evaluation of microleakage in composite-composite and amalgam-composite interfaces in tooth with preventive resin restoration (ex-viva).

this study addresses the question of whether conservative methods of restoration may be applied efficaciously in permanent posterior teeth with proximal lesions and intact occlusal preventive resin restoration (prr). the purpose of the present study was to assess the microleakage at amalgam-composite interface and composite-composite interface in permanent tooth with prr.thirty-five premolar teeth extracted for orthodontic reasons were selected. the occlusal surfaces were sealed as preventive resin restoration. then the teeth were stored in incubator for 6 months. after this period, two single boxes were prepared in mesial and distal surfaces in each tooth and filled with amalgam. another class i composite restoration was prepared in occlusal surface in contact with the first prr. then samples were thermocycled and marginal leakage was assessed by the degree of dye penetration on sections of the restored teeth. friedman and wilcoxon signed-rank tests served for statistical analyses.in 51.4% of amalgam-composite interfaces the dye reached the pulpal wall. the corresponded figures for amalgam-tooth and composite-composite interfaces were 31.4% and 14.3%, respectively. the differences in microleakage among the three interfaces were statistically significant (p<0.05).in the teeth restored with prr technique, restoring proximal lesions with a conservative technique may lead to favorable results concerning microleakage.