INFLUENCE OF POST-BLEACHING TIME INTERVALS USING 37% CARBAMIDE PEROXIDE ON DENTAL SUBSTRATE ADHESION

Abstract

The aim of this study was to evaluate the influence of post-bleaching time intervals using 37% carbamide peroxide on dental substrate adhesion. Fifty bovine incisors were sectioned in two groups of 4X4 mm standard blocks to obtain 50 specimens in each group (n=50). In fifty blocks, the dentin (D) was analyzed and in the other 50 the enamel (E). Blocks were subjected to bleaching treatment and restored with Single Bond/z250 according to post-bleaching time intervals (0, 7, 14 and 21 days). Twenty-four hours after adhesive/resin cylinders on substrate confection, shear bond strength test (SBS) was performed in an universal test machine. Means in MPa and their respective standard deviations were: E – control: 31.89 (2.39); T0: 19.07 (2.00); T7: 24.97 (4.89); T14: 29.71 (4.89); T21: 40.91 (4.75) and D – control: 18.90 (3.64); T0: 2.22 (0.41); T7: 3.79 (0.75); T14: 5.95 (0.79); T21: 8.40 (0.87). Data were submitted to ANOVA and Tukey (p< 0.05) tests. The bond strength value for the enamel was statistically higher than the dentin, and both were lower than the control group that had similar results after 21 days post-bleaching. In dentin group, the control showed superior bond strength and was statistically different in relation to other times. It was concluded that bleaching had negative influence on adhesion. Therefore it is necessary to wait, at least, 21 days after bleaching to restore the enamel. AVALIACAO IN VITRO DA INFLUENCIA DE DIFERENTES INTERVALOS DE TEMPO POS-CLAREAMENTO COM PEROXIDO DE CARBAMIDA 37% NA ADESAO AO SUBSTRATO DENTAL RESUMO: O objetivo deste estudo foi avaliar a influencia do peroxido de carbamida a 37% sobre a adesao dos substratos dentarios em diferentes intervalos de tempo pos-clareamento. Cinquenta incisivos bovinos foram divididos em dois grupos de blocos padrao 4 x 4 mm para obter 50 especimes de cada grupo (n = 50). Em cinquenta blocos, a dentina (D) foi analisada e nos outros 50 o esmalte (E). Os blocos foram submetidos ao tratamento de clareamento e restaurados com Single Bond/z250 de acordo com os intervalos de tempo pos-clareamento (0, 7, 14 e 21 dias). Apos vinte e quatro horas os corpos de prova preparados com adesivo/resina foram submetidos ao teste de resistencia ao cisalhamento (SBS) em uma maquina universal de ensaio. As medias (Mpa) e seus respectivos desvios padrao foram: E - controle: 31,89 (2,39); T0: 19,07 (2,00); T7: 24,97 (4,89); T14: 29,71 (4,89); T21: 40,91 (4,75) e D - controle: 18,90 (3,64); T0: 2,22 (0,41); T7: 3,79 (0,75); T14: 5,95 (0,79); T21: 8,40 (0,87). Os dados foram submetidos a ANOVA e ao teste de Turkey (p <0,05). O valor da resistencia de uniao para o esmalte foi estatisticamente superior a dentina e ambos foram inferiores ao grupo controle que apresentou resultados semelhantes apos 21 dias pos-branqueamento. O grupo controle (D) apresentou valores de resistencia de uniao superior e estatisticamente diferente em relacao aos outros tempos. Concluiu-se que o clareamento teve influencia negativa sobre a adesao. Portanto, tornar-se-a necessario aguardar, pelo menos, 21 dias apos o clareamento para restaurar o esmalte. PALAVRAS-CHAVE: Clareadores; Peroxidos; Dentina; Esmalte Dentario.