Download Visual shade differences when bleaching after

Institutionen för Odontologi
Odontologi, Examensarbete/D
(Medicine Magisterexamen i Odontologi)
(Master of Medical Science in Odontology)
Visual shade differences when
bleaching after debonding?
Maria Tyreman Bandhede
Stockholm 2009
Nr 155
Synlig färgskillnad när man bleker efter avbondning?
Sammanfattning
Det är ett allt större intresse för estetik i samhället idag och i takt med detta har
tandblekning blivit allt vanligare. Det har gjorts flertalet studier som tittat på hur
lång tid efter tandblekning som man kan utföra en fyllning alternativt bonda fast
apparatur. Det finns däremot inte några tidigare studier som tittat på hur effekten
av blekningen blir om man bleker tänderna efter att ha haft fastsittande
tandställning.
Syftet med denna pilotstudie var att undersöka om det syntes en färgskillnad på
tandytan där brackets suttit jämfört med omkringliggande emaljyta, efter avslutad
tandblekning.
Patienter som skulle genomgå tandreglering inkluderande extraktion av första
Premolaren i överkäken erbjöds att delta. 5 tänder var inkluderade i denna
pilotstudie. Innan extraktionerna utfördes bondades buttons på tänderna. Efter
avlägsnandet av buttons utfördes tandblekning av de bondade tänderna.
Effekten av tandblekningen registrerades enligt en 3-gradig skala: 1. Ingen synlig
färgskillnad mellan det bondade området och övrig del av tandytan. 2. Synlig
färgskillnad 3. Störande färgskillnad. Utvärderingen utfördes individuellt av både
operatören
samt
fem
anställda
på
Ortodontikliniken
i
Örebro,
2
ortodontiassistenter och 3 tandläkare.
Samtliga bedömde effekten enligt 1. Ingen synlig färgskillnad där brackets suttit.
Studien visar med stor sannolikhet att tandblekning kan utföras på ungdomar efter
fastsittande apparatur är avlägsnad utan att orsaka färgskillnader där brackets har
suttit.
Handledare: Docent Bertil Lennartsson, Ortodontikliniken, Örebro
Bihandledare: Odont. Dr Anette Fransson, Ortodontikliniken, Örebro
Examinator: Professor Eva Hellsing, Avdelningen för Ortodonti, Institutionen för
Odontologi, Karolinska Institutet, Stockholm
2
Visual shade differences when bleaching after
debonding?
Abstract
There is an increasing interest for the aesthetics in the society today and as part
of that tooth bleaching has become more and more common. Several studies
have looked at how long time after tooth bleaching that a composite restoration
can be performed or the teeth can be bonded. But there are no previous studies
looking in to the bleaching effect on previously bonded teeth.
The purpose of this pilot study was to examine if there was a shade difference
where the bracket had been located compared to the enamel surface around,
after completed tooth bleaching.
Patients that were about to have orthodontic treatment including extractions of the
first maxillary premolars were offered to participate in the study. 5 teeth were
incorporated in this pilot study. Before the extractions were performed, buttons
were bonded at the first premolars. After the buttons were removed the tooth
bleaching was performed. The effect of the tooth bleaching was registered
according to a 3-grade scale: 1. No visible shade difference between the
previously bonded area and the surrounding area. 2. Visible shade
difference. 3. Offending shade difference. Judgements were made individually by
both the operator and five persons at the Department of Orthodontics, Örebro, 2
orthodontic assistants and 3 dentists. Both the operator and the five persons
judged the effect according to 1. No visible shade difference at the previous
bracket location.
The study shows with great possibility that tooth bleaching in adolescents can be
performed after orthodontic treatment without any shade difference at the previous
bracket location.
Key words: Orthodontic treatment, tooth bleaching, shade difference
3
Introduction
There is an increasing interest for the aesthetics in the society today. There are
several advertisements in the magazines and on the advertisement stands about
how
to become successful and how to get a beautiful smile. As a part of that increased
interest, tooth bleaching has become more and more popular and common, also
among young people, though many young people probably have one of the
lightest shades on their teeth already. After completed orthodontic treatment it is
likely that the patients have a bigger awareness of their teeth and they are often
keen to keep them look nice. It is therefore also likely that some of the young
people experiencing tooth bleaching have received an orthodontic treatment
earlier in their lives.
History
The wish for a white smile is nothing new. Mc Laughlin & Freedman reported that
in the 14th century doctor Guy de Chauliac suggested a serial of oral hygiene
instructions which included the following tooth bleaching procedure: “clean the
teeth with a mixture of honey, burnt salt and vinegar”. Guy de Chauliacs
recommendation was active for almost 300 years. Patients interest for tooth
bleaching increased and the first tooth bleaching material for vital teeth came in
1877 when Chappel suggested oxalic acid as a material for tooth bleaching (Mc
Laughlin & Freedman 1991).
