Micro leakage of Posterior Composite Restorations Lined with Self-adhesive Resin Cements

Purpose: This study determined the microleakage of Class II composite restorations lined with self-adhesive resin-cements as bonding agents. Methods: Forty-five caries-free extracted molars were sterilized, mounted in acrylic bases and divided into five equal groups according to the adhesive used: RXU (RelyX-Unicem, self-adhesive resin-cement, 3M ESPE), BRZ (Breeze, self-adhesive resin-cement, Pentron Clinical Technologies), MON (Monocem, self-adhesive resin-cement, Shofu), PAN (Panavia-F-2.0, resin-cement with self-etch primer, Kuraray) and SBMP (Scotchbond Multi-Purpose, total-etch three-step adhesive, 3M ESPE). Class II MOD cavities were prepared with gingival floors located on dentin at one side and on enamel on the other. The bonding agent SBMP, used according to the manufacturer's directions, or a thin layer of resin cement, was applied on all cavity walls and cavosurface margins. Filtek Z250 (3M ESPE) was used to restore cavities in all groups. The specimens were subjected to 1,000 thermo-cycles between 5 degrees C and 55 degrees C. All tooth surfaces were sealed with nail-varnish to within 1 mm from the restoration margins. The specimens were immersed in 2% fuchsine red solution for 24 hours at 37 degrees C. The teeth were then sectioned mesiodistally and dye penetration was assessed according to a five-point scale. Data were statistically analyzed with the Chi-square test (p<0.05). Results: Micro leakage scores revealed that, on enamel margins, the SBMP group had significantly less microleakage than the RXU and BRZ groups, which, in turn, had significantly less microleakage than the MON and PAN groups; whereas on dentin margins, the RXU and BRZ groups had significantly less microleakage than the SBMP, MON and PAN groups. Conclusions: This in-vitro study showed that, when two self-adhesive resin-cements (RXU & BRZ) were used as liners in Class II composite restorations, they resulted in low microleakage scores as compared to the two other cements at both the enamel and dentin cavosurface margins.