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BACKGROUND: Reverse engineering modeling has been widely used in previous studies. However, there are a few studies on implantation modeling, especially in aspects of mandibular molar implantation. The mandibular molar has high miss rate in dentition. Thus, to establish three-dimensional finite element models of a jaw bones with mandibular molar implant denture using reverse engineering shows a great parameter value for research of mandibular molar implantation repair. OBJECTIVE: To establish a three-dimensional finite element model of a mandibular molar with dental implant inserted in mandibular molar area using reverse engineering, and to provide mathematical model basis for biomechanics researches of stomatology.METHODS: Establish three-dimensional model, divide mesh and calculate by Solidworks 2007 through scanning mandible by screw jaw using helix CT, obtaining data from images, separating data, rebuilding three-dimension using Mimics software,optimizing the design of mesh by Magics software, and dealing with solid model by Pro/E preprocessor.RESULTS AND CONCLUSION: A three-dimensional finite element model of mandibular first molar implant with regular depth was established, which has high geometrical similarity, good properties of mechanics and mesh, and can be easily modified. This can provide excellent model support for studying the stress analysis of different designs on restoring mandibular first molar implant.
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AIM: The relationship between muscle force (MF) and bone mass (BM)has become one of the pivotal aspects in research of cause, prevention and treatment of primary osteoporosis. This paper is to probe into the mechanism by which estrogen influences the relationship between MF and BM.METHODS: We searched for the relative papers on the relationship between muscle force and bone mass and the effect of estrogen on relationship between muscle force and bone mass. Combining the literatures with our previous results, we discussed the effects of estrogen on relationship between muscle force and bone mass.RESULTS: Muscle force, which determines bone structure and bone mass,makes bone strength adaptable to work load. Estrogen adjustes adaptability of muscle force and bone mass, mainly by the influence on threshold of bone strain. Estrogen therapy could maintain muscle force, partially by which estrogen exerts the beneficial effects on bone.CONCLUSION: Estrogen could influence the relationship between muscle force and bone mass, and estrogen therapy could have the beneficial effect on muscle force.
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Objective: To detect whether the metal base of the metal-fused-to-ceramic restoration have the same color performance and can be tested as natural teeth, and to evaluate whether they have effect on the color value determination by means of the photoelectrometer. Methods:Two kinds of shade guides of metal ceramic restoration were measured by photoelectric colorimeter, and color difference are analyzed compared with natural teeth of the same color. Results:The empfindung (color difference) of the shade guides with or without metal base and natural teeth is significantly different (P
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Objective:To observe the consistence of the color and optical parameters of metal-ceramic, all-ceramic and composite resin with Vita Classical shade guides. Methods:Specimens of VITA VMK95 metal-ceramic, In-Ceram all-ceramic and Artglass composite resin according to the same area with Vita Classical shade guide were made respectively. ?E_ ab ,L,a,b between specimens and shade guide were calculated. Results:The mean ?E between shade guide and all-ceramic or composite resin was less than 3 NBS. The mean ?E between shade guide and metal-ceramic material was 13.78 NBS, the significant difference could be identified by visual determination (P
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Objective: To study the color reproduction ratio of metal ceramic restoration in clinic. Methods:The color of 150 maxillary incisors and its metal ceramic restorations was measured by MinoltCR 321 chromaticity instrument(D65 daylight simulator inside),the color reproduction ratio was calculated with CIE 1976 L*a*b* system. Results: The color reproduction ratio of metal ceramic restoration measured by clinical eye evaluation was 33.9%.Color error ratio was 66.1%. Conclusion: The color reproduction ratio measured by eye evaluation is low and the color error ratio is high.