Effect of different surface treatment on the repair bond strength of feldspathic porcelain

Abstract

Background. Considering the use of silane-containing universal adhesives to enhance the repair bond strength of porcelain restorations, a question arises whether the application of these adhesives eliminates the need for a separate application of silane or not. Objectives. This study aimed to assess the effect of various kinds of surface treatment, including hydrofluoric acid (HF) etching, the application of bis-silane and the use of universal adhesives, on the repair bond strength of feldspathic porcelain. Material and methods. In this experimental in vitro study, 70 porcelain disks were fabricated and divided into 7 groups (n = 10) for the following types of surface treatment: C (control group) - HF etching + silane + Porcelain Bond; HSB - HF etching + Single Bond; HSSB - HF etching + silane + Single Bond; HAB - HF etching + All Bond; HSAB - HF etching + silane + All Bond; HFB - HF etching + FuturaBond (R); and HSFB - HF etching + silane + FuturaBond. After applying different kinds of surface treatment, the specimens were light-cured and the Filtek (R) Z250 composite was bonded to the treated surfaces. The specimens were incubated in distilled water at 37 degrees C for 24 h, and then underwent 5,000 thermal cycles. The repair bond strength of porcelain was measured and the mode of failure was determined under a stereomicroscope. Data was analyzed using the one-way analysis of variance (ANOVA) and Tukey's test. Results. Differences in the porcelain repair bond strength were significant among the groups (p < 0.001). Bond strength for Single Bond (p < 0.001) and All Bond (p < 0.001) along with silane was significantly higher than for the application of these adhesives without a separate silane application step. This difference was not significant for FuturaBond. Mixed failure was the dominant mode of failure in all groups. Conclusions. The application of silane, irrespective of the use of universal adhesives with or without silane, increased the porcelain repair bond strength. Thus, a separate silane application step following HF etching and the use of universal adhesives with or without silane can enhance the repair bond strength of feldspathic porcelain.