Standardized class II MO cavities with bevelled enamel margins were prepared in 40 extracted human molars. The teeth were randomly assigned to one of the five experimental groups (n=8). The teeth were restored with two horizontal increments of composite (4mm and 2mm thickness). The experimental groups were (1st/2nd increment): Gr. A - Venus Bulk-Fill/Venus Diamond; Gr. B - Tetric EvoCeram BulkFill/Tetric EvoCeram; Gr. C - Surefil SDR/Ceram-X; Gr. D - SonicFill; Gr. E - Ceram-X/Ceram-X (control). After finishing procedures, impressions were made using a polyvinyl siloxane and epoxy resin replicas were obtained. Thermo-mechanical stressing was carried out 24h after the restorative procedure. All specimens were submitted to 240,000 occlusal loading and simultaneous 600 thermal cycles in water at 5°C and 50°C. After loading, a new set of epoxy resin replicas was obtained. Scanning electron microscopy was carried out at 200× magnification. Results for the marginal adaptation were expressed as percentages of continuity relative to the exposed interface and analyzed by ANOVA and Duncan post hoc test (p<0.05).