Orthodontic brackets bonded to glazed and deglazed porcelain surfaces

Edgewise orthodontic brackets were bonded with a light activated composite resin to 100 glazed and 100 deglazed feldspathic porcelain blocks for an in vitro comparative determination of shear/peel bond strengths. The independent variables studied were porcelain surface preparation and the time interval between activation of the composite resin and the debonding procedure. The initial shear/peel bond strength achieved on bonding to deglazed porcelain was statistically significantly greater than that on bonding to glazed porcelain (p<0.05), but after the 10-minute interval, the bond strength in the glazed porcelain sample was greater than in the deglazed sample. Many more porcelain fractures occurred on deglazed porcelain (71%) than on glazed porcelain (36%) during bond strength determination. Scanning electron microscopy evaluation suggests that deglazing does not substantially increase micromechanical adhesion of the composite resin. Bond strength adequate to withstand the application of orthodontic forces were achieved when bonding to glazed porcelain. This study indicates that deglazing may not be necessary for attachment of orthodontic brackets to porcelain surfaces.