Ali Final.doc


J Bagh College Dentistry                    Vol. 26(2), June 2014                        Discoloration of  
   

 
 

Orthodontics, Pedodontics and Preventive Dentistry 125 
 

Discoloration of aesthetic bracket by mouth washes 
 
Ali Mohammed Al-Attar, B.D.S., M.Sc. (1) 
 
ABSTRACT 
Background: The present study aimed to determine the influence of the different types of mouth wash on 
discoloration of different orthodontic ceramic, sapphire brackets and adhesives.  
Materials and methods: The sample composed of 120 ceramic brackets and 120 sapphire brackets, the brackets 
were divided according to bond material into three groups of 40 brackets include unbounded brackets, chemically 
cured (no-mix) bonded brackets and Light cured bonded brackets all these groups were further subdivided 
according to mouth wash type into three groups with 10 brackets each which include; Listerine, cetrimide, 
chlorhexidine 0.2%, and one control group which immersed in artificial saliva;  then Staining measurements were 
performed with UV-Visible spectrophotometer . 
Results and conclusions: all types of mouth wash cause staining, this effect was higher in ceramic than sapphire 
bracket and for no-mix than light cure bond bracket complex; the amount of staining low in Listerine, intermediate in 
cetrimide, high in chlorhexidine for all bracket-bond complex. 
Key words: Discoloration, aesthetic bracket, mouth wash. (J Bagh Coll Dentistry 2014; 26(2): 125-130). 

  صةالخال
  0غسول الفم على تلون الحاصرات التقومیة الخزفیة والیاقوتیة وكذللك اللواصقھدف ھذه الدراسة تحدید تأثیر انواع مختلفة من : الخلفیة

ث مجموعات حاصرة تقومیة یاقوتیة، قسمت  ھذه الحاصرات أعتمادا على نوع الالصق الى ثال 120حاصرة تقومیة خزفیة و    120تم أستخدام  : المواد والطرق
حاصرة تقومیة وھي مجموعة الحاصرات التقومیة غیر المرتبطة بالصق، مجموعة الحاصرات التقومیة المرتبطة بالالصق غیر المعتمد على  40تضم كل مجموعة

ثالث مجامیع اعتمادا نوع غسول المزج ، مجموعة الحاصرات التقومیة المرتبطة بالالصق الضوئي التصلب،ثم قسمت كل مجوعة من ھذة المجامیع الثالثة الى 
  .أستخدم جھاز المطیاف الضوئي لقیاس تلون الحاصرات التقومیة،  ومجموعة رابعة حاكمة غمرت في اللعاب الصناعي) لسترین،سترماید،كلورھكسیدین(الفم

اصرات التقومیة الخزفیة من الیاقوتیة وفي الالصق غیر جمیع انواع غسول الفم سبب تلون الحاصرات التقومیة،ھذا التأثیر اعلى في الح:النتائج واالستنتاجات
  .التلون كان قلیلال بسب غسول اللسترین متوسط  في السترماید،عالیا في الكلورھكسیدین.المعتمد على المزج من الالصق الضوئي التصلب 

 .التلون، الحاصرات التجملیة، غسول الفم :الكلمات المفتاحیة
 

INTRODUCTION 
As the numbers of adults seeking orthodontic 

treatment has increased, tooth-colored brackets 
were introduced to meet the demand for more 
esthetic appliances.(1) Optical properties such as 
color stability of esthetic brackets has clinical 
implications for long-term color matching with 
the underlying teeth. The early plastic brackets 
were made of polycarbonate and plastic molding 
powder, which take up water and change color 
during service. Therefore, these brackets did not 
last long because of discoloration, fragility, and 
breaking under stress. (2-5) Advanced types of 
reinforced plastic brackets such as stainless steel 
slot inserts and composite resin brackets have 
been introduced since then.(6) Brackets made of 
polycrystalline ceramic and monocrystalline 
sapphire became widely available in the mid 
1980s.(7-9) Ceramic brackets combined the 
esthetics of plastic brackets and the reliability of 
metal brackets. These brackets provide excellent 
color fidelity, and resist staining and 
discoloration.(10) 

  There are internal and external causes for the 
discoloration of aesthetic brackets; External 
discoloration can be caused by food dyes and 
colored mouth rinses, material, e.g. the polymeric 
structure or filler content, and surface roughness 
play a decisive role in the extent of discoloration 
caused by diverse substances. (11)  
(1)Lecturer. Department of Orthodontics. College of Dentistry, 
University of Baghdad. 

