Marginal quality of tooth-colored restorations in class II cavities after artificial aging

This in vitro study compared the proximal marginal adaptation of direct composite restorations with composite and ceramic inlays inserted with different resin cements. Standardized MOD Class II inlay cavities with one proximal box extending below and the other above the CEJ were cut in 48 extracted human molars and randomly assigned to six groups (n=8). Incrementally layered direct composite restorations (P60), composite inlays (P60) and ceramic inlays (Empress; Cerec Vitablocs Mark II) were placed in the cavities. Three different resin cements (RelyX ARC; Variolink II high viscosity; Panavia 21) were used for luting the composite inlays. All ceramic inlays were cemented with RelyX ARC. After finishing and polishing, the teeth were stored for 24 hours in Ringer solution at 37 degrees C before they were subjected to thermal and mechanical loading (5/55 degrees C, 2000x; 50 N vertical load, 50000x). Margins were evaluated on epoxy replicas using a scanning electron microscope at X200 magnification. Statistical analysis was performed with non-parametric test methods (alpha=0.05). The adhesive interfaces to enamel exhibited high percentages of perfect margins for all groups (91.8% to 96%) and a maximum of 5.2% marginal gap formation. Dentin-limited cavity segments demonstrated more marginal openings and less perfect margins than enamel-bound areas; however, this was only statistically significant for direct composite restorations and composite inlays inserted with Variolink II and Panavia 21. RelyXARC showed a significantly better adaptation to P60 inlays compared with the leucite-reinforced Empress ceramic but not the Vitablocs Mark II ceramic.