Marginal Quality of Resin Composite Fillings with or without Ceramic Inserts

Objective: Ceramic inserts have been reported to reduce polymerization shrinkage within posterior resin composite restorations. The aim of the present in vitro study was to evaluate marginal and interfacial quality of different insert systems. Methods: Sixty third human sound molars received Class II cavities, forty having proximal margins in enamel and twenty with proximal margins 1 mm below the amelocemental juntion. The specimens were randomly assigned to one of the six experimental groups (n=10). The enamel-limited cavities were restored with ST (Syntac classic+Tetric Ceram), TB (Syntac+Tetric Ceram+ ß-quartz inserts), TC (Syntac+Tetric+Cerana inserts), TS (Syntac+ Tetric Flow+SonicSys approx inserts). The dentin-limited cavities were filled with DT (Syntac+Tetic Ceram) and DS (Syntac+Tetric Flow+Sonic Sys approx inserts). Before and after thermomechanical loading (100,000 x 50 N, 2,500 x 5°C/ 55°C) replicas were made and both interfaces, tooth/composite and insert/composite were examined under SEM at 200x. Results: The mean percentages of gap-free margins [%](SD) were for tooth/restoration interface: Before TML: ST 97,7 (4,2); TB 97,8 (4,4); TC  98,4 (2,4); TS 99,6 (0,7); DT 98,9 (2,1); DS 98,5 (2,8). After TML ST 83,3 (9,3); TB 85,5 (8,1); TC 94,2 (5,5); TS 93,8 (4,5); DT 56,2 (14,1); DS 59,9 (20,6). Insert/composite interface before TML: TB 99,6 (5,6); TC 99,1 (1,3); TS 99,4 (0,9); DS 97,5 (3,6). After TML TB 36,0 (23,3); TC 82,2 (12,1); TS 76,3 (19,5); DS 31,3 (20,4).Cerana and Sonic Sys groups showed significantly less gaps in the enamel-limited specimens (p< 0.05; Wilcoxon test). With ß-quartz inserts, no reduction of gaps was found. Marginal quality in dentin-limited cavities was not enhanced with Sonic Sys inserts (p> 0.05). The interfacial integrity insert/composite was adequate for all IPS Empress inserts (Cerana, SonicSys), but poor for ß-quartz inserts. Conclusion: Among the tested insert systems, no significant potential for ceramic inserts was found.