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Dental impressions are widely used in the field of oral restoration. The materials are used for making impression in oral cavity. In order to measure the thickness of impression for reference in clinic, the real impressions are taken as the object for studying. Through optical method, charge-coupled device (CCD) is used for collecting the grey image of cutting section of the impressions which are located in the same plane with steel dividing ruler. According to convert relationship between dividing ruler and pixels collecting grey image, the thickness of impression specimens can be obtained. The results show that the optical method used for measuring thickness is feasible to the task and the precision can reach micro dimension. The experiment method and technique can also be provided for measuring thickness of similar tissue engineering materials.
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Humanos , Materiais para Moldagem Odontológica , Modelos Dentários , Teste de Materiais , Óptica e FotônicaRESUMO
Modern photo-mechanics testing techniques are widely used in industrial circles and academic circles. In order to solve the problem of biomedical engineering, shadow moiré method is used in oral and dental area in our study. A molar tooth was tested by phase shift shadow moiré method. Through testing molar tooth, the results show that shadow moiré method could be used for measuring the appearance of the oral area and concave and convex parts of molar tooth could also be distinguished and shown by interference patterns. The characteristics of shadow moirh are that it does't need exerting load on the specimen and could realize non-contact measurement.
Assuntos
Humanos , Cefalometria , Métodos , Topografia de Moiré , Dente Molar , FotografaçãoRESUMO
The theories of digital speckle correlation method, shadow moire method, photoelestic method,moire interferometry method and electronic speckle interferometry method were introduced. The applications of these modern photomechanics methods in biomedical engineering from both domestic and abroad were introduced, respectively. This review will provide inspiring methods and experimental technique for biomedical engineering research and promote profound exploration.in the field.
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BACKGROUND: Moiré interferometry method which belongs to the range of experiment mechanics is a modern photo-mechanics test technique. On the other hand, metal-porcelain restorations characterized as beautiful, compatible and stable properties are widely used in oral medicine domain. Moiré interferometry technique is applied in the oral restoration and some mechanics data can be obtained. It can be realized in discipline complementation and interaction between mechanics and bio-medicine engineering. OBJECTIVE: To introduce the moiré interferometry technique in details, and to study the displacement of metal-porcelain restorations under different loads by using the moiré interferometry technique as it is found that porcelains often flake off from the base of restorations in oral clinic. METHODS: The horizontal and vertical displacement of metal-porcelain restorations were measured by using the moiré interferometry method which is sensitive and easy to operate, and suitable for in-plane displacement measurement. The displacement was shown in the form of interferometry patterns. RESULTS and CONCLUSION: The interferometry patterns which represented the in-plane displacement of specimens were obtained and the displacement was linearly related with the loading changes. Moiré interferometry method can be used in measuring the displacement of restorations. Operation is simple and results are shown by interferometry patterns.
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BACKGROUND: Porcelain-fused-metal restoration (PFM) is made by substrata material of alloy, and then porcelain which color is similar to the natural tooth is covered on the metal. At last, the composite of porcelian-metal is sintered in vaccum furnace. Because PFM has the strength of full crown metal and aethetic of full crown porcelain, it is widely applied in the oral clinic. Mechanical property of Porcelain-fused-metal restoration (PFM) contributes to solve mechanical problems occurred in clinic and to elevate success rate of the restoration. In accordance to different objectives, the design of PFM mechanical charger is various in the laboratory.OBJECTIVE: To discuss different experimental methods applied in studying strength of PFM, so that several experimental methods are supplied for further studying behaviors of PFM.METHODS: SpringerLink database and Vip database were retrieved using the key words of "metal-porcelain restoration" to select studies concerning the mechanical behaviors of PFM following reading. 120 literatures were obtained following primary retrieval. Following reading titles and Abstracts, 89 unrelated literatures were excluded. Finally, 31 literatures were used for summary and review.RESULTS AND CONCLUSION: Index system of foreign and domestic are adopted associated with the methods in studying the mechanical behaviors of PFM. Literatures are mainly adopted three-point and four-point bending. Moiré interferometry and speckle interferometry are used in various thickness of dental prosthetic restoration for mechanical property test, with the sensitivity of 0.417 μm and 0.532 μm, respectively. The sensitivity meets the requirements of mouth rehabilitation at present.
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BACKGROUND: Under the pressure of mechanical action, the culture membrane will be stretched and cause the deformation of cells which adhere to the surface of culture membrane. According to this, growth regularity in different external force environments will be observed; however, how to determine the load distributions on the whole culture membrane still remains unclear. OBJECTIVE: Photomechanics method was applied for determining the out-plane displacement so as to obtain the strain distributions of the cell culture membrane. DESIGN, TIME AND SETTING: Contrast study was performed at the Photomechanics Laboratory, School of Mechanical and Automation Engineering, Shanghai Institute of Technology from March to August 2008. MATERIALS: Culture membrane which specially used for biomedicine was made by Dow Coming Corporation, USA and the type was Q7-4750. The dimension and mechanics properties were as follows: diameter = 100 ram, thickness = 150-160 μm, modulus of elasticity E = 2.14 MPa, and Poison's ratio = 0.48. lines per millimeter; phase shift set was controlled by manual and 5 marks equal 0.1 mm; CCD camera was used for capturing moire patterns. Finally, phase was transformed into displacement so as to obtain three-dimensional appearance and manner. MAIN OUTCOME MEASURES: Out-plane displacement information, and deflection of culture membrane including displacement and strain. RESULTS: The three-dimensional profiles of culture membrane after deformation were constructed by image processing method and the out-plane heights could be obtained. Corresponding to the total strains of 1%, 10%, 20%, and 25% for the culture membrane, the displacement of highest point was 2.28 mm, 8.32 mm, 12.12 ram, and 13.52 mm, respectively. The error was 3.5% through comparing the measured heights of culture membrane with the heights which was known for the culture membrane. It indicated that this experiment method was highly sensitivity. According to the out-plane displacements, the strains distributions along symmetrical axis were calculated and the distributions of strain were shown by parabolic curve. displacement distributions of culture membrane is obtained and shown displacement contour. Namely, the out-plane displacement of center for the membrane has the maximum heights, and the strains distributions are shown parabolic curve.