Evaluating microbial regulation as a preventive strategy for radiation-related caries: A review

Radiotherapy is a crucial treatment for head and neck squamous cell carcinoma but is associated with several complications, particularly the onset of radiation-related caries (RRC), which severely compromises patients' oral health and quality of life. Most studies have focused on the direct effects of radiation on host organs. Such as radiotherapy/Concurrent Chemoradiotherapy (CCRT) contributing to RRC primarily by inducing salivary gland hypofunction and directly damaging tooth structure. However, emerging evidence implicates additional mechanisms including dietary modifications and oral microbial dysbiosis in driving pathogenic microbial shifts characterized by cariogenic bacterial/fungal proliferation, thereby exacerbating RRC progression. In particular, changes in common cariogenic bacteria/fungi after radiotherapy remain poorly understood. Furthermore, clinical translation of microbial ecology principles into effective RRC prevention strategies remains underexplored. This review centers on radiation-induced oral microbiota alterations, critically analyzing documented microbial shifts characterized by marked proliferation of cariogenic taxa including Streptococcus mutans, Lactobacillus, Prevotella melaninogenica, Veillonella, and Actinomyces, alongside fungal overgrowth of Candida albicans. We propose a dual-focused intervention protocol: initiating probiotic supplementation at radiotherapy commencement to stabilize microbial ecology and preserve salivary function, combined with standardized oral care encompassing mechanical plaque removal, fluoride therapy, and natural anticariogenic agents. While mechanistically plausible, this paradigm requires rigorous validation through multicenter randomized controlled trials assessing ecological stability maintenance and caries incidence reduction.