Fatigue and FEA of Zygomatic Implant Systems in Bilateral Maxillary Defects

Purpose This study aimed to determine the optimal number of zygomatic implants required to restore bilateral maxillary defects, where conventional implants are contraindicated due to insufficient bone support. It focused on evaluating the mechanical performance and failure mechanisms of different implant configurations. Methods A controlled in vitro model simulating bilateral maxillary defects was constructed using a representative patient case. Zygomatic implant systems with two, three, or four implants were evaluated under vertical cyclic loading applied at the first molar region. Fatigue testing was performed alongside finite element analysis to assess stress distribution, failure patterns, and load-bearing capacity. Results The four-implant configuration completed all fatigue cycles with minimal displacement and sustained the highest static load (741.7 N). FEA confirmed that this group exhibited the lowest von Mises stress across implants and supporting structures. The three-implant configuration also passed fatigue testing but demonstrated increased displacement, lower load capacity (456.7 N). The two-implant configuration failed prematurely at 33,483 cycles, with FEA showing implant stress exceeding the yield strength of titanium, confirming mechanical insufficiency. Conclusion This is the first study to integrate in vitro mechanical testing with FEA in a model simulating bilateral maxillary defects, providing experimentally validated guidance for implant selection. While all configurations exhibited failure modes confined to replaceable components such as screws, reduced implant groups demonstrated significantly lower mechanical thresholds and earlier failure. A four-implant configuration is therefore strongly recommended for clinical use due to its superior biomechanical stability, whereas two-implant configurations are not advisable in functionally demanding scenarios.