Evaluation of wear rate of dental composites polymerized by halogen or LED light curing units

Sufficient polymerization is a critical factor to obtain optimum physical properties and clinical efficacy of resin restorations. The aim of this study was to evaluate wear rates of composite resins polymerized by two different systems Light Emitting Diodes (LED) to and Halogen lamps. In this laboratory study, 20 specimens of A3 Tetric Ceram composite were placed in brass molds of 2*10*10 mm dimensions and cured for 40 seconds with 1 mm distance from surface. 10 specimens were cured with LED and the other 10 were cured with Halogen unit. A device with the ability to apply force was developed in order to test the wear of composites. After storage in distilled water for 10 days, the specimens were placed in the wear testing machine. A chrome cobalt stylus with 1.12 mm diameter was applied against the specimens surfaces with a load of 2 kg. The weight of each samples before and after 5000, 10000, 20000, 40000, 80000 and 120000 cycles was measured using an electronic balance with precision of 10-4 grams. Data were analyzed using t test and paired t test. P<0.05 was considered as the limit of significance. Mean weight in both groups had statistically significant difference before and after all cycles (P<0.05). In halogen group 5000 and 10000 cycles led to significant difference with 40000, 80000 & 120000 cycles (P<0.05). In LED group 20000 cycles had significant difference with both 5000 and 120000 cycles (P>0.05). Based on the results of this study, LED and halogen light curing units resulted in a similar wear rate in composite resin restorations.