Microleakage of a packable composite associated with different materials.

The aim of this in vitro study was to evaluate the extent of marginal leakage with class II composite resin restorations associated with different materials. Twenty extracted sound molars were disinfected and stored in 0.9% saline solution. Four standardized class II cavities were prepared in each tooth, with the gingival margin 1 mm below the cementum-enamel junction. The teeth were then randomly divided into five groups of 16 restorations each: 1) Prime & Bond NT + Surefil; 2) Prime & Bond NT + Dyract Flow + Surefil; 3) Prime & Bond NT + Flow-it + Surefil; 4) Prime & Bond NT + Dyract AP + Surefil; and 5) Fuji II LC + Prime & Bond NT + Surefil. After a storage time of seven days, the restorations were finished and polished. Then specimens were submitted to thermocycling (500 cycles, 5 degrees-55 degrees C, 15 s-dwell time) and immersed in 0.5% methylene blue solution for 24 hours. They were washed and vertically sliced through the middle of the restoration. Both surfaces were evaluated in the gingival margin and one score (0-3) was assigned under a stereomicroscope (40x magnification) by two examiners. The frequency of the scores was evaluated by Kruskal-Wallis and Mann-Whitney tests for pairwise comparisons. None of the associations prevented dye penetration. The statistical analysis showed similar dye penetration among groups 1, 2, 3 and 4 (p > 0.05). The results of penetration in group 5 were significantly lower compared to the other groups (p < 0.05). It was concluded that the use of Fuji II LC as a base material led to the best sealing of the gingival margins based upon the lowest degree of microleakage observed.