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Petrescu, Horia Alexandru, Daniel Vlasceanu, Andrei Stamate, Robert Bololoi y Stela Carmen Hanganu. "Finite Element Analyses Comparison Between Normal Teeth and Prosthetic Teeth". Key Engineering Materials 638 (marzo de 2015): 155–60. http://dx.doi.org/10.4028/www.scientific.net/kem.638.155.
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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.
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Gage, J. P., M. J. O. Francis y R. Smith. "Abnormal Amino Acid Analyses Obtained from Osteogenesis Imperfecta Dentin". Journal of Dental Research 67, n.º 8 (agosto de 1988): 1097–102. http://dx.doi.org/10.1177/00220345880670080701.
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Amino acid analyses were carried out on dentin proteins obtained from 33 normal teeth and 59 teeth from osteogenesis imperfecta patients. The analyses revealed that in the control teeth approximately 95% of the insoluble dentin fraction was collagen. The majority of the analyses for teeth obtained from the O.I. patients were biochemically abnormal (55 out of 59). Specifically, there was a significant increase in the acidic amino acids, with a corresponding decrease in the basic amino acids. A small group of patients showed double peaks in the histidine, hydroxylysine, and lysine areas of the chromatograms. These results emphasize that despite the fact that the teeth of O.I. patients may appear to be clinically normal, all but four of the teeth examined had abnormal dentin collagen.
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Buckley, Lisa G., Derek W. Larson, Miriam Reichel y Tanya Samman. "Quantifying tooth variation within a single population of Albertosaurus sarcophagus (Theropoda: Tyrannosauridae) and implications for identifying isolated teeth of tyrannosauridsThis article is one of a series of papers published in this Special Issue on the theme Albertosaurus." Canadian Journal of Earth Sciences 47, n.º 9 (septiembre de 2010): 1227–51. http://dx.doi.org/10.1139/e10-029.
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Documenting variation in theropod dinosaurs is usually hindered by the lack of a large sample size and specimens representing several ontogenetic stages. Here, variation within 140 disassociated and seven in situ tyrannosaur teeth from the Upper Cretaceous (lower Maastrichtian) monodominant Albertosaurus sarcophagus (Theropoda: Tyrannosauridae) bonebed is documented. This sample represents the largest data set of teeth from one population of A. sarcophagus containing both adult and juvenile specimens. Tooth variation was assessed using multivariate analyses (principal component, discriminant, and canonical variate analyses). Heterodonty in the teeth of A. sarcophagus contributes to the large amount of variation in the data set. Premaxillary teeth are significantly different from maxillary and dentary teeth, but there is no quantifiable difference between a priori identified maxillary and dentary teeth. Juvenile and adult teeth of A. sarcophagus show apparent quantitative differences that are size dependent on closer investigation, suggesting a cautious approach when interpreting multivariate analyses to identify novel tooth morphologies. Multivariate analyses on teeth of A. sarcophagus and published tooth data from other North American tyrannosaurid species reveals species-level clusters with little separation. The degree of separation among tooth clusters may reveal a phylogenetic signal in tyrannosaurid teeth.
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Medaković, Davorin, Tadej Dolenec, Danijel Karlović, Petra Vrhovnik, Nastja Rogan Šmuc, Sanda Rončević, Lovorka Pitarević-Svedružić y Matej Dolenec. "Trace Metals in Fish Biominerals as Environmental Indicators: Handheld XRF Analyses". Key Engineering Materials 672 (enero de 2016): 328–39. http://dx.doi.org/10.4028/www.scientific.net/kem.672.328.
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The parts of jawbones and selected teeth (malleolus) of adult marine benthic fish Sparus aurata and Diplodus sargus was collected from different station during east Adriatic coast (Croatia). Biominerals were prepared for three different instrumental analyses: elemental analysis by X-ray Fluorescence (XRF) and inductively coupled plasma spectroscopy (ICP-AES); mineralogical analysis by X-ray diffraction (XRD).The XRF results showed major and traces elements incorporated in the fish teeth. The concentration of zinc (Zn) expressed in mg kg-1 in the enamel - outside part of the malleolus dental surface (teeth crown) varied from 77 up to 1.975 in both fish species. In the root of the same teeth samples of Zn concentration was lower and amounted from 77 - 153 mg kg-1. Contrary, maximal amount of strontium (Sr) was registered in the teeth root from 801 – 1.310 mg kg-1, and in the enamel 476 – 1.104 mg kg-1 respectively. Multivariate statistical analysis based on the Statistica 6.0. PCA has been used to determine differences among elemental composition of the major and trace elements in teeth enamel (crown) and teeth roots, and in examining correlation among incorporated elements and environmental characteristics of the sampling localities.The XRD patterns of both fish jawbones and malleolus teeth showed characteristic hydroxyapatite lines (HAP). The HAP lines of the fish jawbones are broadened and shifted on the higher angles, indicating that mandible and maxilla biominerals are not fully formed and that mineralization of the fish jawbones is a dynamic process that last permanently during organism growth.Selected elements contents Ni, Co, Fe, Cu, and Cr (expressed in mg kg-1) of bulk fishbone samples was determined by ICP-AES analysis. Investigated metals showed higher values in the teeth than in the fish jawbones. The results revealed the distribution of the heavy metals in teeth to be Fe > Cr > Cu > Ni > Co, and in the jaws Fe > Cr > Cu > Ni > Co.The purpose of this study was to investigate the possibility of using XRF for the routine determination of heavy metals in the fish biominerals, in biomonitoring studies and ecological evaluation of the environment. The over-all data obtained indicated that XRF and ICP-AES showed good agreement for the determination of the heavy metals in test samples and that XRF could be used as cost effective method of accurately and precisely determining heavy metals content of the biomineral, while drastically reducing analysis time for initial sample preparation.
