The effect of different application modes of a 1-step self-etch adhesive on the clinical performance of Class I composite restorations: A randomized controlled clinical trial.

ABSTRACT

OBJECTIVE: To evaluate the clinical performance of a 1-step self-etch dentin adhesive that was applied according to the manufacturers' recommendations, doubling the adhesive application time and layer in Class I cavities with a composite resin. MATERIALS AND METHODS: A total of 39 patients aged between 14 and 43 (mean age 19.1) years were enrolled in the study. Each patient received three restorations. In these three restorations, a 1-step self-etch adhesive was applied according to the manufacturer's recommendations (control group), by doubling the adhesive application time, and with double layers. The restorations were evaluated according to modified USPHS criteria at baseline, and 1, 2, 3, and 4-year recalls. RESULTS: After 4 years, the success rate was 100% for restorations with the adhesive applied according to the manufacturers' recommendations, 96.9% for restorations applied by doubling the adhesive application time, and 93.8% for restorations applied with double adhesive layers. There was no significant difference between the three application methods among all the evaluation periods regarding the evaluation criteria. CONCLUSIONS: The 4-year success rates of a 1-step self-etch dentin adhesive that was applied according to the manufacturers' recommendation, by doubling the adhesive application time, and with double layers were excellent. CLINICAL SIGNIFICANCE: It is not recommended to double the adhesive application time nor apply a double layer of a 1-step self-etch adhesive because it does not improve the clinical performance of Class I composite restorations.