and follow-up studies.
ANOVA with appropriate post hoc evaluation was used to study the differences
among several means. The level of significance was set to 95%. Non-parametric
tests were used for the data that was not normally distributed. The Mann-Whitney
U-test was used to compare two population means. Multivariable models were
fitted to study the significance of several variables while controlling the rest of the
factors. More detailed descriptions of the statistical analyses are given in the
original publications.
4.4 Ethical aspects
Informed consent was obtained form all subjects prior to the study. The ethical
committees of the Institute of Dentistry, University of Helsinki and the Helsinki
University Central Hospital approved the study.
5. RESULTS
5.1 Attendance (Study I)
The mean age for all home-dwelling subjects in the oral sample was 80.0 years. The
mean age for the clinically examined ones was 79.4 years, 80.7 years for those with
non-clinical oral data only, and 81.8 years for those with no oral data at the
baseline. The majority of the participants (68%) were female both at the baseline
and follow-up, and more than half of the participants belonged to the youngest age
group (54% at the baseline and 65% at the follow-up).
Age was one of the strongest factors affecting participation rate in the clinical oral
examination at the baseline. The youngest age group was over-represented: 75% of
the 76-year-olds participated in the oral examination but only 53% of subjects aged
81 or 86 years (P<0.001). Living close or within easy reach by public transportation
of the Institute of Dentistry also strongly affected the participation rate. Subjects
living in the same district as the Institute (75%) attended more often compared to
subjects living further away (60%). Men (72%) participated more frequently than
women, (60%) as did subjects with at least some of their own teeth (79% vs. 63%,
p<0.001) and feeling healthy (67% vs. 52%, p<0.01). The subject’’s functional
capacity and health status were assessed in the clinical medical examinations. Good
ability to move and showing no signs of dementia favorably affected the
participation rate: 66% of the subjects who could move independently participated
compared to 46% of subjects who needed assistance getting to the Institute
(p<0.001) and 65% of subjects showing no signs of dementia vs. 48% subjects with
any signs of dementia (P<0.05). The home-dwelling subjects' educational level did
not affect their participation in clinical dental examinations. The odds ratios for not
participating in the clinical oral examination ranged from 1.7 to 2.7. More details
on the factors affecting the participation rate are presented in Table 1.
Table 1. Participation in the baseline clinical oral examination according to home-dwelling
subjects’’ background factors, oral status, and medical findings.
___________________________________________________________________
Background
Number of
% of subjects
Odds ratio2 for
1
factor
subjects
partcipating
not participating
Age (years)
76
81
86
Gender
Male
Female
Distance to the Institute
Close
Far
Level of education
High school
Elementary school
Data missing
Self perceived general health
Healthy
Ill
Data missing
Dentulousness
Dentate
Edentulous
Data missing
Ability to move
Good/independently
Poor/assisted
Data missing
Dementia
No
Yes
OR
95% CI
209
161
114
75***
55
53
2.5
2.7
1.6-3.9
1.7-4.4
123
361
72*
60
1.7
1.1-2.6
101
383
75***
60
2.0
1.2-3.4
125
344
15
66NS
61
339
126
19
67**
52
1.9
1.4-3.3
221
208
55
79***
63
2.2
1.4-3.3
390
79
15
66***
46
2.3
1.4-3.8
422
62
65**
48
2.0
1.2-3.4
1
Statistical evaluation by chi squared test: *** P<0.001; **P<0.01; *P<0.05;
NSP>0.05
2
Compared with the first category of each factor. Odds ratio estimated only for
factors showing some statistical significance in participation rates by category.
Multicausal analysis revealed that the strongest factors explaining nonparticipation, after controlling for other factors, were the home-dwelling subjects'
old age (OR=3.6), deteriorated ability to move (OR=5.3), clinically diagnosed
symptoms of dementia (0R=4.1), and edentulousness (OR=2.5). Fitting the data
resulted in an exceptionally good fit, and 93% of the variance in the variables
included in this analysis was explained by the fitted model.
5.2. Loss of teeth (Study IV)
Influence of the level of education at baseline
The dentate participants in high education groups 1 and 2 had significantly more
teeth than participants in low education groups 3 and 4 (23.5 ± 2.8 and 17.8 ± 6.9
vs. 12.1 ± 7.6; p<0.05). Almost half of the dentate subjects in the high education
group (45%) had 20 or more remaining natural teeth in contrast to 18% of subjects
in the low education group.
The dentate subjects in the lower education group wore significantly more often
removable dentures than subjects in the high education group (76% vs. 51%; p =
0.001). When looking at both the dentate and edentulous participants, this
difference was found only in women (41% vs. 18%; p<0.05).
Influence of level of education at follow-up
The mean number of teeth in dentate subjects decreased during the follow-up in
both high (from 19.6 to 18.5, p=0.001) and low (from 12.8 to 11.9, p<0.0001)
education groups. The significant differences in number of teeth in different
education groups did not change during the follow-up. In the follow-up 50% of the
dentate subjects in the high education group and 29% of the low education group
had 20 or more natural teeth. The majority (52%) of subjects in the low educational
group had less than ten teeth (p<0.0001).
The decrease in the mean number of teeth during the follow-up was found only in
men belonging to the low education group when we looked at the whole study
population (both dentate and edentulous subjects) (from 9.7±9.9 to 8.9±10.4)
(unpublished data, Table 2). In all other groups there was an increase in the mean
number of teeth, the only significant change was found in women belonging to the
high education group (from 7.7±9.1 to 12.5±9.0, p<0.01).
A similar pattern was observed with participants who had more than 20 teeth. The
percentage of women with functional dentition in high education group increased
from 15% to 29%, p<0.05 during the follow-up, in other groups it remained stable
(unpublished data, Table 2).
Table 2. Number of the elderly men and women with low and high level of education at
baseline (n=332) and at five-year follow-up (n=104) study according to number of teeth.
__________________________________________________________________
Women
Men
Level of education
Low
High
Low
High
Baseline (322)
(63)
(29)
(160)
(80)
Number of teeth
9.7±9.9
6.2±9.0
6.4±8.5
7.7±9.1
<20 teeth
76%
86%
87%
85%
20 teeth
24%
14%
13%
15%
Follow-up (104)
(26)
(6)
(48)
(24)
Number of teeth
8.9±10.4 8.5±10.8
6.7±8.5
<20 teeth
75%
83%
83%
71%
20 teeth
25%
17%
17%
29%
12.5±9.0*
__________________________________________________________________
*p<0.01, Fisher’’s PLSD.
5.3. Caries (Studies II and III)
Occurrence of caries
At the baseline 71% of the men and 48% of the women (p=0.02) had decayed teeth
(DT). The mean number of DT was 2.8 for men and 1.5 for women (unpublished
data).
As the number of teeth decreased in the 5-year follow-up, a significant increase in
DMFT (1.164, p < 0.0001) was consequently found. The level of education was not
associated with the increment in DMFT, but the increment in DMFT was associated
with frequency of brushing (p<0.05).
There was a positive correlation between female gender and DMFT, but no other
factors (level of education, gender, frequency of brushing and eating) fitted the
models correlated with the increments in DMFT. The predictive values of the
models were poor.
Occurrence of root caries
Baseline
Root caries was found more often in men (52%) than in women (35%) (p< 0.05) at
the baseline. The mean number of DRS (decayed root surfaces) (2.0 vs. 1.0; p
<0.01) and DFRS (decayed and/or filled root surfaces) (6.6 vs. 3.8; p <0.01) was
significantly higher in men than in women. Root caries was also found more in the
older (81- and 86-years old) age groups (65%) than among the youngest (76-years
old) age group (40%) (p=0.06) and the mean number of DRS was also higher in the
oldest age group.
Follow-up
A significant increase was found in RCI (0.081, p < 0.0001) but not in DRS (-0403,
ns.) in the 5-year follow-up.
Association between level of education and occurrence and increment of root
caries
Although the number of teeth and root surfaces (p<0.05) at risk were higher in the
high education groups, no significant differences were found in the number of DRS
(0.6 ± 1.3) and RCI (0.13 ± 0.18) for different education groups.
The level of education was not associated with the increment in RCI during the
follow-up.
None of the measured factors (level of education, gender, frequency of brushing
and eating) fitted in the model correlated with the increments in DRS or RCI. The
predictive values of the models in general were poor.
Association between root caries and salivary findings
Both unstimulated and stimulated salivary flow rates were lower in women than in
men: 0.1 ml/min vs. 0.2 ml/min, and 1.3 ml/min and 1.7 ml/min, respectively
(p<0.01).
The correlation analysis showed that DRS and DFRS correlated (r = 0.16 to 0.26)
with salivary microbial counts (SM, LB and yeasts). High microbial counts were
also the only analyzed values found to increase the risk for root caries, the odds
ratios were 2.0, 95% CI 1.0––3.9 for SM; OR 3.5, 95% CI 1.8––6.7 for LB and OR
2.9, 95% CI 1.5––5.6 for yeasts. Decayed root surfaces were recorded in 46 to 57%
of the subjects with high SM, LB, or yeast counts. There was no correlation
between DRS and the subjects’’ salivary flow rates.
After evaluating by a log-linear model high SM and yeast counts together with
male gender were associated with a greater occurrence of root caries (Table 3).
Table 3. Association between DRS and subjects’’ gender, age and salivary findings at the
baseline: a log-linear model.
Interaction with presence of DRS
Estimate
SE
OR1
95% CI
Gender (male)
Old age (81-86 years)
Flow rate (low)
SM count (high)
LB count (high)
Gender (male) and SM (high)
0.25
0.59
1.40
1.05*
0.94
-2.52**
0.80
0.51
0.93
0.50
0.53
0.98
1.3
1.8
4.0
2.8
2.6
0.1
0.3-6.2
0.7-4.9
0.7-24.
1.1-7.6
0-0-7.2
0.0-0.5
*P<0.05; **p<0.01.
General mean = -1.82; SE=0.48; deviance=25.19; d.f.=3.16; coefficient of
determination=0.54
1
Compared with 76-year-old women with ideal salivary findings (stimulated saliva
flow rate 0.7 ml/min, and SM and LB counts <106 CFUs/ml).
Influence of the level of education on salivary findings (unpublished data)
At baseline men with a high level of education had more often high counts of
mutans streptococci that did men with low level of education (p<0.05). In the
follow-up this difference did not occur. No other associations between level of
education and salivary factors were found (unpublished data).
Influence of the level of education on tooth brushing
Most of the elderly in the higher education groups (75%) reported brushing their
teeth more than once a day, when the elderly in the lowest level of education groups
(68%) brushed only once a day. Fluoride toothpaste was used by 72% of the
subjects, no association with level of education or gender was found.
5.4. Periodontal diseases (Study IV)
The influence of level of education on periodontal status at the baseline
Periodontal treatment need was measured at the sextant level. There was a mean of
3.6 sextants present per person at baseline. The elder individuals in the high
education groups had more healthy (CPI 0) sextants (0.6 ± 1.6 in group 1 and
0.8±1.7 in group 2) than those in the low education group 3&4 (0.2 ± 1.0) (p<0.05).
The elderly individuals in the highest education group also had the highest number
of sextants with deepened periodontal pockets (CPI 3 and 4) (1.7 ± 2.1 in group 1
and 1.1±1.7 in group 2 vs. 1.0 ± 1.4 in groups 3&4, p < 0.05). Subjects in
intermediate education group had the best periodontal status when compared to the
other groups. They had the highest number of healthy sextants (0.8 ± 1.7) and one
of the lowest numbers of sextants with periodontal disease (1.1 ± 1.7).
Radiographic examination
Furcation lesions (1.1±1.5 vs. 0.4±0.7; p<0.01) and teeth with restoration overhangs
(2.9±2.7 vs. 0.9±1.5; p<0.0001) were found significantly more frequently in the
higher education groups than the lower education groups at the baseline. No
difference was found in relation to mean number of teeth with calculus and or bone
loss between the high and low groups on radiographic examination.
