Cross-arch biomechanical interaction between opposing maxillary rehabilitation and mandibular implants: a three-dimensional finite element analysis

Abstract

Most finite element studies of full-arch implant rehabilitation evaluate a single dental arch and represent the opposing dentition as a prescribed load or simplified boundary. This approach does not directly capture the contribution of the opposing rehabilitation to load transfer. This study investigated cross-arch biomechanical interaction between opposing maxillary rehabilitation and mandibular implants using a three-dimensional bimaxillary finite element model. A completely edentulous maxillomandibular model was reconstructed from computed tomography data. Six configurations combined either a maxillary tissue-supported complete denture or a four-implant bar-retained overdenture with a mandibular two-implant locator-retained overdenture, four-implant bar-retained overdenture, or six-implant fixed zirconia prosthesis. A uniform 3-mm mucosal layer represented denture-bearing tissue support. Bilateral muscle-force vectors and standardized boundary conditions were applied during static loading through two 10-mm high-stiffness spherical interocclusal simulators positioned bilaterally at the first-molar regions. No direct tooth-to-tooth contacts or a conventional clinical occlusal scheme were simulated. Von Mises stress was assessed in implants and prosthetic components, and maximum and minimum principal stresses were assessed in cortical and trabecular bone. Replacing the maxillary complete denture with a four-implant bar-retained overdenture did not increase any reported peak mandibular stress value in the matched comparisons. Small reductions occurred in most mandibular outputs. Implant von Mises stress decreased by 2.24% in the two-implant overdenture comparison, 1.21% in the four-implant bar-overdenture comparison, and 3.93% in the six-implant fixed-prosthesis comparison. The fixed mandibular configurations generated the highest localized implant, abutment, and peri-implant cortical bone stresses under both maxillary conditions. In the maxilla, implant support reduced acrylic denture-base stress but concentrated stress in the bar-abutment assembly and peri-implant cortical bone. Under the specific simulated conditions, opposing maxillary rehabilitation produced measurable but modest changes in the biomechanical environment of mandibular implants. A maxillary four-implant bar-retained overdenture did not increase mandibular peak stresses compared with a maxillary complete denture. The localized peaks observed in the fixed mandibular configurations should not be interpreted as evidence that a greater implant number or fixed rehabilitation is clinically disadvantageous, and the computational findings should not be extrapolated directly to long-term clinical outcomes.

The authors' abstract, as published at the source. BMC Oral Health, 2026 · DOI ↗