DIRECT BONDING TO ADLLOY-TREATED AMALGAM

The purpose of this study was to test the bond-enhancing effect by mod ifying amalgam surfaces with Adlloy (a gallium-tin liquid alloy) and b onding brackets by using two different resin systems, Bond strength an d location of bond failure was assessed by using (1) Concise (3M Denta l Products) and (2) C&B Metabond (Parkell) systems with and without th e use of Adlloy alloy. Class V buccal amalgam restorations (n = 132) w ere subjected to one of two surface treatments: (1) sandblasting or (2 ) sandblasting plus Adlloy treatment, Mandibular premolar brackets wer e bonded with Concise composite resin or C&B Metabond (adhesive) to am algam surfaces. All specimens were stored in 37 degrees C water for 10 weeks and subjected to thermocycling before bond strength testing. Th e laboratory shear bond strength of Concise material to amalgam was no t improved after Adlloy modification, However, Adlloy-treated amalgam significantly increased the laboratory shear bond strength of orthodon tic brackets bonded with C&B Metabond material. The majority (58%) of the bond failures of C&B Metabond bonded to non-Adlloy treated-amalgam occurred at the amalgam-adhesive, interface, whereas the majority (58 %) of the bond failure of C&B Metabond bonded to Adlloy-treated amalga m failed within the adhesive, Fracture within the amalgam during debon ding was observed with C&B Metabond bonded to sandblasted amalgam (21% ) and Adlloy-treated amalgam (15%), Regardless of Adlloy treatment, C& B Metabond would appear to provide adequate orthodontic bonding to ama lgam; however, there may exist a potential risk of amalgam restoration fracture upon debonding.