Clinical evaluation of four dental amalgams over a two year period.

The aim of this study was to determine the clinical durability of two locally manufactured amalgams. In each of eighty-two patients one class II cavity was restored with Dispersalloy (Johnson and Johnson) which served as the control and all the other class II cavities were randomly restored with one of the following amalgams: Amalgaphase, Amalga 43 (Amalgam Alloys-South Africa) or Permite C (Southern Dental Industries). Matrix bands were placed. Kalzinol bases and Polyvar varnish were applied in all cavities. All amalgams were mixed according to the manufacturers' instructions. The cavities were overpacked with amalgam, and the amalgam condensed by hand, carved and then burnished with a ball burnisher. Twenty-four hours later all restorations were polished with a Shofu polishing system and colour photographs were taken. The restorations were evaluated using the Ryge and Snyder (1973) evaluation system, as well as comparison of the colour photos. The Fisher's Exact Test was used for the statistical analysis. During the second year there were no significant (p < 0.05) differences between the four brands of amalgam restorations except as regards the gloss category. The two South African manufactured amalgams compared well with the two imported amalgams. During the second year the marginal integrity and surface texture of Amalgaphase compared well with that of Permite C. Dispersalloy and Permite C showed more deterioration in anatomic form than the two South African amalgams. Amalgaphase was the only amalgam to show no bulk fracture within a period of two years. Amalgaphase performed better in the gloss category than the other three amalgams during the second year evaluation. According to the weighted product calculation Amalgaphase was the best amalgam followed by Dispersalloy, Amalga 43 and Permite C.