Fracture toughness of a ceramic-resin interface

Objectives. The purpose of this study was to compare the interfacial fracture toughness of smooth and roughened ceramic surfaces bonded with a luting resin using an optimized method of silane treatment. Methods. Ceramic discs were prepared with four different surface preparations (n = 20) consisting of (1) polished, (2) gritblasted, (3) hydrofluoric acid etched and (4) gritblasted and etched. The ceramic discs were then covered by a PTFE tape with a chevron shaped circular hole. The exposed surfaces were treated by an optimized silane treatment followed by an unfilled resin and then a luting resin. Specimens were then stored in distilled water at 37 degrees C for (A) 24h and (B) 30 days. The interfacial fracture toughness was measured, the mode of failure and fracture surfaces were also examined under a stereo-zoom microscope and a scanning electron microscope. Results. One-way ANOVA showed that there was no statistically significant difference in the mean interfacial fracture toughness for groups A1-A4 (P > 0.05). However, the mean interfacial fracture toughness for group B1 was significantly different from that for groups B2, B3 and B4 (P < 0.05). Independent-samples t-test results showed that there was a significant increase in the G(IC) mean value for groups B2 and B3 after 30 days water storage (P < 0.05). The modes of failure were predominantly interfacial or cohesive within the resin. Significance. it can be concluded that micro-mechanical retention by gritblasting the ceramic surfaces could be sufficient with no need for HF acid etching the ceramic surfaces when an appropriate silane application procedure is used. (c) 2007 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.