Direct orthodontic bonding to porcelain: an in vitro study

The shear/peel and tensile/peel bond strengths of mesh-backed orthodontic brackets bonded to porcelain, using a highly filled composite and four different silane bonding agents were determined. Sites of failure were recorded for each method of testing. A method of debonding ane restoring the porcelain surface to its original state after debonding was also investigated. All silane bonding systems tested provided adequate bond strength for clinical use. Fusion produced significantly higher force values to failure in shear testing. There was no significant difference between the bond strengths obtained in tensile testing. Patterns of failure differed in each mode of testing, suggesting that a shear mode of debonding is more likely to cause porcelain fracture and that the possibility of porcelain fracture during function or debonding cannot be excluded. The use of a Lift-Off plier is recommended in debonding brackets from porcelain where a silane bonding agent has been used. Diamond polishing paste was better at restoring the procelain surface to its original appearance than Shofu polishing stones.