A simulated clinical appraisal of base materials for amalgam restorations.

Eight materials were placed as bases on the pulpal surface of cavities prepared in extracted teeth. Seven minutes after mixing of the material commenced, amalgam was condensed on to the lined cavity. The restored teeth were sectioned subsequently for microscopic examination. The results suggested that all uniformly mixed, carefully placed base forming materials that have reached the state of "clinical set" are able to withstand loads applied during amalgam condensation irrespective of their strength.