Download mesiodistal crown dimensions of the permanent dentition in different

Original Article
MESIODISTAL CROWN DIMENSIONS OF THE PERMANENT
DENTITION IN DIFFERENT MALOCCLUSIONS IN SAUDI POPULATION:
AN AID IN SEX DETERMINATION
1
IBAD ULLAH KUNDI
ABSTRACT
The objective of this study was to compare the mesio-distal tooth sizes in Saudi boys and girls
among different malocclusions and to determine whether there is any gender dimorphism present.
The dental casts of 120 subjects (60 boys, 60 girls) between 12 and 16 years of age, with Class I, Class
II div 1, Class II div 2 and Class III malocclusions were used. Each group consisted of 30 subjects.
An electronic digital caliper was used to measure the mesio-distal tooth sizes of the upper and lower
permanent teeth (first molar to first molar). Almost all the teeth mesio distal widths has statistically
significant difference between the malocclusion groups except maxillary right and left first molars
and mandibular right lateral incisor.
Male female comparisons indicate the presence of sexual dimorphism except in the maxillary
and mandibular central and lateral incisors. The mesio-distal sizes of upper right and left second
premolars, upper left canine and first molar were significantly larger in the boys than in the girls.
In the lower arch the mesio-distal widths of right and left canines and right first molar were significantly larger in the boys than in the girls. Statistically highly significant sexual dimorphism shown
by mandibular canines could be used as adjuncts for the determination of gender in individuals, as
well as in groups, such as in mass disasters and archaeological sites.
Key Words: Mesiodistal tooth width, Malocclusion groups, Orthodontic patients, Sexual dimorphism.
INTRODUCTION
Mesiodistal tooth size measurement is an important
step in the diagnostic process, especially in management of complex cases.1 The most common forms of
malocclusion which are crowding and spacing are due
to the discrepancies of the size of the teeth and the size
of the bony bases.2,3 Failure to compensate for these
discrepancies during treatment generally results in
unsatisfactory alignment and occlusion of the teeth
at the end of orthodontic treatment. Crowded dental
arches are associated with the large teeth relative to
the size of the jaws and small teeth are associated
with the spaced dental arches, both conditions can be
localised to a few teeth or affect all teeth.2
Teeth size variations can be caused by multiple
factors such as heredity3, race4, gender5, environment6 and secular changes.7 The genetic basis for this
variation is best explained by a polygenic model of
inheritance by Lundstrom.8 He compared 97 pairs of
Correspondence: Dr Ibadullah Kundi, BDS, FCPS, M Orth
RCS Ed, Assistant Professor Orthodontic, Aljouf College of Dentistry, Aljouf University, Sakaka Aljouf Saudi Arabia
Phone: 00923339172381,
00966542048412
E-mail: [email protected]
Received for Publication:
July 6, 2015
Approved:
July 16, 2015
like-sex monozygotic and dizygotic twins and found a
stronger correlation in mesiodistal tooth size between
monozygotic twins. He concluded that tooth size with
in a given population is determined to a large extent
by genetic factors. Keene9 reported racial differences
in tooth sizes among the American Negroes and their
Caucasian counter parts in caries-free naval recruits.
Before we can know if a tooth is under or oversize it
is necessary to have data on tooth sizes for the relevant
ethnic, gender and malocclusion group.3,10,11 These data
are important for orthodontic clinical diagnosis and
treatment planning and may be useful in forensic dentistry12 and as records marking technological advances,
environmental variations and dietary improvements
affecting tooth size.10 In order to improve the quality
of dental care available, there is a great need for data
on the mesiodistal crown dimensions of the individual
permanent teeth of Saudi population. The main purpose
of the study was to assess whether the diagnostic criteria derived from the mesiodistal crown dimensions of
permanent dentition of other populations can be used
interchangeably in Saudi population. The objectives
of the present study were to compare the mesio-distal
tooth sizes among different malocclusion groups and to
see the gender dimorphism of tooth sizes in different
malocclusion groups.
Pakistan Oral & Dental Journal Vol 35, No. 3 (September 2015)
429
Mesiodistal crown dimensions
METHODOLOGY
In this cross sectional study, mesio-distal tooth sizes
were measured on the dental casts of 120 Saudi adults
(60 boys, 60 girls) . The adults who were between 13
and 22 years of age had Class I (N = 30), Class II div 1
(N = 30), Class II div 2 (N = 30) and Class III (N = 30)
malocclusions. Pretreatment orthodontic casts were
used to obtain the data for this study. Subjects were
included if all permanent teeth, except the third molars,
were present and there was no history of previous orthodontic treatment. Subjects were excluded if a dental
cast had an impression and/or casting artefact affecting
the crowns of the teeth, Clinically evident interproximal
dental caries, an alteration in the number or shape of
the teeth that might affect the diameter of the dental
arch, any oral habit that might influence the dental arch,
experience of orthodontic treatment prior to the start
of examination. Impressions were taken in Alginate
impression material (Lygin Chromatic, Dentamerica)
and were poured in orthodontic plaster within half an
hour to avoid any shrinkage of impressions.