Periodontal status and self-perceived need for treatment at baseline
The elderly subjects in our study were not fully aware of their periodontal status.
Only 30% of the subjects with highest CPI score 3-4 considered themselves in need
of periodontal treatment when 15% of subjects with highest CPI score 1-2 believed
they needed periodontal treatment.
Gingival bleeding was reported more often as the CPI score increased, however
only half of the subjects have noticed gingival bleeding even when the highest CPI
score was 4. No difference in occurrence of reported gingival bleeding was found
between the different educational group levels.
Periodontal status at the follow-up
The periodontal status remained relatively stable during the 5-year follow-up
period. There was an increase in mean number of healthy sextants from 1.08 ± 1.8
to 1.48±2.2 in the high education group but a decrease from 0.3±1.2 to 02.± 0.8 in
the low education group at the follow-up. However, the differences were not
statistically significant. There was also a significant decrease in the mean number
of sextants with deepened periodontal pockets in both groups (1.08 ± 1.6 to 0.5 ±
1.0, p=0.05 in high group and 1.13±1.7 to 0.6±1.0, p=0.05 in low group). The
radiographical status showed only minor changes during the five-year follow-up
and seemed to stay relatively stable.
6. DISCUSSION
The purpose of the present study was to investigate whether level of education had
an influence on oral health, especially the prevalence and increment of tooth loss,
caries and periodontitis of old elderly home dwelling inhabitants of Helsinki, and
further, to investigate the factors related to their non-attendance in a comprehensive
oral study. The study consisted of a questionnaire and clinical oral and radiographic
examinations at baseline and at the 5-year follow-up. The elderly in Helsinki had
high levels of root caries and periodontal treatment need regardless of their level of
education. However, older persons with more education had retained more teeth
and had a higher need for periodontal treatment. During the five-year follow-up the
number of teeth decreased, RCI increased and periodontal treatment need remained
stable and the differences between educational groups remained the same.
6.1. Subjects
This study group was derived from the Helsinki Aging Study (HAS), in which a
representative sample of the general home-dwelling elderly population of Helsinki
City had had a comprehensive medical examination, laboratory tests and interviews
(Valvanne 1992). A year later the participants were invited to the HAS Oral study.
The study design for the follow-up was longitudinal, with the same subjects
examined first at the baseline and then again at the follow-up five years later. This
study was intended to last ten years but due to the erosion of this very elderly study
population it was not possible to give the subjects clinical examinations. The
medical team, however, collected data on morbidity from the Death Register of
Finland ten years after the commencement of HAS.
In epidemiological studies participation rates of around 60% to 80% have been
considered reasonable goals, although these goals have rarely been reached in
studies on elderly individuals living independently (Hunt et al. 1985, Locker et al.
1990, Locker 2000, Heegaard et al. 2010). Response rates are lower when the
survey requires participants to physically attend a clinical examination (Locker et
al. 1990, Locker 2000, Matthews et al 2012). We tried to enhance the participation
rates and obtain some information of the non-attendees in several recommended
response-enhancing strategies: multiple callbacks, offering help to arrange
transportation, offering a written health status and copy of the radiographs, offering
an incentive, and offering the refusals a possibility for an abbreviated clinical
examination at their homes or finishing the survey on the phone (Locker 2000). We
also had data from medical examinations and interview available to gather
information on the non-respondents. The baseline data was used to compare
participants and non-participants in the follow-up study.
The participation rate for the present study at the baseline was high (63%)
especially considering the advanced age of the home dwelling subjects in the
sample and their physical limitations.
Non-response bias is a concern in all surveys, despite the response rate, and it
should not be ruled out until an analysis of non-response has been undertaken. Age
was one of the strongest factors affecting the participation rate at the baseline. The
majority (51%) of the participants belonged to the youngest age group (76 years)
and were female (71%), although the men were more willing to participate than the
women, 72% and 60% respectively. This was also reported by a Swedish study on
70-year-olds (Eriksson et al 1987) but was different from the numbers in a paper on
70-year-olds in New England (Joshi et al. 1994). The gender ratio was similar to the
sample population but the youngest age group was over-represented: 75% of the
76-year-olds participated in the dental examination but only 53% of subjects aged
81 or 86 years. This is in line with other studies (Locker et al. 1991, Heegaard et al.
2010).
Problems related to mobility, dependency on help and general tiredness has shown
to limit utilization of dental services (Avlund et al. 2001). Also in this study
subjects with a good ability to move, in relatively good physical condition or
having no signs of dementia tended to participate in the clinical dental examinations
more frequently than did their counterparts. These findings are in line with earlier
studies in Scandinavia: on elderly men by Janzon and coworkers (Janzon et al.
1986) and on 70-year-olds by Eriksson and coworkers (Eriksson et al. 1987). More
than half of the subjects in the oldest age group in this study population had
difficulties walking for over 0.5 km outdoors and walking up more than 10 stairs,
this compares to onethird of the persons in the youngest age group who reported
these difficulties (Tilvis et al. 1997).
Also the dental status of our subjects had an influence on their participation rates in
favor of the dentate elderly: there were 79% of them but only 63% of the
edentulous were clinically examined. A similar finding was reported in a 3-year
follow-up study on adults aged 50 years or older in Ontario, Canada (Payne et al.
1991). Some studies with quite low participation rates (Eriksson et al. 1987, Locker
1990) reported that the responders had more oral or dental diseases than did their
counterparts. A recent study on Danish elderly individuals found that old age, poor
health and being edentulous were the most common reasons for nonparticipating
(Heegaard et al. 2010).
In our study the level of education did not have an effect on participation rate,
which is in contrast to other studies (Heegaard et al. 2010, Matthews et al. 2011)
where the participants had higher levels of education.
In the Danish study the results could not be generalized to other populations as the
oral diseases were thought to be potentially underestimated in the study cohort
(Heegaard et al. 2010). The underestimation of oral disease has also been found to
be a source of potential non-response bias in another study (Matthews et al. 2011)
although Locker et al (1990) showed that the differences between crude and
adjusted estimates of treatment need were not substantial. The potential for bias
must be taken into account in reporting prevalence of edentulousness and number
of teeth, and most probably also the prevalence of other dental diseases as these
figures could be optimistic also in this present study population. However, this kind
of skewing has much less influence on studies that are concerned with associations
between risk factors and oral diseases
A high attrition rate is common in population based follow-up studies, particularly
in the very old, and it was also evident in this study. At the time of the five-year
follow-up one third of the baseline population were deceased, which was in
accordance with the mortality rate of the general Finnish population of that age
(Official Statistics of Finland 2010). The participation rate in the follow-up was
relatively low: only 40% of the original study group resulting in only small
numbers of people with teeth being available for the analysis. The participants in
the follow-up study enjoyed both better general health and oral health than the
dropouts. The subjects in this study represent the survivors of their age groups and
formed a very special study group as not many studies have been undertaken on the
community-dwelling older people aged 75+ years earlier in Finland.
6.2 Methods
The level of education was assessed based on the information from the
questionnaire. The SEP gradient we chose to use was the level of education of the
individual. Actual income would have been difficult to define for this group as
pensioners often have various sources of income and wealth. Also, the majority of
the participants were women and a large proportion of these women had been
housewives at least for part of their lives. The total family income and wealth
would have had an effect on the amount of money at their disposal. This income
may not have bearing on social attitudes to oral health for these women. Level of
education can be defined on the same grounds for both the economically active and
inactive population and it is fairly stable throughout adult life. Education has
probably larger effect than income and occupation to the production of adult health
(Elo et al. 1996). Further, education is a powerful determinant of health throughout
life, but to a greater extent because of its impact on behaviors rather than its
association with resources (Cutler 2008).
The information on subjects’’ medication was obtained from a questionnaire and
later confirmed by physicians who had performed the medical examinations earlier.
As a reduced salivary flow rate have been reported earlier for the present study
population taking more than three different medications daily (Närhi et al. 1992),
we used the same classification instead of categorizing medicines into groups based
on the possible xerostomic side effect. In the previous report medicines were
further divided into 11 subgroups based on their possible xerostomic effects (Närhi
et al.1992).
Four faculty members at the Institute of Dentistry carried out the clinical oral and
radiological examinations. The 14% of the subjects who were too ill or too tired to
come to the Institute of Dentistry were examined in their homes or hospitals. This
figure is in accordance with a recent paper by Fairhall et al (2009) where he studied
the differences between home- and clinic-based dental examinations for older
people. Calibration on 19 subjects by examiners resulted in high interexaminer
agreement for both exposed root surfaces (93%) and their status (89%). The
examiners also had every opportunity to discuss with each other about criteria,
diagnoses and possible problems to improve reliability as the examinations at the
Institute of Dentistry were carried out simultaneously and the home examinations
by pairs of researchers. The comprehensive, but exhausting, oral, radiological and
microbiological examinations and interviews took on average two hours to
complete. Considering the age of the participants and the chair side time reserved
for the clinical examination we selected to use the Community Periodontal Index
for Treatment Need (CPITN) index (Ainamo et al. 1982). That was also the reason
to use panoramic radiograph supplemented with some periapical radiographs,
which has many advantages: a small dose of radiation, low price, speed, and
convenience (Molander et al. 1995).
CPITN recording has been widely used worldwide, since it has been recommended
by the WHO for the epidemiologic recording of periodontal diseases (WHO 1997,
Pilot et al, 1987, Petersen et al 2005a) to increase international uniformity. The
major advantages of the CPITN are its simplicity, speed, reproducibility, and
international uniformity (Cutress et al. 1987). CPITN also shows the prevalence of
healthy sextants as well as the presence of actual treatment need as sextants with
deep pockets. Probing depth does not provide an accurate measure of periodontal
tissue destruction accumulated over a person’’s lifetime as reliably as assessments of
bone loss or clinical attachment loss (CAL) measured from the cemento-enamel
junction (CEJ) to the bottom of the pocket, this has been considered a limitation of
CPI (Pilot et al. 1987, Baelum et al. 1996, Papapanou 1999). Much of the
attachment loss in an elderly has been said to the result of gingival recession
(Holm-Pedersen et al. 2006). Gingival retraction with no infection can be a result of
the cumulative effect of occlusion, vigorous tooth brushing and/or past periodontal
or restorative treatment. There are cases when probing depth can be misleading as
an indicator of active periodontal disease. Increased probing depth can also be a
result of periodontal disease and its successful treatment and not necessarily in need
of further treatment or well-treated periodontitis with almost total loss of alveolar
bone may give a CPITN score of 0 (no infection, no calculus, no bleeding on
probing). In this study bone loss was assessed with a radiological examination.
In the CPITN system the highest score of an individual is derived from the highest
score of one or more sextants. It is possible that an individual may have an
increased probing depth in only a few sites and thus only one sextant with that
score, this might lead to overestimation of periodontal disease, although CPITN has
also been criticized to underestimate the prevalence and severity of periodontal
attachment loss among elderly adults (Baelum et al. 1995).
6.3 Tooth loss and caries
The prevalence and severity of dental caries is dependent upon the number of teeth
present in the mouth. Tooth retention has increased during the past decades in the
elderly population and this trend will still continue in the future. As the number of
teeth increases, the number of susceptible tooth surfaces also increases and this will
have an important impact on the oral disease burden and the anticipated need for
dental treatments in the coming years. Being completely edentulous and having a
lower number of remaining teeth have been associated with lower level of
education in several studies (Vehkalahti et al. 1991, Drury et al. 1999, Avlund et al.