4
Background
There are several reasons for discoloration of the teeth, either internal or external
(Mc Laughlin et al. 1991, Greenwall 2001).
Internal factors
This kind of discoloration is because of a change of colour in the inner structure,
often referred to as genetic reasons. There can either be discolorations
during the odontogenesis or during the post-eruptive period.
Odontogenesis period
Amelogenesis and dentinogenesis imperfecta can disturb both the deciduous and
the permanent dentition. So can also early medication with tetracycline and high
intake of fluoride. During the mineralization of the permanent dentition the
inorganic part of the tooth structure can be penetrated by colouring matter from for
example jaundice.
Tooth bleaching has been used as a treatment for medical reasons for a long
time, for example because of amelogenesis and dentinogenesis imperfecta and
fluorosis,. When treating fluorosis the white spots don’t disappear but the tooth
structure around gets lighter and the shade difference is decreased (Haywood &
Berry 2001, Goldstein 1998).
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Posteruptive period
The organic part of the tooth structure can be discoloured by age factors. The pulp
chamber decreases in size when you get older and thereby the secondary dentine
gives the tooth a more yellow-brown colour. Discoloration can also depend on for
example long time purpose to tobacco and colouring matter from food and
beverages.
External factors
Discoloration due to external factors can depend on use of tobacco or colouring
by food, beverages and medicines. The degree of discoloration is related to time
of exposure and intensity of the discolouration subjects.
Bleaching procedures of today
Bleaching products of today contain either hydrogen peroxide or carbamide
peroxide. When carbamide peroxide breaks down it results in 1/3 hydrogen
peroxide and 2/3 urea. The urea stabilizes the hydrogen peroxide and increases
the pH. Most carbamide peroxide gels have a pH around 6-7 (Price, Sedarous &
Hiltz 2000).
The bleaching process involve that hydrogen peroxide penetrates the hard
surface of the tooth as an oxidation component. This is possible because
hydrogen peroxide is of low molecular weight and is a small molecule, and can
therefore penetrate the tooth substance through the enamels organic matrix.
Hydrogen peroxide releases water and free oxygen radicals and large, strongly
coloured molecules become smaller and thereby lighter molecules. The dentins
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basic colour is also considered getting lighter (Haywood et al. 2001, Goldstein
1998). An acid-etch-technique with 30-40% phosphoric acid is used prior to
bonding. This provides an enamel surface which is characterized by a profuse
formation of micro porosities. Monomers can then penetrate the micro porosities
to form resin tags for micromechanical retention.
If looking at bleached enamel with a scanning electron microscopy there is a
definite change in the surface texture of bleached enamel compared to
unbleached enamel. Bleached enamel appears to have a partially etched surface
with many shallow depressions and an increase in surface porosity. When etching
previously bleached enamel the
surface appears overetched in the scanning
electron microscopy and the surface lacks a uniform appearance with loss of
prism boundaries.
There are several different methods for tooth bleaching but the most common
techniques are bleaching at home with a splint in which bleaching material is
placed and the splint is used during the night for about 1-2 weeks until adequate
bleaching effect is achieved. The other way is clinical bleaching. The bleaching is
performed at one appointment at the dental clinic after a rubber dam is in place
over the teeth in order to protect the gingiva.
According to laboratory studies composite fillings change concerning colour, micro
hardness and structure, due to tooth bleaching with carbamide peroxide, but the
changes are not significant (Turker & Biskin 2002, Bailey & Swift 1992, Canay &
Cehreli 2003). Because of remnants of oxygen in the tooth structure the bonding
strength between enamel and composite is considered to be reduced when
performed immediately after the tooth bleaching process. After 1-2 weeks the
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bonding can be performed without negative effect on the polymerisation
(Haywood et al. 2001, Titley, Torneck, Smith & Adibfar 1988, Titley, Torneck &
Ruse 1992, McGuckin, Thurmond & Osovitz 1992, Garcia-Godoy, Dodge,
Donohue & O'Quinn 1993).
When bonding orthodontic brackets on the teeth, the surface is etched with 37%
phosphoric acid. The resulting etch pattern is characterized by the profuse
formation of micro porosities to form resin tags that provide micromechanical
retention (Perdigao, Frankenberger, Rosa & Breschi 2000). At debonding the
brackets, the composite remnants are polished from the enamel surface with a
carbide bur. Since the resin adheres into the tags a lot of extra enamel would
have to be lost if all the resin tags were to be removed.
