Finite element evaluation of the biomechanical feasibility of a multi-shield socket shield technique for a vertically fractured maxillary central incisor

The socket shield technique (SST) preserves peri-implant tissues during immediate implant placement in teeth with intact roots, yet its biomechanical behavior in the presence of vertical root fractures (VRFs) remains unquantified. This study evaluated the mechanical feasibility of a modified multi-shield SST (MS-SST) designed for single-fracture-line scenarios in maxillary central incisors. Three-dimensional finite element models representing conventional immediate implantation (CII), classic SST (C-SST), and MS-SST were subjected to 45° oblique occlusal loading from 10 to 100 N in 10 N increments. Bone and tooth structures were modeled as heterogeneous isotropic materials based on computed tomography gray values, whereas the periodontal ligament (PDL) was simulated using a nonlinear first-order Ogden hyperelastic constitutive law. Biomechanical metrics included von Mises stresses on the implant and abutment, displacements of the shield and PDL, hydrostatic pressure in the PDL and peri-implant bone, and strain energy density (SED) of the peri-implant bone. Comparative response patterns remained consistent across all loading magnitudes. At the representative peak load of 100 N, CII produced the most unfavorable peri-implant bone response, with the highest hydrostatic pressure (compressive: 26.94 MPa; tensile: 37.67 MPa) and SED (0.0447 MPa). C-SST yielded the lowest peri-implant SED (0.0302 MPa) and implant-abutment stresses. MS-SST exhibited intermediate SED (0.0347 MPa) and stress magnitudes, while reducing adverse peri-implant bone mechanical indicators relative to CII. Although MS-SST generated higher tensile hydrostatic pressure within the PDL than C-SST (0.0304 vs. 0.0166 MPa), shield displacement remained comparably low (0.0101 vs. 0.0104 mm). Within the assumptions of this finite element model, MS-SST appears mechanically feasible as a compromise design for vertically fractured maxillary central incisors when preservation of an intact buccal shield is not possible. Buccal shield segmentation did not markedly compromise shield stability and reduced adverse peri-implant biomechanical environment relative to CII. Further experimental and clinical validation remains necessary.