SHEAR BOND STRENGTH OF A LIGHT-CURED RESIN COMPOSITE VS DENTIN CHARACTERISTICS

Objectives. The aim of this work was to determine if any significant correlation can be found between dentin characteristics and the shear bond strength of a bonded resin composite. Methods. The number of tubules, the diameter of tubules, the real dentin surface (RDS), the Vickers hardness (VHN), and the Ca and P concentrations ([Ca] and [P]) were measured. Two commercial bonding systems, the All-Bond 2 (Bisco) and Scotchbond 2 (3M Dental Products), were tested on 70 extracted human molars purposely abraded and polished. Experimental results were statistically analyzed. Results The average bond strength ranged from 9.1 +/- 5.3 MPa (All-Bond 2) to 3.2 +/- 1.9 MPa (Scotchbond 2). Only the Bisco adhesive gave rise to cohesive dentin fractures. The Vickers hardness depended on both the real dentin surface and the calcium concentration according to the empirical law: VHN = 0.753 RDS + 0.320 [Ca] - 16.330. The shear bond strength does not depend on the measured dentin characteristics. Significance. Under these testing conditions, the nature of the surface composite determined the adhesion; the properties of the dentin substrate were of minor importance.