Effects of cigarette smoke and denture cleaners on the surface roughness and color stability of...

7/24/2019 Effects of cigarette smoke and denture cleaners on the surface roughness and color stability of different denture t

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Effects of cigarette smoke and denturecleaners on the surface roughness andcolor stability of different denture teeth

Elif Aydogan Ayaz, DDS, PhD,a Subutay Han Altintas, DDS, PhD,b

and Sedanur Turgut, DDS, PhDc

Faculty of Dentistry, Karadeniz Technical University, Trabzon, Turkey

Statement of problem. Denture teeth have the most effect on the esthetics of complete dentures. However, extrinsic factorscan change their roughness and color.

Purpose.The purpose of this study was to investigate the effects of smoking and denture cleaners on the roughness and color(CIE [Commission International de IEclairage] L*a*b*) of denture teeth.

Material and methods.Maxillary central incisors made of acrylic resin, high-strength acrylic resin, and porcelain (Acrylux, SR,Orthosit PE-O, and Enta) were divided into 4 groups (n10): control, denture cleaner, cigarette smoke, and cigarette smoke

and denture cleaner. The dental cleaner group and cigarette smoke and dental cleaner group were immersed in denturecleaner (Protex; Queisser Pharma) for 15 minutes; the cigarette smoke group and cigarette smoke and dental cleaner groupwere exposed to smoke from 20 cigarettes for 10 minutes per cigarette. The roughness was measured with a pro lometer, andthe color was measured with a colorimeter. The CIE L*a*b* values were recorded. The data were analyzed with a 3-wayANOVA and the Fisher least signicant difference test (a.05).

Results. The roughness of Acrylux, SR Orthosit PE-O (P


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color stability of dental materials.13-16

Imirzalioglu et al15 investigated the ef-

fects of tea, coffee, and nicotine on the

color stability of acrylic resin denture

bases and found that the color change

(DE) with each staining solution could

be perceived by the human eye. Mathias

et al16 found that smoking caused sig-

nicant DEs in nanolled compositeresins. Researchers have also evaluated

the efcacy of repolishing in reducing

staining and have reported that repo-

lishing did not return composite resins

to their baseline colors after exposure

to smoke. The DEs of dental materials

can be evaluated visually or instru-

mentally.17 Instrumental devices, such

as colorimeters or spectrophotometers,

provide objective, accurate, and com-

parable data.18-20 The Commission In-

ternational de IEclairage (CIE L* a*

b*) color system has been used to

assess chromatic differences and is

recommended by the American Dental

Association.21,22 According to this sys-

tem, L* indicates lightness, a* indicates

green-red, and b* indicates yellow-blue.

TheDE is calculated by using the values

of L*, a*, and b*, and represents the

relative color difference in the mate-

rial.21 OBrien23 reported that, when

theDE value is more than 3.5, the color

difference can be considered clinically

unacceptable.

Because DEs indicate damage to

the materials, clinical serviceability also

is affected.15 Articial denture teeth

should have color stability in the oral

environment to simulate the appear-

ance of natural teeth, and color sta-

bility is related to the surface roughness

of the material; the surface roughness

value is dened as Ra, a symbol forthe arithmetic mean roughness on a

certain surface. A smooth surface re-

ects a greater amount of light than a

rough surface and is important for the

color of a material.7,8 In addition, a

roughened surface can cause plaque

accumulation and staining. Alandia-

Roman et al24 evaluated the color

stability and Ra of dental composite

resins and reported that the absence

of polishing increased the degree ofstaining.

Patients must have a smooth sur-

face to facilitate denture cleaning and

prevent plaque formation and bacterial

colonization.25,26 Cleaning methods for

dentures include daily brushing and

immersion in denture cleaners (DC).27-29

The use of DCs can affect the physical

properties and color of denture base

and tooth materials.30-33

Moore et al34

and McNeme et al35 reported that

DCs tended to bleach acrylic resin

denture bases. Alam et al36 investigated

the efcacy of 4 currently available

commercial DCs in the removal of

extrinsic stains from chlorhexidine and

tea solutions, and found that all of

the denture-cleaning products removed

staining.

