Papers by Keyword: Tooth

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Authors: Hai Yan Zhu, Qing You Liu, Xiao Hua Xiao, Jia Jia Jing, Chao He
Abstract: Based on the failure mode of air hammer bit, a mechanical model of the tooth on the inclined plane is established. And then a new air hammer flat bit with double declined planes and a big central plat (the outer inclined plane is 40° and the inner one is 20°) is designed. In order to reduce the design cost and cut down the design cycle, we establish a 3D contact model of 12 1/4″ full-scale flat bit, teeth and rock to choose a better end face structure from single and double declined planes, verify the rationality of bit parameters and tooth arrangement, design reasonable shrink range between tooth and tooth-Hole. This 3D FEM methodology for air hammer bit design is economical and useful, it can be used to optimize bit structure and design a new bit.
1435
Authors: Hai Yan Zhu, Qing You Liu, Xiao Hua Xiao, Jia Jia Jing
Abstract: In order to reveal the physical mechanism of air hammer drilling process, using the finite element methods (FEM), a three-dimensional (3D) contact model of full-scale bit, full-scale teeth and rock is established by using free meshing method. We use a Mohr-Coulomb type material model to describe when and how rock fails, and a triangular wave to replace the stress wave. Using the finite element analysis software (ANSYS), the 3D contact analysis of the bit, teeth and rock is carried out. The results show that: aggressive tensile failure may be primarily responsible for rock breakage in air hammer drilling, while compressive failure (or shear failure) may only contribute as a minor player; the distribution of the fragmentation dents can be used to verify the rationality of tooth arrangement; the larger tooth-hole stress of the outside rows mainly responses for the bit failure, while the larger tooth stress of the inside rows contributes as a secondary factor. The results are further calibrated with a series of field applications and research results.
1425
Authors: G.A. Zhuravlev, Y.E. Drobotov
Abstract: The review of researches of stress concentration in elastic bodies with loaded ledges, which are carried out with separate analysis of each of the force factors, is provided. The known results of using of such an approach are shown for example, the effects of geometrical concentrators curvature are revealed, and on their base principally new nonpole gear systems are developed. The recommendations for significant refinement of the known method are given.
350
Authors: Kun Tian, Hui Min Shuai, Xiao Min Yang
Abstract: Based on the basic theory of molecular recognition , we design a organic molecules model to induce the crystallization of hydroxyapatite to synthesized tooth-like calcium phosphate/hydroxyapatite under a controllable way in vitro. The cross-linking of collagen on the dentin surface and extraneous collagen was optimized by varying the molar ratio of N,N-(3-dimethylaminopropyl)- N'-ethyl-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) at a constant EDC concentration. CaCl2 and Na3PO4-12H2O solutions were added after the crosslinking process. X-ray photoelectron spectroscopic (XPS) and Fourier transform infrared spectroscopy (FTIR) analysis of organic protein monolayer for samples. The obtained composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) as well as energy dispersive X-ray (EDX). XPS and FTIR analysis showed the surface organic compositions in experimental group is higher than that of normal dentin and decalcified dentin surface. The results showed that the dentinal tubule were blocked by neonatal hydroxyapatite layer which has a continuous structure of columns crystal with size of 10-40nm. Furthermore, there were column crystal with parallel direction inside, similar to the crystal array in the top of enamel rod. This study showed that the specific organic molecule model can be used as a potential effective crystal growth modifier.
1054
Authors: T.M. Sridhar, A. Kishen, S. Shanmugaraj, R. Praveen, S.K. Srinivas, D. Das, A. Subbiya
Abstract: Human teeth has “structure” and yet is mostly treated as material. Differentiation between material and structure is crucial to understand complex biological material such as human dentine. The aim of the present work is to determine the bioceramic gradient phases of the crystal structure of the teeth across the crown and root region with age. Around 50 samples of teeth of different age groups were collected, decontaminated and sintered at 400, 600 and 800°C. After removal of the enamel the root and crown regions were machined and characterized for their vibrational states by FTIR investigations. The studies indicate the presence of hydroxyapatite as the major phase after sintering along with the typical hydroxyl peaks. A weight loss ranging from 7 - 42 % after sintering at 400 and 800°C respectively was observed across the different age groups. A through analysis would provide us an understanding in studying the desired nature of the teeth and kinetics of tooth mineralization.
