Head and neck radiation therapy tied to dental caries and subsequent extractions: Study

Wagner Gomes-Silva and associates from the Dental Oncology Service, Instituto do Câncer do Estado de São Paulo (ICESP), Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil have conducted the study with the objective to characterize the dental adverse events following head and neck radiation therapy (HNRT) and to investigate the impact of regional radiation dose upon tooth loss outcomes.

Treatment of head and neck cancers (HNCs) involves radiotherapy. Patients undergoing radiotherapy for HNCs are prone to dental complications. Radiotherapy to the head and neck region causes xerostomia and salivary gland dysfunction which dramatically increases the risk of dental caries and its sequelae. Radiation therapy (RT) also affects the dental hard tissues increasing their susceptibility to demineralization following RT. Postradiation caries is a rapidly progressing and highly destructive type of dental caries.

A retrospective dosimetric-based analysis was conducted to assess dental events affecting post-HNRT extracted teeth and the impact of 3 different radiation doses (< 30 Gy, 30-60 Gy, and > 60 Gy) upon tooth loss. In addition, post-HNRT extractions outcomes, mean parotid glands dosimetry and salivary changes were analyzed.

Sixty-six patients who underwent HNRT were included in the analysis. The study showed that radiation caries was the most frequent (67.8%) post-HNRT dental adverse event and maxillary molars ipsilateral to the tumor were lost earlier compared to the others (p < 0.001).

The odds ratio for post-HNRT tooth extraction risk was approximately 3-fold higher for teeth exposed to > 60 Gy (CI: 1.56-5.35; p<0.001), followed by an increased risk of delayed healing and osteoradionecrosis (ORN) in sites receiving doses above 50 Gy.

This led the authors to conclude that "Radiation caries was the major cause of dental extractions following HNRT and the dosimetric analysis suggested that a high dose of radiation may negatively impact the dentition of head and neck cancer survivors, increasing the risk of tooth loss and ORN."