Abstract
This is a report on experiments in applying microwaves to denture resin polymerization of metallic denture. The aim of the experiments was to examine the temperature inside resin, the hardness of cured resin and the internal porosity when 3 mm and 4 mm thick resin was polymerized with metal plate and when polymerization was done with denture resin alone.
When microwaves at a power output 500 W were used to polymerize 3 mm thick resin, properly cured resin could be obtained if irradiation lasted from 1.5 to 5 (or 1.5 to 3) min. When microwaves at a power of 500 W were used to polymerize 4.5 mm thick denture resin, the range of irradiation time for obtaining properly cured resin tended to be narrower than in the case of 3 mm thick resin. This tendency was particularly noticeable when polymerization was done with metal plate. In this case the temperature inside the resin rose sharply with the polymerization of the metal plate. This also caused many internal porosity.
As a countermeasure to slow down the rise in temperature inside the denture resin at the time of polymerization, irradiation using 500 W microwaves was initially limited to one min. This was then followed by another 2 to 4 (or 3 to 5) min of microwave irradiation at a reduced power output of 200 W. A properly cured resin could be obtained under these conditions.