2003, Petersen et al. 2004, Suominen-Taipale et al. 2008). The dentate participants
in our study had significantly higher mean number of teeth in the higher education
groups than in the lower education groups (22.6 and 17.8 vs. 11.3 and 9.7), and
consequently root surfaces at risk. In a Danish study on 75 year olds the figures
were 16.6 in the high education group and 13.3 in the low education group
(Paulander et al. 2003). Our elderly in higher education groups had more retained
teeth than the elderly aged 75 and older in the National Health 2000 Survey where
elderly individuals in high and intermediate education groups had 18.5 and 12.8
mean number of teeth respectively, but less in the basic education group where the
mean number of teeth was 12.2 (Suominen-Taipale et al. 2008). Our more educated
dentate elderly practically reached the WHO goal of every other elderly should
have at least 20 remaining teeth. At the baseline 45% and at the follow-up 50% of
them had more than 20 teeth. Only 18% of the dentate elderly in the lower
education group at the baseline and less than one fifth of the total study population
had a functional dentition. The disparity between different levels of education
seemed to be larger in Helsinki. This can be the consequence of treatment decisions
made earlier in life. The healthy elderly individuals have not received any
reimbursement for the dental treatments from the national health institution or been
entitled to access the public dental health care system in Helsinki until recently.
Therefore, the cost of the treatment, lack of time and attitudes has had an influence
on their decisions to opt for extractions rather than conservative treatment as
treatment choice. The situation has improved in Finland since our study; in a recent
national Health 2011 survey almost half of the population aged 65+ reached this
goal (Koskinen et al. 2012).
The number of teeth decreased in the five-year follow-up in all education groups,
while the significant differences between groups remained. After the examination at
the baseline the dentate participants were given a copy of their panoramic
radiograph and explained their treatment needs. Most probably the teeth with poor
prognosis were extracted. Another explanation can be their deteriorating general
health and ability to maintain oral hygiene resulting in loss of teeth due to caries or
periodontal disease.
There was a gender-related difference in the prevalence of root caries in our study
population, the mean numbers for DRS, DFRS and number of teeth with root caries
were higher in men than in women. Similar disparities have been reported in other
epidemiological studies (Vehkalahti et al. 1983, Papas et al. 1992, Fejerskov et al.
1993). However, no significant differences were found between education groups
at the baseline in DRS, RCI or DMFT, although in NHANES III persons in the
lower SES categories were 7.2 times more likely to have untreated root caries when
compared to higher categories (Drury et al. 1999) and in the Health 2000 Survey
the elderly aged 65 and older had more carious teeth in the basic education than in
the high education group (Suominen-Taipale et al. 2008). The prevalence of root
caries has been shown to increase with age (Fure 2004) this was also seen among
the present study population.
High counts of SM were found more often in men with a high level of education at
the base line, this was the only salivary finding that had an association with level of
education. High counts of salivary microbes were correlated with DRS and DFRS,
however they were poor predictors for caries in this population. Although past root
caries experience has been shown to have a high predictive value for root caries
increment (Scheinin et al. 1992, 1994) it was not fitted into our log-linear analysis.
To use the number of filled surfaces in cross-sectional studies may be slightly
misleading as some of the fillings were not made to restore root caries lesions
(DePaola et al 1989). The number of daily medicines or salivary flow rates were
not correlated with the presence of root caries. This was an interesting finding as
persons with dry mouth are consistently in the high risk category of root caries
(Kitamura et al.1986, Curzon et al. 2004). Our finding was however confirmed by
Beighton and colleagues (Beighton et al. 1991) who reported higher root caries
prevalence in men although salivary flow rate was significantly lower in women.
During the five year follow-up a significant increase was found in RCI. This
increase in RCI was also confirmed in elderly populations in Germany (Splieth et
al. 2004), and increase in DRS in Sweden (Fure 2003), Denmark (Palmqvist et al.
2000) and China (Luan et al. 2000). The increase in RCI was not associated with
the level of education or with tooth brushing or eating frequencies
The findings in this study emphasize the multifactorial nature of caries, and how
difficult it is to assess the risk factors of root caries for a subject. No single risk
factor has been identified in the literature suggesting the need for assessment for
both behavioral and socioenvironmental factors in oral diseases. The high
prevalence of root caries and increase in RCI and DMFT among the very old
subjects in this study indicate that causal treatment of the caries disease has not
been successful in this population, and these people are indeed a caries active
group. This puts even stronger emphasis on the well known and effective means for
preventive and non-operative treatment strategies to treat caries disease
successfully (Caries, Current Care 2009). There will be a growing need for caries
prevention measures in the increasing population of elderly people who will retain
even more teeth into old age in the future.
6.4 Periodontal diseases
The elderly population in our study reported a high prevalence of periodontal
disease regardless of their level of education. Treatment need was higher among the
well-educated elderly, both clinically and radiographically detected periodontal
lesions were more common with this group. This is in disagreement with some of
the other investigations where periodontitis was more common among elderly
individuals with lower levels of education (Beck et al. 1995, Kelly et al. 2000,
Corbet et al. 2001, Borrell et al. 2004, Krustrup 2006, Borges-Yáñez et al. 2006).
In a national Mini-Finland study severe tissue destruction was found more often in
subjects with low levels of education, although differences were small between
educational groups, no clear association was found with level of income
(Vehkalahti et al. 1991). This difference can be related to the differences in study
population. Our study population was older, and our elderly with low level of
education were more often completely edentulous or were frequently using
removable partial dentures. Only 18% of the subjects with low level of education
had 20 or more teeth, which is far below the WHO goal for the year 2000, stating
that at least 50% of the elderly should have a minimum of 20 teeth (WHO 1982).
Of the subjects in the high education group 45% had 20+ teeth. No assessment was
made for the reasons of their tooth loss, but apparently many periodontically
involved teeth have been extracted. This is the most probably the reason why our
study failed to show that the periodontal health status is related to level of
education. Disease experience in our study is based on observation of teeth that are
““healthy survivors””. Consequently, lifetime disease experience is likely to be
underestimated. However, tooth loss has no effect on measures of treatment need or
current disease activity. This situation is most likely going to change in the future
as number of teeth are increasing in all social classes in Finland.
Our findings were confirmed by recent studies in Finland and Sweden. Syrjälä and
coworkers (Syrjälä et al. 2010) investigated elderly individuals aged 65 and older in
Finland as part of the Health 2000 Survey. The prevalence and extent of periodontal
disease was highest among the elderly with a higher level of education, as was the
situation also in our study population. Periodontal diseases were found to be more
common than in our study group and high number of teeth with deepened
periodontal pockets was associated with being very old (80 years or older). The
KEOHS project has evaluated the oral health status of generally healthy,
community-dwelling persons aged 80 years and over living in the Swedish capital
(Holm-Pedersen et al. 2006). Over half of the study population was reported to
have severe periodontits (SP), and persons with higher levels of education were
more likely to have SP (crude OR 2.0, 95% CI 0.9, 4.7). The periodontal treatment
need has remained high in Finland after our study. In Health 2011 survey 71% of
the women and 86% of men aged 75 years or older were reported to have at least
one tooth with a 4 mm or deeper probing depth (Koskinen et al. 2012).
The radiological findings confirmed the need for periodontal treatment in this group
of elderly individuals. However, no difference between different education levels
were found in vertical bone infrabony pockets or mean number of teeth with
calculus. Although furcation lesions and teeth with restoration overhangs were
found significantly more often in higher education groups than lower education
groups at the baseline, this finding was associated with higher number of retained
teeth, especially molars, with these subject. The baseline radiographic periodontal
findings including bone loss have been reported elsewhere (Soikkonen et al. 1998).
The radiological study, like the clinical study, concluded that periodontal disease
was highly prevalent in this elderly population. These results showed similar levels
of periodontitis progression also in men and women in all the three age groups.
Various factors could explain the influence of level of education in periodontal
status. Oral health behavior has been reported to have a stronger relationship with
education than with income (Ronis et al. 1993). It has been proposed that
educational level is related to distinct patterns of behavior and knowledge and
health attitudes exist within certain social groups (Petersen 1990) suggesting that
the differences in attitudes, knowledge and traditions that are linked to educational
level are more important than economic factors in explaining the impact of socioeconomic status. Smoking is well known risk factor for periodontal disease, and
people with lower education have a higher smoking frequency than people with
higher education (Tillgren et al 1996). In a review (Klinge et al. 2005) found that
smoking can be a confounding variable to socio-economic variables in studies
where smoking as a factor was not included. In studies where the smoking factor
has not been analyzed, the effect of socio-economic factors on periodontal diseases
could be masked. In our study group only eight 8 (4%) dentate subjects were
current smokers and 28 (18%) were former smokers, this result was in line with a
prospective study where the effect of educational level on periodontal disease
progression was found to be significant in never smokers (Paulander et al. 2003).
In our study the elderly were not aware of their periodontal treatment need despite
their level of education, although they became increasingly aware of their treatment
need with worsening periodontal condition. Only half of the subjects noticed
gingival bleeding even though their highest CPITN score was 4, and only 30% of
the elderly thought they needed periodontal treatment although they had high
CPITN scores of 3 and 4. There are many reasons for this low subjective treatment
need. The elderly person’’s ability to notice bleeding can be diminished due to poor
vision and their oral hygiene efforts too gentle and ineffective to produce any
bleeding during tooth brushing due to weakened motor skills. Thus in our study,
most of the elderly even with a poor periodontal condition considered themselves
healthy with no need for periodontal treatment. Correlations between clinical
examination by a dentist and patient’’s subjective need of treatment is often weak
(Locker et al. 1994), this was also shown in our study. People with higher education
have often better knowledge of oral diseases and they have also better access to and
use of health care services, unfortunately this did not show in this study. It is
important to increase elderly individuals’’ awareness of oral diseases through health
education, and for dentists and oral hygienists to offer elderly patients professional
guidance and support.
6.5 Tooth brushing practices
Oral hygiene is one of the factors associated with progression and control of carious
lesions and gingivitis. A little over two thirds of the elderly in this study followed
the common recommendation and brushed their teeth twice a day. However, only
42% of the elderly with the lowest level education reported brushing more than
once a day. This is a higher rate than in other Finnish studies (Vehkalahti et al.
1991, Suominen-Taipale et al. 2008) but similar rate than reported in Denmark,
UK, USA and Canada (Payne and Locker 1992, Davidson et al. 1997, Kelly et al.
2000, Christensen et al. 2003) and in a recent Health 2011 survey where 47% of the
men and 68% of men aged 75 and older reported brushing twice daily (Koskinen et
al. 2012). Higher social status has been shown to be associated with higher tooth
brushing frequency and interdental cleaning habits (Suominen-Taipale et al. 2008,
Christensen et al. 2003, Ronis et al. 1993) although we did not find a significant
difference in this study. Also Paulander and coworkers (Paulander et al. 2003) did
not find an association between level of education and tooth cleaning measures in
75- year-old subjects.
Fluoride toothpaste was used by 72% of the subjects, no association with level of
education or gender was found. This is in line with Health 2000 Survey where 76%
of the over 65 year olds reported using fluoride toothpaste (Suominen-Taipale et al.
2008).
We failed to show differences in brushing twice a day and using fluoride toothpaste
between gender and level of education. Our study population was more educated
and had retained more teeth than elderly individuals in other parts of Finland. It is
possible that their knowledge and practice of good oral self-care were earlier
established than in other subpopulations. More than two thirds of our study
population reported good oral self-care behavior, despite this they had high level of
oral diseases. One explanation might be that their ability to clean their teeth was
inadequate. In Health 2000 Survey only 40% of women and 22% of men in the age
group 65 or over, had clean teeth, no marked differences between educational
categories were found (Suominen-Taipale et al. 2008). The amount of dental plaque
of the participants or bleeding on probing were not registered, this is a weakness of
this study, but we did report that subjects in the high education group had on
average 0.8 healthy sextants and the subjects in the low education group had 0.4
healthy sextants, indicating that their level of oral hygiene was not very high. It is
well known that oral self-care becomes more difficult with age because of
compromising somatic and cognitive conditions (de Baat et al. 1993). It is crucial
that the promotion of self-care behaviors is supported at dental visits and is a
priority in dental treatment plans. Professional preventive measures should be
offered to the elderly who are not able to maintain adequate level of oral hygiene.
This becomes even more important in the future where growing number of elderly
are retaining more teeth.
6.6 Strengths and weaknesses of the study
Many studies on the oral health of the elderly have been conducted with focused
groups of subjects. At the commencement of HAS there was relatively little
information on the oral health status of home dwelling elderly in Finland in general.
