Evaluating the bonding of two adhesive systems to enamel submitted to whitening dentifrices
Acta odontol. latinoam; 23 (2), 2010
Publication year: 2010
The aim of this study was to evaluate by micro-shear bond strength test, the bond strength of composite resin restoration to enamel submitted to whitening dentifrices. Forty bovine teeth were embedded in polystyrene resin and polished. The specimens were randomly divided into eight groups (n= 5), according to the dentifrice (carbamide peroxide, hydrogen peroxide and conventional dentifrice) and the adhesive system (Prime & Bond 2.1 and Adper Single Bond 2). Dentifrice was applied for 15 minutes a day, for 21 days. Thirty minutes after the last exposure to dentifrice, the samples were submitted to a bonding procedure with the respective adhesive system. After that, four buttons of resin were bonded in each sample using transparent cylindrical molds. After 24 hours, the teeth were submitted to the micro-shear bond strength test and subsequent analysis of the fracture mode. Data were submitted to analysis of variance and Fisher's PLSD test (α=0.05). The micro-shear bond strength showed no difference between adhesives systems but a significant reduction was found between the control and carbamide groups (p=0.0145) and the control and hydrogen groups (p=0.0370). The evaluation of the failures modes showed that adhesive failures were predominant. Cohesive failures were predominant in group IV. The use of dentifrice with peroxides can decrease bonding strength in enamel.
O objetivo deste trabalho foi avaliar, pelo metodo de microcisalhamento, a resistencia adesiva obtida em restauracoes de resina composta realizadas sobre o esmalte dental previamente exposto a diferentes dentifricios. Para isso, quarenta dentes bovinos foram incluidos em resina de poliestireno e polidos. Os dentes foram divididos aleatoriamente em 8 grupos (n=5) de acordo com o dentifricio utilizado (cremes contendo peroxido de hidrogenio, peroxido de carbamida ou dentifricio convencional) e sistema adesivo (Prime & Bond 2.1 ou Adper single Bond 2). Os dentes foram expostos por 15 minutos por dia durante 21 dias as suspensoes dos respectivos cremes dentais. Trinta minutos apos a ultima exposicao ao dentifricio, os dentes foram restaurados empregando os 2 diferentes sistemas adesivos e resina composta. Apos 24 horas os dentes foram submetidos ao teste de microcisalhamento e posterior analise do padrao de fratura. Os resultados obtidos foram submetidos a analise de variancia e teste de Fisher's PLSD (α=0.05). Nao foi detectada diferenca estatistica entre os adesivos, porem entre os tratamentos com dentifricios, houve reducao estatisticamente significante entre os grupos controle x carbamida (p=0.0145) e entre o grupo controle x hidrogenio (p=0.0370). Na avaliacao do tipo de fratura houve predominancia de falhas adesivas, com excecao do grupo IV que apresentou maior fratura coesiva em esmalte. Assim, a utilizacao de cremes dentais, contendo peroxidos em suas formulacoes, pode provocar uma reducao na resistencia de uniao ao esmalte.