Effect of Additional Heat Treatment of Silane-Coated Machinable Ceramics on Bond Strength

The purpose of this study was to investigate the effect of surface treatment with a silane coupling agent combined with heat treatment on bonding to machinable CAD/CAM ceramics. The polished ceramic specimens were treated with a silane coupling agent, or with a silane coupling agent combined with an additional dry heat treatment (100 oC for 10 min.). The treated specimens were bonded, and tensile bond strengths were measured (n=8) after storage in water at 37 oC for 1 day and 30 days. In addition, the contact angle values of a flowable resin composite dropped on the three types of ceramic specimen (silanized ceramic specimen, silanized and additional dry treatment specimen, and polished ceramic specimen as control) were measured (n=5). Two-way ANOVA revealed that the effects of heat treatment and storage in water were highly significant (p<0.05). One-way ANOVA and the q-test showed that the differences among the contact angle of three specimens were significant (p<0.05). The application of a silane coupling agent combined with an additional heat treatment increased the bond strength of the machinable CAD/CAM ceramics. However, decrease of bond strength showed that additional heat treatment of the silanized ceramic specimen was not able to completely prevent the degradation of bonding in water storage.