893
Authors: M. Uchino, W. Fujisaki, E. Kurihara, K. Matsuda, Toshihiko Koseki
Abstract: This study is concerned with the fundamental characteristics of a new nondestructive measuring technique of the tooth roughness with precisely. In the dental clinics, the estimation of roughness of tooth surfaces with a hand explorer is one of the important tests for the finishing the crown re-shaping and resin fillings. If the tooth surface is rough enough to hold dental plaque, it occasio-nally causes dental diseases around it. Therefore, it is important to measure the roughness of the tooth surfaces for the prevention of furthermore distraction of the tooth. Laser speckle measurement is used as an evaluation method for objectively measuring the surface roughness with non-contact. In this study, a laser speckle measurement system for measuring the surface roughness is constructed. Comparison measurement is carried out for the tooth pieces with the various unidirectional roughness and the metallic test pieces with the standard roughness. The experimental results using the actual measuring system show some important points as follows. Firstly, there is a good correla-tion between the laser speckle pattern and the tooth roughness as well as that of the metallic test pieces. Secondly, the reflection from the tooth shows a different tendency in comparison with the reflection from the metallic test pieces.
1581
Authors: Kun Tian, Dong Hua Guan, Ping Wu, Chun Peng Huang, Lin Niu, Su Qin Xian, Yu Chen, Peng Wang, Yi Li Qu, Yong Mei Ye, Ting Ting Wang, Zhi Qing Chen
Abstract: Based on the molecular recognition theory, an organic molecules model was designed to induce the hydroxyapatite crystallization, to build a tooth-like calcium phosphate/hydroxyapatite under a controllable way in vitro. The cross-linking of collagen on the dentin surface and gelatin was optimized by varying the molar ratio of N,N-(3-dimethylaminopropyl)- N'-ethyl-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) at a constant EDC concentration. CaCl2 and Na3PO4-12H2O solutions were added after the crosslinking process. The whole process requires repeating the crosslinking and mineralization process for five times. The obtained composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) as well as energy dispersive X-ray photoelectron spectroscopy (XPS). The results showed that the dentinal tubule were blocked by neonatal hydroxyapatite layer which has a continuous structure of columns crystal with size of 10-40nm. Furthermore, there was column crystal with parallel direction inside, similar to the crystal array in the top of enamel rod. This study showed that the specific organic molecule model can be used as a potential effective crystal growth modifier.
663
Authors: Miroslav Malák
Abstract: Gear teeth are deformed due to the load. Recently, at ever faster evolving computer technology and the available literature, we can encounter modern numerical methods, such as finite element method (FEM), which can serve as methods for the determination of deflection gearing. This paper deals with stiffness and deformation of teeth of spur gears solution by finite element method.
194
Authors: Hong Ying Li
Abstract: This paper can be used as acar key toothed recognition and detection technology and computer vision, imageprocessing technology combined with interdisciplinary applications. Car lockassembly complicated procedures, identification and car keys tooth detection isone of the key aspects of automotive lock assembly, lock a direct impact on theefficiency of the assembly process. The system can effectively improve theexisting car key tooth detection technology to reduce the cost of car keystooth detection recognition, while also rapid and accurate identification, sothat the entire lock assembly process much more efficient.
1061
Authors: S. H. Jeong, Suck Jin Hong, Choong Ho Choi, B.I. Kim
Abstract: The process of dental caries is dynamic and continuous, with periods of de- and remineralization of the tooth structure occurring over time. When the remineralization potential is superior to demineralization, the caries process can be stopped and early caries lesions can recover. Moreover, the remineralization potential will be increased if active components are added to a dentifrice. Therefore, the aim of this study was to re-evaluate the remineralizaton potential of a dentifrice containing nano-sized carbonated apatite using pH cycling, which simulates the oral environment. Artificial incipient caries was induced on bovine tooth specimens, which were treated with 4 dentifrices containing several concentrations of nano carbonated apatites with pH cycling. The remineralization effect was evaluated at each step by measuring the Vickers Hardness Number, and obtaining SEM and CLSM images of the enamel surface. The micro hardness of the enamel surface increased after the pH cycling treatment of the dentifrices. The dentifrice containing 5% n-CAPs showed the highest level of remineralization followed by 0%, 15% and 30%. One-way ANOVA indicated a significant difference in remineralization between the dentifrice containing 5% and 30% n-CAPs. SEM and CLSM also demonstrated observable differences in each step. From this study, the fluoride dentifrice containing 5% n-CAPs was effective in remineralizing an artificial incipient caries lesion. In conclusion, the dentifrice containing 5% nano carbonated apatites and 25% silica was the most effective in remineralizing early caries lesion.
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