Micromorphology of resin–dentin interfaces using self-adhesive and conventional resin cements: A confocal laser and scanning electron microscope analysis

Purpose: The aim of this study was to evaluate the resin–dentin morphology created by four dual-cured resin cements. Materials and Methods: Two self-adhesive resin cements (RelyX Unicem, 3 M ESPE and Clearfil SA Luting, Kuraray Med.) and two conventional resin cementing systems (RelyX ARC, 3 M ESPE and Clearfil Esthetic Cement, Kuraray Med.) were evaluated. Occlusal dentin surfaces of 32 extracted human third molars were flattened to expose coronal dentin. Teeth were assigned to 8 groups (n=4), according to resin cement products and microscope analysis (SEM: scanning electron microscope or CLSM: confocal laser scanning microscopy). For CLSM, two different fluorescent dyes, fluorescein isothiocyanate–dextran and rhodamine B, were incorporated into the adhesive system and resin cement, respectively. The resin cements were applied to indirect composite resin disks, which were cemented to dentin surface according to manufacturer's instructions. After 24 h, all restored teeth were vertically sectioned into 1-mm-thick slabs for SEM or CLSM analyses. Results: Scotchbond Multi-Purpose Plus/RelyX ARC cementing system formed a thin hybrid layer and resin tags penetration into the dentin tubules. Clearfil DC Bond/Clearfil Esthetic Cement showed only short resin tags. Neither hybrid layer nor resin tags were detected for self-adhesive resin cements. Conclusion: Representative SEM and CLSM images provided resin–dentin interfaces variability among resin cements studied.