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Abstract
’Esthetics, by definition, is the science of beauty, that particular detail of an animate or inanimate object that makes it appealing to the eye. Several factors may alter the appearance of smiles, including alterations in the form, texture, position and color of teeth’1. To a large number of people seeking dental treatment, tooth discoloration creates a wide range of cosmetic problems. Here fore, the dental profession and the public expend considerable amounts of time and money in attempts to improve the appearance of discolored teeth.
However, the correct diagnosis for the cause of discoloration is important as, invariably, it has a profound effect on treatment outcomes. For reduction of tooth discoloration, a variety of solutions are available ranging from removal of surface stain, bleaching techniques and restorative techniques to camouflage the underlying discoloration. Nevertheless, resin composite being the most reliable and widely used tooth-colored restorative material, it is subjected; under oral conditions; to the combined effects of stain, mechanical wear and various physical-chemical conditions which often result in visibly detectable and esthetically undesirable color changes2. Moreover, ’experiments performed on restorative materials proved that staining was not only superficial but that the dietary chromogens penetrate into the outer layers of the material resulting in an intrinsic discoloration of the composite’3. Thus, the major disadvantage of these resin composite materials is their color instability.
On the other hand, bleaching- despite of its effectiveness and its safety to soft tissue from a procedural standpoint- it has its own adverse effects on enamel surface and it may not be safe for dental material with high erosive or degradation characteristics4. Some studies report alterations in the surface morphology of the dental hard tissues and dental materials, and also changes in their chemical and physical properties, whereas other studies have found no changes5. In an examination of highly concentrated carbamide peroxide for office bleaching, it was found that it had little effect in some areas, whereas in other areas, decalcification and increased porosity of the enamel surface was noticed, therefore, alterations were not uniform throughout the surfaces6. Although tooth bleaching is not regarded as creating macroscopically visible defects, microscopic alterations could themselves cause undesirable effects as a rough surface may predispose extrinsic staining7.