Bond strength of adhesive systems with different solvents to dry and wet dentin.

AIM: This study evaluates bond strength between dentin and composite using adhesives with different solvents to dry and wet dentin. MATERIALS AND METHODS: Ninety bovine incisors were used; the vestibular surfaces were worn by the exposure of an area with a diameter of 4 mm of dentin. The specimens were divided into 6 groups, according to the type of adhesive used and hydratation stals: Group SB-wet: Single Bond 2 in wet dentin, Group SBdry: Single Bond 2 in dry dentin, Group SL-wet: Solobond M in wet dentin, Group SL-dry: Solobond M in dentin dry. Group XPwet: XP Bond in wet dentin, Group XP-dry: XP Bond in dentin dry. They were cut to obtain specimens in the shape of stick with 1 × 1 mm and subjected to microtensile test in universal testing machine with a cross speed of 1mm/min. The data were analyzed with ANOVA and Tukey's tests (5%). RESULTS: ANOVA showed significant differences for surface treatment and interaction, but no difference was found for adhesive factor. The Tukey's test showed that the samples with wet dentin shown higher values of bond strength. CONCLUSION: The adhesive did not influence in the bond strength. The groups with wet dentin showed higher values of bond strength than groups with dry dentin.

Evaluation of bond strength of self-adhesive cements to dentin with or without application of adhesive systems.

PURPOSE: To evaluate the bond strength of indirect restorations to dentin using self-adhesive cements with and without the application of adhesive systems. MATERIAL AND METHODS: Seventy-two bovine incisors were used, in which the buccal surfaces were ground down to expose an area of dentin measuring a minimum of 4 x 4 mm. The indirect resin composite Resilab was used to make 72 blocks, which were cemented onto the dentin surface of the teeth and divided into 4 groups (n = 18): group 1: self-adhesive resin cement BiFix SE, applied according to manufacturer's recommendations; group 2: self-adhesive resin cement RelyX Unicem, used according to manufacturer's recommendations; group 3: etch-and-rinse Solobond M adhesive system + BiFix SE; group 4: etch-and-rinse Single Bond 2 adhesive system + RelyX Unicem. The specimens were sectioned into sticks and subjected to microtensile testing in a universal testing machine (EMIC DL- 200 MF). Data were subjected to one-way ANOVA and Tukey's test (α = 5%). RESULTS: The mean values (± standard deviation) obtained for the groups were: group 1: 15.28 (± 8.17)a, group 2: 14.60 (± 5.21)a, group 3: 39.20 (± 9.98)c, group 4: 27.59 (± 6.57)b. Different letters indicate significant differences (ANOVA; p = 0.0000). CONCLUSION: The application of adhesive systems before self-adhesive cements significantly increased the bond strength to dentin. In group 2, RelyX Unicem associated with the adhesive system Single Bond 2 showed significantly lower mean tensile bond strengths than group 3 (BiFix SE associated with the etch-and-rinse Solobond M adhesive system).

Torque de remoção de parafusos em pilares protéticos com conexão tipo hexágonointerno após ciclagem mecânica / Evaluation of the torque removal in internal hexagonal abutments submitted to a cyclic

O sucesso no tratamento reabilitador protético realizado sobre implantes ósseo-integrados pode ser comprometido por falhas mecânicas em seus componentes, tais como desajuste e até mesmo fraturas dos componentes protéticos quando expostos à função mastigatória. O presente estudo teve por objetivo avaliar, in vitro, o desajuste ocorrido na interface implante-intermediário por meio da aferição e comparação do torque inicial utilizado para a colocação do parafuso de fixação dos pilares protéticos em implantes com hexágono interno, com relação ao torque necessário para remoçãodessas estruturas antes e após a simulação da função mastigatória. Testes de ciclagem mecânica foram induzidos sobre os pilares protéticos. Mediu-se o torque de remoção dos parafusos de fixação dos pilares proteticos. Houve diminuição significativa nos valores de torque de remoção de todas as amostras, e a perda foi ainda maior nas amostras submetidas à ciclagem mecânica. Os dados obtidos permitem supor que há sempre diminuição nos valores de torque de remoção desses componentes e que a função mastigatória aumenta a probabilidade de desajuste na interface implante-pilar protético.