Effect of cement base thicknesses on MOD amalgam restorations.

The placement of intermediary cement bases under deep preparations for amalgam restorations is a recommended procedure in restorative dentistry. The base is of low thermal conductivity and thus protects the pulp from thermal shock.1 Bases should also possess sufficient strength to withstand the forces of condensation and mastication transmitted through the amalgam restoration.2'3 The effect of the thickness of various cement bases on the fracture strength of a class II amalgam restoration was recently reported.4 The study stressed the importance of the modulus of elasticity of cements under amalgam restorations. This study examines the effect of the thickness of five cement bases on three types of amalgams in MOD preparations.