Direct bonding of orthodontic brackets to porcelain veneer laminates.

The forces required to debond orthodontic attachments from porcelain veneer laminates were studied in vitro. Brackets were bonded to 160 veneered bovine incisor teeth before the determination of the debond force. The independent variables studied were resin type, priming agent, porcelain surface preparation, and debonding time. The average debond forces were compared with those obtained by debonding brackets bonded to natural teeth by means of the acid-etch technique. The bond between the resin and the porcelain surface was found to be satisfactory for direct bonding of orthodontic attachments. Roughening the porcelain surface and using a silane primer required an average debond force comparable to that of the acid-etched enamel bond at 24 hours. However, it increased the risk for porcelain fracture during debonding. Roughened surfaces and surfaces with micro-fractures could be satisfactorily finished and polished with either a series of graded Ceramiste points or a diamond-impregnated polishing wheel followed by a diamond polishing paste.