ABSTRACT
PURPOSE: To evaluate the influence of particle size of originally designed diamond burs on resin adhesion to sound young human permanent dentin. METHODS: The buccal surfaces of 105 premolars were used. Six test groups were prepared. The adhesive systems and resin-based composites used for Groups 1-3 were Clearfil SE Bond (SE) and Clearfil AP-X, and for Groups 4-6, Single Bond (SB) and Z250. Flat dentin surfaces were finely ground with 25 microm particle size IW-G5 diamond bur (IW-G5, Groups 1 and 4), 50 microm particle size IW-G4 diamond bur (IW-G4, Groups 2 and 5), or 600-grit SiC paper (#600, Groups 3 and 6). The microstructure of the prepared dentin, SE primed or SB etched dentin, and resin-dentin interfaces of each group (3 teeth/group) were studied using SEM. Shear bond strengths (SBS) in MPa were tested (10 teeth/group), and the failed surfaces were observed using SEM. Data was statistically analyzed using ANOVA and Fisher's PLSD at P < 0.05. RESULTS: The dentin ground with the IW-G5 or IW-G4 bur was rougher than the dentin ground with the 600-grit SiC paper. The mean SBS (MPa) for Groups 1-6 were: 32.3 +/- 5.0, 27.6 +/- 6.4, 21.3 +/- 3.6, 5.9 +/- 2.9, 6.5 +/- 3.1 and 5.3 +/- 2.0. The SBS of Groups 1-3 (SE groups) were significantly higher than those of Groups 4-6 (SB groups). The SBS of Group 1 (IW-G5, SE group) was significantly higher than those of Groups 2 (IW-G4, SE group) and 3 (#600, SE group), and the SBS of Group 2 was significantly higher than that of Group 3. There was no significant difference for SBS among Groups 4, 5 and 6. Fracture mode after SBS test mainly showed mixed fracture (adhesive and cohesive resin fracture) for the SE groups, and adhesive fracture for the SB groups.