Every human being have different appearance
among one another in which the smile is more
important factor for their aesthetics, the smile can
be affected in various ways, that can be by the
common factors like tooth shape, texture, position,
and colour. The colour of the teeth will mostly give
the pleasant lookto the people while smiling, for
that the colour should look brighter and attractive.
The darker teeth will remain unaesthetic often so
that the teeth can be modified to give a pleasing
look by restoring it with an aesthetic material. One
of the most popular dental aesthetic materials
is ceramic. Dental ceramics are generally used
to restore the teeth because of their excellent
aesthetics, wear resistance, chemical inertness,
low thermal conductivity, and diffusivity. In addition
to that, they match the characteristics of tooth
structure to quite a large degree1.
After the restoration is placed it is our duty to
maintain it properly with good oral hygiene if
it is not so, the long-term therapeutic targets of
comfort, good function, treatment predictability and
longevity of the fixed and removable prosthesis
is very difficult to achieve. For maintaining the
good oral hygiene we must understand the
infectious nature of dental diseases and increased interest in plaque control and prevention by using
chemicals such as antibacterial mouthrinses
like chlorhexhidine. Several other clinical
investigations confirmed the initial finding that
two daily rinses with 10 ml of a 0.2% aqueous
solution of chlorhexidine digluconate almost
completely inhibited the development of dental
plaque, calculus, and gingivitis in the human
model for experimental gingivitis.
The chemical agents will give medicinal effects
but at the same time the adverse affects too. The
side effects of prolong usage of chlorhexidine
mouthrinse are brown staining of the teeth, tongue,
silicate and resin restorations and transient
impairment of taste perception. Since the usage of
chlorhexidine can cause colour change of aesthetic
material, it is duty to pick up which material is less
susceptible to extrinsic staining.
Many researchers have shown the effect of
cholorhexidine and other chromogenic mouth
washes on different restorative materials. However,
according to Lamba et al have shown that
immersion of composite, glass ionomer cement
and compomer in the respective mouth rinses
will make significant colour change of these
materials2. Reis et al., the smoothest surfaces were not necessarily the most stain-resistant,
comparing colour resistance of these materials with
each other3. Celik et al. evaluated the effects of 3
mouth rinses including chlorhexidine on 4 different
resin-based composite restorative materials, and
concluded that although visually non-perceptible,
all resin restorative materials tested showed a
colour change4.
The manufacturers claiming that a newly available
product chlorhexidine ADS(Anti-Discolouration
System) will have reduced staining effect. Though
we know the fact that ceramics are the most
common material in indirect aesthetic dentistry,
there is no published article regarding the effect of
staining agents including mouth rinses on colour
stability of ceramics through chlorhexidine ADS.
Therefore the aim of this study was to evaluate
and compare the influence of chlorhexidine (CHX)
mouth wash and chlorhexidine Anti-Discolouration
System (CHX-ADS) mouth wash on colour stability
of porcelain.
Aim:
To assess the amount of colour change during the
usage of chlorhexidine anti-discolouration system
on dental ceramic.
Objectives:
20 specimens were prepared by mixing porcelain
powder and liquid of shade B1 (VITA VMK
Master®). Then the specimens were formed by condensing body porcelain on square shaped
metal plates 10mm length, 10mm breadth and
2mm in thickness
According to manufacturer’s instructions, all
specimens were fired in vacuum furnace in 890ºC,
and 900ºC. After air-cooling at room temperature,
they were ground flat and wet polished with
progressively finer grit aluminum oxide abrasive
papers and then these specimens were cleaned
with 1 min air water spray and stored in distilled
water for 24 hours. Then the specimens in each
group were numbered from 1 to 10 (A1 to A10 for
regular chlorhexidine mouthwash and B1 to B10
for chlorhexidine ADS mouthwash).
After that, the baseline colour values (L*, a*,
b*) were measured with a Photo obtained and
evaluated in adobe photoshope 7.0 software
against a Grey background. Quality of colour
was examined using the Commission International
de I’Eclairage (CIE L* a* b*) system as tristimulus
values and reported as colour differences (ΔL*,
Δa*, and Δb*) compared with standard conditions.
Measurements were repeated 3 times in each
specimens and mean values were calculated
and tabulated.
Each group were immersed in respective mouth
rinses twice daily in 15 ml of the 0.2% chlorhexdine
mouth rinse and chlorhexidine ADS mouth
rinse (DR. REDDYS CLOHEX, INDIA) for 2 min
respectively. After immersion specimens were
washed in distilled water and then it was placed
in the artificial saliva for the next consecutive
rinses for the time period of 3 weeks.
