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. Keywords: dentin bond strength, operator experience, etch-and-rinse, self-etching