Avaliação dos parâmetros de testes empregados para induzir fadiga cíclica em materiais restauradores dentários

• Ano de defesa: 2021
• Autor(a) principal: Velho, Helder Callegaro
• Tipo de documento: Dissertação
• 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: Análise de sobrevivência; Cerâmicas odontológicas; Fadiga; Materiais dentários; Parâmetros de testes de fadiga; Resina composta; Dental ceramics; Dental materials; Fatigue; Fatigue test parameters; Resin composite; Survival analysis; CNPQ::CIENCIAS DA SAUDE::ODONTOLOGIA
• Link de acesso: http://repositorio.ufsm.br/handle/1/21114

The present dissertation is divided into two studies. Study 1 systematically reviewed the literature to identify what are the methods and testing parameters used to induce fatigue on non-anatomic specimens of commercially available dental restorative materials, to discuss their indication, limitations, and implications. In vitro studies written in English which evaluated commercially available non-anatomic dental restorative material samples subjected to mechanical cyclic fatigue were selected. The search was performed in the PubMed, Scopus, and Web of Sciences databases by 2 independent researchers. The initial search yielded 1,848 articles, of which 92 were included. Among the studies included, most evaluated dental ceramic materials, tested without the presence of a luting agent, or supporting substrate, evaluated the materials using accelerated fatigue tests, frequencies ≤2 Hz, stainless steel indenters with a spherical tip, axial loading, and a wet test environment. Thus, it was possible to conclude that the definition of the test configuration and the fatigue method must be strictly related to the objective of the study, and the findings must be compatible with the clinical failure pattern or as described in the international standards for mechanical tests, in which fractographic analysis is recommended. Study 2 aimed to evaluate the influence of loading frequency on the mechanical fatigue behavior of polymer-infiltrated ceramic-network (PICN) and lithium disilicate (LD) simplified restorations. Thirty discs (Ø= 10 mm; thickness= 1.0 mm) of each ceramic material were adhesive cemented onto dentin analogue discs (Ø= 10 mm; thickness= 2.0 mm). The specimens were randomly allocated in 4 groups (n= 15) according to the ceramic (LD or PICN) and the loading frequency used (2 Hz or 20 Hz). Stepstress fatigue test (initial load= 200 N; increment= 100 N; 10,000 cycles) was performed and the data were analyzed by survival tests (Kaplan Meier and Mantel-Cox) and Weibull analysis. No statistical difference was detected in relation to fatigue failure load and number of cycles for failure between the groups of the same ceramic for the different frequencies evaluated. All failures were radial cracks in the cementation surface. Therefore, the use of a 20 Hz loading frequency shows to be a viable alternative to accelerate fatigue tests without changing the fatigue failure load values, number of cycles for failure and the failure pattern of simplified restorations made of lithium disilicate glass ceramic or polymer infiltrated ceramic network.