RESUMO
PURPOSE: To evaluate the bond strength between human dentin and composites, using two light-activated single-bottle total-etch adhesive systems with different pHs combined with chemically activated and light-activated-composites. The tested hypothesis was that the dentin bond strength is not influenced by an adhesive system of low pH, combined with chemically activated or light-activated composites. MATERIAL AND METHOD: Flat dentin surfaces of twenty-eight human third molars were allocated in 4 groups (n=7), depending on the adhesive system: (One Step Plus-OS and Prime & Bond NT-PB) and composite (light-activated Filtek Z-100 [Z100] and chemically activated Bisfil 2B [B2B]). Each adhesive system was applied on acid-etched dentin and then one of the composites was added to form a 5 mm-high resin block. The specimens were stored in tap water (37°C/24 h) and sectioned into two axes, x and y. This was done with a diamond disk under coolant irrigation to obtain beams with a cross-section area of approximately 0.8 mm². Each specimen was then attached to a custom-made device and submitted to the microtensile test (1 mm.min-1). Data were analyzed using two-way ANOVA and Tukey's tests (p<0.05). RESULTS: The anticipated hypothesis was not confirmed (p<0.0001). The bond strengths (MPa) were not statistically different between the two adhesive systems when light-activated composite was used (OS+Z100 = 24.7±7.1ª; PB+Z100 = 23.8±5.7ª). However, with use of the chemically activated composite (B2B), PB (7.8±3.6b MPa) showed significantly lower dentin bond strengths than OS (32.2±7.6ª). CONCLUSION: The low pH of the adhesive system can affect the bond of chemically activated composite to dentin. On the other hand, under the present conditions, the low pH did not seem to affect the bond of light-activated composites to dentin significantly.
RESUMO
PURPOSE: To evaluate the bond strength between human dentin and composites, using two light-activated single-bottle total-etch adhesive systems with different pHs combined with chemically activated and light-activated-composites. The tested hypothesis was that the dentin bond strength is not influenced by an adhesive system of low pH, combined with chemically activated or light-activated composites. MATERIAL AND METHOD: Flat dentin surfaces of twenty-eight human third molars were allocated in 4 groups (n=7), depending on the adhesive system: (One Step Plus-OS and Prime & Bond NT-PB) and composite (light-activated Filtek Z-100 [Z100] and chemically activated Bisfil 2B [B2B]). Each adhesive system was applied on acid-etched dentin and then one of the composites was added to form a 5 mm-high resin block. The specimens were stored in tap water (37 degrees C/24 h) and sectioned into two axes, x and y. This was done with a diamond disk under coolant irrigation to obtain beams with a cross-section area of approximately 0.8 mm(2). Each specimen was then attached to a custom-made device and submitted to the microtensile test (1 mm*min-1). Data were analyzed using two-way ANOVA and Tukey's tests (p<0.05). RESULTS: The anticipated hypothesis was not confirmed (p<0.0001). The bond strengths (MPa) were not statistically different between the two adhesive systems when light-activated composite was used (OS+Z100 = 24.7+/-7.1 feminine; PB+Z100 = 23.8+/-5.7 feminine). However, with use of the chemically activated composite (B2B), PB (7.8+/-3.6b MPa) showed significantly lower dentin bond strengths than OS (32.2+/-7.6 feminine). CONCLUSION: The low pH of the adhesive system can affect the bond of chemically activated composite to dentin. On the other hand, under the present conditions, the low pH did not seem to affect the bond of light-activated composites to dentin significantly.
RESUMO
O objetivo deste trabalho foi avaliar a influência de restaurações temporárias de óxido de de zinco eugenol (OZE) na microinfiltração marginal de restaurações de resina composta em esmalte e cemento-dentina, utilizando dois sistemas adesivos. Foram realizadas duas cavidades classe V padronizadas (3 X 3 X 2 mm) em quarenta molares humanos extraídos. Os dentes foram divididos em dois grupos: teste e controle. As cavidades do grupo-teste receberam restaurações provisórias com OZE e foram armazenadas por cinco dias em ambiente com umidade de 100 por cento. Os dentes do grupo de controle foram armazenadas nas mesmas condições do grupo-teste sem o OZE. O material foi removido com cureta e para cada dente dos grupos-teste e de controle uma das cavidades foi restaurada empregando-se um adesivo com condicionamento ácido total (Single Bond) e, na outra, um adesivo com primer autocondicionante (Cleartil SE Bond). A resina composta Filtek foi utilizada para restaurar as cavidades. Posteriormente à termociclagem, os dentes foram corados com azul de metileno (0,5 por cento)por 2h. Após lavados e secos, os espécimes foram cortados longitudinalmente e avaliados em lupa (40X), sendo os dados analisados estatisticamente pelo teste de Kruskal-Wallis. Em cemento-dentina observou-se que o OZE influenciou apenas o adesivo com primer autcondicionante e o Single Bond apresentou menor microinfiltração que o Clearfil tanto nos grupos com quanto naqueles sem OZE. Em esamlte não houve diferença estatísitica entre os grupos com e sem OZE quando utilizado o Clearfil. Este mostrou menor índice de microinfiltração em esmalte quando comparado ao Single Bond no grupo sem OZE e não houve diferença significativa em relação ao grupo com OZE.
