The effect of surface coating on the bond strength of machinable ceramics

This study examined the nature of the surface presented by a machinable feldspathic porcelain and by a machinable glass-ceramic for bonding to conventional composite luting agents and measured the bond strengths which may be achieved with various surface treatments. There was no significant difference between the bond strengths achieved to etched porcelain, Silicoated porcelain or etched glass-ceramic. Silicoated glass-ceramic specimens showed a significantly higher adhesive assembly strength (p = 0.02). Examination of the fractured specimens showed that in all cases the failure involved part cohesive failure of the ceramic surface and part failure at the cement-ceramic interface.