Purpose: To compare the in vitro fracture resistance and the microtensile bond strength (muTBS) of premolar teeth restored with two light-cured resin composite inlay systems.
Methods: 50 sound human maxillary premolars were divided randomly into five equal groups. Four groups received mesial-occlusal-distal (MOD) inlay preparations. Restorative treatments comprised: Group 1 (Renew direct resin composite), Group 2 (Renew direct resin composite inlay), Group 3 (Tescera indirect resin composite inlay), Group 4 (non-restored), Group 5 (intact). All teeth were loaded axially until fracture. The same resin-based materials as used in Groups 1-3 were bonded to the superficial coronal dentin of 15 teeth. Beams approximately 1.0 mm x 1.0 mm were prepared and tested in microtensile mode. Results were compared using one-way ANOVA and Tukey's multiple comparison tests.
Results: Mean fracture strengths (KN): Group 1, 2.06 (0.76); Group 2, 2.30 (0.49); Group 3, 2.62 (0.68); Group 4, 1.24 (0.44); Group 5, 2.40 (0.71). Group 4 was significantly weaker that the other four groups, P < 0.01. Mean muTBSs (MPa): Group 1, 33.38 (6.24); Group 2, 20.38 (6.24); Group 3, 20.87 (4.62). Group 1 was significantly stronger than the other two groups, P < 0.01.