Anterior implant support across four ZAGA-informed pathways in hybrid zygomatic rehabilitation: a finite element analysis

To determine how anterior conventional support and four controlled ZAGA-informed zygomatic trajectories jointly affect load transfer in hybrid maxillary rehabilitation. A deterministic 2 × 4 finite element experiment used one symmetrized Visible Human Project-derived midface. H4 comprised conventional implants at FDI 12/22 and zygomatic implants at 15/25; H6 added implants at 13/23. Four mirrored 40-mm trajectories varied distal position and maxillary engagement. Manufacturer-derived implant–abutment geometries supported a polymethyl methacrylate prosthesis and cobalt–chromium framework. Eight configurations received unilateral 230-N posterior vertical and 93-N canine oblique loads. Primary outcomes were cortical maximum principal stress P95 (Pmax P95), compression P05 magnitude, loaded zygomatic-fixture von Mises P95, and maximum framework displacement. Bonded linear-static models used a 0.658-mm C3D8 grid; all 16 conditions were repeated with a 1-mm cortical shell. All 16 baseline models met numerical acceptance criteria. From A to D, cortical Pmax P95 decreased by 24.3–24.6% vertically but increased by 21.0–21.7% obliquely. Zygomatic-fixture P95 increased by 15.1% vertically and 37.0–37.9% obliquely; framework displacement increased by 11.5–13.0%. H6 changed primary outcomes by ≤ 1.70% but reduced matched conventional-fixture and abutment P95 by 18.9–33.8% and 24.2–28.4%. A 1-mm shell increased cortical Pmax P95 by 45.8–75.0% and compression P05 magnitude by 49.7–58.9%; the small A-to-D oblique compression increase (0.4–1.3%) became a decrease (3.2–3.7%). Adjacent-grid checks met the < 5% criterion at both shell thicknesses; formal mesh independence was not established. Combined trajectory geometry changed most primary outcomes more than adding two anterior implants. Additional support reduced matched conventional-assembly stress. Cortical thickness substantially affected absolute predictions and some trajectory comparisons.