Impacto da radioterapia e do protocolo de tratamento endodôntico no selamento coronário da câmara pulpar e no comportamento biomecânico radicular

• Ano de defesa: 2025
• Autor(a) principal: Pauletto, Guilherme
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Santa Maria; Brasil; Odontologia; UFSM; Programa de Pós-Graduação em Ciências Odontológicas; Centro de Ciências da Saúde
• Palavras-chave em Português: Radioterapia; Resistência de união; Resistência à fadiga; Endodontia; Radiotherapy; Bond strength; Fatigue resistance; Endodontics; CNPQ::CIENCIAS DA SAUDE::ODONTOLOGIA
• Link de acesso: http://repositorio.ufsm.br/handle/1/33792

This Thesis is composed of two studies. The objective of the first study was to evaluate the influence of radiotherapy and different endodontic treatment protocols on the bond strength to pulp chamber dentin. Eighty mandibular molars were randomly divided into two groups (n = 40): non-irradiated and irradiated (60 Gy). Posteriorly, the pulp chambers were sectioned and each group was subdivided into five subgroups (n = 8), according to the endodontic treatment protocol: no treatment (Control); Single-visit; Two-visits; Immediate dentin sealing (IDS) + single-visit; and IDS + two-visits. Each endodontic treatment visit was simulated with 20 mL of 2.5% sodium hypochlorite (NaOCl), 5 mL of 17% ethylenediaminetetraacetic acid (EDTA) and 10 mL of distilled water. IDS was performed by applying two coats of a universal adhesive to the lateral walls of the pulp chamber. Then, the samples were restored with resin composite and four sticks were obtained per sample for microtensile test and failure mode analysis. Furthermore, the coronal portion corresponding to the roof of the pulp chamber, after irrigation, was evaluated for surface roughness (n = 4) and chemical composition and topography (n = 4). The treatment protocol influenced the bond strength, while radiotherapy did not. The control group presented the highest values. The single-visit group demonstrated higher bond strength than the two-visits, IDS + single-visit, and IDS + two-visits groups, which in turn, did not differ from each other. The use of IDS increased surface roughness and changed the chemical distribution of dentin, in addition to modifying the topography. In general, predominantly adhesive failure was the most prevalent. The second study aimed to investigate the influence of different tapers of preparation and dental substrate irradiation on the biomechanical behavior of the mesial roots of mandibular molars. The eighty mesial roots with two canals of the mandibular molars used in the first study were used, resulting in two groups (n = 40): nonirradiated and irradiated (60 Gy). Posteriorly, each group was subdivided into five subgroups (n = 8), according to the preparation taper: no preparation (Control); 25.03; 25.04; 25.06; and 25.08. The groups were considered homogeneous regarding their dimensions, weight and morphology. The prepared specimens were embedded in plastic molds and subjected to a cyclic fatigue test. A failure analysis was performed according to the extension and course of the fractures. As a result, fatigue resistance decreased as the taper of the preparation increased. Preparation 25.03 presented significantly higher values only than 25.08, while 25.04, 25.06 and 25.08 were similar. Irradiation significantly reduced the biomechanical performance. There were no differences in the distribution of fracture types among the groups. As a general conclusion, irradiation did not influence coronal sealing, but negatively affected root biomechanical behavior. The different endodontic treatment protocols investigated influenced the outcomes analyzed.