Research that pertains to the effects

of CS on the Ra and color stability of

denture tooth materials is lacking. In

addition, the effects of DCs after

exposure to CS are unknown. There-

fore, the purpose of this study was to

analyze the effect of CS and DC on the

Ra and color of denture teeth. The null

hypothesis was that CS and DCs would

not affect the Ra or color stability of

denture teeth.

MATERIAL AND METHODS

Three brands of commercially

available denture teeth and 1 DC so-

lution were used for this study (Table I).

Forty maxillary central incisor denture

teeth (shade A2) were selected from

each brand. The teeth from each brand

were divided into 4 groups (n10):

group C, which was kept in distilled

water and was considered the control;

group DC, which was immersed in DC;

group CS, which was exposed to CS;

and group CSDC, which was

immersed in DC after exposure to CS.

Denture teeth (group CS and group

CSDC) were exposed to CS with a

device similar to the one used in a

previous study,24 which simulated the

conditions of smoking. The test speci-

mens were placed in the vertical posi-

tion in a box, which exposed them toCS on the greater and middle parts of

their surfaces. For each specimen, 20

cigarettes were used, and each cigarette

was burned for a standard time of 10

minutes; the teeth then were washed

under running water. Denture teeth (G2

and G4) were immersed in denture

cleaning solution (Protex; Queisser

Pharma). The DCs were prepared ac-

cording to the manufacturers in-

structions, and the teeth remained in

the solution for 15 minutes before be-

ing washed under running water.

The Ra of the teeth was measured

with a prolometer (SJ-201P; Mitutoya

Corp). Three measurements were ob-

tained from different sides of the tooth

surfaces. The arithmetic means of the

values were recorded for the nal Ra.

The color measurements, based on the

International Organization of Stan-

dardization standards (ISO 7491), were

obtained with a tristimulus colorimeter

(ShadeEye NCC; Shofu) under D65

standard illumination on a gray back-

ground. The teeth were dried with

absorbent paper, and the colorimeter

was calibrated according to the manu-

facturers instructions before the color

analysis. The colorimeter was posi-

tioned in the middle of each tooth

during the measurements. The L*a*b*

color notation of each tooth was

measured 3 times consecutively, and

Table I. Denture teeth and denture cleaner used

Material Manufacturer Composition

Dentureteeth

Acrylux Polymethyl methacrylate

SR Orthosit PE-O; Ivoclar Reinforced polymethyl methacrylate (Isosit)

Enta; Unilux Porcelain

Denturecleaner

Protex; Queisser Pharma Sodium bicarbonate, potassiumcaroate, sodium perborate,

citric acid, sodium lauryl sulfate

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The Journal of Prosthetic Dentistry Ayaz et al


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the average of the 3 readings was

calculated to yield the nal color of the

specimen. The CIE color difference was

calculated by using the following

equation21:

DE DL2 Da2 Db21=2.

The surfaces of the denture teeth

were sputter coated with a 40-nm lm

of gold-palladium and were imaged

with a scanning electron microscope

(SEM) (JSM 6400; JEOL) under500

magnication. All of the measurements

were performed by 1 operator. Statis-

tical analyses were performed with a

statistical package (SPSS for Windows,

v15.0; IBM Corp). The results were

tested regarding their normality ofdistribution with the Shapiro-Wilk test.

Because all of the data demonstrated

normal distribution, parametric tests

were used. The data were analyzed

with a 3-way ANOVA and the Fisher

post hoc least signicant difference

test at a level of 95% signicance

(a.05).

