BOND STRENGTH OF ORTHODONTIC COMPOSITE CEMENT TO TREATED PORCELAIN

A porcelain-fused-to-metal ceramic was prepared for bonding by five tr eatments: sandblasting, sandblasting and silanating, hydrofluoric acid etching, hydrofluoric acid etching and silanating, and 600-grit polis hing and silanating. Two commercial, all-purpose bonding agents were u sed to bond a composite cement to the porcelain samples. In vitro tens ile bond strengths were compared with samples for which no bonding age nt was used. Highest bond strengths (22 to 41 MPa) were obtained, with one exception, when the porcelain surface was silanated; however, the use of silane increased the occurrence of porcelain fracture on debon ding, Composite cement bonded without bonding agent to nonsilanated po rcelain prepared by sandblasting or etching with hydrofluoric acid had bond strengths of 6.5 MPa and 18 MPa, respectively, with all bond fai lures at the bracket/composite interface. The use of all-purpose bondi ng agents and silanating agents may not be necessary for adequate orth odontic direct bonding.