Abstract
BACKGROUND: Restorative procedures following endodontic treatment are crucial for preserving the functional integrity of the tooth, preventing coronal leakage, and protecting the root canal system from contamination. The present study aims to compare the effects of different marginal elevation strategies and restorative material combinations on stress distribution and fatigue life, using three-dimensional (3D) finite element analysis (FEA) of mandibular first molar models prepared with DO, MO, and MOD cavity designs. METHODS: The anatomical structure of tooth number 36 was scanned using cone beam computed tomography. Three different cavity types were then created on the tooth. In the same model, deep margin elevation (DME) was applied in single and double layers of filler materials, each with 1 mm step increments. For the FEA, bulk-fill composite, conventional composite, hybrid composite, and flowable composite (Smart Dentin Replacement; SDR) were used as filling materials, whereas polymer-infiltrated ceramic networks (PICN) and lithium disilicate (LDS) were used as endocrown materials. After modeling, the stress values obtained from the analysis were evaluated according to the von Mises stress criterion and the results were reported in megapascals (MPa). RESULTS: The DME technique provided uniform stress distribution, increased fracture resistance, and increased the incidence of repairable fractures. Among the restorative materials studied, SDR demonstrated superior stress management and marginal adaptation. PICN restorations provided more uniform load distribution, supporting overall restoration integrity. This in silico study suggests that the application of the DME technique, combined with the appropriate selection of restorative and crown materials, may have a positive influence on stress distribution and fracture behavior in endodontically treated molars. However, as this study was conducted solely based on FEA and relies on an in vitro modeling approach, the findings need to be supported by long-term clinical data. Further laboratory and clinical studies are required to validate these mechanical findings under real-world clinical conditions. CONCLUSIONS: The use of DME combined with appropriate material selection can significantly improve the mechanical behavior of restorative treatments. These findings can guide clinicians in selecting materials and techniques for optimal long-term outcomes.