Heat-released stress in acrylic dentures.

Dimensional changes in an acrylic resin denture blank that are sufficient to cause changes in fit on a gypsum cast occur primarily when the dentures are heated in water to a temperature of 90 degrees C or more. The poor correlation between observed fit and the intermolar distance change indicates that the dimensional change of dentures is much more complex than suggested previously and may be the product of factors that are not as yet fully understood. Enough heat to cause distortion of the denture can be produced during the process of grinding the denture. It should be recognized by the dentist, the dental assistant, and the dental laboratory technician that denture resins are sensitive to the techniques that are used in finishing. Overheating even small regions may allow localized dimensional changes that result in distortion of the denture.