Mandibular Incisor Rbfpd Biomechanics: Cad/Cam Materials Stress-Failure Analysis

This study aimed to evaluate the suitability of various CAD/CAM materials for resin-bonded fixed partial dentures (RBFPDs) by comparing stress distribution and failure probability in mandibular incisor restorations under different designs and loading conditions. Finite-element models of single- and double-ended RBFPDs were generated using CBCT-derived mandibular incisor geometry. Five CAD/CAM materials (IPS e.max CAD, IPS e.max ZirCAD, Vita Enamic, Lava Ultimate, Vitablocs MarkII) were analyzed under vertical and 45° oblique loading (100 N). Stress distribution (principal/equivalent stress), displacement, and failure risk were assessed across materials and designs. Single-ended RBFPDs exhibited the highest stress and displacement under oblique loading. Lava Ultimate showed the largest displacement (0.52 mm) and principal stress (245 MPa), while IPS e.max ZirCAD recorded the highest equivalent stress (318 MPa). For double-ended designs under oblique loading, IPS e.max CAD demonstrated superior performance with minimal displacement (0.21 mm) and principal stress (128 MPa). Vita Enamic exhibited the highest failure risk (89% probability), whereas IPS e.max ZirCAD had the lowest (12%). Double-ended RBFPDs significantly reduce stress concentrations and displacement compared to single-ended designs, particularly under oblique loading. Material selection critically influences restoration longevity: IPS e.max ZirCAD and IPS e.max CAD showed optimal mechanical performance, while Vita Enamic posed elevated failure risks. These findings provide evidence-based guidelines for material and design choices in RBFPDs, enhancing clinical outcomes for mandibular incisor restorations.