Dental caries following radiotherapy for head and neck cancer: a systematic review

Post-radiotherapy head and neck cancer patients are at increased risk of dental caries due to radiotherapy-induced salivary gland hypofunction and radiation damage to tooth structure. Dental caries causes pain and discomfort and is likely to have a detrimental impact on patients' quality of life. This systematic review appraised and synthesised best available evidence regarding the incidence and severity of post-radiotherapy dental caries in head and neck cancer patients. Six databases and two trial registries were searched from their inception to May 2019. A total of 22 papers met the inclusion criteria. The pooled percentage of patients that developed dental caries post-radiotherapy was 29% (n=15 studies; 95% CI 21%, 39%; I2=88.0%). Excluding studies with longer than two years follow-up, the pooled percentage was 37% (n=9 studies; 95% CI 25%, 51%; I2=88.6%). Meta-regression analysis revealed that studies with a higher mean/median radiotherapy dose exposure had an increased incidence of dental caries (p=0.02). Furthermore, studies with a higher proportion of patients treated with chemotherapy had an increased incidence of dental caries (p=0.02) after the exclusion of an outlier. It is important to be mindful of the high degree of observed heterogeneity and the inclusion of a large number of non-randomised studies. Data regarding the number of carious teeth, the number of carious tooth surfaces, and the number of carious lesions that developed post-radiotherapy were unsuitable for meta-analysis. There is a need for well-designed studies to improve understanding about dental caries-risk in post-radiotherapy head and neck cancer patients.