RESULTS

The Ra values of the experimental

groups are reported inTable II. The high-

strength acrylic resin teeth in the control

group presented the lowest Ra values,

whereas the porcelain teeth in the CS

group had the highest value. The denture

teeth and CS (P


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The average L*, a*, and b* values of

the experimental groups are reported in

Table VI. The L* values decreased, and

the a* and b* values increased after

exposure to CS for all denture teeth

(P


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According to the statistical analyses

of the present study, both for Ra and

DEs, signicant interactions were found

between denture teeth and CS; denture

teeth and DC; and denture teeth, CS,

and DC. Although 2- and 3-factor

interaction terms were signicant, the

interaction effects seem to be mostly

related to CS and immersion in DC,

singly or together. In parallel with this,

acrylic resin and porcelain denture

tooth materials already showed signi-

cant results in control groups, inde-pendently from CS and DC. This

nding could be explained by differ-

ences in the material properties.

In the present study, the discolor-

ation of denture teeth was assessed

with a colorimeter, which is appropriate

when providing standardization and

numerical expression, rather than visual

evaluation.17-19 The discoloration of

dental materials can be dened ac-

cording to DE values, and, based onclinical studies, a DE value of more

than 3.5 is unacceptable.23 In the pre-

sent study, all of the denture teeth

showed statistically signicant DEs

when exposed to CS. The DE values of

acrylic resin denture teeth were more

than 3.5 and were thus clinically unac-

ceptable. The discoloration of the

acrylic resinebased materials might

have been due to the polar properties of

the resin molecules because this prop-

erty is known to increase staining.14

Although porcelain denture teeth

showed statistically signicant DEs inall of the groups, theirDE values were

less than 3.5 and thus were clinically

acceptable.

The greatest DEs were observed in

the CS group for acrylic resin

(DE7.94), high-strength acrylic resin

(DE4.12), and porcelain denture

teeth (DE1.75). Wasilewski et al13

investigated the color stability of

dental composites after exposure to CS,

and they reported that the DE valuesvaried between 7.0 and 18.0. The

discoloration caused by CS also may be

related to the pigments in tobacco.

OConnor et al10 and Kozlowski et al11

reported that the tar retained in ciga-

rette lters caused distinctive color

stains. All of the denture teeth showed

lower L* values and higher b* values

after being subjected to CS, which

indicated decreased translucency and

an increased yellowish appearance.

These results are in accordance with

those of an in vitro study that reported

that CS caused yellow pigmentation incomposite resin restorations.16

Acrylic resin denture teeth showed

the greatest DE, followed by high-

strength acrylic resin and then by

porcelain teeth. Porcelain denture

teeth showed improved staining resis-

tance compared with acrylic resine

based denture teeth in the present

study. This nding could be attributed

to the chemical compositions of the

materials. The staining susceptibility ofdental materials is not related to

1 Scanning electron microscope image (500 magnication) of Acrylux denture teeth. A, control group. B, denture cleanergroup. C, cigarette smoke group. D, cigarette smoke and denture cleaner group.

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Ayaz et al


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extrinsic factors, such as Ra alone, but

rather to intrinsic factors, such as

chemical composition and matrix for-

mation.9 Mutlu-Sagesen et al7

compared the color stability of con-

ventional acrylic resin, reinforced acrylic

resin, and porcelain denture teeth

exposed to staining solutions (ltered

coffee, tea, and cola), and similar to

the ndings of this study, they reported

that porcelain denture tooth materials

were more color stable. The greaterDEs

of acrylic-based denture teeth mightpertain to the water sorption properties

of these materials.

Immersion in DC decreased theDEs

of the acrylic resin (DE4.83) and

high-strength acrylic resin teeth

(DE1.90) after exposure to CS. These

results may indicate the removal by DC

of the excess substances caused by

smoking that adhered to the surfaces,

thus, decreasing the staining effects of

CS. When these cleaners dissolve inwater, sodium perborate decomposes

to form an alkaline peroxide solu-

tion,33 and the decrease in staining

from CS might be attributed to alka-

line peroxide. This peroxide solution

releases oxygen, which is effective in

whitening colored teeth.26 Despite the

whitening effect of DCs,30,31 the color

of acrylic resinebased denture teeth

did not reach the initial color values.

