Long-Term Survival of a Maxillary Subperiosteal Implant After Blast Injury: A 17-Year Follow-Up Case Report

Abstract Subperiosteal implants (SPIs) have re-emerged as a treatment option for the rehabilitation of patients with severe maxillary atrophy, although evidence on their long-term performance remains limited. We report the case of a 53-year-old female patient who underwent maxillary rehabilitation with a custom subperiosteal implant in 2006 due to insufficient bone volume for conventional endosseous implant placement. The implant was fabricated using a direct bone impression technique and designed to achieve mechanical engagement within the anatomical undercuts of the maxilla, providing primary stabilization without extensive screw fixation. The patient maintained satisfactory functional and aesthetic outcomes over a 17-year follow-up period. In 2023, she sustained a high-energy facial blast injury resulting in damage to the prosthetic superstructure. Clinical and radiological evaluation revealed preservation of implant stability, absence of pathological bone resorption, and only a localized intrusion of the implant framework of approximately 2 mm in the anterior region. No implant mobility or functional impairment was observed. The patient was successfully rehabilitated with a new prosthetic restoration without the need for additional surgical intervention. This case highlights the potential long-term stability of subperiosteal implants and provides a rare clinical observation of their behavior under extreme traumatic conditions. Further studies are needed to better understand the biomechanical performance of these systems.