Influence of operator experience on in vitro bond strength of dentin adhesives

Purpose: To examine the influence of operator experience level on shear bond strength (SBS) of a self-etching adhesive (Clearfil SE Bond [CSE], Kuraray) and an etch-and-rinse adhesive (Single Bond [SB], 3M ESPE). Materials and Methods: Flat dentin surfaces were created on 120 extracted human third molars. Bonding agents and composite resin were applied and light cured according to manufacturers’ directions (n = 15). Four operators with different levels of experience in operative dentistry performed the same specimen preparation steps independently: group 1: specialist in operative dentistry; group 2: post-graduate student; group 3: undergraduate dental student; group 4: private general practitioner. Specimens were stored in distilled water for 24 h at 37°C before SBS testing. Statistical analyses were carried out with Mann-Whitney U- and Kruskall-Wallis tests. Results: For CSE, mean SBS and standard deviations were: (1) 54.4 ± 15.6a, (2) 55.3 ± 7.6a, (3) 49.4 ± 10.5ab, (4) 41.6 ± 13.1b. For SB, they were: (1) 28.6 ± 10.3c, (2) 32.7 ± 11.2c, (3) 17.5 ± 5.6d, (4) 24.4 ± 9.5cd. Groups with the same superscript letters are not significantly different. CSE showed higher bond strengths than SB in all groups (p < 0.05). There was no significant difference in mean bond strengths between groups 1 and 2 for each adhesive (p > 0.05). Depending on the adhesives, groups 3 and 4 were significantly different from groups 1 and 2, but not different from each other. Conclusion: Operator experience influences dentin bond strength values of dentin adhesives. An increased level of experience with a specific adhesive system and the associated application procedures correlates with higher SBSs.