نقش پوشش كاسپ در تقويت ميناي فاقد پشتيبان در ترميمهاي خلفي كامپوزيت

Role of cusp coverage in the protection of unsupported enamel in posterior composite restorations

Background and aim: Removal of unsupported enamel is one of Blockʹs important principles in cavity preparation. The aim of this study was to determine the effect of bonding materials in the protection of unsupported enamel and sound tooth structure. Materials and Methods: In this study, 30 sound mandibular molars were selected. After cusp reduction, a 3mm depth occlusal cavity with walls consisting of pure unsupported enamel of 3mm height, was prepared. The samples were divided into two groups. In the first group, the cavities were filled by composite. In the second group, the cavities were filled like the first group and the unsupported enamel surfaces were then etched extending 2mm buccocclussally and enamel dentin bonding was applied. These surfaces were finally covered by composite and light cured. The compressive strength of both groups were evaluated by an instron machine. Results: Date were subjected to t-student test for analysis. The mean required force to break unsupported enamel was 344ON/mm^2 in the first group and 4213N/mm^2 in the second group showing the effective role of etching and buccal coverage of enamel in the protection of remaining weak enamel. Conclusion: The findings of this study suggest that the application of adhesives and coverage of the buccal surfaces support the weak enamel and dentin walls.