Effects of Clinical Experience and Adhesive Systems on Dentin Bonding Strength and Dentin Bonding Reliability

<p> Purpose: In composite resin restoration, universal adhesives have become popular due to their broad applicability in various clinical situations. The clinical success of adhesive systems depends not only on material-related but also on operator-related factors. The purpose of this study was to evaluate the dentin bond strength of two adhesive systems performed by operators with or without clinical experience.</p><p> Methods: Two types of adhesive system, a two-step self-etch adhesive, Clearfil Mega Bond 2 (MB2), and a 1-bottle universal adhesive, Clearfil Universal Bond Quick (UBQ), were used in this study. The operators were five undergraduate dental students with no clinical experience at all (undergraduates) and five dentists with extensive experience in adhesive dentistry (mean experience of 7.4 years) (professionals). Forty bovine dentin surfaces were prepared with #600-grit SiC paper under running water. MB2 or UBQ was applied to the dentin surfaces and light-cured according to the manufacturer’s instructions, followed by 2-mm composite buildups by each operator. The specimens were sectioned and subjected to a microtensile bond strength (μTBS) test after being stored in water for 24 h. The data were statistically analyzed by two-way ANOVA and t-test (p=0.05). Weibull analysis was also performed on the μTBS data.</p><p> Results: The mean μTBSs in MPa/Weibull modulus value were MB2-undergraduate: 33.7/3.6, MB2-professionals: 36.7/4.2, UBQ-undergraduate: 26.0/2.0, and UBQ-professionals: 28.1/2.6. Two-way ANOVA revealed that “adhesive system” influenced μTBS (p<0.05), while “operator” did not (p>0.05). The Weibull modulus of each group was significantly different (p<0.05).</p><p> Conclusion: MB2 is superior to UBQ in terms of dentin bond strength and bonding reliability. The practitioner’s clinical experience does not affect the dentin bond strengths of both MB2 and UBQ. Professionals attained superior bonding reliability of both MB2 and UBQ compared with undergraduates.</p>