Pterygoid Anchorage of Subperiosteal Implants: An Overview and Case Report

Abstract

Severely atrophic maxillae (Cawood and Howell Class V-VI) often prevent conventional implant placement in the absence of extensive bone grafting, which carries risks, especially in elderly patients. Modern subperiosteal implants, digitally designed and manufactured in titanium using additive technologies, offer a graftless solution by anchoring the implant to basal bone structures such as the canine pillars and the zygomatic buttress. This case report explores the clinical feasibility of adding pterygoid anchorage to increase subperiosteal implant stability. A 71-year-old edentulous female with extreme maxillary atrophy received two custom subperiosteal implants designed with fixation points in the canine, zygomatic, and pterygoid regions. The digital workflow included cone beam computed tomography (CBCT) imaging, digital smile design, and implant modeling with a triply periodic minimal surface (TPMS)-gyroid structure to promote osseointegration. The implants were manufactured using Direct Metal Laser Sintering in Ti-6Al-4V ELI titanium and loaded immediately with a provisional titanium-reinforced polymethyl methacrylate (PMMA) bridge. Surgical placement included the insertion of bicortical pterygoid screws that penetrated the pterygomaxillary suture, so increasing posterior support and countering the occlusal forces associated with anterior cantilevers. Postoperative results showed excellent implant stability and patient satisfaction. This report confirms that pterygoid anchorage is a viable addition to subperiosteal implant design. It offers improved mechanical stability and expands treatment options for patients with extreme bone loss, without requiring bone grafting. Further biomechanical and long-term studies are recommended to validate these promising findings.