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MITANI, YOKO, NOBUAKI ARAI, WATARU SAKAMOTO y KOJI YOSHIDA. "PIXE ANALYSIS OF TRACE ELEMENTS IN CETACEAN TEETH". International Journal of PIXE 07, n.º 03n04 (enero de 1997): 135–39. http://dx.doi.org/10.1142/s0129083597000163.
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PIXE was adopted for analysis of trace elements in teeth of two species of cetaceans, sperm whale (Physeter macrocephalus) and pantropical spotted dolphin (Stenella attenuata). The analyses were performed along with the growth layer of the teeth, which is formed annually, suitable for age determination. Mn , Fe , Cu , Zn and Sr were detected in the teeth of sperm whale and pantropical spotted dolphin. Among these trace elements, gradual increase was observed for Zn/Ca ratio in the sperm whale's teeth.
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Markovic, Dejan, Dusan Pavlica y Tamara Peric. "Microbiological assessment of the chemo-mechanical caries removal". Serbian Dental Journal 50, n.º 4 (2003): 192–96. http://dx.doi.org/10.2298/sgs0304192m.
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The aim of the study was to assess the efficacy of the chemo-mechani- cal method for caries removal based on microbiological analyses of dentine samples. Sixty freshly extracted teeth with coronaly caries were analysed. In the experimental group (30 teeth) chemo-mechanical caries removal was performed, and in the control group (30 teeth) rotary instruments were used. Before the caries treatment and at the completion of cavity preparation dentine samples were taken by sterile round ISO 012 bur for microbiological analyses. Results of the study showed significant differences between initial and final dentine samples, while differences between the experimental and control group were not significant. The microbiological analyses in the present study imply that the chemo-mechanical method for caries removal is as efficient as the conventional technique.
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Sulyanto, R. M., M. Kang, S. Srirangapatanam, M. Berger, F. Candamo, Y. Wang, J. R. Dickson, M. W. Ng y S. P. Ho. "Biomineralization of Dental Tissues Treated with Silver Diamine Fluoride". Journal of Dental Research 100, n.º 10 (29 de julio de 2021): 1099–108. http://dx.doi.org/10.1177/00220345211026838.
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Silver diamine fluoride (SDF) is a dental biomaterial used to arrest dental caries. To better understand SDF’s mechanism of action, we examined the localization of silver within the tissues of SDF-treated teeth. Carious primary teeth fixed within 2 min of SDF application (SDF-minutes, n = 3), at 3 wk after SDF application in vivo (SDF-weeks, n = 4), and at 2 y after multiple SDF applications in vivo (SDF-multiple, n = 1) were investigated in this study. Carious primary teeth without SDF application (no-SDF, n = 3) served as controls. Mineral density and structural analyses were performed via micro–X-ray computed tomography and scanning electron microscopy. Elemental analyses were performed through X-ray fluorescence microprobe and energy-dispersive X-ray spectroscopic techniques. SDF-treated teeth revealed higher X-ray–attenuated surface and subsurface regions within carious lesions, and similar regions were not present in no-SDF teeth. Regions of higher mineral density correlated with regions of silver abundance in SDF-treated teeth. The SDF penetration depth was approximated to 0.5 ± 0.02 mm and 0.6 ± 0.05 mm (mean ± SD) for SDF-minutes and SDF-weeks specimens, respectively. A higher percentage of dentin tubular occlusion by silver or calcium phosphate particles was observed in primary teeth treated with SDF-weeks as compared with SDF-minutes. Elemental analysis also revealed zinc abundance in carious lesions and around the pulp chamber. SDF-weeks teeth had significantly increased tertiary dentin than SDF-minutes and no-SDF teeth. These results suggest that SDF treatment on primary teeth affected by caries promotes pathologic biomineralization by altering their physicochemical properties, occluding dentin tubules, and increasing tertiary dentin volume. These seemingly serendipitous effects collectively contribute to the cariostatic activity of SDF.
