Effect of thiol compound on the dentin bond strength when using experimental one-bottle self-etch adhesive system

This study evaluated improvements in the micro-tensile bond strength of a one-bottle adhesive to dentin upon incorporating a thiol compound. Formulations containing 0, 0.1, 0.3 or 0.5% of the thiol were prepared (TH78-0, TH78-0.1, TH78-0.3 and TH78-0.5). Flat dentin surfaces were produced on non-carious extracted human molars using a diamond saw and 600 grit SiC paper. Each surface was subsequently treated with one of the four experimental adhesives or a commercially available adhesive (Scotchbond Universal Adhesive), following the manufacturers' instructions. A resin composite was then incrementally built on the adhesive-treated surfaces and light-cured, after which the bonded specimens were sectioned and subjected to micro-tensile bond strength tests. Bond strengths ranging from 28.7 MPa (for the TH78-0.5) to 45.9 MPa (for the TH78-0.1) were obtained from the experimental specimens, whereas the commercial adhesive showed a strength of 36.9 MPa. A 0.1% thiol concentration therefore increased the baseline bonding of the adhesive and gave the highest strength, with significantly decreased values in the cases of 0.3% and 0.5% concentrations.