One of the major advantages of this study is that for the first time it was possible to
retrieve comprehensive data on several aspects of oral health among the elderly
population of Helsinki representing three birth cohorts, gender distribution and
areas of living. This can also be seen as a limiting factor since the elderly in
Helsinki are not a representative group of all elderly populations in Finland.
The extensive oral examination allowed the collection of data on several aspects of
oral health. Indexes that are frequently used in population-based studies to describe
the conditions of oral health were also applied in this study. This makes data
comparisons possible, while it also limits the amount of data for follow-up
examinations. For example the DMFT index recommended by WHO is not the best
indicator for caries experience among the populations with a high number of
missing teeth. The increase in the index during the follow-up was mostly related
with loss of teeth and therefore is not a reliable indicator for the increment of caries
among the study population. The DMFS index would have given more reliable
information about caries in general. The accuracy of cariological status would
probably have benefitted from the use of bitewing radiographs. However, the oral
examination took altogether two hours and we decided to focus the caries
examination on the occurrence of root caries, which is the specific caries problem
among the older persons. Data on pocket depth, loss of attachment, bleeding of
probing and the presence of plaque would have provided more reliable information
on the periodontal health than the used CPI index, which only describes the need
for periodontal treatment among the study population. Detailed information about
caries and periodontal conditions would have allowed the use of more sophisticated
statistical models for the evaluations of risk factors of these conditions. This would
have been important especially for the follow-up examinations.
At the commencement of the HAS sample size was calculated to be sufficient for
medical examinations. Due to the fact that it was not possible to conduct oral health
examinations for all the elderly individuals who participated in the medical
examinations the sample size became rather limited for the follow-up study. This
came apparent at the time of 10 years follow-up, which could not conducted
because too few participants were alive and available for examination. Larger
sample size would have better tolerated the high drop out rate. This study was
designed to be longitudinal, but due to high attrition rate only limited amount of
information was available at the follow-up and the findings are mainly crosssectional. This makes it more difficult to draw conclusions concerning causal
relations. However, the results may have some useful clinical implications.
Another limitation is that we were not able to verify the data on the level of
education from any official records. This was not a major problem for those who
had a professional degree from educational institutions. Some of the elderly in the
lower education groups could not exactly remember the number of years they had
been in school and might have been placed into the wrong educational level. This,
however, was not big concern since for the data analysis the two lower and two
higher educational groups were combined into one low or high educational group.
6.7 Implications for the future
The education level in Finland is rising steadily and the new cohorts of elderly
individuals are better educated than the elderly have ever been in Finland. At the
same time edentulousness is declining at a fast rate and the mean number of teeth is
growing, thus leaving the older people more at risk of caries, periodontal disease
and other oral diseases. The expectations regarding to acceptable oral health are
also changing. The older people of today are more motivated to retain their teeth
into old age and don’’t easily accept becoming edentulous as an inevitable part of
aging. The decision to extract teeth was very uncommon in Finland during the first
decade of this century (Koskinen et al. 2012). The adults now entering older age,
““the heavy metal generation””, have retained much or most of their natural dentition,
but in a state that requires a lot of more complex restorative treatment and
maintenance if they want to retain their natural dentition and avoid dentures. The
disparities in oral health have remained, even here in Finland where the financing
and delivery of oral health care have been a public responsibility.
The old elderly in this study population are a special group as they have lived
beyond the normal life expectancy of their age cohorts in Finland. They have been
successful in aging and it is most likely that they have, and have had, many positive
health behaviors regardless of their levels of education, and yet they had high levels
of oral treatment need. Unless significant improvements are made, oral diseases and
oral health-related problems will increasingly generate major impact on the general
health and the quality of life of older people and impose a significant financial
burden on the individuals and society.
Another challenge is to identify older adults whose positive oral health behaviors
are about to change due to decline in cognition, functional ability and other effects
of age––related disease, and help them to protect their oral health from deteriorating.
As oral diseases share many common risk factors with several chronic diseases,
WHO encourages national health authorities to use common risk factors approach
to integrate interventions for oral health among older adults into general health
programmes of chronic diseases, as well as of health promotion (Petersen et al.
2005b, Petersen 2003, 2008). We should be able to decrease the impacts of oral
diseases on the general health and quality of life of older adults, and improve the
oral health of high risk groups such as older adults, thereby alleviating disparities in
these vulnerable subgroups requiring significant one-to one special oral care.
We have to remember that good oral health is a human right and essential to
general health and the quality of life.
7. CONCLUSIONS AND RECOMMENDATIONS
The participation rate was reduced by high age and female gender. The participants
were more mobile, were more often dentate and seldom showed signs of dementia.
This will lead the prevalence figures on number of teeth being too optimistic for the
entire elderly population.
Level of education was associated with the number of retained teeth and
periodontal treatment need in our cohort of older adults of Helsinki. The number of
teeth was higher and both periodontal treatment need and radiographically detected
periodontal lesions were more common among the older adults with higher
education levels. The mean number of teeth decreased and only modest changes in
periodontal health were detected during the five-year follow-up while the
disparities prevailed. Most of the older adults did not consider that they were in
need of periodontal treatment even with though their periodontal condition was
poor. The occurrence of root caries was high and more prevalent in men. There was
a clear increase in RCI during the five-year follow-up. However, this increase was
not directly associated with the level of education.
On the basis of the findings of this thesis and the previous scientific literature, the
following recommendations can be made:
1) The oral health literacy levels of older adults should be increased so they
would be able to seek treatment and preventive care in time. Good health
behaviors and preventive treatment should be made a priority in oral
treatment plans and public health interventions delivering oral health
promotion activity should be linked to general health promotion. Older
adults should be encouraged and supported to enable them to achieve
effective self-care and overcome the obstacles old age might bring.
Professional preventive measures should be offered to the older adults who
are not able to maintain adequate levels of oral hygiene.
2) The older adults continue to have high caries rates. The emphasis should be
changed from restorative treatment to preventive and non-operative
treatment strategies to treat caries disease successfully. There will be a
growing need for caries prevention measures and complex restorative
treatments in the future.
3) Periodontal diseases are still a major oral health burden among older adults.
Early diagnosis of periodontal disease signs, analysis of risk factors and
proper treatment plan should be part of everyday practice. Well organized
maintenance periodontal care is recommended.
4) Education and training of health care professionals providing oral
healthcare services for older people should be prioritized to equip them
with the clinical and communication skills needed to treat older patients.
This should be covered in the undergraduate curriculum and both CPD and
postgraduate courses should be offered.
5) The disparities in oral health between older adults should be decreased and
even eliminated.
ACKNOLEDGEMENTS
This study was carried out at the Institute of Dentistry, University of Helsinki,
Finland and it was supported by grants from the Miina Sillanpää Foundation and
the Finnish Dental Society Apollonia. I am grateful to late Professor Jukka Ainamo,
the former Dean of the Institute of Dentistry and Professor Jarkko Hietanen, the
present Dean of the Institute of Dentistry for the facilities placed at my disposal. I
also would like to thank Jukka Ainamo for his encouragement and support in the
early phases of this work.
I am deeply grateful to my supervisor, Professor Anja Ainamo for giving me an
opportunity to be a part of Helsinki Aging Study. She has gently and patiently
introduced the world of research to me and guided me through this process. I
appreciate her expertise and friendship tremendously.
I am also deeply indebted to Professor Timo Närhi, my other supervisor. His role
changed from co-worker to supervisor through out the years, and his constant
support and the occasional gentle push forward have made the completion of this
thesis possible. He has been a tireless advisor, always finding time to answer my
questions with his expert knowledge. It has been a privilege to work under his
guidance and have him as a friend.
I wish to thank my co-authors Miira Vehkalahti, Shilpi Ajwani, Juhani Wolf and
Reijo Tilvis, for their valuable input into the study. Miira VehkaIahti deserves also
my gratitude for sharing her scientific insight, inspiration and support. I also would
like to thank my colleagues and coworkers in the HAS team Juha Nevalainen, Kari
Soikkonen, Klaus Schmidt-Kaunisaho, Maarit Saario, Niina Kurki and Kaija
Hiltunen for their hard work collecting the data. Kaija Hiltunen is especially
thanked for all the inspiring conversations and encouragement in the final phases of
my thesis.
I sincerely thank Professor Liisa Suominen, University of Eastern Finland, and
Professor James Newton, University of Aberdeen, the official reviewers of this
thesis, for their careful review. Their expert knowledge, constructive criticism and
suggestions for improvements have helped me to improve and clarify the
manuscript.
Many thanks to all my colleagues and personnel at the Institute of Dentistry for
their help and especially Terhi Karaharju-Suvanto, Eva Siren, Ritva Lindblad and
Heli Hirvikangas for their friendship and support. Katja Narva is thanked for her
help and encouragement and friendship. My warmest thanks go to my dear friends
Annamari Nihtilä and Ulla Piltz for always being there for me.
I also acknowledge Donald Smart for revising the language of this thesis. The
personnel of the library at the Institute of Dentistry are thanked for providing me
with all the references I needed.
I want to thank my parents and my dear sister Riikka and her family for always
unconditionally loving, encouraging and supporting me.
Finally, I express my warmest gratitude to my husband Mikko and our children
Aku and Jonatan, for their love and understanding and all the joy in life they give
me.
Helsinki, April 2013
Päivi Siukosaari
REFERENCES
Aas, J.A., Griffen, A.L., Dardis, S.R., Lee, A.M., Olsen, I., Dewhirst, F.E., Leys, E.J. &
Paster, B.J. 2008, "Bacteria of dental caries in primary and permanent teeth in children
and young adults", Journal of clinical microbiology, vol. 46, no. 4, pp. 1407-1417.
Abdellatif, H.M. & Burt, B.A. 1987, "An epidemiological investigation into the relative
importance of age and oral hygiene status as determinants of periodontitis", Journal of
dental research, vol. 66, no. 1, pp. 13-18.
Adler, N.E. & Newman, K. 2002, "Socioeconomic disparities in health: pathways and
policies", Health affairs (Project Hope), vol. 21, no. 2, pp. 60-76.
Ahlqwist M. 1989, Women's teeth. A cross-sectional and longitudinal study of women in
Gothenburg, Sweden, with special reference to tooth loss and restorations. Thesis,
University of Gothenburg.
Ainamo, J. 1983, "Changes in the frequency of edentulousness and use of removable
dentures in the adult population of Finland, 1970-80", Community dentistry and oral
epidemiology, vol. 11, no. 2, pp. 122-126.
Ainamo, J., Barmes, D., Beagrie, G., Cutress, T., Martin, J. & Sardo-Infirri, J. 1982,
"Development of the World Health Organization (WHO) community periodontal
index of treatment needs (CPITN)", International dental journal, vol. 32, no. 3, pp.
281-291.
Albandar, J., Brunelle, J. & Kingman, A. 1999, "Destructive periodontal disease in adults
30 years of age and older in the United States, 1988-1994", Journal of periodontology,
vol. 70, no. 1, pp. 13-29.
Albandar, J.M. 2002, "Global risk factors and risk indicators for periodontal diseases",
Periodontology 2000, vol. 29, no. 1, pp. 177-206.
Albandar, J.M. 2005, "Epidemiology and risk factors of periodontal diseases", Dental
clinics of North America, vol. 49, no. 3, 517-32.
Ambjørnsen E. 1986, "Remaining teeth, periodontal condition, oral hygiene and tooth
cleaning habits in dentate old-age subjects". Journal of Clinical Periodontology,
vol.13, no.6, pp.583-589.
Armitage, G.C. 1995, "Clinical evaluation of periodontal diseases", Periodontology 2000,
vol. 7, no. 1, pp. 39-53.
Aromaa, A. & Koskinen, S. (eds) 2004, Health and functional capacity in Finland.
Baseline results of the Health 2000 health examination survey. Series B 12/2004).
National Public Health Institute, Helsinki.
