Evaluation of the Bond Strength of Resin Cements to New Lithium Disilicate-Reinforced Glass Ceramic Materials

摘要

The aim of the present study was to evaluate the suitable acid etching time of recently-introduced lithium disilicate-reinforced glass ceramic materials. Two types of lithium disilicate-reinforced glass ceramic materials [Upcera ceramic (Upcera) and IPS e.max CAD (e.max)] and the same resin cement (Multilink N) were used. A total of 240 ceramic blocks (n = 8) underwent different acid etching time (20, 40, 60 and 80 sec). After 24 h in a water bath and 5000 cycles of thermocycling (5/55 degrees C), the bond strengths of specimens were recorded. Following acid etching, an atomic force microscope and a scanning electron microscope were used to characterize the specimens' surface roughness and morphology. Tukey's LSD post hoc test and two-way ANOVA were used for the statistical analysis of the obtained data. The results showed that the type of ceramic material, acid etching duration, as well as the interaction among these variables (P < 0.05), can markedly affect the bond strength. The e.max group exhibited the maximum bond strength following acid etching for 80 sec (P < 0.05); The Upcera groups exhibited the maximum bond strength following acid etching for 20 sec (P < 0.05). No significant difference was observed in the maximum bond strength between the e.max and Upcera ceramics (P > 0.05). When e.max specimens were pre-treated according to the manufacturers' instructions, they achieved maximum bond strength. The successful bonding performance of Upcera for adhesive luting showed the best bond strength at acid etching for at least 40 sec when using the same resin cement. The duration of acid etching was found to significantly influence the bond strength of ceramic materials. Therefore, when Multilink N was chosen for adhesive luting, Upcera required etching for at least 40 sec.