Influence of radiotherapy on dental implants placed in individuals before diagnosed with head and neck cancer: focus on implant-bed-specific radiation dosage

Objectives: The influence of radiotherapy on implants placed before diagnosed as head and neck cancer (HNC) is a potentially informative but poorly explored topic. The aims of this study were to investigate the influence of implant-bed-specific radiation dose on dental implants and to evaluate the impact of these implants on radiation dosimetry. Material and methods: We conducted a retrospective study with 58 irradiated patients that received dental implant restorations before undergoing radiation treatment for HNC. The radiological success rate and the peri-implant bone resorption values were measured radiographically at 1 and 3 years after radiotherapy. Patients with no implants matching tumor site and stage served as a control group (n = 58). Results: The median implant-bed-specific radiation dose was 40.3 Gy, which was significantly lower than tumor bed 62.4 Gy. An implant-bed-specific radiation dose higher than 40.0 Gy showed a significantly decreased radiologic success rate when compared to lower doses. Finally, evaluation of the radiation treatment plans revealed similar radiation hot spots in the test group of patients with implants and those of the control group. Conclusion: Our study confirms that radiotherapy negatively worsens peri-implant bone resorption, especially for implant-bed-specific dose more than 40 Gy, and the presence of implants within the radiation fields does not alter radiation dosimetry. The findings could be clinically informative to both surgeons and radio-oncologists. Clinical relevance: The interactions between radiotherapy and implants placed prior to radiotherapy treatment remain a largely unexplored topic. Based on the analysis of 3-dimensional modulated radiation plans, this study demonstrates the impact of implant-bed-specific radiation dose on marginal bone resorption of implants placed pre-radiation and considers the influence of these implants on radiation dosimetry. Registration number: ChiCTR2100051923: (http://www.chictr.org.cn/usercenter.aspx).