Influence of Class II amalgam fillings on attachment loss

176 extracted teeth restored with Class II amalgam fillings, having identical distribution regarding tooth type, jaw and proximal surface localization, were investigated. The loss of attachment was measured on stained teeth under a stereomicroscope fitted with an ocular micrometer. The cervical margins of restorations were examined with a probe. Defective cervical margins were found in 85.8% of the 176 restorations. The mean loss of attachment on the restored surfaces (1.4 mm) was significantly higher (P less than 0.001) than on the sound unrestored surfaces of the same teeth (0.9 mm). Little difference was found between mesial and distal surfaces. The restored surfaces of the lower molars showed less loss of attachment, when compared to similar surfaces of upper molars and lower premolars (P less than 0.05).