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Chen, Xiao Xia, Shu Zhong Lin y Jing Zhong Xing. "Modeling of Flexspline and Contact Analyses of Harmonic Drive". Key Engineering Materials 419-420 (octubre de 2009): 597–600. http://dx.doi.org/10.4028/www.scientific.net/kem.419-420.597.
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Harmonic drive has widespread applications for its compact size and high reduction ratios. It is often favored for electro-mechanical systems with space and weight limitation. In order to minimize the volume and improve its transmission capacity, more and more aborative design technologies are adopted. For structural analyses in assembly state and in transmission stage, Finite Element Analysis (FEA) can be widely applied to get proper parameters and performance. Flexspline usually endures large deformation under assembly force from wave generator. In transmission state, driving force leads to multiple tooth mesh contact between flexspline and circular spline teeth. In this paper, shell element is applied to build flexspline cone, and tapered beam element is used to model the teeth on the flexspline. Contact relation between flexspline and wave generator is simulated by contact element. Forced displacement of flexspline is imposed by contact analysis. Transmission forces are acted at the teeth tips on the flexspline in mesh state, whose values are determined according to experimental distribution. Simulations of assembly state and transmission state are computed in ANSYS. Deformation and stress distribution in assembly state are compared with that in transmission state. Some suggestions for long life and high performance design are present.
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Reichel, Miriam. "The variation of angles between anterior and posterior carinae of tyrannosaurid teeth". Canadian Journal of Earth Sciences 49, n.º 3 (marzo de 2012): 477–91. http://dx.doi.org/10.1139/e11-068.
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Tyrannosaurid tooth measurements have been shown to be a powerful tool for systematic analyses, as well as for studies on function and evolution of theropod dentition. In this analysis, a variable not previously addressed in depth is added to the tyrannosaurid data set. The angle between the anterior and posterior carinae can be difficult to measure consistently and a method is hereby proposed through the use of a digitizer. Five tyrannosaurid genera were analyzed: Tyrannosaurus , Tarbosaurus , Albertosaurus , Daspletosaurus , and Gorgosaurus . Only in situ data were used, and therefore some of the taxa had a limited amount of information available for this analysis. The measurements were analyzed through multivariate analyses using Paleontological Statistics (PAST), version 2.06. The analyses included principal component analyses (PCAs), discriminant analyses (DAs), and canonical variates analyses (CVAs). The results of these analyses revealed that the angle between carinae contributes significantly to the variation in the tyrannosaurid tooth data set. Additionally, this variable showed a strong correlation to tooth function (and, consequently, to tooth families), rather than tooth size. The variation observed between taxa at this stage seems insufficient for systematic purposes, however additional in situ data would help improve the effectiveness of this tool.
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Gaboutchian, A. V., V. A. Knyaz, M. M. Novikov, S. V. Vasilyev, N. A. Leybova, D. V. Korost, S. A. Cherebylo y A. A. Kudaev. "AUTOMATED DIGITAL ODONTOMETRY: MEASUREMENT DATA ANALYSES IN CASES OF COMPLICATED DENTAL MORPHOLOGY". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B2-2020 (12 de agosto de 2020): 851–56. http://dx.doi.org/10.5194/isprs-archives-xliii-b2-2020-851-2020.
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Abstract. 3D imaging techniques, which started to be exact in regard to the current study with photogrammetry, have brought to development of measurement method – automated digital odontometry (aDo) – with wider opportunities in terms of understanding morphological characteristics of human (or, non-human) teeth and dentition. Revealing them through odontometric parameters, not as visual descriptions, as it has been accepted for decades and is widespread till today, digital measurement methods provide for various previously unattainable detailed objective studies including descriptions or comparisons. These types of studies, carried out for dental and anthropological applications, are of high demand in palaeoanthropology, especially in cases of rare combination of finding uniqueness and preservation degree with considerations of unusual morphology. Thus odontological samples from the Upper Palaeolithic Sunghir’ (individual C2) are of particular interest in the current study which is aimed to detect distinctive parameters related to morphological features and to compare the degree of feature expression on antimere teeth and teeth with lower degree of that feature expression.
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Strajnic, Ljiljana. "Positioning of anterior teeth in removable dentures". Medical review 55, n.º 11-12 (2002): 490–94. http://dx.doi.org/10.2298/mpns0212490s.
