Influência de diferentes protocolos de radiação ionizante nas estruturas dentais e manejo odontológico dos pacientes oncológicos de cabeça e pescoço

Abstract

Head and neck cancer patients may experience side effects resulting from radiotherapy (RT) or chemotherapy treatment, including complications that directly impact the dentist's area of expertise. Mucositis, xerostomia, dysgeusia, trismus, dysphagia, soft tissue necrosis, osteoradionecrosis and radiation-related caries are some of the oral complications resulting from cancer treatment. RT is a therapeutic modality widely used in the treatment of head and neck neoplasms. RT protocols involve daily doses of 2 Gy, 5 days a week, for a period of 5 to 7 weeks. However, there is no standardization in the protocol of in vitro radiation of teeth for scientific studies, with some studies applying ionizing radiation in a fractional form, while others apply the total amount of radiation in a single dose. Thus, three objectives are part of this thesis. Objective 1: to evaluate the chemical and mechanical properties of enamel subjected to different in vitro radiation protocols; Objective 2: to evaluate the chemical and mechanical properties of dentin subjected to different in vitro radiation protocols; Objective 3: to review the literature and discuss important aspects in the dental treatment of head and neck cancer patients during the COVID-19 pandemic. In objectives 1 and 2, 56 third molars were divided into seven groups (n=8): non-irradiated (NI); irradiated in a single dose of 30 Gy (SD30), 50 Gy (SD50) or 70 Gy (SD70); irradiated in fractionated doses up to 30 Gy (FD30), 50 Gy (FD50) or 70 Gy (FD70). After sectioning the teeth, the specimens were analyzed by Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS) and Knoop microhardness test (KHN). The data obtained were submitted to parametric analysis, with a significance level of 5%. In objective 1, it was found that a dose of 70 Gy applied in a fractional way produced changes in the chemical and mechanical properties of the enamel, and from 50 Gy of radiation onwards, changes in the organic portion were already found. Doses of 30 Gy did not produce significant changes in enamel, regardless of fractionation or not. In objective 2, the dose of 70 Gy applied in a fractional way changed the chemical composition and microhardness of dentin, while doses of 30 Gy and 50 Gy did not result in significant changes, regardless of fractionation or not. Therefore, it is concluded that the use of fractionation in in vitro studies more faithfully reproduces the way RT is applied in head and neck cancer patients and that the dose of 70 Gy produces the most expressive changes in dental tissues. In objective 3, the critical review discussed the impact of COVID-19 on the oral health of patients undergoing head and neck antineoplastic treatment, presenting suggestions to minimize or control side effects. The performance of the dentist was divided into two fronts: preventive treatments for patients without pain and interventional treatments for patients with pain, respecting all biosafety protocols against COVID-19. The final decision on treatment always depends on the professional's judgment, taking into account the patient's consent and general health condition.