A ten-year follow-up study of alveolar bone loss influenced by two dissimilar Class II amalgam restorations

Twenty paired approximal amalgam restorations (E) extended and unextended (NE) placed in twelve patients were followed up for 10 years. Measurements of the distance between the alveolar crest and (a) the apical margin of the filling (E and NE) or (b) the cementoenamel junction of the untreated control surface (C) were performed 1, 4 and 10 years following restoration placement. The bone loss associated with NE filling did not differ significantly from that of the control group and amounted to 0.4 mm in 10 years. The 10-year cumulative bone loss adjacent to the extended restoration (E) was 1.07 mm. Bone loss associated with the E restoration was significantly higher (P less than 0.001) than that of the NE and control groups at every period measured. During the first 4 years the yearly bone loss of the E group was 0.14 mm and then decreased to 0.08 mm during the last 6 years.