SHEAR BOND STRENGTH OF DIFFERENT ADHESIVE RESIN CEMENTS TO DENTIN

Objective: This study investigated the shear bond strength SBS of different adhesive resin cements [self-adhesive resin cement RelyX Unicem(RXU), adhesive resin cement with self-etch adhesive RelyX Ultimate with Single bond Universal adhesive (RXUT) and adhesive resin cement that utilize etch and rinse technique RelyX ARC with Single bond2 adhesive (ARC)] to dentin.
Methods: Sixty extracted molars embedded in epoxy resin were prepared by sectioning the buccal surface to expose flat Buccal dentin and were ground with 400-grit SiC paper. The samples were divided into 3 groups (N=20) based on the adhesive resin cements used. Sixty composite discs 3mm in diameter Z 350 (3M ESPE)) were constructed & bonded to the prepared dentin surfaces according to manufacturer instructions. For each group half the samples were thermo-cycled (TC) between 5-55˚C for 2500 cycles and then all samples were tested using a universal testing machine using chisel blade. The results were statistically analyzed using Mann-Whitney &Wilcoxon Signed Ranks tests.
Results: The mean SBS (± standard deviation) were: 6.95±1.5 MPa for RXU, 0 for RXU(TC), 22.58±5.45 for RXUT, 15.20±3.98 for RXUT (TC), 25.9±5.3 for ARC, and 19.5±4.3 for ARC(TC). RXU had significant lower bond strength than both RXUT &ARC (P<0.05). No significant difference between RXUT & ARC after thermo-cycling (P>0.05).
Conclusions: (1) The self-adhesive resin cement (RXU) had significant lower bond strength to dentin than that of RXUT & ARC. (2) No significant difference was found between the used adhesive resin cements that utilized self-etch adhesive and that utilized etch & rinse adhesive.