Influence of cervical margin relocation and adhesive system on microleakage of indirect composite restorations

Aim The aim was to evaluate the influence of the cervical margin relocation (CMR) and the adhesive system on the microleakage of indirect composite restorations with proximal margins located below the cemento-enamel junction (CEJ). Materials and methods Standardized MOD cavities with proximal margins located 1 mm below CEJ were prepared in 20 human molars and divided into 2 groups. Mesial margins in both groups were elevated with a flowable composite. Distal margins were not elevated. Composite CAD/CAM overlays were cemented with a resin composite; in Group 1 in combination with a universal adhesive in selective enamel etch mode, whereas in Group 2 with a three-step total-etch adhesive. Differences in leakage either at mesial or distal adhesive interface were evaluated for statistical significance (P < 0.05). Results In Group 1 statistically significant differences emerged in microleakage scores between CMR and non-CMR sites; higher scores were present at CMR sites. In Group 2 no statistically significant differences existed between CMR and non-CMR margins. When the non-CMR sites were compared between the two groups, significantly lower scores were observed in Group 1 compared to Group 2. Conclusion The CMR technique and the adhesive system employed for luting indirect restorations might represent a significant factor affecting microleakage at the interface below CEJ.