Artnik, B., Premik, M. & Zaletel-Kragelj, L. 2008, "Population groups at high risk for poor
oral self care: the basis for oral health promotion", International journal of public
health, vol. 53, no. 4, pp. 195-203.
Attin, T. & Hornecker, E. 2005, "Tooth brushing and oral health: how frequently and when
should tooth brushing be performed?", Oral health & preventive dentistry, vol. 3, no.
3, pp. 135-140.
Avlund, K., Holm-Pedersen, P. & Schroll, M. 2001, "Functional ability and oral health
among older people: a longitudinal study from age 75 to 80", Journal of the American
Geriatrics Society, vol. 49, no. 7, 954-962.
Avlund, K., Holm-Pedersen, P., Morse, D.E., Viitanen, M. & Winblad, B. 2003, "Social
relations as determinants of oral health among persons over the age of 80 years",
Community dentistry and oral epidemiology, vol. 31, no. 6, pp. 454-462.
Avlund, K., Holm-Pedersen, P., Morse, D.E., Viitanen, M. & Winblad, B. 2004, "Tooth
loss and caries prevalence in very old Swedish people: the relationship to cognitive
function and functional ability", Gerodontology, vol. 21, no. 1, 17-26.
Axelsson, P. 1993, "Mechanical plaque control." in Proceedings of the 1st European
Workshop on Periodontology. , ed. K.T. Lang N.P., 1st edn, Quintessence Publishing
Co. Ltd, London, pp. 219-243.
Baelum, V., Manji, F, Wanzala, P. & Fejerskov, O. 1995, "Relationship between CPITN
and periodontal attachment loss findings in an adult population", Journal of clinical
periodontology, vol. 22, no.2, pp. 146-152.
Baelum, V. & Papapanou, P.N. 1996. " CPITN and the epidemiology of periodontal
disease", Community dentistry and oral epidemiology, vol. 24: pp. 367-368.
Beck, J.D., Koch, G.G. & Offenbacher, S. 1995, "Incidence of attachment loss over 3 years
in older adults--new and progressing lesions", Community dentistry and oral
epidemiology, vol. 23, no. 5, pp. 291-296.
Beck, J.D., Koch, G.G., Rozier, R.G. & Tudor, G.E. 1990, "Prevalence and risk indicators
for periodontal attachment loss in a population of older community-dwelling blacks
and whites", Journal of periodontology, vol. 61, no. 8, pp. 521-528.
Beighton, D., Hellyer, P., Lynch, E. & Heath, M. 1991, "Salivary levels of mutans
streptococci, lactobacilli, yeasts, and root caries prevalence in non-institutionalized
elderly dental patients", Community dentistry and oral epidemiology, vol. 19, no. 5,
pp. 302-307.
Beighton, D. & Lynch, E. 1993, "Relationships between yeasts and primary root-caries
lesions", Gerodontology, vol. 10, no. 2, pp. 105-108.
Beikler, T. & Flemmig, T.F. 2011, "Oral biofilm-associated diseases: trends and
implications for quality of life, systemic health and expenditures", Periodontology
2000, vol. 55, no. 1, pp. 87-103.
Birkhed, D. & Hintze, U. 1989, ““Salivary secretion, buffer capacity and pH”” in Tenovuo
JO (ed): Human Saliva: Clinical Chemistry and Microbiology. Boca Raton, CRC
Press, vol 1.
Bellomo, F., Preux, F.d., Chung, J., Julien, N., Budtz-Jørgensen, E. & Müller, F. 2005,
"The advantages of occupational therapy in oral hygiene measures for institutionalised
elderly adults", Gerodontology, vol. 22, no. 1, pp. 24-31.
Bergdahl, M. 2000, "Salivary flow and oral complaints in adult dental patients",
Community dentistry and oral epidemiology, vol. 28, no. 1, pp. 59-66.
Borges-Yáñez, S.A., Irigoyen-Camacho, M.E. & Maupomé, G. 2006, "Risk factors and
prevalence of periodontitis in community-dwelling elders in Mexico", Journal of
clinical periodontology, vol. 33, no. 3, pp. 184-194.
Borrell, L., Burt, B., Neighbors, H & Taylor, G. 2004, "Social factors and periodontitis in
an older population", American journal of public health, vol. 94, no. 5, pp. 748-754.
Bourgeois, D., Nihtila, A. & Mersel, A. 1998, "Prevalence of caries and edentulousness
among 65-74-year-olds in Europe", Bulletin of the World Health Organization, vol.
76, no. 4, pp. 413-417.
Braveman, P.A., Cubbin, C., Egerter, S., Chideya, S., Marchi, K.S., Metzler, M. & Posner,
S. 2005, "Socioeconomic status in health research: one size does not fit all", The
journal of the American Medical Association, vol. 294, no. 22, pp. 2879-2888.
Brown LR, Dreizen S, Daly TE, Drane JB, Handler S, Riggan LJ, Johnston DA. 1978 "
Interrelations of oral microorganisms, immunoglobulins, and dental caries following
radiotherapy", Journal of dental research vol. 57, pp. 882––893.
Bruun K. 1954 Uusi sosiaaliryhmitys. Tilastollisia kuukausitietoja Helsingista. 3, pp. 37––
44.
Budtz-Jorgensen, E., Mojon, P., Rentsch, A., Roehrich, N., von der Muehll, D. & Baehni,
P. 1996, "Caries prevalence and associated predisposing conditions in recently
hospitalized elderly persons", Acta Odontologica Scandinavica, vol. 54, no. 4, pp.
251-256.
Burt B.A. & Eklund S.A. 2005. Dentistry, dental practice and the community. 6th ed. St.
Louis, Missouri, USA. Elsevier Saunders .
Caries. Current Care guideline. Working group set up by the Finnish Medical Society
Duodecim and the Finnish Dental Society Apollonia. Helsinki: Finnish Medical
Society Duodecim, 2009. Available online at: www.kaypahoito.fi
Chalmers, J.M., Carter, K.D. & Spencer, A.J. 2005, "Caries incidence and increments in
Adelaide nursing home residents", Special care in dentistry, vol. 25, no. 2, pp. 96-105.
Chew, M.L., Mulsant, B.H., Pollock, B.G., Lehman, M.E., Greenspan, A., Mahmoud, R.A.,
Kirshner, M.A., Sorisio, D.A., Bies, R.R. & Gharabawi, G. 2008, "Anticholinergic
Activity of 107 Medications Commonly Used by Older Adults", Journal of the
American Geriatrics Society, vol. 56, no. 7, pp. 1333-1341.
Christensen, L.B., Petersen, P.E., Krustrup, U. & Kjoller, M. 2003, "Self-reported oral
hygiene practices among adults in Denmark", Community dental health, vol. 20, no. 4,
pp. 229-235.
Claydon, N.C. 2008, "Current concepts in toothbrushing and interdental cleaning",
Periodontology 2000, vol. 48, no. 1, pp. 10-22.
Colonna-Romano, G., Bulati, M., Aquino, A., Vitello, S., Lio, D., Candore, G. & Caruso,
C. 2008, "B cell immunosenescence in the elderly and in centenarians", Rejuvenation
research, vol. 11, no. 2, pp. 433-439.
Corbet, E.F., Wong, M.C. & Lin, H.C. 2001, "Periodontal conditions in adult Southern
Chinese", Journal of dental research, vol. 80, no. 5, pp. 1480-1485.
Curzon, M.E. & Preston, A.J. 2004, "Risk groups: nursing bottle caries/caries in the
elderly", Caries research, vol. 38 Suppl 1, pp. 24-33.
Cutress, T.W., Ainamo, J. & Sardo-Infirri, J. 1987, "The community periodontal index of
treatment needs (CPITN) procedure for population groups and individuals",
International dental journal, vol. 37, no. 4, pp. 222-233.
Davidson, P.L., Rams, T.E. & Andfrsen, R.M. 1997, "Socio-Behavioral Determinants of
Oral Hygiene Practices Among USA Ethnic and Age Groups", Advances in dental
research, vol. 11, no. 2, pp. 245-253.
Dawes, C. 2004, "Factors influencing salivary flow rate and composition." in Saliva and
Dental Health, ed. Edgar WM, Dawes,C, and O'Mullane DM, 3rd edn, British Dental
Association, London, pp. 32-49.
Dawes, C. 2008, "Salivary flow patterns and the health of hard and soft oral tissues", The
journal of the American Dental Association, vol. 139, no. suppl 2, pp. 18S-24S.
de Baat, C., Kalk, W. & Schuil, G.R. 1993, "The effectiveness of oral hygiene programmes
for elderly people -a review", Gerodontology, vol. 10, no. 2, pp. 109-113.
DePaola, P.F., Soparkar, P.M. & Kent, R.L. 1989, ““Methodological issues relative to the
quantification of root surface caries”” Gerodontology vol. 8, pp. 3––8.
Drury, T.F., Garcia, I. & Adesanya, M. 1999, "Socioeconomic Disparities in Adult Oral
Health in the United States", Annals of the New York Academy of Sciences, vol. 896,
no. 1, pp. 322-324.
Dye, B.A. & Vargas, C.M. 2002, "The use of a modified CPITN approach to estimate
periodontal treatment needs among adults aged 20-79 years by socio-demographic
characteristics in the United States, 1988-94", Community dental health vol. 19, no.4,
pp. 215-223.
Dye, B.A., Tan, S., Smith, V., Lewis, B.G, Barker, L.K., Thornton-Evans, G., Eke, P.I.,
Beltrán-Aguilar, E.D., Horowitz, A.M. & Li, C.H. 2007, "Trends in oral health status:
United States, 1988-1994 and 1999-2004". Vital Health Stat 11, vol. 248, pp. 1-92.
Edelstein, B. 2002, "Disparities in Oral Health and Access to Care: Findings of National
Surveys", Ambulatory pediatrics suppl, pp.141-147.
Eke P, Dye B, Wei L, Thornton-Evans GO & Genco RJ, 2012““Prevalence of periodontitis
in adults in the United States: 2009 and 2010. Journal of dental research, vol.91, no.
10, pp. 914-920.
Ekelund, R. 1984, "The dental and oral condition and the need for treatment among the
residents of municipal old people's homes in Finland", Proceedings of the Finnish
Dental Society, vol. 80, no. 1, pp. 43-52.
Ekelund, R. 1989, "National survey of oral health care Finnish private old people's homes",
Community dentistry and oral epidemiology, vol. 17, no. 3, pp. 158-161.
Ellen, R.P., Banting, D.W. & Fillery, E.D. 1985, " Streptococcus mutans and Lactobacillus
detection in the assessment of dental root surface caries risk". Journal of dental
research, vol. 64, pp. 1245––1249.
Elo, I.T. & Preston, S.H. 1996, "Educational differentials in mortality: United States, 197985", Social science & medicine, vol. 42, no. 1, pp. 47-57.
Emilson, C & Thorselius, I. 1988, " Prevalence of mutans streptococci and lactobacilli in
elderly Swedish individuals". Scandinavian journal of dental research, vol. 96, pp.
14––21.
Eriksson, B.G., Mellstrom, D. & Svanborg, A. 1987, "Medical-social intervention in a 70year-old Swedish population. A general presentation of methodological experience",
Comprehensive gerontology. Section C, Interdisciplinary topics, vol. 1, pp. 49-56.
Eurostat yearbook 2011 -Europe in figures. 2011. European Commission, Publications
Office of the European Union, Luxembourg.
Fadel, H., Al Hamdan, K., Rhbeini, Y., Heijl, L. & Birkhed, D. 2011, "Root caries and risk
profiles using the Cariogram in different periodontal disease severity groups", Acta
Odontologica Scandinavica, vol. 69, no. 2, pp. 118-124.
Featherstone, J.D. 1994, "Fluoride, remineralization and root caries", American journal of
dentistry, vol. 7, no. 5, pp. 271-274.
Fejerskov, O., Baelum, V. & Østergaard, E.S. 1993, "Root Caries in Scandinavia in the
1980's and Future Trends to be Expected in Dental Caries Experience in Adults",
Advances in dental research, vol. 7, no. 1, pp. 4-14.
