This randomized split-mouth clinical trial aims to evaluate the clinical performance of bioactive restorative materials used in Class II restorations in permanent posterior teeth. The study compares a giomer-based bulk-fill restorative material, a giomer restorative material, and a resin-modified glass ionomer cement in terms of clinical success and overall clinical performance. Patients requiring at least three Class II restorations in posterior teeth are treated under standardized clinical conditions. Clinical evaluations are performed at baseline and follow-up visits to assess short- and long-term outcomes.