Efeito da idade nos aspectos morfológicos, químicos e físicos das dentinas radiculares humana e bovina

• Ano de defesa: 2019
• Autor(a) principal: Francisco Ivison Rodrigues Limeira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; Brasil; ODONTO - FACULDADE DE ODONTOLOGIA; Programa de Pós-Graduação em Odontologia; UFMG
• Palavras-chave em Português: Dentina; Raiz dentária; Microscopia; Análise físico-química; Mecânica; Testes de dureza; Resistência à flexão; Fraturas por compressão; Pinos dentários; Cimentos de resina
• Link de acesso: http://hdl.handle.net/1843/31084

Bovine teeth have been used as a substitute for human teeth in dental research. However, there is a lack of data that support the use of bovine root dentin, mainly, that analyze the effect of age on the properties of the substrate. Thus, the effect of age on the morphological, chemical and physical aspects of human and bovine root dentin was analyzed, in function of the root thirds. This is an in vitro experimental study, approved by the Research Ethics Committee (protocol number: 1.803.933) and the Ethics Committee on the Use of Animals (protocol number: 372/2016). The sample was composed of single-rooted teeth and root dentin was categorized into: young human (YH, 20-30 years); old human (OH, above 60 years); young bovine (YB, 24-36 months); and adult bovine (AB, over 48 months). The roots were sectioned below the cement-enamel and longitudinally to produce two hemi-sections. One hemi-section was chosen and sections were made to obtain the specimens, according to each method of analysis. For the analyzes of the morphological aspects - number, diameter and area of the dentinal tubules - the specimens were analyzed in Scanning Electron Microscope. The chemical composition was analysed by Energy Dispersive Spectroscopy, Wavelength Dispersive Spectroscopy and Fourier Transformed Raman Spectroscopy. In the analysis of the mechanical properties, the specimens were submitted to nano-indentation, three-point flexural and compression tests. For the analysis of the push-out bond strength test, the roots received endodontic treatment and fiber post with resin cements (conventional and selfadhesive dual) were fixed. The roots were sectioned in the root thirds and the specimens tested in a universal testing machine. Additionally, the degree of conversion of the resin cements was evaluated. The data were analyzed in statistical software, level of significance of 5%. The OH presented the lowest values for number, diameter and area of dentinal tubules (p<0.05). OH showed higher values of calcium, Ca/P ratio and relative mineral concentration, with decrease in the organization and quality of the collagen (p<0.05). The OH showed the highest values of nano-hardness, elastic modulus and compressive strength, but the lowest values of flexural strength and flexural modulus (p<0.05). The OH presented the lowest values of bond strength, with differences among the root thirds (p<0.05). The degree of conversion of the cements showed a decrease along the root thirds (p<0.05). It was concluded that age has an effect on the morphological, chemical and physical aspects of human root dentin, with no effect on bovine dentin. Thus, when it is necessary to replace the human root dentin by the bovine in research, it is necessary to consider the effect of age on the analysed outcomes.