Effects of removal of posterior overhanging metallic margins of restorations upon the periodontal tissues

Periodontal patients with overhanging amalgam restorations were randomly assigned to four groups so that the effects of removal of the overhangs could be observed in terms of Gingival and Plaque Index scores and in reversal of the early radiographic signs of alveolar bone destruction during a period of 3 months. A total of 80 overhanging restorations were studied, 20 in each group. Group I served as a control group, overhangs were left in situ, and the subjects practised their habitual oral hygiene methods. In Group II the overhangs were removed and habitual oral hygiene methods practised. In Group III the overhangs were left in situ but professional plaque control including prophylaxis and interdental flossing was carried out at 2‐week intervals. In Group IV overhangs were removed and a similar professional plaque control programme followed. Gingival Index and Plaque Index scores were obtained at the commencement of the study and 3 months later. Reproducible intra oral radiographs were obtained at the same examinations and the differences in mean bone height changes calculated for each group. Analysis of the transformed values for Plaque and Gingival Indices by Anova demonstrated (Table 2) a significant effect on gingival inflammation when both plaque and overhang were removed. The treatments showed no significant effect on plaque accumulation. Bone scores initially and after 3 months showed a highly significant treatment interaction. The greatest improvement occurred in Group IV. The results suggest that regular plaque removal results in disappearance of gingival inflammation and in increased alveolar bone support, and is more effective when overhanging margins are removed.