The Importance Of Tooth Discoloration

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Tooth is composed of three hard tissues enamel, dentin and cementum .The colour of the tooth is determined by reflectance of dentin and thickness of enamel[30].As cementum is in root portion of the tooth its influence on determining the color of the tooth is not much. Tooth color is different among the different people, different teeth in same person and different areas of the same tooth[31].Tooth color is not constant and it changes due to various reasons.According to the location of the stain the tooth discoloration can be intrinsic or extrinsic. Internalized stain or discoloration has also been described[32].

2.2.1 Intrinsic tooth discoloration
Intrinsic tooth discoloration occurs during odontogenesis and post eruption. It alters the light transmission properties of enamel and dentin.
Etiology of intrinsic tooth discoloration [2].
a.Pre eruptive causes
»Medications (Tetracycline)
»Metabolism (Fluorosis)
»Genetics (Hyperbilirubinaemia,Amelogenesis imperfecta,Cystic fibrosis of pancreas, Congenital erythropoietic porphyria, Enamel hypoplasia, Alkaptonuria, Dentinogenesis imperfecta)
»Dental trauma (Turner’s tooth)

b.Post eruptive causes
»Pulpal necrosis
»Intra-pulpal hemorrhage
»Residual pulp tissue after endodontic treatment
»Endodontic material (Medications/irrigants ,root canal sealer)
»Filling Materials
»Root resorption
»Aging
2.2.2 Extrinsic tooth discoloration
Extrinsic tooth discoloration lies outside the tooth substance on tooth surface. Extrinsic discoloration can be the result of incorporation of chromogenic compound into the tooth pellicle which is direct in origin or due to chemical interaction with another compound which is indirect in origin. So according to the origin extrinsic discoloration may be direct or ...

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...be applied directly, or produced in a chemical reaction from sodium perborate or carbamide peroxide (CH6N2O3, or CH4N2O.H2O2)[6]. Hydrogen peroxide (30-35%) and carbamide peroxide are mainly used for vital bleaching, while sodium perborate is used for non-vital bleaching.
Hydrogen peroxide oxidizes organic and inorganic compounds by free radicals (OH•, O•-2).O•-2 is produced in large no by ionization of weakly acidic aqueous hydrogen peroxide while OH• is produced by ionization of buffered hydrogen peroxide at ph 9.5-10.8.But OH• has better bleaching effect than O•-2 [35].
2.4. Bleaching agents
According to Federal Health Office of Switzerland and the Medications Institute Swissmedic as cosmetics patients can directly use maximum of 6% hydrogen peroxide or equivalent amount of other free radicals releasing agents. Higher concentration are only for professional use.

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