Effect of gingival health of removing overhanging margins of interproximal subgingival amalgam restorations.

This study was designed to clarify the relationship between amalgam restorations with subgingival overhanging margins and gingival health. This required the presence of such a restoration defect as the sole variable parameter. This was achieved by pairing 26 defective premolar and molar amalgams with similarly defective restorations in the same mouths, test and control being allocated randomly. Test amalgams were contoured to remove overhangs. All other procedures, namely, scaling, polishing and oral hygiene instruction were applied with equal emphasis. Plaque accumulation, gingival inflammation and pocket depths were recorded at 0, 4, 8 and 12 weeks. At the baseline (week 0) there were no significant differences between test and control sides for any of the parameters. Significant differences between test and control sides for all parameters were apparent at all other times. The greatest change took place during the first 4 weeks of the study. It was concluded that the presence of a subgingival overhanging defective margin may be the only important clinically significant feature of an amalgam restoration related to the pathogenesis of chronic inflammatory periodontal disease. It was also demonstrated that correction of defective restorations should be effected during the initial phase of periodontal therapy.