Fejerskov, O., Luan, W.M., Nyvad, B., Budtz-Jorgensen, E. & Holm-Pedersen, P. 1991,
"Active and inactive root surface caries lesions in a selected group of 60- to 80-yearold Danes", Caries research, vol. 25, no. 5, pp. 385-391.
Flemmig, T.F. & Beikler, T. 2011, "Control of oral biofilms", Periodontology 2000, vol.
55, no. 1, pp. 9-15.
Fure, S. 2003, "Ten-year incidence of tooth loss and dental caries in elderly Swedish
individuals", Caries research, vol. 37, no. 6, pp. 462-469.
Fure, S. 2004, "Ten-year cross-sectional and incidence study of coronal and root caries and
some related factors in elderly Swedish individuals", Gerodontology, vol. 21, no. 3,
pp. 130-140.
Fure, S. & Zickert, I. 1990, "Prevalence of root surface caries in 55, 65, and 75-year-old
Swedish individuals", Community dentistry and oral epidemiology, vol. 18, no. 2, pp.
100-105.
Fure, S. & Zickert, I. 1997, "Incidence of tooth loss and dental caries in 60-, 70- and 80year-old Swedish individuals", Community dentistry and oral epidemiology, vol. 25,
no. 2, pp. 137-142.
Galobardes, B., Shaw, M., Lawlor, D.A., Lynch, J.W. & Davey Smith, G. 2006, "Indicators
of socioeconomic position (part 1)", Journal of epidemiology and community health,
vol. 60, no. 1, pp. 7-12.
Ghezzi, E., Wagner-Lange L., Schork M., Metter E., Baum B., Streckfus C& Ship J. 2000,
"Longitudinal influence of age, menopause, hormone replacement therapy, and other
medications on parotid flow rates in healthy women", The Journals of Gerontology
Series A: Biological Sciences and Medical Sciences, vol. 55, no. 1, pp. M34-M42.
Haikola, B., Oikarinen, K., Söderholm, A., Remes-Lyly, T. & Sipilä, K. 2008, "Prevalence
of edentulousness and related factors among elderly Finns", Journal of oral
rehabilitation, vol. 35, no. 11, pp. 827-835.
Heegaard, K.M., Holm-Pedersen, P., Bardow, A., Hvidtfeldt, U.A., Gronbaek, M. &
Avlund, K. 2011, "The Copenhagen Oral Health Senior Cohort: design, population
and dental health", Gerodontology, vol. 28, no. 3, pp. 165-176 .
Heitz-Mayfield, L.J.A. 2005, "Disease progression: identification of high-risk groups and
individuals for periodontitis", Journal of clinical periodontology, vol. 32, pp. 196-209.
Hodgkins, B. 1995, "Social and psycholocical issues in aging and health." in Therapeutics
in the elderly, ed. S.R. Delafuente JC, second edn, Harwey Whitney Books Company,
Cincinnati, Ohio, pp. 31-50.
Holm-Pedersen, P., Agerbaek, N. & Theilade, E. 1975, "Experimental gingivitis in young
and elderly individuals", Journal of clinical periodontology, vol. 2, no. 1, pp. 14-24.
Holm-Pedersen, P., Russell, S., Avlund, K., Viitanen, M., Winblad, B. & Katz, R.V. 2006,
"Periodontal disease in the oldest-old living in Kungsholmen, Sweden: findings from
the KEOHS project", Journal of clinical periodontology, vol. 33, no. 6, pp. 376-384.
Hugoson, A., Koch, G., Gothberg, C., Helkimo, A.N., Lundin, S.A., Norderyd, O., Sjodin,
B. & Sondell, K. 2005, "Oral health of individuals aged 3-80 years in Jonkoping,
Sweden during 30 years (1973-2003). I. Review of findings on dental care habits and
knowledge of oral health", Swedish dental journal, vol. 29, no. 4, pp. 125-138.
Hunt, R.J. & Beck, J.D. 1985, "Methodological Considerations in a Dental Epidemiologic
Survey of an Elderly Population", Journal of public health dentistry, vol. 45, no. 4, pp.
257-260.
Islas-Granillo, H., Borges-Yañez, S., Medina-Solís, C., Casanova-Rosado, A., MinayaSánchez, M., Villalobos Rodelo, J. & Maupomé, G. 2012, "Socioeconomic,
sociodemographic, and clinical variables associated with root caries in a group of
persons age 60 years and older in Mexico", Geriatrics and gerontology international.
vol.12, no.2, pp.71-76.
Janzon, L., Hanson, B.S., Isacsson, S.O., Lindell, S.E. & Steen, B. 1986, "Factors
influencing participation in health surveys. Results from prospective population study
'Men born in 1914' in Malmo, Sweden", Journal of epidemiology and community
health, vol. 40, no. 2, pp. 174-177.
Joshi A., Douglass C.W., Jette A. & Feldman R. 1994, "The distribution of root caries in
community-dwelling elders in New England". Journal of public health dentistry, vol.
54, pp. 15-23.
Juva, K., Sulkava, R., Erkinjuntti, T., Valvanne, J. & Tilvis, R. 1993, "Prevalence of
dementia in the city of Helsinki", Acta Neurologica Scand, vol. 87, no. 2, pp. 106-110.
Jyrkkä, J., Vartiainen, L., Hartikainen, S., Sulkava, R. & Enlund, H. 2006, "Increasing use
of medicines in elderly persons: a five-year follow-up of the Kuopio 75+Study",
European journal of clinical pharmacology, vol. 62, no. 2, pp. 151-158.
Järvenpää I. 1964. Sosiaaliryhmaätutkimus vuonna 1961. Tulosten vertailu vuonna 1954
suoritettuun tutkimukseen. Tilastollisia kuukausitietoja Helsingistä vol.7,pp. 289––295.
Kaila-Kangas, L. (ed) 2007. Musculoskeletal disorders and diseases in Finland. Results of
the Health 2000 Survey. Publications of the National Public Health Institute, B 25 /
2007, National Public Health Institute, Helsinki.
Katz, R.V. 1980, "Assessing root caries in populations: the evolution of the root caries
index", Journal of public health dentistry, vol. 40, no. 1, pp. 7-16.
Kelly, M., Steele, J., Nuttall, N., Bradnock, G., Morris, J., Nunn, J., Pine, C., Pitts, N.,
Treasure, E. & White, D. 2000., "Adult Dental Health Survey: Oral Health in the
United Kingdom 1998. " in Her Majesty’’s Stationery Office, London, England.
Kirkegaard E., Petersen G., Poulsen S., Holm S.A. & Heidmann J., 1986. "Cariespreventive effect of Duraphat varnish applications versus fluoride mouthrinses: 5-year
data", Caries research, vol 20, no. 6, pp.548-555.
Kitamura, M., Kiyak, H.A. & Mulligan, K. 1986, "Predictors of root caries in the elderly",
Community dentistry and oral epidemiology, vol. 14, no. 1, pp. 34-38.
Klaukka, T. 1988, "Users of prescription drugs in Finnish primary care", Scandinavian
journal of primary health care, vol. 6, no. 1, pp. 43-50.
Klinge, B. & Norlund, A. 2005, "A socio-economic perspective on periodontal diseases: a
systematic review", Journal of clinical periodontology, vol. 32, pp. 314-325.
Klock B., Svanberg M. & Petersson L.G., 1990 "Dental caries, mutans streptococci,
lactobacilli, and saliva secretion rate in adults", Community dentistry and oral
epidemiology, vol. 18, pp. 249––252.
Komulainen, K., Ylöstalo, P., Syrjälä, A-M., Ruoppi, P., Knuuttila, M., Sulkava, R. &
Hartikainen, S. 2012a, "Associations of instrumental activities of daily living and
handgrip strength with oral self-care among home-dwelling elderly 75+".
Gerodontology, vol. 29, pp. e135––e142.
Komulainen, K., Ylöstalo, P., Syrjälä, A-M., Ruoppi, P., Knuuttila, M., Sulkava, R. &
Hartikainen, S. 2012b, "Preference for dentist’’s home visits among older people",
Community dentistry and oral epidemiology, vol. 40, pp. 89––95.
Koskinen, S., Lundqvist, A., Ristiluoma, N. 2012, Health, functional capacity and welfare
in Finland in 2011. National Institute for Health and Welfare (THL), Reports 68/2012.
Krasse, B. 1989, "Specific microorganisms and dental caries in children", Pediatrician,
vol. 16, no. 3-4, pp. 156-160.
Krustrup, U. & Petersen, E. 2006, "Periodontal conditions in 35-44 and 65-74-year-old
adults in Denmark", Acta Odontologica Scandinavica, vol. 64, no. 2, pp. 65-73.
Käyser AF. 1981, "Shortened dental arches and oral function", Journal of oral rehabilation
vol. 8, pp. 457-462.
Laukkanen, P., Sakari-Rantala, R., Kauppinen, M. & Heikkinen, E. 1997, "Morbidity and
disability in 75- and 80-year-old men and women. A five-year follow-up",
Scandinavian journal of social medicine. Supplementum, vol. 53, pp. 79-106.
Lawrence R., Hemlick C., Arnett F., Deyo R., Felson D., Giannini , Heyse, S., Hirsch R,
Hochberg, M.C., Hunder, G.G., Liang, M.H., Pillemer, S.R., Steen, V. & Wolfe, F.
1998. Estimates of the prevalence of arthritis and selected musculoskeletal disorders
in the United States", Arthritis and rheumatism, vol.41,no.5, pp.778-799.
Lindhe, J., Socransky, S., Nyman, S., Westfelt, E. & Haffajee, A. 1985, "Effect of age on
healing following periodontal therapy", Journal of clinical periodontology, vol. 12,
no. 9, pp. 774-787.
Linjakumpu, T., Hartikainen, S., Klaukka, T., Veijola, J., Kivelä, S.L. & Isoaho, R. 2002,
"Use of medications and polypharmacy are increasing among the elderly", Journal of
clinical epidemiology, vol. 55, no. 8, pp. 809-817.
Lobo, A., Launer, L.J., Fratiglioni, L, Andersen, K., Di Carlo, A., Breteler M.M.,
Copeland, J.R., Dartigues, J.F., Jagger, C., Martinez-Lage, J., Soininen, H. & Hofman,
A. 2000, "Prevalence of dementia and major subtypes in Europe: a collaborative study
of population-based cohorts", Neurology vol. 54, Suppl 5, pp. 4-9.
Locker, D., Slade, G. & Leake, J. 1990, "The response rate problem in oral health surveys
of older adults in Ontario", Canadian journal of public health vol. 81, pp. 210-214.
Locker, D. 1993a, "Subjective reports of oral dryness in an older adult population",
Community dentistry and oral epidemiology, vol. 21, no. 3, pp. 165-168.
Locker D.& Leake J.L., 1993b. " Risk indicators and risk markers for periodontal disease
experience in older adults living independently in Ontario, Canada. " Journal of dental
research vol. 72, pp. 9––17.
Locker, D. & Slade, G. 1994. Association between clinical and subjective indicators of oral
health status in an older adult population. Gerodontology vol. 11, no.2, pp. 108-114.
Locker, D. 1996, "Incidence of root caries in an older Canadian population", Community
dentistry and oral epidemiology, vol. 24, no. 6, pp. 403-407.
Locker, D., Slade, G.D. & Murray, H. 1998, "Epidemiology of periodontal disease among
older adults: a review", Periodontology 2000, vol. 16, pp. 16-33.
Locker, D. 2000, "Response and nonresponse bias in oral health surveys", Journal of
public health dentistry, vol. 60, no. 2, pp. 72-81.
Locker, D., Matear, D., Stephens, M. & Jokovic, A. 2002, "Oral health-related quality of
life of a population of medically compromised elderly people", Community dental
health, vol. 19, no. 2, pp. 90-97.
Löe, H. 2000, "Oral hygiene in the prevention of caries and periodontal disease",
International dental journal, vol. 50, no. 3, pp. 129-139.
