Maintenance of Custom-Made Subperiosteal Implants: A Narrative Review of Indirect Evidence and Preliminary Clinical Considerations

Background: Custom-made subperiosteal implants have re-emerged as a valuable option for the rehabilitation of patients with severe maxillofacial atrophy and post-oncological defects. Despite advances in digital workflows and implant design, their unique anatomical, biological, and prosthetic characteristics pose specific challenges for long-term maintenance, and no dedicated standardized guidelines are currently available. Methods: This narrative review critically appraises the available literature on implant maintenance and related fields. A comprehensive search was conducted across PubMed, Scopus, and Web of Science, including studies on peri-implant maintenance, supportive periodontal therapy, full-arch and zygomatic implant rehabilitations, and subperiosteal implants. Due to the lack of direct evidence, a qualitative narrative synthesis was adopted to develop preliminary clinical considerations for maintenance of custom-made subperiosteal implants. These considerations should be interpreted as an expert-informed perspective rather than validated clinical guidelines. Results: Conventional maintenance protocols developed for endosseous implants are not directly transferable to subperiosteal implants due to differences in the implant-tissue interface, biomechanics, diagnostic parameters, and hygiene accessibility. Key challenges include the absence of a conventional peri-implant sulcus, possible implant exposure, complex prosthetic geometries, and potential susceptibility to biofilm accumulation in areas with limited access. Evidence from related fields highlights the importance of structured maintenance, individualized risk-based follow-up, effective biofilm control, and patient-specific home-care strategies. Conclusions: Preliminary evidence-informed clinical considerations for the maintenance of subperiosteal implants are proposed, with emphasis on plaque control, individualized follow-up, descriptive clinical monitoring, and hygiene-oriented prosthetic and surgical planning. These considerations are not intended as validated guidelines, but as a practical starting point for clinical reasoning in an area where dedicated evidence remains limited.