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Introduction The aim of this paper was to present methods of placement of artificial anterior teeth in edentulous individuals. The following review takes account of the majority of papers published during the last 100 years. The review has been divided into sections regarding the method used to determine the position of artificial anterior teeth. Geometric aspect Gysi (1895-1920) produced the first scientific theory about the position of artificial anterior teeth. Physiognomic theory The aim of this theory is to find the most natural position for artificial anterior teeth for each individual. Camper's "face angle" as a physiognomic criterion, has been introduced in papers of Wehrli (1961), Marxhors (1966), Tanzer (1968), Lombardi (1973). Esthetic aspect Important names in the field of dental esthetics are: Sch?n and Singer (1961), Arnheim (1965), Krajicek (1969), Tanzer (1968), Lombardi (1973), Goldstein (1976). They have introduced principles of visual aspects for selection of contours, dimension and position of artificial anterior teeth. Constitution aspect Flagg (1880), Williams (1913) and Hrauf (1957, 1958), have considered body constitution and individual characteristics regarding position of artificial anterior teeth. Physiological theory In 1971, Marxhors pointed to the fact that the position of artificial teeth corresponds with the function of the surrounding soft tissue and from the aspect of physiognomy as well. Phonetic aspect According to Silverman (1962) artificial anterior teeth are nearest when we pronounce the sound "S". Cephalometrical research Rayson (1970), Watson (1989), Strajnic Lj. (1999), Bassi F. (2001) have presented cephalometric radiographic analyses of natural anterior teeth compared with cephalometric radiographic analyses of artificial anterior teeth. A review of dental literature shows several factors suggesting modalities which should determine the position of artificial anterior teeth. Numerous methods have been designed for evaluation of the position of artificial anterior teeth. However, there is no universally reliable method regarding determination of the position of artificial anterior teeth.
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Huang, Yan, Xiaoying Tang, Zafer C. Cehreli, Xiaoyun Dai, Jiangjingjun Xu y Hongshui Zhu. "Autologous transplantation of deciduous tooth pulp into necrotic young permanent teeth for pulp regeneration in a dog model". Journal of International Medical Research 47, n.º 10 (31 de julio de 2019): 5094–105. http://dx.doi.org/10.1177/0300060519862094.
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Objectives To investigate the potential for pulpal regeneration via autologous transplantation of deciduous tooth pulp into immature necrotic permanent teeth using an experimental dog model. Methods Experimental apical periodontitis was induced in 60 teeth of six Beagle dogs. Following canal disinfection and pulpotomy, autologous deciduous pulp tissue was transplanted into the root canals (n = 30); as controls, contralateral teeth were treated in accordance with the recommendations of the American Association of Endodontists. Radiographic examinations were performed immediately before transplant, as well as 3 and 6 months after transplant. At the 6-month examination, root samples were collected and histological and immunohistochemical analyses were used to examine tissue regeneration. Results Radiographic analysis showed no significant differences in most histopathological parameters examined; however, apical diameter reduction was greater in the experimental group. Histological and immunohistochemical analyses showed that the canal walls of the experimental group had newly formed dentin-like tissue with dentinal tubules, while the control group had cementum-like deposits along the canal wall and apical foramina. Conclusions Autologous transplantation may be useful for regeneration of dental pulp in necrotic young permanent teeth.
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Duncan, William N. "Supernumerary Teeth from Two Mesoamerican Archaeological Contexts". Dental Anthropology Journal 22, n.º 2 (2 de septiembre de 2018): 39–46. http://dx.doi.org/10.26575/daj.v22i2.90.
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Supernumerary teeth are uncommon but have been well documented clinically. The majority of cases are isolated anterior teeth; examples of multiple or posterior supernumerary teeth are less common. This paper describes two examples of supernumerary teeth from archaeological contexts in Mesoamerica. The first case is of three individuals with supernumerary posterior teeth found in skull rows and pairs in a Postclassic Maya temple at the site of Ixlú in northern Guatemala. Two of these individuals exhibited bilateral supernumerary mandibular teeth. The second context is a Zapotec burial from the Jalieza site in Oaxaca, Mexico. This individual exhibited a single supernumerary tooth. The paper reviews supernumerary teeth with regard to frequency, ontogeny, and mode of inheritance and discusses the cases’ relevance for biological distance analyses.
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Stegemiller, M. E. y D. R. Houser. "A Three-Dimensional Analysis of the Base Flexibility of Gear Teeth". Journal of Mechanical Design 115, n.º 1 (1 de marzo de 1993): 186–92. http://dx.doi.org/10.1115/1.2919317.
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This paper presents the development of a simple model which computes the deflection of the base of wide face width gear teeth. The model was developed using the results of numerous finite element analyses of gear teeth and a nondimensional analysis of the results. Tooth end effects are considered through the application of the moment image method. The method is very simple and allows easy implementation in three-dimensional gear tooth deflection analysis schemes.
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Christensen, Kiana y Keegan M. Melstrom. "Quantitative analyses of squamate dentition demonstrate novel morphological patterns". PLOS ONE 16, n.º 9 (10 de septiembre de 2021): e0257427. http://dx.doi.org/10.1371/journal.pone.0257427.
