Objective:The purpose of this study was to compare the surface hardness of composite resins polymerized with conventional halogen light source or LED light. Methods:Teflon moulds were used to build cylindrical specimens 3 mm high and 8 mm diameter. The specimens prepared with A110, P60, Supreme (3M, U.S.A.) composite resins were randomly assigned to two groups of seven samples each and polymerized with conventional halogen light (Lunar, Benlioglu Inc., Turkey) and LED light (Elipar FreeLight II, 3M, U.S.A.). After storing the samples for 7 days in the dark and in %100 humidity at 37 ºC, Vicker’s hardness were determined. Three measurements were made at the top and bottom surfaces of each specimens. Data were analysed using Mann-Whitney U test. Results:Vicker’s hardness values (mean ± SD) obtained on the top and bottom surfaces by conventional halogen light and LED light respectively were: A110:32.23±2.29, 6.96±2.93, 64.76±8.21, 29.94±16.33 P60:35.84±6.94, 16.75±2.43, 58.24±23.82, 42.51±9.28 Supreme:34.70±9.22, 9.35±3.60, 65.27±15.71, 31.38±14.41
Significant differences (p<0.001) were obtained between the top and bottom surfaces of composite resins among two curing lights. No statistical difference (p>0.05) in hardness of the top and bottom surfaces was found between the three composite resins polymerized with LED light. Conclusion:The results indicate that LED light produced higher hardness values compared with conventional halogen light. As LED technology continues to improve, LED curing should become a useful adjunct to existing curing methods.