The amount of color change can be influenced 
by a number of factors including oral hygiene, 
water sorption, and incomplete polymerization. 
The reason for internal discoloration can be found 
in UV irradiation and thermal energy. UV light is 
able to induce physico-chemical reactions in the 
polymer, which cause irreversible color changes 
of the brackets. Heat, acids, alkalis, oxygen, 
abrasion, enzymes, and radiation can all cause the 
chemical breakdown of esthetic brackets.(12) 

As to the color stability of ceramic brackets, it 
has been reported that monocrystalline and 
polycrystalline ceramic brackets resist staining or 
discoloration from any chemical substance likely 
to be encountered in the mouth; (10) However, 
ceramic brackets in the oral environment can be 
affected by color pigments in tea, coffee, and 
mouth wash.(13) 

One of the measures that help to ensure self 
maintenance of good oral hygiene is the use of 
mouthwashes. These mouthwashes may be 
fluoridated or non-fluoridated. The use of 
fluoridated mouth washes aims mainly to reduce 
the effects of enamel demineralization, while the 
other non fluoridated mouthwashes –the subject 
of this study- act in a major way as an anti-plaque 
agents (14,15). 

The aim of the present study was to determine 
the influence of the different types of mouth wash 
on discoloration of different orthodontic ceramic, 
sapphire brackets and adhesives.  
 



J Bagh College Dentistry                    Vol. 26(2), June 2014                        Discoloration of  
   

 
 

Orthodontics, Pedodontics and Preventive Dentistry 126 
 

MATERIALS AND METHODS 
Two types of orthodontic bracket were used; 

ceramic brackets (Reflection©) and sapphire 
(Pure©), also two types orthodontic bonding 
system were used chemically cure (no-mix) and 
light cure, all above materials supplied from 
Ortho Technology/USA. Mouthwashes include 
Listerine (Pfizer, USA), cetrimide 
(Pharcopharmaceuticals, Egypt) and 
chlorhexidine 0.2%, (GlaxoSmithKline (gsk), 
UK). 
 
Bonding procedure 

The sample composed of 120 ceramic brackets 
(Reflection©) and 120 sapphire brackets (pure©), 
the brackets were divided according to bond 
material into three groups of 40 brackets: 

• Unbounded brackets which were not 
bonded to any bond materials. 

• Chemically cured (no-mix) bonded 
brackets in which the brackets were 
bonded using chemically cured adhesive 
resin (no-mix). 

• Light cured bonded brackets in which the 
brackets were bonded using light cured 
adhesive resin. 

The ceramic and sapphire brackets were 
bonded with a chemically cured (no-mix), light-
cured orthodontic adhesive as follow: 
• Resilience Primer® was applied by brush on 

each bracket base or Resilience light cure 
Primer® used with Resilience® Light-Cure 
orthodontic adhesive.   

• A small amount of the adhesive paste was 
applied onto the bracket base, and then by 
using a clamping tweezers the bracket was 
placed lightly onto a horizontal flat plastic 
plate mounted on the table of surveyor (Dent 
aurum, Germany) covered by a celluloid strip 

to facilitate detachment of the bracket–
adhesive complex with a recovery of the set 
material . 

•  A constant load of two hundred grams was 
placed on the bracket to ensure a uniform 
thickness of the adhesive, the load fixed to the 
upper part of the vertical arm of the surveyor, 
a surveyor rod was fixed in the lower part of 
the vertical arm of the surveyor and put it in 
contact with the bonded bracket, excess 
adhesive was removed from around the 
bracket base with a sharp scalar.  

