Thermally induced stresses and rapid temperature changes in teeth

✍ Scribed by Barker, Robert E. ;Rafoth, Robert F. ;Ward, Robert W.

• Publisher: John Wiley and Sons
• Year: 1972
• Tongue: English
• Weight: 890 KB
• Volume: 6
• Category: Article
• ISSN: 0021-9304
• DOI: 10.1002/jbm.820060503

✦ Synopsis

Abstract

The central theme of this paper revolves about an attempt to provide information and ideas that might be useful to persons interested in cryogenic dental procedures. However, a broad spectrum of thermal properties is also considered. For convenience a summary table is given for pertinent thermal and mechanical properties of dental materials. A point demonstrated is that observations which are of direct empirical utility to dentists often can be enhanced in value if viewed in terms of simple analytical models. For example, a tooth can be expected to be somewhere between a sphere and a long rod in its cooling or heating characteristics. The importance of the thermal diffusivity rather than thermal conductivity in transient phenomena is discussed. Some graphical techniques that circumvent mathematical difficulties are developed in detail. An isolated extracted tooth in contact with a coolant approaches to within 98% of its final temperature in less than 1 min but in the jaw, in contact with a cold (or hot) probe, the equilibration will take much longer. Thermally generated stresses, either due to differences in expansivities of the dentin and enamel or to large temperature gradients across a single component, can be quite large (comparable to the reported tensile strength, 9.3 MN/m^2^ for enamel) at cryogenic temperatures. Our observations and analysis make us believe that the reported strength of 9.3 MN/m^2^ is too low by at least an order of magnitude.