Abstract
To systematically evaluate the biomechanical effects of cavity preparation and restorative procedures on cuspal strain, deflection, and load distribution in posterior teeth, while critically appraising methodological quality in experimental and computational models. This systematic review followed PRISMA guidelines and was prospectively registered in PROSPERO (CRD420251247979). Eligibility criteria included in vitro investigations on human posterior teeth evaluating primary biomechanical outcomes across varying cavity designs and restorative interventions. A comprehensive literature search was conducted through December 2025 across PubMed, Scopus, and Dentistry & Oral Sciences Source (EBSCO). Out of 612 identified records, 18 studies met the full eligibility criteria and were included in the qualitative synthesis. Cavity geometry and the extent of structural loss showed the most consistent association with increased cuspal strain and deformation across the included studies, while restorative materials, polymerization behavior, fiber reinforcement, and endodontic access design further modified the biomechanical response. Adhesively bonded restorations, bulk-fill systems, and selected fiber-reinforced strategies generally reduced cuspal deformation compared with non-adhesive restorations or conventional incremental approaches, although their effects varied according to material composition and placement protocol. However, these interventions did not fully offset the structural compromise caused by marginal ridge loss. While most studies demonstrated acceptable methodological quality, reporting gaps remain regarding sample size calculation and standardized aging protocols. Future research should prioritize dynamic in vivo loading models and advanced computational analyses incorporating proximal contacts and antagonist teeth to better translate biomechanical trends into clinical longevity.