• The visible light-cured adhesive specimens 
were photopolymerized with a light-curing 
unit (woodpecker Co., China); the light guide 
of curing light unit was directed toward the 
bracket, the light shined through the bracket 
for 20 second. 

 
The bonded brackets were allowed to bench 

set for 24 hr to ensure complete polymerization of 
adhesive  material, then after setting; the celluloid 
strips were removed and the resultant bracket-
bonded adhesive were flat. 
 
Immersion in mouth wash 

Unbonded and bonded brackets were further 
subdivided according to mouth wash type into 
three groups with 10 brackets each which include 
Listerine, cetrimide, chlorhexidine 0.2%, and one 
control group which immersed in artificial saliva 
fig. (1). The immersion procedure was done by 
positioned each bracket on a black rectangular 
cardboard (30×11×0.2 mm) with central window, 
the cardboards were numbered and using the 
number of the card as a reference ,The specimens 
then immersed in mouth wash contained in inert 
plastic containers for one hours at 37˚C in the 
incubator (16). 

Figure 1: Organization of sample 
 



J Bagh College Dentistry                    Vol. 26(2), June 2014                        Discoloration of  
   

 
 

Orthodontics, Pedodontics and Preventive Dentistry 127 
 

Assessment of staining   
The samples were taken out of the immersion 

media; then Staining measurements were 
performed over the 800 to 200 ŋm visible 
wavelength range with UV-Visible 
spectrophotometer (T6UV, Korea) fig. (2). The 
chamber of the spectrophotometer was opened, 
and then the black rectangular cardboard with 
bracket positioned in central window put inside 
cubit of the spectrophotometer fig. (3), then the 
chamber was closed and the machine was given 

the order to start scanning starting from 800ŋm 
wavelength in the infra-red zone to 200ŋm 
wavelength in the UV zone passing through the 
entire visible spectrum.  

The light passes through the sample; then the 
intensity of the remaining light was measured 
with a light sensor, the results appeared as a graph 
from which the amount of light absorption was 
plotted and the amount of absorbed light at a 
345ŋm wavelength visible light was obtained and 
used in the later statistical analysis.  

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Statistical analysis 
1. Descriptive statistics: including mean, 

standard deviation, and standard error.  
2. Inferential statistics: including: One way 

analysis of variance (ANOVA) to test any 
statistically significant difference among the 
light absorption of groups and least significant 
difference (LSD) to test any statistically 
significant differences between each two 
subgroups when ANOVA showed a statistical 
significant difference within the same group. 

Significance for all statistical tests was 
predetermined at P ≤ 0.05. 

 
RESULTS 

Descriptive statistics show that light absorption 
increase when immersed bracket in mouth wash, 
light absorption was higher in ceramic than 
sapphire bracket and for no-mix than light cure 
bond bracket complex; the amount of light 
absorption low in Listerine, intermediate in 
cetrimide, high in chlorhexidine for all      bracket-
bond complex types (table 1) 

 
Table 1:  Descriptive statistics of the amount of light absorption by different bracket groups in 

different mouth washes 

 
Ceramic brackets 

There was significant difference among all 
group of ceramic brackets immersed in different 

types of mouth wash except unbounded control – 
Listerine and Listerine- cetrimide groups show 
non- significant difference by LSD test (table 2). 

 
 

Bracket Control Listerine Cetrimide Chlorhexidine Mean SD Mean SD Mean SD Mean SD 

Ceramic 
Unbounded 2.080 0.0043 2.088 0.0044 2.121 0.012 2.251 0.0461 

+No-mix 2.143 0.0280 2.238 0.525 2.347 0.042 2.519 0.0463 
+Light cure 2.123 0.0127 2.199 0.049 2.328 0.069 2.449 0.0631 

Sapphire  
Unbounded 2.073 0.0064 2.081 0.0077 2.119 0.0129 2.193 0.0300 

+No-mix 2.1336 0.0279 2.211 0.494 2.300 0.0411 2.503 0.0486 
+Light cure 2.1134 0.1333 2.185 0.0487 2.292 0.0727 2.439 0.0599 

Figure 2: UV-Visiblespectrophotometer 
(T6UV, KOREA). 

