Bond strength of orthodontic composite cement to treated porcelain

A porcelain-fused-to-metal ceramic was prepared for bonding by five treatments: sandblasting, sandblasting and silanating, hydrofluoric acid etching, hydrofluoric acid etching and silanating, and 600-grit polishing and silanating. Two commercial, all-purpose bonding agents were used to bond a composite cement to the porcelain samples. In vitro tensile bond strengths were compared with samples for which no bonding agent 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 debonding. Composite cement bonded without bonding agent to nonsilanated porcelain prepared by sandblasting or etching with hydrofluoric acid had bond strengths of 6.5 MPa and 18 MPa, respectively, with all bond failures at the bracket/composite interface. The use of all-purpose bonding agents and silanating agents may not be necessary for adequate orthodontic direct bonding.