Temperature rise during polymerization of light-activated resin composites

There has been a steady rise in the use of resin-based composites in the re storation of large posterior cavities. Visible light-activated materials ha ve come to dominate the market for direct posterior composites because of t he convenience offered to the operator by their command set nature. Manufac turers have produced more powerful light-activation units in response to co ncerns over inadequate depth of cure. However, some authors have warned of the danger to the dental pulp induced by excessive heat generated during po lymerization. Variables governing heat generation include output intensity of the light-activation unit, quality of light filter, irradiation time, ma terial composition and material surface-light guide exit window distance, r esidual dentine thickness and cavity dimensions. This in vitro study assess ed the relative influence of some of these factors under controlled conditi ons. The findings suggest that minimum irradiation times should be used whe n curing bonding agents in unlined cavities where residual dentine thicknes s is limited and high output intensity light-activation units are employed. Material composition is identified as an important variable in determining the magnitude of the temperature rise.