Mechanical Design Maturity and Validation Pathways of Patient-Specific Subperiosteal Implants for Oral and Maxillofacial Rehabilitation: A Scoping Review

Contemporary patient-specific subperiosteal implants (SPIs) have re-emerged as digitally planned, additively manufactured solutions for oral and maxillofacial rehabilitation when conventional endosseous implants are limited by severe atrophy, anatomical constraints, or reconstructive defects. Unlike conventional implants, SPIs behave as fixation-based skeletal frameworks whose performance depends on passive fit, screw fixation, anchorage, framework architecture, material properties, manufacturing accuracy, and prosthetic load transfer. This scoping review evaluated the maturity of mechanical design and validation evidence for contemporary SPIs. Following a predefined internal protocol and PRISMA-ScR, MEDLINE/PubMed, Scopus, Web of Science, Embase, and the Cochrane Library were searched from inception to 13 June 2026. Reference-list screening and citation tracking supplemented the electronic search. Two reviewers independently screened records against predefined eligibility criteria. Data were charted using a predefined extraction form and synthesized descriptively by evidence type, engineering domain, validation stage, and translational status. No meta-analysis was undertaken because of methodological heterogeneity, and no formal risk-of-bias grading was applied. Across 65 included records, the evidence was dominated by descriptive technical studies and comparative computational analyses, whereas direct mechanical testing, fatigue assessment, manufacturing verification, and clinical correlation were limited. Finite element analysis was useful for comparing design alternatives and identifying stress concentrations, but models were heterogeneous and often insufficiently validated. Design modifications generally redistributed stress across the implant–prosthesis–bone system rather than reducing it globally. Titanium and Ti6Al4V were the most established framework materials, whereas polymeric, ceramic, and scaffold-assisted strategies remained preliminary. The principal contribution of this review is a cross-domain appraisal of progression from anatomical feasibility and comparative modeling to manufacturing verification, experimental testing, and clinical validation. An evidence map, minimum reporting checklist, and integrated validation pathway are provided to support reproducible device development.