Composite resins have been largely utilized for esthetic dentistry purposes. These materials allow the use of minimally invasive cavity preparations or even the absence of any cavity preparation, resulting in the maximum preservation of sound tooth structure. Besides that, composite resin restorations might be repaired, present good longevity, and acceptable esthetic properties.
In an attempt of performing invisible direct restorations, not only should the color of the composite be properly selected but also surfaces must be texturized to replicate the morphologic natural characteristics of the teeth. This morphologic texture characterization can give the restoration a natural look but might also allow a higher concentration of pigments over surfaces, as the increased surface roughness of composites seems to be related to higher surface discoloration. Exogenous sources of colorants may result from the patients diet or from the smoking habit.
Texturized surfaces present greater color change and increased yellowish appearance when exposed to tobacco smoke compared with non-texturized surfaces. This suggests that irregular surfaces can be easily pigmented because staining agents accumulate in the macroscopic and microscopic superficial defects. Also to be noted is the fact that diamond finishing points produced rougher surfaces on different types of composites, and that a greater dye concentration was noted on composite surfaces finished with such instruments, compared with carbide burs and rubber points.
Also, composites exhibit a decrease in luminosity when exposed to tobacco smoke. The effect of tobacco-smoke on the color parameters of esthetic restorative materials is attributed to the brown pigments from tobacco leaves, present on the particulate phase of tobacco smoke known as tar. Therefore, one can speculate that the staining potential might be worsened with cigarettes with elevated content of tar.
The thermal effect of smoking habit might be another area of concern. During cigarettes smoking, the oral environment might experience some degree of temperature change. Because of the difference in the thermal expansion co-efficient between resin matrix and filler particles, thermal cycling might cause repetitive shrinkage and expansion, resulting in a difference in thermal volumetric changes between resin matrix and filler particles. The thermal variations from cigarette smoking together with hydrolytic degradation that occurs during storage in saliva might have provided changes on the surface of texturized and not texturized composites, consequently increasing the staining potential from tobacco smoke.
A reduction in the superficial staining of esthetic restorative materials can be accomplished with repolishing procedures performed with abrasive instruments on restoration surfaces or through bleaching agents. Some studies demonstrated that the repolishing procedures caused perceptible color changes in esthetic restoratives stained with coffee, redwine, and tea, and mainly referred to the increase in the luminosity and to the decrease in the yellowish appearance.
.
