Microleakage and Marginal Integrity of Direct and Indirect Composite Resin Restorations in MOD Cavities After Thermo-Mechanical Loading

Abstract

Objective: The aim of this in vitro study is to compare the microleakage of mesial-occlusal-distal (MOD) composite resin restorations made by using CAD/CAM block and methacrylate/ormocer-based direct resin composites after thermo-mechanical loading. Methods: Standard 40 noncarious human third mandibular molars were selected for the study. Standardized MOD (3x4x2mm) cavities were prepared on the mesial and distal sides. The gingival margin was placed above the cementoenamel junction (CEJ) on the mesial side and below the CEJ on the distal side. The prepared samples were divided into three experimental groups [indirect group-GrandioBlock (GB), directmethacrylate group-TetricN-Ceram+TetricN-Flow (T+TF), direct-ormocer group-Admira Fusion+Admira Fusion Flow (A+AF)] and control group [direct-methacrylate group-GrandioSo+GrandioSoFlow (G+GF)] (n=10). After finishing restorations samples were subjected to 50 N to 240.000 thermo-mechanical cycles (5-55 degrees C, for 60 sec) and kept in 0.2% methylene blue. Samples sectioned longitudinally in the mesiodistal direction with a precision cutting device were examined under stereomicroscope at X8 and X25 and microleakage values were scored. In the evaluation of the data, descriptive statistical methods as well as the chi-square test was used for the comparison of qualitative data. Results: No significant difference was found among the coronal and gingival-enamel microleakage distributions of the groups (p>0.05). A statistically significant difference was observed among the gingival-cementum microleakage distributions of the groups (p=0.003). The distribution of gingival-cement microleakage with the no dye penetration score in the T+TF group was found to be statistically significantly lower than the G+GF and GB groups (p = 0.010, p = 0.001). Conclusion: Under the limitation of this in vitro study; restoring MOD cavities using different matrix structures of the composites could not eliminate the leakage at the gingival seat under CEJ.