RESUMO
Conservative techniques for improving the appearance of discolored teeth have become popular in the past decade. These include: in-office bleaching with 30% hydrogen peroxide, which is applied on etched enamel with a gauze pad and then exposed to a bleaching light; home bleaching with a mild form of peroxide, such as 10% carbamide peroxide, which is applied on the tooth surface with custom-made mouthguards; and enamel micro-abrasion with 18% hydrochloric acid, which is applied in a pumice slurry. In this study, the in-office bleaching and enamel micro-abrasion techniques were performed on extracted teeth for investigation of their microscopic effects on the surface enamel. Specimens treated only with 37% phosphoric acid showed an enamel loss of 5.7 +/- 1.8 microns. The specimens treated with 37% phosphoric acid followed by 30% hydrogen peroxide showed enamel loss of 5.3 +/- 1.6 microns; this loss was probably not caused by the hydrogen peroxide, but rather by the etching with 37% phosphoric acid which preceded the hydrogen peroxide application. A direct application of 18% hydrochloric acid for 100 s resulted in a loss of 100 +/- 47 microns. The extent of enamel loss was much greater when the 18% hydrochloric acid was applied in a pumice slurry for the same period of time (360 +/- 130 microns), and the effect was time-dependent. Thus, the pumice and rotary prophy cup used in conjunction with the 18% hydrochloric acid contributed markedly to the loss of surface enamel, enhancing the non-selective stain-removing action of the hydrochloric acid. Therefore, the hydrochloric acid-pumice technique must be used clinically with caution.
Assuntos
Condicionamento Ácido do Dente/efeitos adversos , Esmalte Dentário/efeitos dos fármacos , Silicatos , Clareamento Dental/efeitos adversos , Adolescente , Análise de Variância , Peróxido de Carbamida , Criança , Esmalte Dentário/ultraestrutura , Combinação de Medicamentos , Humanos , Ácido Clorídrico/efeitos adversos , Peróxido de Hidrogênio/efeitos adversos , Microscopia Eletrônica de Varredura , Pessoa de Meia-Idade , Peróxidos/efeitos adversos , Ácidos Fosfóricos/efeitos adversos , Ácido Silícico/efeitos adversos , Clareamento Dental/métodos , Descoloração de Dente/terapia , Ureia/efeitos adversos , Ureia/análogos & derivadosRESUMO
Secondary caries formation around restorations is a major cause for their replacement. This in vitro study assessed the capacity of various restorative materials to to resist caries attack. An acidified gel technique was used to produce carieslike lesions around the restored teeth. Assessment of the occurrence and extension of carious lesions was performed using polarized light microscopy. The results showed wide variations in the ability of the restorative materials to resist erosion.
