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MARGINAL ADAPTATION OF A SELF-ETCH ADHESIVE/ SILORANE-BASED RESIN COMPOSITE IN CLASS V RESTORATIONS

The objective of the study was to evaluate and compare marginal adaptation of a self-etch adhesive/silorane-based resin composite in Class V restorations with that of a total-etch adhesive/ microhybrid methacrylate-based resin composite. Forty freshly extracted premolars were selected for this study. Standardized Class V cavities were prepared on the buccal and lingual aspects of each tooth. The occlusal margin of each cavity was prepared 1 mm above the cemento-enamel junction, while the gingival margin extended 1 mm beyond it onto the root. Prepared teeth were divided randomly into four groups of 10 teeth each. Cavities in Groups 1 and 3 were restored with the total-etch adhesive Adper TM Single Bond 2/Filtek Z250 microhybrid methacrylate-based composite (controls), whereas self-etchant P90 System Adhesive/Filtek P90 low shrinkage silorane-based composite was used to restore cavities in Groups 2 and 4. After finishing and polishing, teeth in Groups 1 and 2 were thermocycled for 1500 times, while teeth in Groups 3 and 4 were thermocycled for 3000 times. Specimens were then sectioned longitudinally, bucco-lingually through the center of each restoration. Epoxy replicas were made of sectioned surfaces and examined by SEM at x100 to detect marginal gaps along composite/tooth interfaces at occlusal and gingival margins. Two-way Analysis of Variance and Student’s t-test analyzed the marginal adaptation data. At the occlusal enamel margins, the mean values of the largest gaps in Groups 2 and 4 were significantly higher than those in Groups 1 and 3 (P = 0.000). By contrast, at the gingival dentin margins, the mean values of the largest gaps were significantly higher in Groups 1 and 3 (P = 0.000). When the numbers of thermal cycles increased from 1500 to 3000, no statistically significant differences were detected in the mean widths of gap formation at both occlusal enamel margins (P = 0.54) and gingival dentin margins (P = 0.19). The results of this study show that none of the restorative materials used is capable of perfectly adapting to the cavity margins.