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Squamates are ideal subjects for investigating relationships between diet and dental patterns because they exhibit wide dietary diversity, marked variation in dental shape, and are taxonomically abundant. Despite this, well-established links between diet and dental morphology are primarily qualitative in nature, with specific patterns of squamate dental complexity remaining largely unknown. Here, we use quantitative methods and a broad taxonomic dataset to quantify key patterns in squamate dental morphology, including re-examining the relationship between dentition and diet, testing for differences in complexity between dentigerous elements, and exploring the effect of ontogenetic dietary shifts in dental complexity in two iguanid genera. Our findings support previous research by demonstrating that species consuming more plant material possess more complex teeth. We did not find significant complexity differences between the left and right dentigerous elements nor the upper and lower jaws, with the exception of Amblyrhynchus cristatus, the marine iguana, which possesses significantly more complex dentary teeth than premaxillary and maxillary teeth. We find discordant patterns when testing for dental complexity changes through ontogeny. Amblyrhynchus, which is primarily herbivorous throughout its lifetime, increases dental complexity through ontogeny, whereas Ctenosaura, which is generally insectivorous as juveniles and herbivorous as adults, decreases dental complexity. Although preliminary, this research documents and quantifies novel patterns of squamate dental complexity and exhibits the possibilities for further research on the diversity of squamate dental morphology.
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Sabiniak, Henryk G. y Robert Cichowicz. "The Numerical Methods in Geometric Construction Mapping". Key Engineering Materials 490 (septiembre de 2011): 312–22. http://dx.doi.org/10.4028/www.scientific.net/kem.490.312.
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A dynamic development of numerical methods enables even so complicated geometrical modelling as modelling of hypoidal teeth, and in particular of worm teeth. Building on the basis of the finite element method of this type of geometrical mathematical model enables observing and analysing physical phenomena taking place in the teeth, e.g. changes of pressure distribution along the contact lines depending on the phase of meshing for particular cooperating pairs of teeth. Due to limited technical possibilities and mathematical apparatus such analyses were carried out only on the basis of the theory of plates with constant thickness. An unquestionable advantage of such numerical modelling is a short time needed to obtain final results, which enables profound analysis of the transmitted load. The knowledge of course of pressure distribution along the contact lines of particular pairs of intermeshing teeth in worm gears already in the design phase enables taking into consideration in adequate correction or even modification of the working surface of teeth, with the aim to equalise the distribution of pressure.
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Kahn-Jetter and, Zella L. y Suzanne Wright. "Finite Element Analysis of an Involute Spline". Journal of Mechanical Design 122, n.º 2 (1 de enero de 2000): 239–44. http://dx.doi.org/10.1115/1.533573.
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Two finite element analyses of an involute spline are performed; one is axisymmetrically loaded and the other is nonaxisymmetrically loaded. An entire cross section of both an internal and external pair is analyzed for both models. It is shown that on the axisymmetrically loaded spline the highest stress experienced is the maximum compressive contact stress although the tensile stress in the shaft is also quite high. It is also shown that stress concentrations exist at the root and top of the tooth for both models. Furthermore, on the nonaxisymmetrically loaded spline at low torque, only a few teeth make initial contact, however, as torque is increased, more teeth come in contact. All the stresses remain relatively constant under increasing torque as more teeth are engaged. Once all teeth are in contact stress increases with higher torques. However, the maximum tensile stress (arising from stress concentrations) remains fairly constant, even at high torques, because the stress concentrations that occur at tooth roots appear to be relatively independent of the number of teeth in contact. [S1050-0472(00)00102-1]
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Torices, Angelica, Miriam Reichel y Philip J. Currie. "Multivariate analysis of isolated tyrannosaurid teeth from the Danek Bonebed, Horseshoe Canyon Formation, Alberta, Canada". Canadian Journal of Earth Sciences 51, n.º 11 (noviembre de 2014): 1045–51. http://dx.doi.org/10.1139/cjes-2014-0072.
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A significant number of fossil remains of the hadrosaurid Edmontosaurus have been recovered from the Danek Bonebed (Horseshoe Canyon Formation, Upper Cretaceous, Alberta). Bones from theropod dinosaurs are scarce in this hadrosaur-dominated bonebed, but more than 60 tyrannosaurid theropod teeth have been found. The isolated tyrannosaurid teeth include juvenile and adult specimens, although the precise ontogenetic stage has not been determined. The use of multivariate analyses helps determine the variance of the sample and verifies the initial taxonomic affinities given to these teeth, showing their high potential as a useful tool to better discriminate tyrannosaurid teeth. It also provides an insight into the tyrannosaurid intraspecific variability in the Horseshoe Canyon Formation.
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Kawashita, Y., M. Kitamura, Y. Ando y T. Saito. "Relationship between Metabolic Syndrome and Number of Teeth in Japan". JDR Clinical & Translational Research 2, n.º 1 (27 de septiembre de 2016): 87–92. http://dx.doi.org/10.1177/2380084416667931.