Measuring technique:
Measurements were made directly on the unsoaped
plaster dental casts. All the measurements were done
by the author under natural light. An electronic digital
vernier caliper (Figure I) specially designed for dental
use, (Mitu toyo; Kawasaki, Kanakawa, Japan) with
sharpened points was used to measure the mesiodistal
tooth width.
The procedure for measuring the mesiodistal
tooth width was performed as described by Hunter
and Priest.13 The caliper beaks were inserted from the
facial aspect of the teeth and held perpendicular to the
long axis of the tooth. The beaks were then closed until
gentle contact with the predetermined contact points
of the tooth was made. The measurements included
the mesiodistal width of all the twelve maxillary and
mandibular teeth from the right first permanent molar
to the left first permanent molar.
STATISTICAL ANALYSIS
Statistical analysis was performed using computer
software Statistical Package for Social Sciences (SPSS)
version 18. An analysis of variance (ANOVA) was used to
determine whether statistically significant differences
existed between malocclusion groups and the post hoc
Scheffe test was used to determine which groups were
different from each other. Student’s t-test was used
to investigate gender differences in the samples. The
significance level was set at p < 0.05 for all statistical
tests.
cant difference between the malocclusion groups except
mandibular right and left first molars and mandibular
right lateral incisor. The upper lateral incisors in the
Class II div 1 group were significantly smaller than the
upper lateral incisors in the Class I malocclusion group.
Both upper and lower canines were significantly larger
in the Class I group than the corresponding canines in
the Class II div 1 group. Maxillary second premolars
were significantly larger in Class 1 group than Class
II div 1 group which were again significantly smaller
than Class III group. (Table 1)
In the mandibular arch canines were significantly
larger in Class 1 malocclusion than Class II div 1 malocclusion. Second premolars were significantly larger in
Class II div 1 malocclusion than Class I malocclusion.
First permanent molars were significantly larger in
Class I than Class II div 1 malocclusion and in Class
III malocclusion first molars were significantly larger
than Class II div 1 malocclusion. (Table 1)
To investigate the sexual dimorphism, the malocclusion groups were combined. The data from 60 boys
were compared with the data from 60 girls (Table 2).
The mesio-distal sizes of upper right and left second
premolars, upper left canine and first molar were significantly larger in the boys than in the girls. In the
lower arch the mesio-distal widths of right and left
canines and right first molar were significantly larger
in the boys than in the girls.
DISCUSSION
One of the basic fundamentals with which the
orthodontist has to deal in constructing the denture
is tooth size, specifically the mesiodistal width of the
teeth.14 It is essential for the clinician to know the
size of individual tooth and groups of teeth, to make
an adequate diagnosis and treatment plan.15 The Orthodontic examination may be incomplete without a
careful analysis of the patterns of mesiodistal crown
size relationships. A discrepancy in tooth size may
affect the relationship between the upper and lower
arches and the excellence of the treatment outcome.
We compared the tooth sizes in Saudi population at
Aljouf with Class I, Class II Div 1, Class II Div 2 and
Class III malocclusions and in the boys and girls.