 

Figure 3: Black rectangular cardboard 
with bracket positioned in central window 
put inside cubit of the spectrophotometer. 
 



J Bagh College Dentistry                    Vol. 26(2), June 2014                        Discoloration of  
   

 
 

Orthodontics, Pedodontics and Preventive Dentistry 128 
 

Table 2: Difference in the amounts of light absorption of ceramic brackets immersed in different 
mouth washes 

Brackets ANOVA(df=39) LSD F-test p-value Mouth wash Mean difference p-value 

Unbounded 108.72 0.000 * 

Control 
Listerine -0.0060 0.746 

Cetrimide -0.041 0.028* 
Chlorhexidine -0.1702 0.000* 

Listerine Cetrimide 
-0.035 0.060 

Chlorhexidine -0.164 0.000* 
Cetrimide Chlorhexidine -0.129 0.000* 

Ceramic +No-mix 138.04 0.000 * 

Control 
Listerine -0.046 0.000* 

Cetrimide -0.203 0.000* 
Chlorhexidine -0.375 0.000* 

Listerine Cetrimide 
-0.108 0.000* 

Chlorhexidine -0.281 0.000* 
Cetrimide Chlorhexidine -0.172 0.000* 

Ceramic +Light cure 72.48 0.000 * 

Control 
Listerine -0.076 0.000* 

Cetrimide -0.205 0.000* 
Chlorhexidine -0.326 0.000* 

Listerine Cetrimide 
-0.128 0.000* 

Chlorhexidine -0.249 0.000* 
Cetrimide Chlorhexidine -0.121 0.000* 

 
*significant 

 
Sapphire brackets 

 There was significant difference among all 
group of sapphire brackets immersed in different 

types of mouth wash except unbounded control – 
Listerine group show non- significant difference 
by LSD test (table 3). 

 
Table 3: Difference in the amounts of light absorption of sapphire brackets immersed in 

different mouth washes 
Brackets ANOVA(df=39) LSD F-test p-value Mouth wash Mean difference p-value 

Unbounded 101.37 0.000 * 

Control 
Listerine -0.0076 0.679 

Cetrimide -0.0459 0.014* 
Chlorhexidine -0.1192 0.000* 

Listerine Cetrimide 
-0.0382 0.04* 

Chlorhexidine -0.1115 0.000* 
Cetrimide Chlorhexidine -0.0733 0.000* 

Sapphire +No-mix 139.50 0.000 * 

Control 
Listerine -0.0776 0.000* 

Cetrimide -0.1669 0.000* 
Chlorhexidine -0.3698 0.000* 

Listerine Cetrimide 
-0.0893 0.000* 

Chlorhexidine -0.2922 0.000* 
Cetrimide Chlorhexidine -0.2029 0.000* 

Sapphire +Light cure 70.27 0.000 * 

Control 
Listerine -0.0722 0.000* 

Cetrimide -0.179 0.000* 
Chlorhexidine -0.326 0.000* 

Listerine Cetrimide 
-0.1068 0.000* 

Chlorhexidine -0.2538 0.000* 
Cetrimide Chlorhexidine -0.147 0.000* 

 
Effect of adhesive 

The amount of light absorption significant 
differ when compare unbounded bracket versus 
nomix and light cure bond bracket complex 
except sapphire brackets immersed in Listerine 

there was non- significant difference between 
unbounded and light cure bond bracket. 

There was non- significant difference between 
no-mix and light cure bond bracket except for 
Listerine and chlorhexidine   there was significant 
difference (table 4).   