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The 2004 Japanese National Health and Nutrition Survey collected data on several measures, including self-reported dental health. In addition, this was the first nationwide survey to focus on metabolic syndrome (MetS) in Japan. Therefore, the authors used this nationwide data set to assess the relationship between number of teeth present and MetS. Anonymized data were available with permission from the Ministry of Health, Labour and Welfare of Japan. Data from 3,195 men and women aged 35 to 99 y were examined, and logistic regression analyses were used to evaluate the association between number of teeth and MetS. Moreover, the authors performed an analysis of covariance to compare the mean number of teeth between those with and those without MetS, after adjusting for confounders. In comparison with those having ≥28 teeth, those with fewer remaining teeth demonstrated significantly higher odds of having MetS. Specifically, those having 1 to 9 teeth had higher odds of having MetS than those with more teeth and were more than twice as likely to be affected than those with ≥28 teeth. Furthermore, individuals with MetS in the age groups of 45 to 54, 55 to 64, and 65 to 74 y had significantly fewer teeth than those without MetS in the same age groups. These results suggest that the number of teeth present is associated with the prevalence of MetS in the Japanese population. Knowledge Transfer Statement: The results of this study can be used by clinicians when they examine patients with periodontal disease or extensive tooth loss to refer for a general medical examination.
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Townsend, G. C., T. Brown, L. C. Richards, J. R. Rogers, S. K. Pinkerton, G. R. Travan y V. B. Burgess. "Metric Analyses of the Teeth and Faces of South Australian Twins". Acta geneticae medicae et gemellologiae: twin research 35, n.º 3-4 (octubre de 1986): 179–92. http://dx.doi.org/10.1017/s0001566000005699.
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AbstractProcedures are described for the acquisition and analysis of data in a study of the dental and facial characteristics of South Australian twins. Comparisons of the mesiodistal diameters of maxillary incisors in MZ and DZ twins revealed heterogeneity of total variances and evidence of inequality of mean values for some dimensions between MZ and DZ twins. Previous estimates of heritabilities for tooth size, relying on classical assumptions in twin research, may be exaggerated. A preliminary analysis of facial shape was undertaken using a procedure for shape matching based on a least squares fit of homologous coordinates. There was evidence of mirror-imaging in some MZ twin pairs and differences in facial asymmetry between male and female DZ twins. Future extensions of the study using methods for three-dimensional shape analysis are described.
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Cattaneo, P. M., M. Dalstra y B. Melsen. "FE-analyses of orthodontic movements of single and multi-rooted teeth". Journal of Biomechanics 39 (enero de 2006): S204. http://dx.doi.org/10.1016/s0021-9290(06)83741-3.
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Damyanov, Nikola D., Dick J. Witter, Ewald M. Bronkhorst y Nico H. J. Creugers. "Dental Status and Associated Factors in a Dentate Adult Population in Bulgaria: A Cross-Sectional Survey". International Journal of Dentistry 2012 (2012): 1–11. http://dx.doi.org/10.1155/2012/578401.
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This study aimed to determine variations in the dental status of a dentate adult population in terms of “decayed,” “missing,” and “filled” teeth in relation to several sociodemographic and behavioral factors. Quota sampling was used to draw 2531 subjects aged 20 years and over. Data were collected by means of a questionnaire and an oral examination. Multiple logistic regression analyses were performed to observe associations between “decayed,” “missing,” and “filled” teeth and the factors of interest. The mean numbers of “decayed,” “missing,” and “filled” teeth were 2.2, 6.7, and 4.9, respectively. Molar teeth were significantly more often “missing” than premolar and anterior teeth. Age, gender, education, and tooth brushing revealed most noticeable associations. Increasing age was associated with a lower chance of having “decayed” and “filled” teeth, but with a higher chance of having “missing” teeth. Females were more likely to have “missing” and “filled” teeth. Higher education was associated with a lower chance of having “missing” teeth. More frequent tooth brushing was associated with a lower chance of having “decayed” and “missing” teeth, but with a higher chance of having “filled” teeth. These risk indicators should be considered in prevention program planning if reduction of tooth loss is to be achieved.
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Solaymani, Shahram, Ştefan Ţălu, Mahmood Ghoranneviss, Seyed Mohammad Elahi, Azizollah Shafiekhani, Mohammadreza Hantehzadeh y Negin Beryani Nezafat. "Multifractal analysis of human canine teeth at nano scale: atomic force microscopy studies". International Nano Letters 10, n.º 1 (31 de diciembre de 2019): 15–22. http://dx.doi.org/10.1007/s40089-019-00293-7.
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AbstractThe aim of the present study is to explore the 3-D micromorphology of human canine teeth materials using multifractal analysis through atomic force microscopy (AFM). The 3-D surfaces of ten extracted canine teeth of a group of 40 year old men were studied (enamel, inter enamel, inter dentin, and cementum) by AFM images in tapping mode and on square areas of 1 μm × 1 μm (512 × 512 points). The AFM images and surface multifractal analysis confirm the dependency of surface micromorphology to their structure–property of these materials across the length scales of the teeth structural architecture. Surface statistical parameters and hence, multifractal approach have been considered as reliable and sensitive tools for quantifying the 3-D surface microtexture changes of human canine teeth materials. The surface of inter dentin had the most irregular topography (the width spectrum Δα = 2.8361, value bigger than all the other Δα sample values), while the most regular topography (the width spectrum Δα = 2.6804, value lower than all the other sample values) was found in cementum. It has been concluded that multifractal analyses can be used as mathematical tools to explore the 3-D micromorphology of human canine teeth materials.