The early permanent dentition provides the best
time for tooth size measurements because there is
RESULTS
The results are given in Tables 1 and 2. Almost all
the teeth mesio distal widths has statistically signifiPakistan Oral & Dental Journal Vol 35, No. 3 (September 2015)
Fig 1: Electronic digital vernier caliper (Mitu-toyo;
Kawasaki, Kanakawa, Japan)
430
Mesiodistal crown dimensions
TABLE 1: COMPARISONS OF THE MESIO-DISTAL TOOTH WIDTHS (MM) IN THE
MALOCCLUSION GROUPS
Arch
Tooth
Upper
1 R
L
2 R
L
3 R
L
4 R
L
5 R
L
6 R
L
1 R
L
2 R
L
3 R
L
4 R
L
5 R
L
6 R
L
Lower
Class I Mean
± SD
9.53 ±0.77 a
9.51±0.73 a
7.81± 0.84 a
7.78 ± 0.85 a
8.58 ±0.72 a
8.58 ± 0.73 a
7.87 ± 0.70 a
7.85 ± 0.72 a
7.98 ± 0.64 a
7.98 ± 0.61 a
7.42 ± 0 .73
7.37 ± 0.60
6.06 ± 0.76 a
6.00 ± 0.55
6.85 ± 0.65
6.85 ± 0.65
7.72 ± 0.62 a
7.73 ± 0.64 a
7.98 ± 0.64 a
7.98 ± 0.60 a
7.42 ± 0.73
7.37 ± 0.60 a
11.73 ± 0.67 a
11.73 ± 0.67 a
Class II div 1
Mean ± SD
9.03±0.67
9.00±0.64 a
7.00±0.64a
7.09±0.62 a1
7.98±0.44 a
7.92±0.53 a
7.32±0.56 a
7.30±0.61 a1
6.79±0.63 a
6.79±0.64 a
10.33±0.69
10.33±0.69
5.65±0.51
5.65±0.51
6.37±0.52
6.53±0.64
7.21±0.40 a
7.21±0.41 a
7.30±0.59 a1
7.27±0.67 a1
7.27±0.62
7.27±0.63 a1
10.98±0.76 a1
10.98±0.76 a1
Class II div 2
Mean ± SD
9.22±0.58
9.22±0.58
7.30±0.89
7.18±0.81 a1
8.35±0.71
8.35±0.73
7.47±0.66
7.37±0.68
7.02±0.62
7.05±0.65
10.53±0.77
10.55±0.74
5.62±0.43 a
5.62±0.43
6.42±0.51
6.47±0.54
7.42±0.64
7.45±0.65
7.65±0.60
7.62±0.61
7.67±0.58
7.62±0.61
11.43±0.68
11.43±0.68
Class III
Mean ± SD
8.83±1.45 a
9.17 ±0.63
7.31±0.81
7.48±0.63
8.28±0.69
8.38±0.56
7.45±0.61
7.39±0.60 a2
7.23±0.64 a2
7.26±0.61 a2
10.42±0.98
10.59±0.69
5.96±0.95
5.72±0.48
6.60±0.56
6.55±0.51
7.54±0.64
7.50±0.65
7.51±0.52
7.58±0.47 a1
7.76±0.62
7.78±0.60 a2
11.51±0.66 a2
11.62±0.55 a2
P
0.03*
0.02*
0.00*
0.00*
0.01*
0.00*
0.00*
0.01*
0.00*
0.00*
0.09
0.07
0.01*
0.03*
0.06
0.00*
0.01*
0.01*
0.00*
0.00*
0.00*
0.00*
0.00*
0.00*
The letters indicate groups significantly different from each other (Scheffe test)
a1: Significantly different from group 1
a2: Significantly different from group 2
* : Significant values
P > 0.05
TABLE 2: GENDER COMPARISON OF THE MESIO-DISTAL TOOTH WIDTHS (mm)
Upper
Lower
Tooth
11
12
13
14
15
16
41
42
43
44
45
46
Male
9.150
7.360
8.393
7.550
7.232
10.633
5.726
6.650
7.667
7.675
7.775
11.567
Female
9.158
7.319
8.110
7.498
6.992
10.427
5.770
6.467
7.278
7.545
7.555
11.317
P
0.962
0.975
0.035*
0.671
0.058*
0.173
0.770
0.089
0.000*
0.176
0.066
0.058*
Tooth
21
22
23
24
25
26
31
32
33
34
35
36
Male
9.300
7.418
8.437
7.475
7.247
10.707
5.842
6.658
7.667
7.692
7.775
11.525
Female
9.150
7.347
8.182
7.478
6.992
10.443
5.842
6.542
7.285
7.533
7.580
11.308
P
0.222
0.616
0.040*
0.979
0.033*
0.050*
0.638
0.294
0.001*
0.263
0.101
0.109
* : Indicates Significant difference
P > 0.05
Pakistan Oral & Dental Journal Vol 35, No. 3 (September 2015)
431
Mesiodistal crown dimensions
generally less attrition and fewer teeth have been
extracted.16 It is also more convenient and accurate
to measure the mesiodistal widths of teeth on study
casts than intra-orally.17 Dunn and Dobzhansky15 have
indicated that although all human beings belong to a
single species, humans inhabiting different parts of
the world and different malocclusions are exposed to
different environments and are not alike. Ajayi et al
found some variations in tooth sizes between gender
and among different racial and ethnic groups.18
In the mandibular arch, the mean mesiodistal crown
dimension of the central incisor was smaller than the
lateral incisor as reported in other studies.15,19 However,
these results do not agree with the findings of Moss
whose approach could have been influenced by a small
sample size and the fact that they used extracted teeth
which were less in number than the complete set of
teeth available from each individual.15
The boys in our study had larger teeth than girls.
