Clinical Evaluation of Subgingival Open Sandwich Restorations: 3-year Results of a Randomized Double-blind Trial

The description of the experimental design followed the Consolidated Standards of Reporting Trials (CONSORT) statement. The present study was a double-blinded (patients and examiner) randomized clinical trial anticipating the parallel design. Ninety-five adult patients seeking dental treatment in the Operative Department clinic at the Faculty of Dentistry, University of Mansoura were enrolled in the current study with a total of 120 Class II restorations. No advertisement was made for participant recruitment, forming a sample of convenience. Each patient must signs a consent form before participating in the current study. The study was conducted from January 2020 to January 2023 as a part of the Doctoral dissertation. Mansoura University institution's ethics committee approved the form and protocol before conducting the study. The sample size was calculated based on the clinical success rate (100% success rate at 2 years) of posterior class II restorations restored with open sandwich and deep margin elevation techniques observed in previous studies. According to several parameters including a significance level of 5%, the power of the test was calculated to be 80%, and equivalent limit of 15%. Upon these data, a sample size of 120 subjects was appropriate to allow for a 20% drop-out.