Avaliação in vitro da força de união, através de teste de tração, de porcelana feldspática com diversos tratamentos superficiais à resina composta

Abstract

In the search for the recovery of the dental aspect, the porcelain stands out among restoring materials. The use of this material has increased considerably over the last years, therefore increasing the probability of fractures. Even so, not every failure demands the restoration of the material: the possibility of a repair exists with compounded resin. This study proposed to evaluate in vitro the bonding strength of the composite resin to feldspathic porcelain with several surface treatments: roughened with diamond burs or sandblasted with aluminum oxide of 50 micra, isolated or associatedly etched with phosphoric acid for 15 seconds, or with hydrofluoric acid for 1 or 4 minutes. All the specimens were previously regularized with 220-grit silicon carbide paper. After the superficial treatments, they received the adhesive system for porcelain, Scotchbond Multi-Purpose Dental Plus Adhesive System (3M). After making the union with the composed resin (Restorative Z100, 3M), they were stored in distilled water at 37oC, for 7 days, followed by thermocycling (600 cycles of 1 minute, between 5 and 55oC), and submitted to a tensile strength test. With the obtained results, the conclusion was that with all the proposed treatments an improvement happened in the resistance of the tensile bonding strength (when compared to those observed in the group control without any superficial treatment). The sandblasting produced a better resistance than the roughening with a diamond bur; but, when associated to the etching with any of the selected acids, independent of the time of application, there was no statistical difference among those treatments.