Methods: Four groups of 14 extracted human molars were prepared with Mesio-occlusal or disto-occlusal cavities – two groups in which proximal box ended on enamel (1.0mm occlusal to the CEJ), and two groups in which the proximal box ended in dentin/cementum (1.0mm apical to the CEJ). Teeth in each group were restored in two different techniques – Incremental and Centripetal, with light-curing, Micro hybrid composite resin and bonding agent. In group 1, the gingival wall was in the enamel and restored with the incremental technique. In group 2, the gingival wall was in the dentin and restored with the incremental technique. In group 3, the gingival wall was in the enamel and restored with the centripetal technique. In group 4 the gingival wall was in the dentin and restored with the centripetal technique. After polishing, the teeth went under thermo-cycling (1000 thermo cycles between 5° C and 55° C, with 10 seconds dwell time at each temperature) and load-cycling (500 cycles at 10 kg for 0.5 second) and their gingival margin exposed to 0.5% basic fuchsine solution for 7 days. Specimens were sectioned mesiodistally and scored for micro leakage.
Results: The results of the present study indicate that the insertion technique has no influence on the leakage values (P=0.328). Cervical margins that ended on the enamel showed significantly less micro leakage (P=0.001) than cervical margins that ended on dentin/cementum.
Conclusions: It can be concluded that the centripetal method compared to the conventional, does not lead to a significant difference in the degree of marginal leakage.