Effect of light curing modes and filling techniques on microleakage of posterior resin composite restorations

This in vitro study evaluated the microleakage of a posterior resin composite restoration (P60-3M ESPE) filled with two techniques and light cured with three different modes. Standardized Class V cavities were prepared on the enamel buccal surface of freshly extracted inferior bovine incisors. Teeth were randomly divided into six experimental groups: two filling techniques (bulk and incremental filling) and three polymerization methods (conventional-680 mW/cm2/30 seconds; soft-start-380 mW/cm2/10 seconds + 680 mW/cm2/20 seconds; 1.3 cm light tip distanced -200 mW/cm2/10 seconds + 680 mW/cm2/20 seconds). All specimens were thermocycled for 3,000 cycles at 5 degrees C and 55 degrees C before immersion in a 2% methylene blue solution for 12 hours. Specimens were then washed and prepared for spectrophotometric analysis in order to quantify the dye infiltration around each restoration. Results showed that three polymerization modes presented no statistically significant differences for the incremental filling groups, whereas for the bulk filling group, conventional polymerization presented the highest leakage means that was statistically different from the other two polymerization modes. It was concluded that even though polymerization with initial low intensity light and bulk filling resulted in lower leakage means, no polymerization or filling techniques avoided microleakage.