Increases in cavity volume associated with the removal of class 2 amalgam and composite restorations

Removal of amalgam restorations from class 2 cavities has been shown to cause increases in cavity volume. The aim of this study was to test whether the removal of composite resin from class 2 cavities was associated with greater increases in cavity volume compared to that produced during removal of amalgam. Class 2 cavities were prepared in previously extracted human molar teeth and the cavity volumes calculated. The teeth were restored with either amalgam or a composite resin and appropriate dentin bonding agent (APH/Optibond). Two dentists removed the restorations, and the resultant cavity volumes were calculated. The results were analyzed using a standard t-test, ANOVA, and a Scheffe F-test. Removal of composite from class 2 cavities resulted in significantly increased cavity volumes compared to that when amalgam was removed. While there was significant interoperator difference in cavity volumes following removal of amalgam from class 2 cavities, there was no significant interoperator difference in cavity volumes following the removal of composite. These differences were related to the methods used to eliminate the restorations from the cavities.