Influence of operator skill on microleakege of total-etch and self-etch bonding systems

Objectives To evaluate the influence of operator skill on microleakage in class V restorations using simplified bonding systems. Methods Two cavities were carried out on the buccal and lingual surfaces of 50 human bicuspid teeth. The teeth were randomly assigned to two groups according to the operatorʹs skill: student group and expert group. The two cavities of each tooth were randomly treated with Adper Scotchbond 1 XT (total-etch adhesive) and Adper Prompt L-Pop (self-etch adhesive). All cavities were restored with a 0.2 mm thick layer of flowable composite (Filtek flow) followed by one bulk increment of resin composite (Filtek Supreme XT). Specimens were thermocycled, immersed in 2% methylene blue and sectioned in a bucco-lingual plane. They were then examined under a stereomicroscope and scored according to microleakage. The data was subjected to a multilevel statistical model. Results At the dentine margin the microleakage resulting from both the self-etch adhesive and the total-etch one was similar in the student and in the expert groups. The interaction term skill × adhesive was not statistically significant (p = 0.4156). At the enamel margin the self-etch adhesive microleakage within the student group resulted lower than that within the expert group. On the other hand, the total-etch adhesive microleakage within the expert group resulted lower than that within the student group. The interaction term skill × adhesive was statistically significant (p = 0.0037). Conclusions Both the adhesives used were sensitive to operator skill in obtaining a reliable seal with the enamel. On the dentine, both adhesives demonstrated little sensitivity to operator skill.