Efeitos da radioterapia na cavidade oral: bases laboratoriais e manejo multidisciplinar integrado do paciente

Abstract

Radiotherapy induces chemical and mechanical changes in the oral environment, affecting the properties of dental structures, salivary glands, oral mucosa, periodontium, bones, and all anatomical elements exposed to the radiation field. Glandular atrophy–related hyposalivation and changes in the chemical composition of dental tissue, combined with dysphagia and dysgeusia—which often result in a more cariogenic diet—create a favorable environment for the development of radiation-related caries. In view of this complex clinical scenario, the first specific objective of this thesis is to describe the clinical management of a patient who underwent radiotherapy for head and neck cancer, presenting with radiation-related carious lesions in teeth with gingival recession. The treatment approach involved restoration of the carious lesions, surgical correction of the gingival recession using a gingival graft, and enrollment in an individualized preventive program. A two-year follow-up showed improvement in gingival tissue quality, greater comfort in the use of removable prostheses, better oral hygiene, relief of dentin hypersensitivity, and a reduced risk of new lesions. Aiming to address two of the most prevalent and debilitating consequences of radiotherapy—xerostomia and hyposalivation—including a complaint reported by the patient in the first objective, a systematic review with network meta-analysis was conducted as the second specific objective to compare the effectiveness of topical treatments in reducing xerostomia and stimulating salivary flow in post-radiotherapy patients. A total of 27 clinical trials were included, evaluating 22 topical treatments. Pilocarpine, salivary enzymes, and combinations with devices proved significantly more effective than placebo. Sodium hyaluronate and thyme honey were significantly less effective than most of the evaluated treatments and even than placebo. Finally, recognizing the importance of ensuring appropriate conditions for in vitro laboratory studies investigating the integrity of dental structure in irradiated patients, an experimental study was conducted with the aim of identifying storage media that do not interfere with the chemical composition and mechanical properties of human dentin. Among the tested solutions, distilled and deionized water demonstrated pH instability in the early storage periods and caused significant reductions in dentin microhardness, as well as changes in the organic and inorganic components of the tissue. These findings underscore the need for rigorous standardization in experimental models focused on this topic. Altogether, the three objectives of this thesis—a clinical case report, a systematic review with network meta-analysis, and a laboratory study—complement one another by offering an integrated and evidence-based approach to dental care for patients undergoing radiotherapy for head and neck cancer, contributing with clinical guidelines, effective therapeutic strategies, and methodological foundations for future research.