Ceramic bracket debonding: the evaluation of two debonding techniques and their effect on enamel

Enamel fractures have been associated with the debonding of some ceramic brackets which have a chemical bond to the enamel. The purpose of this study was to assess the enamel surface subsequent to debonding Transcend series 2000 ceramic brackets using two debonding techniques. One hundred extracted human premolars were divided randomly into groups of two and prepared for bonding. Group 1 teeth had brackets bonded with Transbond light-cured adhesive and Group 2 teeth had brackets bonded with Unite chemically-cured adhesive. Bonded teeth were stored in normal saline at 37 degrees C for 5 days and thermocycled. Teeth in both groups were subdivided randomly into Subgroups A and B. Teeth in Subgroup A had brackets debonded with the Transcend debonding instrument while teeth in Subgroup B had brackets debonded with ligature cutters. Each tooth was examined under light microscopy and those teeth suspected of enamel fracture were assessed by scanning electron microscopy. Three out of the 100 teeth exhibited enamel fracture. There was no difference between the adhesive used and the number of enamel fractures or between the debonding technique used and the number of enamel fractures. A high proportion of brackets debonded with ligature cutters exhibited tie wing fracture.