Clinical evidence of bone apposition and potential osseointegration in additively manufactured subperiosteal implants: a report of three cases

Subperiosteal implants were historically conceived as fixation-based devices rather than osseointegrated implants and were progressively abandoned due to unfavorable long-term outcomes. Recent advances in digital planning and additive manufacturing have led to the reintroduction of custom-made titanium subperiosteal implants; however, direct clinical evidence of osteointegration in humans has not been reported. This case series presents three patients rehabilitated with additively manufactured titanium subperiosteal implants who underwent surgical re-entry for the removal of loosened osteosynthesis screws associated with recurrent, non-infective inflammatory episodes. In all cases, intraoperative exploration revealed partial to complete bone coverage of the subperiosteal implant framework and the associated titanium fixation screws. Two patients showed complete bone coverage of the implant arms anchored to basal bone structures, while early bone apposition was observed in the third case. Removal of the loosened screws resulted in complete resolution of clinical symptoms in all patients. These findings provide direct clinical evidence of bone apposition and ossification and suggest the possibility of osseointegration in modern subperiosteal implants. Further clinical studies with larger cohorts and long-term follow-up are required to determine the impact of bone coverage and potential osteointegration on the long-term survival of contemporary subperiosteal rehabilitations.