This gender difference is supported by previously
published studies on the sizes of teeth in different
populations.3,15,20-23 This is in contrast with the previous
findings on Bangladeshi population where there was
no significant difference between males and females.24
Various theories have been given in the literature
for this sexual dimorphism
According to Moss, it is because of the greater
thickness of enamel in males due to the long period of
amelogenesis as compared to females. However, in females the completion of calcification of the crown occurs
earlier in both deciduous and permanent dentition as
quoted by de Vito.25
Sex chromosomes are also known to cause different
effects on tooth size. The 'Y' chromosome influences the
timing and rate of body development, thus producing
slower male maturation, and acts additively and to a
greater extent than the 'X' chromosome.25 According to
Pratibha et al25, ‘Y’ chromosome has a direct effect on
tooth size, which may be related to a more non-specific
effect of hetrerochromatism or cellular activity.
Kalia26 quoted that according to Townscend, the
difference in size has been attributed to differently
balanced hormonal production between the sexes consequent to the differentiation of either male or female
gonads during the sixth or seventh week of embryogenesis rather than any direct effect of sex chromosome
themselves. According to Lewis et al. there is a low
significant correction between sexual dimorphism of
teeth and body size and it has been supported by Frayer
and Wolpoff.25
Our results showed that sexual dimorphism was
observed for maxillary and mandibular canines and
maxillary second premolars included in the study be-
tween males and females. Highly statistically significant dimorphism was exhibited by only two permanent
maxillary anterior teeth, i.e right and left maxillary
canines. In this study, result of maxillary canine dimorphism was in accordance with Khangura et al27 who
also reported similar findings in their study. Otuyemi
and Noar28 showed dimorphism in maxillary canines
bilaterally.
According to Garn et al22, teeth have behaved in
many ways through the course of evolution, ranging
from reduction of the entire dentition to reduction of
one group of teeth in relation to another. It has been
postulated that in the evolution of primates, canines are
functionally not masticatory but are related to threat
of aggression. A transfer of this aggressive function
occurred from the teeth to the fingers in man. Until
this transfer was complete, survival was dependent on
canines especially in the males. Thus in present day
humans the sexual dimorphism in canines is not mere
coincidence but based on functional activity.29 Another
reason for this dimorphism could be a biologic variation,
which is a characteristic of life and is attributed to
family, genetics and environmental factors.29 Variation
in food resources exploited by different populations has
also been explained as one such environmental cause.25
Our results showed statistically highly significant
sexual dimorphism for mandibular canine as compared
to maxillary canine (Table 2). This corroborates with
the findings of Kaushal et al30 and Garn et al22 who also
reported statistically significant sexual dimorphism for
mandibular canine. However, Minzuno reported that
maxillary canine showed a higher degree of sexual
dimorphism compared to the mandibular canine in a
Japanese population.27 Khangura et al27 quoted various
factors for this dimorphism. They suggested variation
in food resources exploited by different populations as
one such environmental cause. Other authors have
suggested that there could be a complex interaction
between a variety of genetic and environmental factors
that are responsible for dimorphism.
A study conducted by Hashim and Murshi on Saudi
males and females in the age group of 13-20 years, to
determine the teeth in human dentition with the highest likelihood of dimorphism, had found that only the
canines in both the jaws exhibited a significant sexual
difference, while the other teeth did not.31
CONCLUSION
Almost all the teeth mesio distal widths has statistically significant difference between the malocclusion
groups. A higher variability was found in the maxillary
lateral incisor as compared to other teeth. This tooth
should be examined carefully to exclude any major size
and shape discrepancy.
Pakistan Oral & Dental Journal Vol 35, No. 3 (September 2015)
432
Mesiodistal crown dimensions
Our values for mesiodistal crown dimensions for
the present population could be used for treatment
planning regarding space management, operative dentistry and management of malocclusion for the local
population. These conclusions could greatly influence
clinical decision making, and further studies should
be undertaken in this field.
Male female comparisons indicate the presence
of sexual dimorphism. Girls have smaller permanent
teeth than boys. No significant differences were present between male and female in the mesiodistal crown
dimensions of mandibular and maxillary incisors. The
results of the present study revealed that mandibular
canines showed statistically highly significant sexual
dimorphism and could be used as adjuncts for the
determination of gender in individuals, as well as in
groups, such as in mass disasters and archaeological
sites.
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