A radiographic method of estimating surface area of amalgam restorations

Mercury released from the surface of amalgam fillings has been linked to a variety of disorders, but without proof of correlation. Studies use surface counts to estimate this variable, but large-scale studies would require a tool to rapidly and accurately assess restoration surface area. Objectives This study investigated digital analysis of conventional dental radiographs as a means of estimating amalgam surface area. Methods Amalgam fillings were placed in 40 typodont teeth, the surface areas of the restorations were determined by measuring standardized photomicrographs of each surface. The teeth were radiographed, and area of the radiographic image of the restorations was measured. Data were used to produce expressions to estimate actual area from radiographic area. Results Regression analyses showed that surface area estimation from radiographic area was more accurate than estimation from surface counts. The accuracy of the surface area count was further improved by combining the radiographic area with a photographic occlusal area measurement or surface count, the latter giving the highest correlation. Conclusions This study demonstrated that two-dimensional dental radiographs may be used to estimate surface area of amalgam restorations.