The reason might be that DCs remove

only extrinsic staining and that the

substances from CS also can be

absorbed into the resin matrix, whichcauses intrinsic staining. In another

in vitro study, the researchers investi-

gated the effects of polishing pro-

cedures on the DEs in composite resin

restorations after exposure to CS.24

They reported that the use of repo-

lishing procedures reduced the yellow

pigmentation caused by CS, but this

procedure did not return the compos-

ite resin to its baseline color. These

results were similar to those of thepresent study, which showed that the

staining caused by CS cannot be

completely removed.

Increased Ra has a detrimental ef-

fect on the esthetics of dental mate-

rials.16 The results of the present study

support the conclusion that denture

teeth initially have a smooth, shiny

surface nish. Damage to these sur-

faces from the tannins in CS increased

the Ra values, which result in a surface

that was more susceptible to staining.

Mathias et al12 investigated the staining

resistance of composite resins withdifferent surface textures to CS. They

found that discoloration increased

when the Ra values were higher, which

explains that, as staining agents accu-

mulate in macroscopic and micro-

scopic supercial defects, irregular

surfaces can be more easily pigmented.

Although smooth surfaces might have

retained less pigmentation, the porce-

lain denture teeth, which had higher

Ra values than the acrylic resine

basedteeth, presented smaller DEs when

2 Scanning electron microscope image (500 magnication) of SR Orthosit PE-O denture teeth. A, control group. B,denture cleaner group. C, cigarette smoke group. D, cigarette smoke and denture cleaner group.

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exposed to CS. This nding could be

explained by the stain resistant proper-

ties of porcelain.

Prolometry is useful in the evalua-

tion of the Ra properties of dental ma-

terials because it produces numerical

data.29 In addition, the surfaces were

examined with SEM to provide visual

comparisons. In the present study, both

a prolometry and SEM analysis were

performed to assess qualitatively the

surface characteristics of different den-ture teeth after exposure to CS and DC.

The SEM gures obtained from the

specimens supported the prolometric

data. The control groups of all of the

denture tooth surfaces were smoother

compared with the other test groups,

and the lowest Ra values already

belonged to the controls. Numerous

microcracks, pores, and voids were

noted in the CS groups of all of the

teeth. In addition, these irregularitieswere more prominent in acrylic resin

denture teeth, whereas the deteriora-

tion of the porcelain denture teeth af-

ter smoking seemed to be slight. The

surfaces of the teeth, when immersed

in DC, presented with some scratches

and ssures that were different from

the control groups, possibly due to the

abrasiveness of the DC. The SEM im-

ages showed that the surfaces of the

CSDC group were smoother than

those of the CS group for all teeth,

which supports the decreases in Raand DE values. The present study did

not completely simulate oral condi-

tions for denture teeth. Other factors,

such as oral hygiene and diet, can

affect the DEs of dental materials.

Analysis of these ndings suggests that

the surfaces of denture teeth can

become irregular and pigmented when

they are subjected to CS. Immersion in

DC can decrease the deleterious effects

of CS but cannot reverse these effectsentirely.

CONCLUSIONS

Within the limitations of this in vitro

study, the following conclusions were

drawn:

1. Cigarette smoke and DC changed

the Ra and color of articial denture

teeth.

2. Porcelain denture teeth were more

stable than acrylic resinebased denture

teeth in terms of Ra and DEs.

3. The Ra and DE of denture teeth

that were subjected to CS decreased

when the teeth were immersed in DC.

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Corresponding author:

Dr Elif Aydogan Ayaz

Faculty of Dentistry

Karadeniz Technical University

61080 Trabzon

TURKEY

E-mail:[email protected]

Copyright 2014 by the Editorial Council for

The Journal of Prosthetic Dentistry.

Volume - Issue -

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Effects of cigarette smoke and denture cleaners on the surface roughness and color stability of...

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