The effect of amalgam bonding on resistance form of Class II amalgam restorations.

OBJECTIVE

This study evaluated the load required to produce failure in Class II bonded amalgam restorations.

METHOD AND MATERIALS

Five groups of 12 maxillary molars were mounted. Class II mesio-occlusal preparations were cut: group 1, extension through central grooves, without retention grooves; group 2, proximal slot preparation, without retention grooves; groups 3 and 5, slot preparation with long facial and lingual retention grooves; group 4, slot preparation without grooves, with unsupported proximal enamel allowed to remain. Groups 1 to 4 were restored with an amalgam-bonding system and amalgam; in group 5, no amalgam-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 trend toward greater resistance to dislodgment or fracture when an amalgam-bonding technique was used, its use did not significantly increase the resistance to failure when compared to retention grooves alone.