Journal of Dental Research, Vol 55, 441-451, Copyright © 1976 by International & American Associations for Dental Research Online Journals
Thermal diffusion through amalgam and cement base: comparison of in vitro and in vivo measurements
V. R. Tibbetts, R. J. Schnell, M. L. Swartz and R. W. Phillips
Thermal diffusion was measured in vitro and in vivo through amalgam and
amalgam underlaid with bases of zinc phosphate, zinc oxide-eugenol, and
calcium hydroxide cements. Although the magnitudes differed, there
generally was good agreement between in vitro and in vivo data with respect
to the relative rates of thermal diffusivity through amalgam restorations
underlaid with bases of each of the three materials. In all tests, both in
vitro and in vivo, the zinc oxide-eugenol base proved to be the best
thermal insulator. Calcium hydroxide was the next best thermal barrier and
was followed by zinc phosphate cement. In vitro tests indicated dentin to
be a better thermal insulator than zinc phosphate cement but inferior to
the zinc oxide-eugenol and calcium hydroxide base materials used here.
Although a method has been presented here for the in vivo assessment of the
efficacy of thermal insulating bases and a number of in vivo experiments
were conducted, much research remains to be done in this area. Additional
investigation is needed to better define the parameters of thermal change
beneath various types of restoratives and also to establish more exactly
the role of base thickness in providing thermal protection beneath clinical
metallic restorations.
