Resistência adesiva ao cisalhamento de reparos em porcelana condicionada com laser

Abstract

The aim of this study was to evaluate in vitro the shear bond strength of repairs in porcelain conditioned with laser and to compare it to the traditional repair methods conditioned with hydrofluoric acid and phosphoric acid. In this study, were used two conditioning porcelain (10% hydrofluoric acid Dentsply; 37% phosphoric acid 3M ESPE), a silane agent (Rely X Silano 3M ESPE), an adhesive system (Scotchbond Multi-uso 3M ESPE), a composite resin (Filtek Z250 3M ESPE), a porcelain (Ceramco 3 Dentsply) and a laser of high potency in femtosecond (Ti:Safira Libra-S, Coherent). Sixty porcelain discs were made and embedded in PVC rings using a polymethyl methacrylate resin. All specimen were smoothed with abrasive sandpapers in decreasing order of abrasiveness for the leveling of the surface. Six Groups were formed (n=10) being divided: G1 conditioning with laser with potency 760mW; G2 conditioning with laser with potency of 760mW and application of 37% phosphoric acid for 15s; G3: conditioning with laser with potency of 900mW; G4 conditioning with laser with potency of 900mW and application of 37% phosphoric acid for 15s; G5 application of 37% phosphoric acid for 15s (group control) and G6 application of 10% hydrofluoric acid for two minutes. After the conditioning of the porcelain, silane agent was applied for all of the specimens, following by the application of the adhesive system and photoactivation for 20s. Specimens of composed resin were made in the surface of the porcelain aided with a metal matrix and insert of incremental layers (2 increments) with photoactivation of 20 seconds for increment. The photoactivation was performed with a visible light unit (XL 3000, 3M Dental Products). Afterwards the metal matrix was removed and the specimens were submitted to the new photoactivation for more 20 seconds. The specimens were submitted a thermal cycling by 1000 cycles of 30 seconds in each bath with temperature between 5oC and 55oC. After the thermal cycling , specimens were submitted to the shear bond strength. The results were evaluated statistically through analysis of variance ANOVA One Way and Tuckey test (α =0,05). The averages and standard deviation: G1 11,25 ± 3,10(ab); G2 12,32 ± 2,65(ab); G3 14,02 ± 2,38(a); G4 13,44 ± 2,07(a); G-5 9,91 ± 2,18(b); G6 12,74 ± 2,67(ab), (same letters demonstrate there not to be difference among groups).