ABSTRACT
Introduction and Objective: Photoelasticity consists of an experimental technique of stress analysis. This technique is very used in most different areas including Dentistry. This literature review presents the several applications of photoelastic technique in Dentistry as well as its advantages and disadvantages. Literature review: Based on this method of analysis, it is possible the verification of the stress distribution and deformation in structures with complex geometry as maxilla and mandible. It can be used to evaluate the distribution of stress on several types of prosthesis as removable partial denture systems with different retention systems, conventional implant prosthesis, overdentures and Brånemark protocols. Moreover, photoelasticity can be used to assess the stress generated by various orthodontic movements, different orthodontic systems and different materials (orthodontic wires). In addition, it is used to analyze different defects of maxillectomy, splint types on traumatized tooth and post-core restoration methods. This technique can also be used to assess dental instruments such as evaluation of different designs of periodontal probe. Conclusion: The photoelastic analysis has been a technique of great importance in health area studies, more specifically in Dentistry. Based on this method of analysis, it is possible to measure the stress distribution and deformation in structures with complex geometry as maxilla and mandible.
ABSTRACT
O objetivo deste trabalho foi analisar a dureza e a caracterização metalográfica doTi c.p. quando submetido a tratamentos térmicos e à corrosão por solução de fluoretos de sódioa 1%. As amostras foram submetidas a dois tipos de tratamento térmico, têmpera e recozimento.Em seguida, foram submersas em solução de fluoreto de sódio por 30 dias e depois por mais30 dias. Entre cada etapa, foi feita a caracterização por meio de teste de dureza e microscopia óptica.No ensaio de dureza Vickers, verificou-se diferenças estatísticas entre os grupos estudados e queos tratamentos térmicos realizados elevaram a dureza do Ti c.p. por aliviar a tensão do material etorná-lo uma estrutura cristalina, fato este que deve melhorar as propriedades do material. Alémdisso, verificou-se que os grupos estudados, ao serem submetidos à ação de íons fluoreto apósos tratamentos térmicos, tiveram seus valores de dureza aumentados devido, provavelmente, aoprocesso de friabilidade. Na análise metalográfica, foram observadas diferenças entre as amostrasquando submetidas à ação dos íons fluoreto, e essa exposição à solução fluoretada danificou asuperfície desse biomaterial.
The purpose of this study was to measure the c.p. Ti hardness and to analyze thestructure of the c.p. Ti surface using an optical microscopy, when submitted to heat treatmentsand to corrosion by 1% sodium fluoride solution. The samples were submitted to two types ofheat treatment, tempering and annealing, after been submitted to sodium fluoride solution by30 days and then by more 30 days, and the characterization was made through tests of hardnessand optical microscopy technique. Statistical differences amongst the studied groups were verifiedby the Vickers hardness test, which resulted higher hardness c.p. Ti when used the heat treatments,that could be explained by relieving the mechanical stress of the material and making the crystallinestructures more defined, and this fact should improve the material properties. Besides that, it wasverified that the groups submitted to ions fluoride action, after the heat treatments, had their valuesof hardness increased, due, probably, to the heat process that increases the material friability. Inthe optical metalograph analysis, differences amongst the samples were observed when they weresubmitted to ions fluoride action, probably because the exposure of the titanium to fluoride solutionresulted damages to the surface of this important biomaterial.