J Bagh College Dentistry                    Vol. 26(2), June 2014                        Discoloration of  
   

 
 

Orthodontics, Pedodontics and Preventive Dentistry 129 
 

Table 4: Difference between the different adhesives for light absorption after immersion in 
different mouth washes 

Brackets  
ANOVA 

Df=29 LSD 

F-test p-value 1Vs2 1Vs3 2Vs3 

Ceramic 

Control 31.852 0.000* 0.001* 0.023* 0.272 
Listerine 41.415 0.000* 0.000* 0.000* 0.040* 

Cetrimide 68.988 0.000* 0.000* 0.000* 0.316 
Chlorhexidine 70.013 0.000* 0.000* 0.000* 0.000* 

Sapphire  

Control 27.675 0.000* 0.001* 0.034* 0.277 
Listerine 28.985 0.000* 0.000* 0.087 0.000* 

Cetrimide 43.629 0.000* 0.000* 0.000* 0.662 
Chlorhexidine 117.331 0.000* 0.000* 0.000* 0.001* 

(1 Vs 2) Unbonded bracket versus bracket bonded with no mix 
(1 Vs 3) Unbonded bracket versus bracket bonded with light cure 

(2 Vs 3) bracket bonded with no mix versus bracket bonded with light cure 
          

DISCUSSION 
The test bracket in this study were ceramic and 

sapphire bracket because they are the most 
esthetic bracket now use. 

The use of listerine, cetrimide and 
chlorhexidine mouth washes because they widely 
use during  orthodontic treatment as antiseptic 
agent ; but the side effects of reversible staining 
affect its wide spread; therefore study of this 
effect was done in this study. The immersion time 
intervals 60 minutes corresponded to an 
accumulative effect of daily use of the mouthwash 
for one month, considering that mouthwashes are 
usually used for one minute twice daily, the same 
time interval was used by other researchers (17,18) 

 The increase stain of bracket when immerse in 
the mouth wash due to diffusion and adsorption of 
mouth wash molecule to the surface of bracket, 
sapphire bracket is more glazed surface and the 
bond between molecules are more stronger since 
its monocrystaline, so reduce overall surface 
roughness and adsorption of mouth wash on 
bracket surface  than ceramic bracket. 

The stronger staining effect of chlorhexidine 
mouth wash due to probable electrostatic 
interaction between the positively charged 
(cationic) Chlorhexidine molecules and the 
negatively charged ceramic surface, also 
chlorhexidine contain alcohol(15%) in its 
composition which increase surface degradation 
of bracket. The effect of cetrimide due to cationic 
nature of cetrimide and the negatively charged 
ceramic surface (electrostatic interaction), while 
Listerine has slight acidic nature make effect less 
than other mouth wash (table 1). 

The lowest staining effect of Listerine makes 
the difference between control-Listerine group in 
both unbounded ceramic and sapphire brackets 
insignificant (table2 and 3).   

The significant difference between unbounded 
and bonded bracket (table 4) is due effect of 
adhesive, chemical cure resin(nomix)absorbed 
water molecules (physisorption), water is a 
softener of plastics and increases the deterioration 
of the resin matrix, which increase the monomer 
release from composite and increase the surface 
degradation of adhesive; produce rough surface 
which increase mouth wash deposition leading to 
increase stain(19), while the effect of light adhesive 
may be due to the ‘‘incomplete polymerization’’ 
phenomenon of light cure adhesive which occur 
due to number of factors that affect the depth of 
photo activated cures, including factors of 
illumination from the edges of bracket  and 
critical total transmittance value  of bracket in 
which duration and intensity of light exposure 
may be attenuated by the bracket structure, 
incomplete polymerization increase monomer 
leaching and cause alteration in light absorption 
values indicating a decreased color stability of 
light cure composite. Since sapphire bracket more 
transparent than ceramic bracket so light 
transmission is more leading to more complete 
polymerization and since Listerine less staining 
effect than other mouth wash making the 
difference between unbounded sapphire bracket 
and light cure bonded insignificant in Listerine 
group (table 4). 

The significant difference in light absorption 
between no-mix and light cure in Listerine and 
chlorhexidine mouth wash group may be due to 
acidic content of Listerine and alcohol content of 
chlorhexidine which effect more in no-mix than 
light cure this agree with Sargison et al (20) and 
Sanders et al (21)  
 
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Orthodontics, Pedodontics and Preventive Dentistry 130 
 

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