The shear bond strength of composite brackets on porcelain teeth

Recent advances in materials and techniques suggest that direct bonding of orthodontic attachments to surfaces other than enamel may now be possible. To test the effectiveness of bonding orthodontic attachments to porcelain t eeth, composite brackets (Spirit MB) were bonded to 64 porcelain teeth by m eans of a self-cure non-mixed resin system (Unite). The 64 porcelain teeth were divided into groups of eight and after roughening with a green stone t hey were subjected to a combination of treatments. Some were etched, some p rimed with a silane coupling agent and some received both treatments before the brackets were bonded to them. Half of the teeth were then thermally-cy cled 500 times between 4 and 60 degreesC before all the brackets were remov ed in a shear test. The shear data was analysed by one way analysis of vari ance and the Student-Newman-Keul test. The results showed that the highest bond strength existed in the group whic h had been both etched and primed but not thermocycled (P < 0.05). The fact ors that affected the bond strength, beginning with the most significant, w ere acid etching, primer application, and then thermocycling, A mechanical based composite bracket can offer good bond strength to porcelain teeth.