Orthodontic bonding to porcelain—Bond strength and refinishing

Abstract

Glazed porcelain surfaces are not amenable to resin penetration for orthodontic bonding. The aims of this study were to evaluate (1) the bond strengths of two orthodontic composite materials to treated porcelain surfaces, (2) the effect of thermocycling, and (3) the porcelain surfaces after refinishing. Sixty glazed poocelain disks were assigned to three surface treatment groups: Silane (S), roughening and silane (RS), and roughening (R). The acid-etched enamel surfaces of 20 extracted teeth served as a control group. Ten specimens in each group were bonded with either Concise or System 1. They were stored in water at 37° C or thermocycled 8° to 45° C. Shear bond strength was tested with an Instron testing machine (0.05 cm/min). Analysis of variance showed that the four surface treatment groups and the two composite materials produced significantly different bond strengths ( P < 0.01 and P < 0.05, respectively). The effect of thermocycling was not significant ( P > 0.05). Acid-etched enamel/Concise produced the highest mean bond strength (17.4 MN/m 2). This was significantly greater ( P < 0.05) than the mean bond strengths of S/Concise (11.1), RS/System 1 (8.6), RS/Concise (8.1), and enamel/System 1 (7.8). The latter four mean bond strengths in turn were significantly greater ( P < 0.05) than S/System 1 (2.5), R/Concise (2.1), and R/System 1 (1.8). Of the four refinishing systems evaluated, all produced smooth surfaces but were unable to reproduce a glazed appearance. Roughening of porcelain and the silane treatment achieve bond strengths that should be clinically successful. With appropriate composite material selection, the silane procedure alone may be adequate. Surface roughening without silane treatment may not produce clinically acceptable bond strengths.