Luan, W., Baelum, V., Fejerskov, O. & Chen, X. 2000, "Ten-year incidence of dental
caries in adult and elderly Chinese", Caries research, vol. 34, no. 3, pp. 205-213.
Lynch J. & K.G. 2000, "Socioeconomic position." in Social epidemiology., ed. K.I.
Berkman L.F., Oxford University Press, New York, pp. 13-35.
MacEntee, M.I., Stolar, E. & Glick, N. 1993, "Influence of age and gender on oral health
and related behaviour in an independent elderly population", Community dentistry and
oral epidemiology, vol. 21, no. 4, pp. 234-239.
Mackenbach, J.P., Bos, V., Andersen O., Cardano, M., Costa, G., Harding, S., Reid, A.,
Hemström, Ö., Valkonen, T. & Kunst, A.E. 2003. "Widening socioeconomic
inequalities in mortality in six Western European countries" International journal of
epidemiology, vol 32, no. 5, pp. 830-837.
Makhija, S.K., Gilbert, G.H., Boykin, M.J., Litaker, M.S., Allman, R.M., Baker, P.S.,
Locher, J.L. & Ritchie, C.S. 2006, "The Relationship Between Sociodemographic
Factors and Oral Health? Related Quality of Life in Dentate and Edentulous
Community-Dwelling Older Adults", Journal of the american geriatrics society, vol.
54, no. 11, pp. 1701-1712.
Markkula, J., Ainamo, J. & Murtomaa H. 1973, "Dental knowledge and behavior in
Finland. I. An interview on edentulousness and occurance of removable dentures",
Proceedings of the Finnish Dental Society, vol. 69, no. 6, pp. 266-272.
Matthews, D.C., Brillant, M.G.S., Clovis, J.B., McNally, M.E., Filiaggi, M.J., Kotzer,
R.D., Lawrence, H.P. 2011, "Assessing the oral health of an ageing population:
methods, challenges and predictors of survey participation", Gerodontology.
Mattila, P.T., Niskanen, M.C., Vehkalahti, M.M., Nordblad, A. & Knuuttila, M.L.E. 2010,
"Prevalence and simultaneous occurrence of periodontitis and dental caries", Journal
of clinical periodontology, vol. 37, no. 11, pp. 962-967.
Meyer, J. 2001, US Census 2000.
Mojon, P., Rentsch, A. & Budtz-Jorgensen, E. 1995, "Relationship between prosthodontic
status, caries, and periodontal disease in a geriatric population", The International
journal of prosthodontics, vol. 8, no. 6, pp. 564-571.
Molander, B., Ahlqwist, M. & Gröndahl, H-G. 1995, "Panoramic and resctrictive intraoral
radiography in comprehensive oral radiographic diagnosis", European journal of oral
sciences, vol. 103, pp. 191-198.
Morris, A.J., Steele, J. & White, D.A. 2001, "The oral cleanliness and periodontal health of
UK adults in 1998", British dental journal, vol. 191, no. 4, pp. 186-192.
Morse, D.E., Holm-Pedersen, P., Holm-Pedersen, J., Katz, R.V., Viitanen, M., von Strauss,
E. & Winblad, B. 2002, "Dental caries in persons over the age of 80 living in
Kungsholmen, Sweden: findings from the KEOHS project", Community dental health,
vol. 19, no. 4, pp. 262-267
Mosby's Medical Dictionary, 2008, 8th edition, Elsevier.
Murtomaa, H. & Meurman, J.H. 1992, "Mechanical aids in the prevention of dental
diseases in the elderly", International dental journal, vol. 42, no. 5, pp. 365-372.
Mäkilä, E. 1979, "Oral health among the inmates of old people's homes. VI. Need for
treatment", Proceedings of the Finnish Dental Society, vol. 75, no. 1-2, pp. 1-5.
National Center for Health Statistics (NCHS) 1996. Third National Health and Nutrition
Examination Survey (NHANES III) reference manuals and reports. NCHS, U.S.
Department of Health and Human Services, Public Health Service, Centers for
Disease Control and Prevention, Hyattsville, Maryland.
National Center for Health Statistics (NCHS) 2011, Health, United States, 2010: With
Special Feature on Death and Dying. National Center for Health Statistics,
Hyattsville, Maryland.
Navazesh, M. 2003, "How can oral health care providers determine if patients have dry
mouth?", The Journal of the american dental association, vol. 134, no. 5, pp. 613-618.
Nederfors, T., Isaksson, R., Mörnstad, H. & Dahlöf, C. 1997, "Prevalence of perceived
symptoms of dry mouth in an adult Swedish population - relation to age, sex and
pharmacotherapy", Community dentistry and oral epidemiology, vol. 25, no. 3, pp.
211-216.
Nevalainen, M.J., Närhi, T.O. & Ainamo, A. 1997, "Oral mucosal lesions and oral hygiene
habits in the home-living elderly", Journal of oral rehabilitation, vol. 24, no. 5, pp.
332-337.
Nevalainen, M.J., Närhi, T.O. & Ainamo, A. 2004, "A 5-year follow-up study on the
prosthetic rehabilitation of the elderly in Helsinki, Finland", Journal of oral
rehabilitation, vol. 31, no. 7, pp. 647-652.
Nunn, M.E. 2003, "Understanding the etiology of periodontitis: an overview of periodontal
risk factors", Periodontology 2000, vol. 32, no. 1, pp. 11-23.
Närhi, T.O., Meurman, J.H., Ainamo, A., Nevalainen, J.M., Schmidt-Kaunisaho, K.G.,
Siukosaari, P., Valvanne, J., Erkinjuntti, T., Tilvis, R. & Makila, E. 1992,
"Association between salivary flow rate and the use of systemic medication among
76-, 81-, and 86-year-old inhabitants in Helsinki, Finland", Journal of dental research,
vol. 71, no. 12, pp. 1875-1880.
Närhi, T.O., Ainamo, A. & Meurman, J.H. 1993, "Salivary yeasts, saliva, and oral mucosa
in the elderly", Journal of dental research, vol. 72, no. 6, pp. 1009-1014.
Närhi, T.O. 1994, "Prevalence of Subjective Feelings of Dry Mouth in the Elderly",
Journal of dental research, vol. 73, no. 1, pp. 20-25.
Närhi, T.O., Ainamo, A. & Meurman, J.H. 1994, "Mutans streptococci and lactobacilli in
the elderly", Scandinavian journal of dental research, vol. 102, no. 2, pp. 97-102.
Official Statistics of Finland, 2010. Official Statistics of Finland 2010, Social Insurance
Institution (SII), Vammalan kirjapaino, Sastamala.
Official Statistics of Finland, 2012. OSF Statistical report 25/2012, Statistics Finland
Oliver, R.C., Brown L.J. & Löe H. 1991. ““Variations in the prevalence and extent of
periodontitis””. Journal of american dental association vol. 122, pp. 43––48.
Oliver, R.C., Brown, L.J. & Löe H., 1998. ““Periodontal diseases in the United States
population””. Journal of periodontology vo. 69, pp. 269––278.
O’’ Sullivan I. (ed) 2011. Adult Dental Health Survey –– 2009. The Health and Social Care
Information Centre. UK
Page, R.C. 1984, "Periodontal Diseases in the Elderly: A Critical Evaluation of Current
Information1", Gerodontology, vol. 3, no. 1, pp. 63-70.
Pajukoski, H., Meurman, J.H., Snellman-Grohn, S., Keinanen, S. & Sulkava, R. 1997,
"Salivary flow and composition in elderly patients referred to an acute care geriatric
ward", Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics,
vol. 84, no. 3, pp. 265-271.
Pajukoski, H., Meurman, J.H., Snellman-Grohn, S. & Sulkava, R. 1999, "Oral health in
hospitalized and nonhospitalized community-dwelling elderly patients", Oral surgery,
oral medicine, oral pathology, oral radiology, and endodontics, vol. 88, no. 4, pp.
437-443.
Palmqvist, S., Soderfeldt, B., Vigild, M. & Kihl, J. 2000, "Dental conditions in middleaged and older people in Denmark and Sweden: a comparative study of the influence
of socioeconomic and attitudinal factors", Acta Odontologica Scandinavica, vol. 58,
no. 3, pp. 113-118.
Papapanou, P.N. 1999, "Epidemiology of periodontal diseases: an update", Journal of the
international academy of periodontology. 1999 vol.1, no.4, pp.110-116.
Papas, A., Joshi, A. & Giunta, J. 1992, "Prevalence and intraoral distribution of coronal
and root caries in middle-aged and older adults", Caries research, vol. 26, pp. 459––
465.
Paulander, J., Axelsson, P. & Lindhe, J. 2003, "Association between level of education and
oral health status in 35-, 50-, 65- and 75-year-olds", Journal of clinical
periodontology, vol. 30, no. 8, pp. 697-704.
Payne, B.J. & Locker, D. 1992, "Oral self-care behaviours in older dentate adults",
Community dentistry and oral epidemiology, vol. 20, no. 6, pp. 376-380.
Peltola, P., Vehkalahti, M.M. & Wuolijoki-Saaristo, K. 2004, "Oral health and treatment
needs of the long-term hospitalised elderly", Gerodontology, vol. 21, no. 2, pp. 93-99.
Persson, R.E., Hollender, L.G., MacEntee, M.I., Wyatt, C.C.L., Kiyak, H.A. & Persson,
G.R. 2003, "Assessment of periodontal conditions and systemic disease in older
subjects", Journal of clinical periodontology, vol. 30, no. 3, pp. 207-213.
Petersen, P.E., 1990, "Social inequalities in dental health. Towards a theoretical
explanation", Community dentistry and oral epidemiology, vol. 18, no. 3, pp. 153-158.
Petersen, P.E., 2008, "World Health Organization global policy for improvement of oral
health -World Health Assembly 2007", International dental journal, vol 58, no.3, pp.
115-121
Petersen, P.E., Kjoller, M., Christensen, L.B. & Krustrup, U. 2004, "Changing dentate
status of adults, use of dental health services, and achievement of national dental
health goals in Denmark by the year 2000", Journal of public health dentistry, vol. 64,
no. 3, pp. 127-135.
Petersen, P.E. & Ogawa, H. 2005 a, "Strengthening the prevention of periodontal disease:
the WHO approach", Journal of periodontology, vol. 76, no. 12, pp. 2187-2193.
Petersen, P.E. & Yamamoto, T. 2005 b, "Improving the oral health of older people: the
approach of the WHO Global Oral Health Programme", Community dentistry and oral
epidemiology, vol. 33, no. 2, pp. 81-92.
Pifer, A. & Bronte, L. 1986, "Longevity and social structure: The potential of the added
years. " in: Our aging society: Paradox and promise. , ed. Riley M.W., Norton, W.W,
New York.
Pilot, T. & Barmes, D.E. 1987, "An update on periodontal conditions in adults, measured
by CPITN", International dental journal, vol. 37, no. 3, pp. 169-172.
Pitts, N., Amaechi, B., Niederman, R., Acevedo, A.M., Vianna, R., Ganss, C., Ismail, A.,
Honkala, E. 2011, "Global oral health inequalities: dental caries task group--research
agenda". Advances in dental research vol 23, no 2, pp. 211-220.
Polvikoski T., Sulkava R., Myllykangas L., Notkola I.L., Niinistö L., Verkkoniemi A.,
Kainulainen K., Kontula K., Pérez-Tur J., Hardy J. & Haltia M. 2001, "Prevalence of
Alzheimer’’s disease in very elderly people: a prospective neuropathological study".
Neurology vol 56, pp. 1690-1696.
Preza, D., Olsen, I., Aas, J.A., Willumsen, T., Grinde, B. & Paster, B.J. 2008, "Bacterial
profiles of root caries in elderly patients", Journal of clinical microbiology, vol. 46,
no. 6, pp. 2015-2021.
Ravald, N., Hamp, S. & Birkhed, D. 1986, "Long-term evaluation of root surface caries in
periodontally treated patients", Journal of clinical periodontology, vol. 13, no. 8, pp.
758-767.
