The resin cement bond strength to lithium disilicate ceramic can be affected by Tryin paste removal method?

Abstract

The aim of this study was to evaluate four methods of Try-in paste removal from the lithium disilicate ceramic surface before the cementation procedure, and assess their influence on the bond strength to resin luting cement. Slices of dentin 1,6 mm thick were sectioned from the crown of human third molars and truncated cone shape cavities were made with diamond burs. IPS e.max Press ceramic blocks were obtained for each cavity, etched with hydrofluoridric acid and fixed with temporary paste (Try-in, IvoclarVivadent), except for Group G1 cemented according to manufacturer’s instructions. Try-in paste was removed from the experimental groups using different techniques: G2, ultrasonic bath in distilled water (5 min.); G3, air/water spray (1min.); G4, etched with phosphoric acid (2 min) + air/water spray (30s) and G5, etched with phosphoric acid before and after hydrofluoridric acid application + air/water spray (30s). The ceramic restorations were cemented with the same procedures as in G1. Push-out bond strength test (MPa) was performed in a universal testing machine with a crosshead speed of 0.5mm/min. One way ANOVA and Tukey’s test (p<0,05) was applied: G4(19.21)a, G2(17.09)ab, G1(16.82)ab, G3(16.18)ab and G5(15.9)b. The results showed that all the experimental groups showed remaining particles of Try-in paste. The bond strength in G4 was statistically higher than in G5. In the other groups no significant difference was shown. In G5 there was predominance of adhesive failures between resin cements and ceramics. In conclusion, the techniques used were not totally effective at removing the paste Try-in, however the presence of remaining material that did not influence the bond strength of restorations. It was observed that the methods of the temporary paste removal may affect the bond strength of ceramic restorations.