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Broomell, Christopher C., Rashda K. Khan, Dana N. Moses, Ali Miserez, Michael G. Pontin, Galen D. Stucky, Frank W. Zok y J. Herbert Waite. "Mineral minimization in nature's alternative teeth". Journal of The Royal Society Interface 4, n.º 12 (5 de septiembre de 2006): 19–31. http://dx.doi.org/10.1098/rsif.2006.0153.
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Contrary to conventional wisdom, mineralization is not the only strategy evolved for the formation of hard, stiff materials. Indeed, the sclerotized mouthparts of marine invertebrates exhibit Young's modulus and hardness approaching 10 and 1 GPa, respectively, with little to no help from mineralization. Based on biochemical analyses, three of these mouthparts, the jaws of glycerid and nereid polychaetes and a squid beak, reveal a largely organic composition dominated by glycine- and histidine-rich proteins. Despite the well-known metal ion binding by the imidazole side-chain of histidine and the suggestion that this interaction provides mechanical support in nereid jaws, there is at present no universal molecular explanation for the relationship of histidine to mechanical properties in these sclerotized structures.
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Chakraborty, Santu, Sandip Bag, Subrata Pal y Alok K. Mukherjee. "Structural and microstructural characterization of bioapatites and synthetic hydroxyapatite using X-ray powder diffraction and Fourier transform infrared techniques". Journal of Applied Crystallography 39, n.º 3 (10 de mayo de 2006): 385–90. http://dx.doi.org/10.1107/s0021889806010351.
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Bioapatite, the main constituent of mineralized tissue in mammalian bones and teeth, is similar in structure and composition to calcium hydroxyapatite (HAP), Ca10(PO4)6(OH)2. The crystallographic analyses of four bioapatites of human-, goat- and rabbit-bone and human-teeth origin, and one synthetic HAP preparedviamicrowave irradiation, have been carried out using X-ray powder diffraction techniques. Fourier transform infrared spectra and Rietveld analyses indicate partial replacement of PO43−ions by CO32−ions in all bioapatites.
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Yin, Minghu, Yahui Cui, Xiangjun Meng, Jinzhong Zuo y Yuhao Qi. "Dynamic analysis of double-helical gear system considering effect of oil film among meshing teeth". Advances in Mechanical Engineering 12, n.º 5 (mayo de 2020): 168781402092011. http://dx.doi.org/10.1177/1687814020920117.
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The oil film among meshing teeth is just like a spring-damping element, and it can dominate the friction and meshing characteristics of the gear pair and influence its dynamic performances further. Thus, this article focuses on a double-helical gear system and makes efforts to consider the effect of the oil film among meshing teeth more deeply, which can enhance the precision of dynamic analysis for the gear system. First, based on the elasto-hydrodynamic lubrication theory and “microtomy” method, the models of friction and meshing characteristics are developed including the friction state and spring-damping effect of the oil film among meshing teeth; then, the dynamic models of the double-helical gear system with the effect of the oil film among meshing teeth are established, and finally, the experiments are carried out to verify the value of the models developed in this article. According to the theoretical and experimental analyses, it can be seen that the dynamic model considering the effect of the oil film among the meshing teeth is more precise and practical, and the effect of the oil film should be considered in the dynamic analysis of the gear system, especially at the condition with heavy load or high speed.
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Sposito, Otavio da Silva, Tatiana Pereira-Cenci, Noéli Boscato y Rogério de Castilho Jacinto. "Analysis of endodontic success using a Periapical Index in teeth with different types of intraradicular posts". Research, Society and Development 10, n.º 8 (9 de julio de 2021): e15110816932. http://dx.doi.org/10.33448/rsd-v10i8.16932.
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This randomized clinical trial evaluated the influence of the type of intraradicular posts (glass fiber post or cast metal post) in the success of endodontic treatment in teeth that received single metal-ceramic restoration. The sample consisted of adult patients, who presented for the first time seeking routine dental care at the dental school over a period of 5 years. Seventy-six out of ninety-six teeth that received endodontic treatment and intraradicular post were analyzed, randomly distributed in two groups – glass fiber post (n=38), and cast metal post (n=38). The quality of the endodontic treatment was radiographically evaluated, and the apical status was assessed using the periapical index (PAI). Statistical Analyses were performed to a significance level of 5%. Descriptive analyses were used to characterize the teeth and survival curves were created using the Kaplan–Meier method. The success rate of endodontic treatment was 90.8% (n=69) including glass fiber post and cast post. When appropriate endodontic treatment was performed is possible to conclude that the success of endodontic treated teeth that received posts was not related to the post type.
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Md Ghazaly, Mariam, Tan Aik Choon, Che Amran Aliza y Sato Kaiji. "Force Characterization of a Rotary Motion Electrostatic Actuator Based on Finite Element Method (FEM) Analysis". Applied Mechanics and Materials 761 (mayo de 2015): 233–37. http://dx.doi.org/10.4028/www.scientific.net/amm.761.233.
