Site-specific radiation dosage and implant survival in oral cancer patients: A cohort study

OBJECTIVES: We assessed the radiation dosages (D mean ) on implant regions to identify the threshold for implant loss in patients with an intraoral malignancy treated with dental implants to support a mandibular denture during ablative surgery before volumetric-modulated arc therapy (VMAT).

MATERIALS AND METHODS: Data was collected prospectively from 28 patients treated surgically for an intraoral malignancy, followed by postoperative radiotherapy (VMAT) and analyzed retrospectively. Patients received 2 implants in the native mandible during ablative surgery. Implant-specific D mean values were retrieved from the patients' files. Radiographic bone loss was measured 1 year after implant placement and during the last follow-up appointment. Implant survival was analyzed with the Kaplan-Meier method. Univariate logistic regression and Cox-regression analyses were performed to investigate the effect of increasing implant-specific radiation dosages on implant loss.

RESULTS: Five out of 56 placed implants were lost during follow-up (median 36.0 months, IQR 39.0). Radiographically, peri-implant bone loss occurred in implants with a D mean  > 40 Gy. Implant loss occurred only in implants with a D mean  > 50 Gy.

CONCLUSION: An implant-specific D mean higher than 50 Gy is related to more peri-implant bone loss and, eventually, implant loss.