Beyond Prescription Dose: Implant-Site Radiation Dosimetry and Clinical Outcomes of Dental Implants Placed After Head and Neck Radiotherapy—A Systematic Review and Proposed Dosimetric Framework

Background: Dental implants can improve oral rehabilitation following head and neck radiotherapy (RT). The relationship between radiation dose and implant outcomes is not well defined, because specific radiation doses at the implant site are inconsistently reported. Methods: This systematic review evaluated dental implants placed after head and neck RT to determine the impact of the level of radiation dose reporting on outcomes. Studies were assessed for the quality of the reported radiation dosimetry, implant survival, and osteoradionecrosis (ORN). Radiation reporting was classified using a five-level hierarchy ranging from implant-site-specific dosimetry (Level I) to no dose information (Level V). Results: Forty-eight studies met inclusion criteria. Implant-site data (Levels I–II) were reported in <15%, 65% reported only prescribed dose, and 13% reported no RT dose data. High-quality Level I–II studies demonstrated clear differences between prescription tumor dose and implant-site dose and demonstrated more consistent dose–response relationships, with implant outcomes worse for implant-site doses of >50 Gy and even higher risks above 60 Gy. Conclusions: Dental implantation after head and neck RT can achieve favorable outcomes, but most studies are limited by inadequate evaluation of implant-site radiation dose. Studies evaluating IS radiation dose provide important insights into risk-assessment and implant outcomes. Future studies should report implant-site dose in prospective studies in order to assess and validate useful dose–response thresholds.