Earlier studies of bond strength after bleaching
Several studies have looked at the bonding strength between the composite
resin and the previously bleached enamel. The conclusions varies from different
studies.
Josey et al (Josey, Meyers, Romaniuk & Symons 1996) examined the effect of a
vital bleaching procedure on enamel surface morphology and the shear bond
strength. Electron microscopy showed a definite change in the surface texture of
the bleached enamel surface, as the enamel appeared overetched. The mean
bond strength tended to be lower for bleached enamel surface, but no significant
difference was noted.
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Dishman et al (Dishman, Covey & Baughan 1994) studied the bond strength
immediately after, 1 day after, 1 week after and 1 month after bleaching. They
found a significant lower bond strength when bonding immediately after tooth
bleaching. The bond strength did however return to normal values after 1 day and
remained normal for at least 1 month. Scanning electron microscope showed an
apparent decrease in number of resin tags present in the enamel/composite
interface in the group bonded immediately. He concluded that the likely reason for
lower bond strength immediately after tooth bleaching was polymerization
inhibition of the resin bonding agent.
Lai et al (Lai, Tay, Cheung, Mak, Carvalho, Wei, Toledano, Osorio & Pashley
2002) also suggested that the reduction in resin-enamel bond strength could be
due to the delayed release of oxygen as mentioned earlier, which affects
polymerization.
Sung et al (Sung, Chan, Mito & Caputo 1999) studied the bond strength of
composite to enamel bleached with 10% carbamide peroxide when comparing 3
different dental bonding agents, alcohol based and acetone based. With the
alcohol based bonding agents no statistical difference concerning bond strength
was found between the bleached and unbleached enamel. However, the bond
strength of composite to bleached enamel with acetone based bonding was
significantly lower than to unbleached enamel. They found that the bond strength
was dependent on the bonding agent used and recommended alcohol based
bonding agent when bonding immediately after bleaching.
Oltu and Gürgan (Oltu & Gurgan 2000) on the other hand found that the
concentration of carbamide peroxide was decisive for the bond strength. When
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comparing 10, 16 and 35% carbamide peroxide concentrations, only 35%
carbamide peroxide showed lower bond strength. As a result they recommended
the use of lower concentrate of carbamide peroxide.
Bishara et al (Bishara, Oonsombat, Soliman, Ajlouni & Laffoon 2005) didn’t find a
significant effect on the bond strength when bonding orthodontic brackets
occurred 7-14 days after bleaching. Because of the large variations in bond
strength values one week after bleaching he still recommends to wait at least 2
weeks after bleaching before bonding orthodontic brackets.
Aim
There are several studies looking at the bond strength after completed tooth
bleaching but to our knowledge no studies have looked at what happens when
bleaching is performed after bonding. When bonding a bracket the tooth surface is
first etched with phosphoric acid. Then a resin is applied on the etched surface
before the bracket is bonded with composite. A mechanic retention is
accomplished when the resin penetrates the enamel tags. When debonding the
tooth surface is polished in order to remove the composite remnants but the
enamel tags might still be blocked by the residual resin
Will the hydrogen
peroxide still penetrate that area and/or diffuse from the surroundings, or will the
blocked tags result in a visible shade difference after the bleaching is completed?
Since the patients treated with fixed appliances usually are young they have not
experienced tooth bleaching before the orthodontic treatment. Therefore, in
contrary to earlier studies, it seems more important to study the bleaching effect
after the fixed appliance is removed.
10
The purpose of this study is to see whether the enamel tags that are blocked with
resin will give a visible shade difference after tooth bleaching is completed. The
hypothesis is that the blocked tags will leave a visible shade difference.
11
Materials and Methods
In vitro evaluation
Before this pilot study started a reconnoitring in vitro study was performed. The
reason for this was to be able to find possible problems with the study plan and to
be able to correct this before the study started. Six extracted teeth were collected
and stored in distilled water and a similar bleaching procedure as in the present
study was performed on the extracted teeth.
Study Outline
Patients at the Department of Orthodontics who should have orthodontic therapy
including extractions of the first premolar were offered to participate in the study.
The study protocol consisted of three extra visits before the orthodontic treatment
could start.
Ethical considerations
An ethical approval for the study was accepted by the ethical committee in
Uppsala.
Before the patients entered the study the patients received oral and written
information and the parents/legal guardians signed a written consent. The patients
had agreed to the study as well. The patients did not receive any contribution for
participating in the study.
