Quantitative evaluation of marginal leakage of two resin composite restorations using two filling techniques

This in vitro study evaluated the marginal leakage of two light-cured resin composites used for posterior restorations using two filling techniques. Standardized Class V cavities were made on the enamel vestibular surface of 30 freshly extracted sound inferior bovine incisors. The teeth were randomly restored according to three experimental groups (Group 1--Z250 with 1 mm vertical increments; Group 2--Z250 with 1 mm horizontal increments; Group 3--SureFil with 1 mm horizontal increments). All samples were thermocycled (3000 cycles at 5 degrees C and 55 degrees C) with a dwell time of one minute at each temperature and immersed in a dye solution for 12 hours. After being ground into powder, the samples were individually immersed into glass tubes with absolute alcohol. The solution was centrifuged and the supernatant was analyzed using a spectrophotometer to quantify its dye concentration. Results showed that Group 2 exhibited the lowest leakage means, which was significantly different from Groups 1 and 3 (p<0.05). It was concluded that despite the lower leakage means exhibited by medium viscosity composites, no restorative material or filling technique was able to avoid leakage.