THE EFFECT OF AMALGAM BONDING ON RESISTANCE FORM OF CLASS-II AMALGAM RESTORATIONS

Objective: This study evaluated the load required to produce failure i n Class II bonded amalgam restorations. Method and materials: Five gro ups of 12 maxillary molars were mounted. Class II mesio-occlusal prepa rations were cut: group I, extension through central grooves, without retention grooves, group 2, proximal slot preparation, without retenti on grooves; groups 3 and 5, slot preparation with long facial and ling ual retention grooves, group 4, slot preparation without grooves, with unsupported proximal enamel allowed to remain. Groups 1 to 4 were res tored with an amalgam-bonding system and amalgam; in group 5, no amalg am-bonding material was used. Results: Mean (SD) failure loads: group 1, 281 (77) N; group 2, 246 (101) N; group 3, 238 (84) N; group 4, 254 (100) N; and group 5, 191 (66) N. Conclusion: Although there was a tr end toward greater resistance to dislodgment or fracture when an amalg am-bonding technique was used, its use did not significantly increase the resistance to failure when compared to retention grooves alone.