Radiation Caries: Can Prevention Become a Reality?

Sir, Radiation caries (RC) is a rapidly progressing dental complication primarily affecting head and neck cancer patients undergoing radiotherapy. First described by Juan Del Regato in 1939, it typically develops within 6 to 12 months following treatment, initially presenting as superficial enamel changes near the cervical region leading to widespread demineralization, progressive occlusal and incisal wear, and dark discoloration of the dentin. Unlike conventional caries linked to poor oral hygiene and diet, RC is primarily caused by radiation-induced salivary gland damage, leading to hyposalivation, dietary changes, impaired oral hygiene, and alterations in enamel and dentin integrity.[1] Radiation doses exceeding 20–39 Gy are associated with significant hyposalivation, altering the quantity and composition of saliva. Hey et al. (2013) reported that doses below 20 Gy cause minimal dental damage, suggesting a predictive threshold. Loss of saliva’s buffering capacity, antimicrobial properties, and remineralization abilities accelerates dental destruction, resulting in substantial loss of tooth structure within a year.[2] Pain caused by mucositis and decreased salivary flow frequently compels patients to adopt a soft, sticky diet that is rich in fermentable carbohydrates, thereby increasing the risk of dental caries. Additionally, weight loss resulting from dysphagia and oral mucositis often leads patients to prefer sweet foods, as sweet taste perception is typically the last to decline during treatment. These dietary modifications, along with difficulty in maintaining oral hygiene due to trismus and pain, contribute to plaque buildup and further accelerate the progression of caries. The extent of dental damage correlates with the radiation dose. Higher radiation doses decrease enamel hardness, tensile strength, and elastic modulus, thereby increasing the risk of tooth fracture. Radiation doses of 30–60 Gy induce significant morphological alterations in enamel, leading to disruption of its prismatic structure and increasing susceptibility to caries. Radiation exposure also negatively impacts dentin by disrupting its organic framework and reducing its microhardness which may result in the formation of microscopic gaps at the dentin–enamel junction (DEJ), weaken the cohesion between enamel and dentin. Consequently, the DEJ becomes structurally compromised and more vulnerable to fracture and progressive deterioration. Preventing RC requires a multidisciplinary approach involving oncologists, dental professionals, and patients, beginning before radiotherapy and continuing lifelong. A thorough dental evaluation before radiation is crucial to educate patients on oral hygiene and implement preventive strategies. Reinforcement of enamel with 0.4% stannous fluoride, 1.23% sodium fluoride, or 1.23% acidulated phosphate fluoride significantly mitigates the risk of RC. Dreizen et al. (1977) demonstrated that daily application of 1% neutral sodium fluoride gel using custom trays substantially reduced caries incidence in irradiated patients.[3] During radiotherapy, proactive oral care is vital. Sialogogues like sugar-free chewing gums, CPP-ACP gums, and regular non-medicated rinses aid in maintaining oral hydration. Xylitol-based gums and lemon-flavored lozenges can further stimulate salivary flow and improve the buffering capacity of the oral environment. In cases of severe xerostomia, pharmacologic agents like pilocarpine may be prescribed to enhance salivary secretion. Additionally, artificial saliva substitutes containing animal mucin, carboxymethyl cellulose, xanthan gum, or aloe vera can effectively mimic the lubricating properties of natural saliva and provide symptomatic relief.[4] Post-radiotherapy, lifelong maintenance of oral health care is crucial. Continued fluoride therapy, regular dental visits, and dietary modifications, such as reducing acidic and sugary foods, play a critical role in preventing RC. Using high-fluoride toothpastes, neutral fluoride mouthrinses, and antimicrobial solutions supports long term oral health. Moreover, calcium phosphate (CD-CP) formulations combined with 0.05% sodium fluoride are particularly beneficial for xerostomia patients. Additional oral care includes rinsing with hydrogen peroxide saline, sodium bicarbonate solution, or salt and baking soda mixtures to maintain oral hygiene and clear debris. Sodium bicarbonate rinses are especially beneficial in increasing salivary pH and enhancing buffering capacity. Alcohol-based mouthwashes should be avoided as they can worsen oral dryness and mucosal irritation.[3] Advanced radiation techniques such as intensity-modulated radiation therapy (IMRT) should be utilized to minimize salivary gland exposure and reduce the severity of hyposalivation. The prevention of RC depends on a coordinated effort among healthcare providers and patients. With proper preventive strategies, dental professionals and oncologists can preserve oral health and improve the quality of life in head and neck cancer patients. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.