Papers by Keyword: Teeth

Abstract: The work addresses the issues of increasing processing accuracy and productivity by controlling technological connections that act during the formation of shaped surfaces by grinding and plastic deformation, presents the main indicators of the quality of teeth on the working surface, provided by the developed technology, with a decrease in the maximum value of the actual cutting depth by more than 1.5 times when grinding toothed surfaces by copying, determined influence of the position of the workpiece on the accuracy of the pitch and half-angles of the profile for rolling threads of high precision by radial feed, the purpose of which is movement and measurement, design features determined of rollers for thread rolling on workpieces with low rigidity with tangential feed, the parameters of their threads, including the functional and structural relationship of the helix angles with the dimensions of the rolled thread.

Abstract: In this paper, we consider a detailed technological process for manufacturing parts, namely, a gear wheel. The proposed method with the intervention of modern 3D modelling makes it possible to improve the main indicators of quality and strength of parts. Based on the results obtained, a cycloid transcendental system of circular motion of a gear wheel with the specified basic parameters was modelled. Using multifunctional modules, we studied the vibrations of the gear wheel at different points in time. It was found that due to the fatigue and contact strength, it is possible to ensure uniform flexural strength of the gear teeth. And also, by adjusting the profile of the teeth of the part, we selected the desired strengthening coefficient. The presented dependence of the angles of inclination of the gear teeth on the transformation coefficient allows you to improve the main indicators of quality and strength by at least 2 %.

Abstract: Normal oral food ingestion processes such as mastication would not have been possible without the teeth. The human teeth are subjected to many cyclic loadings per day. This, in turn, exerts forces on the teeth just like an engineering material undergoing the same cyclic loading. Over a period, there will be the creation of microcracks on the teeth that might not be visible ab initio. The constant formation of these microcracks weakens the teeth structure and foundation that result in its fracture. Therefore, the need to predict the fatigue life for human teeth is essential. In this paper, a continuum damage mechanics (CDM) based model is employed to evaluate the fatigue life of the human teeth. The material characteristic of the teeth is captured within the framework of the elastoplastic model. By applying the damage evolution equivalence, a mathematical formula is developed that describes the fatigue life in terms of the stress amplitude. Existing experimental data served as a guide as to the completeness of the proposed model. Results as a function of age and tubule orientation are presented. The outcomes produced by the current study have substantial agreement with the experimental results when plotted on the same axes. There is a notable difference in the number of cycles to failure as the tubule orientation increases. It is also revealed that the developed model could forecast for any tubule orientation and be adopted for both young and old teeth.

Abstract: The present study reports the analytical approaches for characterization of teeth whitening gels based on natural extracts of fruits and medicinal plant. High performance liquid chromatography (HPLC) with UV detection were used for identification and quantification of (oxalic, citric, tartaric, malic, succinic and fumaric acids), flavonoids (catechin, epicatechin, rutin and quercetin) and phenolic acids (vanillic acid, p-coumaric acid, ferullic acid) from studied gels samples used for teeth whitening. The organic acids were used as active agent with action in tooth discoloration and stain removal. Organic acids were separated through a Carbosep Coregel 87H3 column at 35°C and detection at 214 nm. The mobile phase was the sulphuric acid 0.005 M solution. The total quantity of organic acids of these gel samples was determined. The action of flavonoids have controlled dental caries and inhibited plaque formation. Separation of flavonoids and phenolic acids was carried out on Lichrosorb RP-C18 column at 40 oC and detection at 290 nm. The mobile phase was a mixture of methanol and solution 0.1% formic acid in a gradient elution. The flavonoids, catechin, epicatechin, rutin and quercetin and phenolic acids, vanillic acid, p-coumaric acid, ferullic acid, were determined quantitative in the teeth whitening gels on natural extracts of fruits and medicinal plant.

Abstract: The teeth of sea urchins are highly complex composite structures, composed predominantly of high magnesium calcite, and of a minor heterogeneous assemblage of organic macromolecules that are occluded within the mineral. The organic matrix fulfils important functions in mineralization, in addition to giving the mineral phase peculiar mechanical properties, different from that of purely inorganic calcite. Nevertheless, the composition and function of individual components of the organic matrix still remains largely unknown. Up to now, the detailed protein repertoire of teeth from a single sea urchin species (Strongylocentrotus purpuratus, order Camarodonta) was investigated. In this study, we characterized for the first time the teeth skeletal matrix of another sea urchin, Arbacia lixula (order Arbacioida). The acetic acid soluble and acetic acid insoluble matrices, namely ASM and AIM respectively, were extracted and characterized with different biochemical methods including mono-dimensional SDS-PAGE, FT-IR spectroscopy, HPAE-PAD for monosaccharide analysis, and finally, proteomics. In spite of the paucity of peptide data, several of them displayed a high abundance of hydrophobic residues, i.e., alanine, glycine and valine, and of the apolar proline. We assert that the alanine- and proline-rich domains are important features of some of the matrix proteins associated to the teeth of sea urchins. None of the known skeletal matrix proteins from S. purpuratus teeth were identified in the organic matrix of A. lixula teeth. This might suggest major differences in teeth matrix protein repertoires of these two species belonging to orders that diverged in the Mesozoic times.

