Efeito do pré-tratamento da dentina com dimetilsulfóxido e da temperatura de volatilização do adesivo na resistência de união de pinos de fibra

Abstract

Dentin pretreatment using dimethyl sulfoxide (DMSO) can result in higher resin infiltration and warm air to volatilize the adhesive can increase solvent evaporation, improving adhesion to root dentin. The aim in this "ex vivo" study was to evaluate the effect of pretreatment of root canal dentin using DMSO and the volatilization temperature of solvents of a universal adhesive system on the bond strength of fiberglass posts fixed with a dual curing resin cement in single-rooted teeth. Forty bovine roots (n = 10) with a length of 15 mm were used, which the root canal was endodontically treated and prepared (10 mm) for fixation of a fiberglass post (Exacto, Angelus) with the luting system Single Bond Universal + RelyX Ultimate (3M ESPE). Initially, the dentin was pre-treated with DMSO or distilled water (control) for 60 s and excess moisture was removed. Then, the adhesive system was applied in the self-etching mode and its volatilization is carried out at 23ºC (room temperature) or 40ºC (warm air stream) for 10 s. Light curing of the materials was carried out for the time recommended by the manufacturer with a polywave LED at irradiance of 1,000 mW/cm2. After the cementation of the fiber posts, the specimens were subjected to thermal cycling (10,000 cycles - 5 and 55ºC). Then, the roots were sectioned to obtain 1 mm thick slices of the cervical, middle, and apical thirds. Bond strength of the thirds was measured by the push out test using a universal testing machine. Failure pattern was evaluated under a stereomicroscope. Data were submitted to three-way split-plot ANOVA and Tukey's test ( = 0.05). Adhesive volatilization at 40ºC promoted an increase on bond strength compared to a temperature of 23ºC. The cervical third had the highest bond strength, followed by the middle third, with the lowest bond strength observed in the apical third, with statistical difference between them. Thus, it can be concluded that the solvent volatilization of adhesive system using warm air stream promotes an increase on bond strength of fiberglass post.