Three-dimensional finite element analysis of full-arch implant-supported dental restorations: complete vs. segmented frameworks

Purpose Given the reported clinical advantages of segmented implant-supported mandibular frameworks, multiple segmentation patterns were evaluated and compared with a complete (one-piece) framework to determine their effects on peri-implant bone stress. Methods Thirteen cases were studied via 3-D finite element analysis (FEA), combining complete and segmented full-arch frameworks across different implant layouts. Screws were preloaded according to manufacturer recommendations. Cortical and trabecular bone were modeled as homogeneous, isotropic, linearly elastic materials, and a fully osseointegrated implant–bone interface (shared-node mesh) was assumed. A static vertical load of 200 N was applied in three separate load cases: first molar, first premolar, and bilateral incisors. The primary outcome was peak von Mises equivalent stress in the peri-implant bone surrounding each implant as a comparative indicator of mechanical demand. Results When the load fell between two splinted implants (e.g., lateral segment without cantilever), peri-implant bone stresses were similar for complete and segmented frameworks. Under premolar loading, the complete framework yielded the lowest stresses; segmenting with a mesial cantilever on the lateral segment approximately doubled stresses at the adjacent implant, while placing a distal cantilever on the central segment increased stresses near the anterior support by up to ∼7× versus the complete configuration. Eliminating cantilevers by moving support from 5 to 4 closely approached the complete framework. Incisor loading challenged the central span: supports at 3–3 produced markedly higher stresses than complete frameworks; shifting supports to 2–2 reduced stresses but did not match the complete design, whereas triangulating the central span (3–2–3) further lowered stresses and approached complete-framework levels. Conclusion Segmented frameworks are biomechanically viable provided segmentation avoids central-span cantilevers, preferentially places any unavoidable cantilever on a straight lateral segment, and—when feasible—adds an anterior support to triangulate the central span or eliminates cantilevers by advancing support distally. With a properly planned segmented framework, peri-implant bone stresses can remain close to those of complete frameworks under the loading conditions investigated.