Effect of different intensity light curing modes on microleakage of two resin composite restorations

This in vitro study evaluated the marginal leakage of two resin composites light cured in four different polymerization modes. Standardized Class V cavities were prepared on the buccal enamel surface of 80 sound, freshly extracted inferior bovine incisors. The teeth were randomly divided into eight experimental groups: two resin composites (Z250 Charisma) and four polymerization modes (conventional-680 mW/cm2/30 seconds; soft start-380mW/cm2/10 seconds + 680 mW/cm2/20 seconds; plasma arc curing- 1480mW/cm(2)-3 seconds; combined- 380mW/cm2-10 seconds + 1480mW/cm(2)-3 seconds). All specimens were thermocycled (1,000 cycles at 5 degrees C and 55 degrees C) with a dwell time of one minute at each temperature and immersed in a 2% methylene blue solution for more than 12 hours. The specimens were then washed and prepared for spectrophotometric analysis to quantify the dye concentration. Soft start and combined polymerization modes presented better results and were statistically different from conventional and plasma arc curing polymerization methods for both resin composites. There were no statistical differences between the two resin composites.