الفهرس 
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Abstract
The most common electronic nicotine delivery system is electronic cigarettes.
Most of electronic cigarettes consist of a battery and electric heater used to aerosolize a liquid
to produce vapor which the user inhales. Poly methyl methacrylate comes in contact with a
variety of foods and beverages of different temperatures, as a result, it is prone to absorbing a
variety of pollutants, altering its physical structure and appearance. Also, conventional
cigarettes smoking resulted in increase of the surface roughness of acrylic resin.
Aim of the study: This study aimed to investigate the effects of electronic cigarettes smoking
on color stability and surface roughness of acrylic resin.
Material and methods: This study was in vitro study in which sixty specimens of
CAD/CAM acrylic resin was exposed to aerosols which were flavored and non-flavored with
nicotine content (0 mg, 6 mg and 12 mg). A portable suction machine was modified to
simulate smoking in vivo. Each specimen was exposed to 20 cycles of aerosol released by a
single ECIG device using the smoking chamber. Spectrophotometer was used to measure the
color change of the specimens. Surface roughness was quantitatively analyzed using a
profilometer and qualitatively analyzed under scanning electron microscope (SEM).
Results: No significant difference in color change found between groups exposed to
flavorless e-liquid, while a significant difference found between flavored 0 mg. nicotine and
12 mg. nicotine groups (P = 0.002). Also, a significant difference found between flavored 6
mg. nicotine and 12 mg. nicotine groups (P = 0.002). According to Two Way ANOVA, both
flavor and nicotine contents have a significant effect on color change (P <0.0001). There was
a significant difference in surface roughness between group exposed to flavorless e-liquid
with 6 mg. nicotine and control group (p=0.001) and between 12 mg. nicotine and control
group (p=0.014).Also, There was a significant difference in surface roughness between group
exposed to flavored e-liquid with 6 mg. nicotine and control group (p=0.034) and between 12
mg. nicotine and control group (p=0.016).
Conclusion: Exposure to flavored and non-flavored ECIG aerosol of different nicotine
concentrations has a significant effect on the color and surface roughness of denture acrylic
resin. Higher concentrations of flavored nicotine had visually perceptible color changes and
were deemed clinically unacceptable. Also, ECIG aerosols of 6 mg. and 12 mg. either
flavored or non-flavored increased the surface roughness of acrylic resin significantly.