Evaluation of radiological and clinical influence of dental implantborne prosthetic rehabilitation in head and neck cancer patients after radiotherapy

The aim of the present investigation was the analysis of peri-implant bone level changes of irradiated patients after head and neck cancer therapy. Furthermore, the implant-site specific radiation dose on the peri-implant bone, the survival and success rate of the implants and clinical parameter of the soft tissue have been recorded. A total of 15 patients (6 women, 9 male) with 81 implants were involved in the study. To evaluate the site-specific radiation dose radiotherapy planning data were combined with three-dimensional follow-up CT-data, pre- and postimplant insertion. Peri-implant crestal bone changes were measured after implantation, after one and three years using standardized orthopantomograms. Peri-implant soft tissue was assessed using modified plaque index and modified bleeding index clinically. For statistical analysis parameters such as age, gender, implant localization (maxilla/mandible) were analyzed in association to implant-specific radiation dose distribution. A mean crestal bone loss of 1 mm mesial and 1,1 mm distal was measured after one year, after three years mean crestal bone changes of 1,5 mm (mesial and distal) were documented. Women showed temporarily significantly more bone loss than men after one year observation time. After three years implant-specific radiation dose showed significant impact on peri-implant bone loss, independently of gender. Mean implant-bed-specific radiation dose was 45,9 Gy in the mandible and 29 Gy in the maxilla. Both were significantly lower than the tumor-bed dose. The described method for radiation dose evaluation showed a potential pathway for further scientific investigations but also a practical way for "radiation based implant planning" were planned implant position can be analyzed focusing potential consequences for the peri-implant hard and soft tissue and therefor their longtime survival.