12
Patients
Since no previous studies are reported on this subject, this study was performed
as a pilot study. We estimated that a sample size of 20 teeth was desired to be
able to perform a fully adequate study but in this pilot study we had to be satisfied
with 5 teeth. Patients, living in the city of Örebro, Sweden, and about to be treated
with maxillary first premolar extraction at the Department of Orthodontic in Örebro,
Sweden were offered to participate in the study. The patients offered to participate
were all adolescents and both boys and girls were asked. The reason of just
including patient’s from the city of Örebro and not the whole county was to make
sure that the extra visits for the study might be easier than if the distance to the
orthodontic clinic would be longer.
The inclusion criterias were patients who were about to be treated with extraction
of at least one upper first premolar. Exclusion criterias were caries that affected
the buccal surface or discoloration that effected the buccal surface.
Five teeth from three patients were included in the study. There were three girls,
13,14 and 17 years old when the study was performed. Another eleven patients
were offered to participate but did not want to be included in the study.
The buttons were bonded randomly on the mesial or distal half of the buccal
surface. At one tooth the button was bonded on the mesial half of the buccal
surface and at four teeth the button was bonded on the distal half (Table 1).
13
Table 1. Number of teeth that were bonded with a button and which surface the button was
bonded at.
1
2
3
4
5
Tooth
24
14
24
14
24
Surface
distal
distal
distal
distal
mesial
_________________________________________________________________
__
Before the ordinary orthodontic treatment started patients included in the study
had 3 visits at the orthodontic clinic. At the first visit an examination was
performed containing visual inspection and photographs of the teeth that were
topical for the study. The photographs were taken with an Olympus E-510 IS and
they were used to evaluate that no caries or other discoloration that affected the
buccal surface existed. All photographs were taken by the same person (MTB). At
the same visit, the upper first premolars that were to be extracted were polished
with pumice. The surface was then etched with Ultra-Etch 37% phosphoric acid,
Ultradent, for 20 seconds. After that the surface was rinsed with water for 20
seconds and then dried with air-syringe. Transbond XT primer, 3M Unitek, was
applied to the etched surface, dried with air-syringe for 1-2 seconds and then lightcured for 10 seconds. A button was then bonded to the etched surface with
Transbond XT 3M Unitek, and light-cured for 20 seconds. The buttons were
randomly bonded on the mesial or distal half of the buccal surface. The reason for
bonding on either the mesial or the distal half of the tooth is that the other half of
14
the tooth was used as a control. Instead of a split mouth test we made a split tooth
test.
Since an ordinary bracket was too big to be bonding on one half of the buccal
surface and would not get a sufficient fit, a button was used instead. The button
was small enough to be able to fit and the vault fitted the buccal surface well.
After the bonding, the teeth were photographed again. Photograph number two
was to be used later as a key if there was a need to see exactly where the button
had been bonded. These photographs were not to be used before the study was
completed and after the evaluations of the effects.
Within 3-7 days the patients came back for a second visit. The buttons were
debonded whereas the remaining composite was removed with a carbide bur,
Busch 23R ISO 016, Nordenta. The teeth were then photographed again.
The last visit was after another 3-7 days when the patients came back for the
tooth bleaching. The reason for waiting a few days was that the enamel surface
would get a chance to recover after the bonding and debonding procedure. A
rubber dam was applied to the teeth that were about to be treated. Thirty-five %
Opalescence Xtra, Ultradent gel, 1 mm thick layer, was applied on the buccal
surface. The surface was then light activated for 2x20 seconds. After 10 minutes
the gel was removed, first by vacuum suction only and then the remaining gel was
removed by water rinse and suction. The procedure was performed 3 times after
each other in order to get a thorough effect.
After the bleaching procedure the teeth were judged by the operator (MTB)
according to the following scale:
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1. No visible shade difference between the previously bonded area and the
surrounding area
2. Visible shade difference
3. Offending shade difference
All teeth were then photographed one last time. All photographing took place in
the same room, with the same camera, with the same light conditions and by the
same photographer (MTB).
The photographs taken after the completed bleaching treatment were also to be
judged by a group of five persons using the same shade difference scale as
mentioned earlier. This group consisted of 2 orthodontic assistants and 3 dentists.
The participants were blinded to earlier results and they were to give individual
judgements.
Statistics
No power-analysis was performed for this pilot study.
Descriptive statistics will be used and the data will be worked at with SPSS 15.0,
SPSS Inc. 444 North Michigan Av Chicago Il. USA. The results will be presented
in tables with frequency and median values.
16
Results
In the in vitro study that was performed before the present study six extracted
teeth were treated. They were judged by the operator but no visible shade
difference was detected at the previous bracket location.
The five teeth that were included in the study were bonded with buttons as
described in Table 1.