After the immersion period, the colour values
of each specimen were remeasured, and the
colour change value (ΔE) L*a*b* was calculated
according to the following formula [5].
ΔE = [(ΔL*) 2+ (Δa*) 2+ (Δb*) 2]1/2
Where L* stands for lightness, a* for green-red
(-a=green; +a=red) and b* for blue-yellow
(-b=blue; +b=yellow)
∆E stands for colour change value.
The key objective of the study is to differentiate between 2 mouthwashes based on levels of stain
on ceramics. So, analysis and compare the 2
groups by using Mann-Whitney U test, since the
total sample size within the group is less than 30.
Mann-whitney U test was used instead of T-test
because the sample does not compliment the
central limit theorem.
Where L* stands for lightness,
a* for green-red(-a=green; +a=red) and
b* for blue-yellow (-b=blue; +b=yellow)
∆E stands for colour change value
Explanation: Mann-Whitney test is performed
between Chlorhexidine mouthwash group and
Non staining Chlorhexidine mouthwash group.
The calculated test statistic value in table (Table:
2) is lesser than the critical value that there is no
significant difference between the Test (Group A)
and Control (Group B).
The value of p exact is greater than 0.05 which
further aids Acceptance of null hypothesis, which is
Chlorhexidine mouthwash group and Non staining
Chlorhexidine mouthwash are not significantly
different from each other.
The mean colour change (∆E) value for regular
chlorhexidine is 2.05 and for chlorhexidine
ADS is 1.66 which is lesser than that of regular
chlorhexidine mouthwash value. Hence we can tell
that the property of chlorhexidine ADS is little bit superior than regular chlorhexidine mouthwash
solution.
The dentist should know about all the properties
of the restorative material. They should have the
clear idea about the colour change of restorative
materials. Discolouration can be evaluated with
different instruments and techniques. In this study,
digital analysis of colour changes was done with
photographs obtained before and after immersion
in chlorhexidine mouthrinses and chlorhexidine
ADS mouthrinses respectively and which was
evaluated in the adobe photoshop software for
the L*,a*,b* values and the colour change values
are measured by colourimeter.
Colourimeter uses the CIE L* a* b* colour system,
which is a method developed in 1978 by the
Commission Internationale de I’Eclairage for
characterizing colour based on human perception.
L* coordinates are located along a vertical axis
that ranges from a value of 0 (blackest) to 100
(whitest). a* and b* coordinates revolve on axes
around L*. Coordinate a* measures red at the
positive value and green at the negative value,
similarly, coordinate b* measures yellow at the
positive value and blue at the negative value.
Absolute measurements can be made in L* a* b*
coordinates and colour change calculated as ΔE
(L* a* b*).
So far in dental literature, only a few studies have
been reported on the colour stability of porcelain6,7,8.
Kokosal and Dikbas showed that porcelain denture teeth were more colour stable than acrylic denture
teeth against coffee, tea and coke9. Bernardi
stated that there is no statistically significant
difference in the ability of the mouthwashes to
prevent bacterial plaque, however evidence of the
stain was much less with the ADS mouthwash in
natural teeth10, Varoni EM assessed that there was
no evidence to support the 0.12% chlorhexidine
with anti-discoloration agent to reduce staining
of natural teeth11, Solis stated that the test group
with ads had less staining than the control group
during a usage period of 15 days. However, the
two mouthwashes seemed to be equally effective
as antiplaque and antigingivitis agents in natural
teeth12, so many studies were done to assess the
staining effect of chlorhexidine mouthwash with
ADS system on natural teeth. Most of the studies
gave the result as no significant colour change
was appreciated.
However, no investigation has been done on the
effect of chlorhexidine ADS on discolouration of
porcelain materials, hence we decided to conduct
this in-vitro study to compare the staining of
ceramic by regular chlorhexidine mouthwash
and chlorhexidine mouthwash.
We experienced that the regular chlorhexidine
mouthwash gave more colour change value when
compared with chlorhexidine ADS mouthwash
Since this is the first study about the discolouration
of porcelain by chlorhexidine ADS mouthwash
further research is essential to determine the effect
of discolouration of other mouthwashes on different
ceramic materials.
When compared in terms lab parameters we also
find there is no significant difference between
chlorhexidine mouthwash group and non-staining
chlorhexidine ADS mouthwash group based on
staining level. But the colour change value of
regular chlorhexidine mouthwash is greater than that of the chlorhexidine mouthwash. So it can be
concluded that the chlorhexidine ADS mouthwash
is somewhat giving lesser discolouration on
ceramic when compared to regular chlorhexidine
mouthwash.