Effect of post-cure temperature and heat duration on monomer conversion of photo-activated dental resin composite

Objectives. This research evaluated the relationship between post-cure heating temperature and duration on the monomer conversion of a commercial light-activated resin composite. Methods. Disc-shaped composite specimens (10 x 1 mm) were initially light-cured and then submitted to one of the following post-cure conditions: none (control), 50 degrees, 75 degrees, 100 degrees or 125 degrees C for 0.5, 1, 3, 5, or 7 min. After curing, specimens were stored in the dark at room temperature. Monomer conversion of all specimens was then determined using infrared spectroscopy. Results. Post-cure temperature was 12 times more influential than was heat duration on the extent of resin cure. The extent of cure increased linearly with an increase in post-cure temperature. Post-cure specimens that were heated between 3 and 7 min demonstrated equivalent cure values. All post-cure heating conditions resulted in significantly higher cure values than the light-cured only control. Significance. Physical properties of post-cure heated composites may change with respect to aging and water, but monomer conversion values of post-cure heated materials remain unaltered. Results of this study validate the use of relatively high temperatures for increasing the extent of monomer conversion. Such increases may lead to more biocompatible restorations.