The operator examined and judged the teeth after completed tooth bleaching
according to a visual shade difference scale: 1. No visible shade difference
between the previously bonded area and surrounding area.
2. Visible shade
difference
3. Offending shade difference.
No visible shade difference was detected at the previous bracket location.
The photographs of the five teeth after completed tooth bleaching were also
judged by a group of five employees, 2 orthodontic assistants and 3 dentists, at
the Department of Orthodontics in Örebro according to the same scale. (Figures
1-5) The judgements were unanimous for all 5 teeth and they were all registered
as: 1. No visible shade difference between the previously bonded area and the
surrounding area.
17
Figure 1. Tooth number 1 (24) in the study, after completed bleaching procedure
Figure 2. Tooth number 2 (14) in the study, after completed bleaching procedure
Figure 3. Tooth number 3 (24) in the study, after completed bleaching procedure
18
Figure 4. Tooth number 4 (14) in the study, after completed bleaching procedure
Figure 5. Tooth number 5 (24) in the study, after bleaching procedure
19
Discussion
There are a large number of studies looking at the bond strength after tooth
bleaching and how long time after completed tooth bleaching that a composite
restoration or bonding procedure can be performed (Josey et al. 1996, Dishman et
al. 1994, Lai et al. 2002, Sung et al. 1999, Oltu et al. 2000, Bishara et al. 2005).
Today the recommendations are that one should wait for 2 weeks after completed
tooth bleaching before making a composite restoration or bonding the teeth
(Bishara et al. 2005, Garcia-Godoy et al. 1993, McGuckin et al. 1992, Titley et al.
1992, Titley et al. 1988, Haywood et al. 2001).
On the other hand no previous studies have been found looking at the bleaching
effect on previously bonded teeth. The young patients receiving orthodontic
treatment have usually not experienced tooth bleaching before the fixed
appliance. Therefore it seems important to perform this study looking at the tooth
bleaching effect after removal of the fixed appliance in stead of before.
Normally an orthodontic treatment lasts about 18 months but in this study the
buttons were removed after 3-7 days. Since the resin penetrates the etched
surface immediately at the bonding performance the results shouldn´t be affected
by the time difference.
Unfortunately it was hard to find patients who wanted to participate. According to
the plan the study was to consist of 20 teeth but it was not possible to collect more
than 5 teeth. Eleven patients were offered to participate but did not want to be
included in the study. A lot of the patients said that there were so many
appointments in the beginning of the treatment anyway so they didn’t want to be
away from school more than necessary.
20
None of the patients received a contribution for participating in the study but
maybe it had been an increased interest if a contribution had been offered.
Even if there were not as many patients participating in the study as had been
planned, the results from the study are unanimous and are all pointing in the same
direction. The results of the previous in vitro test also gave the same results as in
the pilot study.
The buttons were bonded randomly on the mesial or distal half of the tooth and in
this study 4 out of 5 buttons were bonded on the distal half of the tooth. There is a
bigger risk for dark shades on the distal half of the tooth and it is harder to get a
correct view with the camera. That might be a reason for not seeing a shade
difference in the photographs after the bleaching procedure was completed.
However, the results were probably not influenced by the randomisation because
it was possible to take the photographs from a good angle. The possibility of
getting a good camera angle and a good judgement was the reason for including
only the first premolar and not both the first and the second premolar in the study.
The study plan was to use descriptive statistics and show the results in tables with
frequency and median values. Since so few teeth were incorporated in the study it
was not possible to use tables and descriptive statistics.
This pilot study was only performed at adolescent teeth since adolescents are the
most common orthodontic patients. Adolescents however normally have rather
light teeth from the beginning. Had the results been different if adults had been
incorporated in the study? Adults normally have a darker shade on the teeth
compared to adolescents. If the enamel tags are blocked from the resin and the
bleaching material can not penetrate or diffuse the area, that would make it more
21
likely to see a greater shade difference after completed tooth bleaching
procedure.
There might have been a difference if another 15-20 adolescent teeth had been
included in the study. However, the results from this pilot study are pointing in the
same direction. It is therefore likely that tooth bleaching can be performed in
adolescents after completed orthodontic treatment without leaving a visual shade
difference at the location of the previous brackets.
22
Conclusion
•
Further studies must be performed to be able to draw a secure conclusion
•
So far it seems likely that tooth bleaching can be performed in adolescents
after completed orthodontic treatment without leaving a visual shade
difference at the location of the previous brackets.
Acknowledgements
I would like to thank my supervisors during this study, associate professor Bertil
Lennartsson and D.D.S, PhD Anette Fransson, for their support during the work
and to encouraging me to do this research project.
23
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