Rahkonen, T,. Eloniemi-Sulkava, U., Rissanen, S., Vatanen, A., Viramo, P. & Sulkava, R.
2003, "Dementia with Lewy bodies according to the consensus criteria in a general
population aged 75 years or older", Journal of neurology, neurosurgery, and
psychiatry, vol. 74, no. 6, pp. 720-724
Richards, W., Ameen, J., Coll, A.M. & Higgs, G. 2005, "Reasons for tooth extraction in
four general dental practices in South Wales", British dental journal, vol. 198, no. 5,
pp. 275-278.
Ronis, D.L., Lang, W.P., Farghaly, M.M. & Passow, E. 1993, "Tooth brushing, flossing,
and preventive dental visits by Detroit-area residents in relation to demographic and
socioeconomic factors", Journal of public health dentistry, vol. 53, no. 3, pp. 138-145.
Salonen, L., Allander, L., Bratthall, D., Togelius, J. & Helldén, L. 1989 "Oral health status
in an adult Swedish population. Prevalence of caries. A cross-sectional
epidemiological study in the Northern Alvsborg county", Swedish dental journal, vol.
13, no. 3, pp. 111-123.
Sánchez-García, S., Reyes-Morales, H., Juárez-Cedillo, T., Espinel-Bermúdez, C.,
Solórzano-Santos, F. & García-Peña, C. 2011, "A prediction model for root caries in
an elderly population", Community dentistry and oral epidemiology, vol. 39, no. 1, pp.
44-52.
Sandberg, G.E., Sundberg, H.E., Fjellstrom, C.A. & Wikblad, K.F. 2000, "Type 2 diabetes
and oral health: a comparison between diabetic and non-diabetic subjects", Diabetes
research and clinical practice, vol. 50, no. 1, pp. 27-34.
Saotome, Y., Tada, A., Hanada, N., Yoshihara, A., Uematsu, H., Miyazaki, H. & Senpuku,
H. 2006, "Relationship of cariogenic bacteria levels with periodontal status and root
surface caries in elderly Japanese", Gerodontology, vol. 23, no. 4, pp. 219-225.
Scheinin, A., Pienihäkkinen, K., Tiekso, J. & Holmberg, S. 1992, " Multifactorial modeling
for root caries prediction", Comm dentistry and oral epidemiology vol. 20, pp. 35––37.
Scheinin, A., Pienihäkkinen, K., Tiekso, J., Holmberg, S., Fukuda, M. & Suzuki A. 1994,
"Multifactorial modeling for root caries prediction: 3-year follow-up results",
Community dentistry and oral epidemiology, vol 22, pp. 35––37.
Shah, N. & Sundaram, K.R., 2003, "Impact of socio-demographic variables, oral hygiene
practices and oral habits on periodontal health status of Indian elderly: a communitybased study", Indian journal of dental research, vol. 14, no. 4, pp. 289-297.
Shavers, V.L. 2007, "Measurement of socioeconomic status in health disparities research",
Journal of the national medical association, vol. 99, no. 9, pp. 1013-1023.
Sheiham, A. & Netuveli, G.S. 2002, "Periodontal diseases in Europe", Periodontology
2000, vol. 29, no. 1, pp. 104-121.
Ship, J.A., Pillemer, S.R. & Baum, B.J. 2002, "Xerostomia and the Geriatric Patient",
Journal of the American Geriatrics Society, vol. 50, no. 3, pp. 535-543.
Slade, G.D., Spencer, A.J., Gorkic E. & Andrews, G. 1993, "Oral health status and
treatment needs of non-institutionalized persons aged 60+ in Adelaide, South
Australia", Aust Dent J. vol. 38, no. 5, pp. 373-380.
Slots, J. & Slots, H. 2011, "Bacterial and viral pathogens in saliva: disease relationship and
infectious risk", Periodontology 2000, vol. 55, no. 1, pp. 48-69.
Soikkonen, K., Wolf, J., Närhi, T. & Ainamo, A. 1998. "Radiographic periodontal findings
in an elderly Finnish population", Journal of clinical periodontology, vol. 25, no. 6,
pp. 439-445.
Soskolne, W.A. & Klinger, A. 2001, "The relationship between periodontal diseases and
diabetes: an overview", Annals of Periodontology / The American Academy of
Periodontology, vol. 6, no. 1, pp. 91-98.
Splieth, C., Schwahn, C., Bernhardt, O. & John, U. 2004, "Prevalence and distribution of
root caries in Pomerania, North-East Germany", Caries research, vol. 38, no. 4, pp.
333-340.
Sreebny, L. 1992, "Saliva--salivary gland hypofunction (SGH). FDI Working Group 10",
The journal of the dental association of South Africa, vol. 47, no. 11, pp. 498-501.
Sreebny, L.M. & Schwartz, S.S. 1997, "A reference guide to drugs and dry mouth, 2nd
edition", Gerodontology, vol. 14, no. 1, pp. 33-47.
Stanford, T.W. & Rees, T.D. 2003, "Acquired immune suppression and other risk
factors/indicators for periodontal disease progression", Periodontology 2000, vol. 32,
pp. 118-135.
Steele, J.G., Sheiham, A., Marcenes, W., Fay, N. & Walls, A.W.G. 2001, "Clinical and
behavioural risk indicators for root caries in older people", Gerodontology, vol. 18,
no. 2, pp. 95-101.
Strayer, MS. 1993, "Dental health among homebound elderly", Journal of public health
dentistry, vol. 53, no.1, pp. 12-16.
Sulander, T., Helakorpi, S., Nissinen, A. & Uutela, A. 2004 "Health behaviour and health
among Finnish elderly, spring 2003, with trends 1993––2003", Publications of the
National Public Health Institute B6/2004. Department of Epidemilogy and Health
Promotion. Health Promotion Research Unit. Helsinki: Haka-paino.
Sulkava, R., Wikström, J., Aromaa, A., Raitasalo, R., Lehtinen, V., Lahtela K. & Palo, J.
1985, "Prevalence of severe dementia in Finland", Neurology, vol. 35, pp./1025-1029.
Suominen-Taipale, L., Nordblad, A., Vehkalahti, M., Aromaa, A., (ed) 2008, Oral Health
in the Finnish Adult Population. Health 2000 Survey, the National Public Health
Institute.
Syrjälä, A.M., Ylöstalo, P. & Knuuttila, M. 2010, "Periodontal condition of the elderly in
Finland", Acta Odontologica Scandinavica, vol. 68, no. 5, pp. 278-283.
Syrjälä, A.-M., Raatikainen, L., Komulainen, K., Knuuttila, M., Ruoppi, P., Hartikainen,
S., Sulkava, R. & Ylöstalo, P. 2011, " Salivary flow rate and periodontal infection –– a
study among subjects aged 75 years or older", Oral diseases, 17: 387––392
Syrjälä, A.-M. H., Pussinen, P. I., Komulainen, K., Nykänen, I., Knuuttila, M., Ruoppi, P.,
Hartikainen, S., Sulkava, R. and Ylöstalo, P. 2012a, "Salivary flow rate and risk of
malnutrition –– a study among dentate, community-dwelling older people",
Gerodontology, Epub ahead of print.
Syrjälä, A.-M. H., Ylöstalo, P., Ruoppi, P., Komulainen, K., Hartikainen, S., Sulkava, R.
and Knuuttila, M. 2012b, "Dementia and oral health among subjects aged 75 years or
older", Gerodontology, 29: 36––42
Tanzer, J., Livingston, J. & Thompson, A. 2001, "The microbiology of primary dental
caries in humans", Journal of dental education, vol. 65, no. 10, pp. 1028-1037.
Taylor P, Morin R, Parker K, Cohn D, Wang W 2009, "Growing old in America:
Expectations vs. Reality". A social & demographic trends report, 2009.,
PewResearchCenter.
Thomson, W.M. 2005, "Issues in the epidemiological investigation of dry mouth",
Gerodontology, vol. 22, no. 2, pp. 65-76.
Thomson, W.M., Chalmers, J.M., Spencer, A.J. & Ketabi, M. 1999, "The occurrence of
xerostomia and salivary gland hypofunction in a population-based sample of older
South Australians", Special care in dentistry, vol. 19, no. 1, pp. 20-23.
Tomar, S.L. & Asma S. 2000, "Smoking-attributable periodontitis in the United States:
findings from NHANES III", Journal of periodontology, vol 71, pp. 743-751.
Tillgren, P., Haglund, B.J., Lundberg, M. & Romelsjö, A. 1996, "The sociodemographic
pattern of tobacco cessation in the 1980s: results from a panel study of living
condition surveys in Sweden", Journal of epidemiology and community health, Vol.
50, no. 6, pp. 625-630.
Tilvis, R.S., Lallukka, K.M., Saarela, M., Sairanen, S. & Valvanne, J. 1997, "Prognostic
significance of difficulties in mobility in a five-year follow-up study of four birth
cohorts", Archives of gerontology and geriatrics, vol. 25, no. 3, pp. 311-319.
Turrell, G. 2000, "Income non-reporting: implications for health inequalities research",
Journal of epidemiology and community health, vol. 54, no. 3, pp. 207-214.
Valvanne, J. 1992, The prognostic significance of clinical findings in the elderly, Thesis,
University of Helsinki.
Vehkalahti, M., Paunio, I. & Nyyssönen, V. (eds) 1991, Suomalaisten aikuisten
suunterveys ja siihen vaikuttavat tekijät., Kansaneläkelaitos, Helsinki, Finland.
Vehkalahti, M., Rajala, M., Tuominen, R. & Paunio, I. 1983, "Prevalence of root caries in
the adult Finnish population", Community dentistry and oral epidemiology, vol. 11,
pp. 188––190.
Vehkalahti, M.M. 1987, "Relationship Between Root Caries and Coronal Decay", Journal
of dental research, vol. 66, no. 10, pp. 1608-1610.
Vigild 1988, "Oral hygiene and periodontal conditions among 201 dentate institutionalized
elderly", Gerodontics, vol. 4, no. 3, pp. 140-145.
Vilstrup, L., Holm-Pedersen, P., Mortensen, E.L. & Avlund, K. 2007, "Dental status and
dental caries in 85-year-old Danes", Gerodontology, vol. 24, no. 1, pp. 3-13.
WHO 1997, Oral health surveys. Basic methods, 4th Edition ed, WHO, Geneva.
WHO 1982, A review of current recommendations for the organization and administration
of community oral health services in Northern and Western Europe ––Report of WHO
Workshop. Copenhagen: WHO Regional Office for Europe.
Wierzbicka, M., Petersen, P.E., Szatko, F., Dybizbanska, E. & Kalo, I. 2002, "Changing
oral health status and oral health behaviour of schoolchildren in Poland", Community
dental health, vol. 19, no. 4, pp. 243-250.
Witter, D.J., van Palenstein Helderman, W.H., Creugers, N.H. & Kayser, A.F. 1999, "The
shortened dental arch concept and its implications for oral health care", Community
dentistry and oral epidemiology, vol. 27, no. 4, pp. 249-258.
Wu, A.J. & Ship, J.A. 1993, "A characterization of major salivary gland flow rates in the
presence of medications and systemic diseases", Oral surgery, oral medicine, and oral
pathology, vol. 76, no. 3, pp. 301-306.
Österberg, T., Landahl, S. & Hedegard, B. 1984, "Salivary flow, saliva, pH and buffering
capacity in 70-year-old men and women. Correlation to dental health, dryness in the
mouth, disease and drug treatment", Journal of oral rehabilitation, vol. 11, no. 2, pp.
157-170.
Österberg, T. & Mellström, D. 1986, "Tobacco smoking: a major risk factor for loss of
teeth in three 70-year-old cohorts", Community dentistry and oral epidemiology vol.
14, pp. 367–– 370.
Österberg, T. & Carlsson, G.E. 2007 " Dental state, prosthodontic treatment and chewing
ability - a study of five cohorts of 70-year-old subjects". Journal of oral
rehabilitation, vol. 34, no. 8, pp.553-559.