Gingival seal of deep Class II direct and indirect composite restorations.

PURPOSE: To evaluate in vitro the gingival microleakage of Class II direct and indirect composite restorations with cervical margins 0.5 mm apical to the cemento-enamel junction (CEJ).

METHODS: Mesial-occusal (MO) preparations of similar size were made in 10 homologous pairs of caries-free extracted human third molars. One specimen for each pair was prepared for a direct composite restoration and the other for an indirect composite restoration. Direct preparations were restored per manufacturer's instructions. Indirect preparations were impressed, and composite restorations were fabricated and cemented with a dual-cure cement. A total-etch technique was used for all restorations. Restorations were finished, polished, stored for 1 week in distilled water at 37 degrees C, thermocycled (5 degrees-55 degrees C x 1000), sealed with fingernail polish (leaving a 1.5 mm open periphery adjacent to the gingival margin), and placed in 0.5% basic fuchsin dye for 24 hours. Teeth were sectioned longitudinally (mesio-distally) within the restoration in two cuts and the four resulting surfaces (two inner cut surfaces, two outer cut surfaces) were evaluated for dye penetration with a x10 stereoscope using a scale of 0 (no penetration) to 4 (dye penetration involving more than half the axial wall).

RESULTS: All 20 specimens had at least one score of three (dye penetration involving less than half of the axial wall) or four. Statistical analysis (Wilcoxon paired-sample test) disclosed a significant decrease in the indirect composite microleakage scores for the two outer cuts (P = 0.006, P = 0.002). No significant differences in microleakage scores were found between materials for the inner cut surfaces of the specimens. Overall, the results of die penetration showed no statistical difference between Class II direct and indirect composite restorations for microleakage.