Abstract: Dental medicine represents a very important part of our life. As our appearance or looks is a major concern for us, a beautiful smile can improve our life. Moreover, our teeth health reflects on our overall health. This paper presents a method for highlighting the differences between a natural tooth and a prosthetic one. In order to determine the stress distribution in teeth during the use of prosthetics pivots, several virtual geometric models of the teeth were created (canine, first premolar, first molar and second molar), both in their natural form and when using pivots. The results obtained from these analyses were compared in order to reveal the behavior of a prosthetic tooth during normal life loads. Such results of real life behavior can be used by dental medics in order to predict the life span of restored teeth.

Abstract: The calculation of the stress in the tooth is based on a number of assumptions. Here is calculated so-called comparative stress. This is useful if they are used in calculating the results and findings from research and practice in the determination of any effects that affect the actual teeth stress. The complicated shape of the teeth is the theoretical determination of stress in the teeth difficult. The starting assumption is highly idealized notion of a linear displacement of the tooth for and tooth load is considered as a beam loaded by bending. The paper deals with the problems of stress examining in a dangerous section of the foot tooth with asymmetrical profile. The stress of tooth is solution by finite element method.

Abstract: The fracture resistance of all-ceramic restorations is one of the major concerns in clinical applications of these materials. An in vitro study can help to estimate the in vivo behavior of a new dental material and design method. The FEM (finite element method) seems to be a proper tool to study material behavior in relation to their composition, relationship and geometry, by analyzing the distribution of stress. The purpose of this study was to evaluate, by finite element analysis, the importance of meshing accuracy on stresses induced in all-ceramic restored teeth during protrusion loading. For the experimental analysis, a 3D model of a central incisor was achieved: intact teeth, unrestored teeth with chamfer marginal preparation, the same tooth restored with full pressed ceramic crown. Stress analysis was performed on the restored incisor during protrusion. To evaluate the importance of the meshing accuracy for stresses in all-ceramic restored teeth three kinds of meshing options were chosen: coarse, medium and fine. For the analysis choosing of the proper meshing options is essential for accurate results. The medium meshing is enough to obtain favorable results.

Abstract: Dental enamel is the most highly mineralised and hardest biological tissue in human body [1]. Dental enamel is made of hydroxylapatite (HAP) - Ca5(PO4)3(OH), which is hexagonal (6/m). The lattice parameters are a = b = 0.9418 nm und c = 0.6875 nm [1]. Although HAP is a very hard mineral, it can be dissolved easily in a process which is known as enamel demineralization by lactic acid produced by bacteria. Also the direct consumption of acid (e.g. citric, lactic or phosphoric acid in soft drinks) can harm the dental enamel in a similar way. These processes can damage the dental enamel. It will be dissolved completely and a cavity occurs. The cavity must then be cleaned and filled. It exists a lot of dental fillings, like gold, amalgam, ceramics or polymeric materials. After filling other dangers can occur: The mechanical properties of the materials used to fill cavities can differ strongly from the ones of the dental enamel itself. In the worst case, the filling of a tooth can damage the enamel of the opposite tooth by chewing if the interaction of enamel and filling is not equivalent, so that the harder fillings can abrade the softer enamel of the healthy tooth at the opposite side. This could be avoided if the anisotropic mechanical properties of dental enamel would be known in detail, hence then another filling could be searched or fabricated as an equivalent opponent for the dental enamel with equal properties. To find such a material, one has to characterise the properties of dental enamel first in detail for the different types of teeth (incisor, canine, premolar and molar). This is here exemplary done for a human incisor tooth by texture analysis with the program MAUD from 2D synchrotron transmission images [2,3,4].

Abstract: . The aim of this paper is to evaluate surface properties of natural temporary teeth from high polluted area by dynamics of balance hydrophil hydrophob in connection with surface analysis type atomic force microscopy (AFM). All the data were discussed in relation with the state of degradation of such teeth, taking into account that teeth are biological archive.