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Two types of rotary motion electrostatic actuators were designed and analyzed using Finite Element Method (FEM) analysis. This paper discussed the comparisons and detailed thrust force analysis of the two actuators. Both designs have similar specifications; i.e the number of rotor’s teeth to stator’s teeth ratio, radius and thickness of rotor, and gap between stator and rotor. Two structures were designed & evaluated; (a) Side-Driven Electrostatic Actuator and (b) Bottom-Driven Electrostatic Actuator. The paper focuses on comparing & analyzing the generated electrostatic thrust force for both designs when the electrostatic actuator’s parameters are varied. Ansys Maxwell 3D software is used to design and analyze the generated thrust force of the two rotary motion electrostatic actuators. The FEM analyses have been carried out by (i) varying the actuator size; (ii), varying the actuator thickness and (iii) varying the actuator teeth ratio. The FEM analysis shows that the Bottom-Drive Electrostatic Actuator exhibit greater thrust force, 4931.80μN compared to the Side-Drive Electrostatic Actuator, 240.96μN; when the actuator’s radius is 700μm, thickness is 50μm, gap between the stator and rotor is 2μm and the teeth ratio is 16:12.
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Ivanovic, L., G. Devedzic, N. Miric y S. Cukovic. "Analysis of Forces and Moments in Gerotor Pumps". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 224, n.º 10 (12 de febrero de 2010): 2257–69. http://dx.doi.org/10.1243/09544062jmes2041.
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This article presents the analyses of the forces and moments between gears in contact with a gerotor pump. The objective was to reach a more accurate solution for the problems related to load distribution in trochoidal pumps with fixed shaft axes. Calculation of contact forces is complex due to the simultaneous contact of several trochoidal teeth during the load transfer and additional compressive fluid forces that act on the teeth flanks. A simple physical model and a suitable analytical model are used for this analysis. Compressive fluid forces are simulated with single force applied in the middle of the line that separates the suction and upward pressure zone. During the teeth engagement there is also a change in fluid volumes between teeth. This creates pressure change that needs to be considered and calculated at an arbitrary moment of the engagement process. Finite element analysis (FEA) was used to determine the reaction forces that depend on instantaneous moments as well. Analysis shows that if a chamber pressure variation is taken into account, higher values of driving moment and support reaction forces will be generated. Designers can use the obtained results to develop a higher efficiency gerotor pumps.
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Romanos, Helena Freire, Leonardo Santos Antunes, Ludiana Barbosa Lopes, Ticiana de Medeiros Sabóia, Patricia Nivoloni Tannure, Andrea Lips, Livia Azeredo A. Antunes et al. "BMP2 Is Associated with Caries Experience in Primary Teeth". Caries Research 49, n.º 4 (2015): 425–33. http://dx.doi.org/10.1159/000371715.
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Bone morphogenetic proteins (BMPs) play an important role during the initial process of enamel development and therefore may play a role in caries susceptibility. The purpose of this study was to evaluate the association between the polymorphisms in the BMP2, BMP4 and BMP7 genes and their association with caries experience and primary enamel microhardness characteristics. DNA from buccal cells as well as clinical and demographic information from 1,731 subjects from three different data sets from Brazil were included. Polymorphisms in BMP2, BMP4 and BMP7 were analyzed by real-time polymerase chain reaction from genomic DNA. Association between caries experience, genotype, and allele distribution in both cohorts was evaluated using χ2 and logistic regression analyses. In the family-based set, the association between caries experience and alleles was tested using the transmission disequilibrium test. In the Rio de Janeiro cohort, microhardness data on 108 exfoliated primary teeth before and after demineralization and remineralization challenges was included. Associations between microhardness values and genotype and allele distribution were evaluated using χ2 and logistic regression analyses. Differences between caries experience and some risk factors were statistically significant. In the cohort from Nova Friburgo, BMP2 was associated with caries experience in primary dentition during logistic regression analysis (p = 0.023; OR = 2.58; 95% CI 1.13-5.86). There was no association between genotype and allele distribution for BMP polymorphisms and primary enamel microhardness alterations. Our result suggests that BMP2 may be involved in caries experience in primary dentition from a Nova Friburgo cohort.
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Brown, Emma L., Ronald A. Dixon y Jason W. Birkett. "The Discolouration of Human Teeth from Archaeological Contexts: Elemental Analysis of a Black Tooth from a Roman Cranium Recovered from the River Witham, Lincoln, UK". Journal of Anthropology 2014 (14 de septiembre de 2014): 1–7. http://dx.doi.org/10.1155/2014/859153.
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A human cranium was recovered from the River Witham, Lincoln, UK, at Stamp End Lock during a police operation in 2002. Although extensive trauma was noted, the skull was not of forensic interest since radiocarbon dating revealed that the individual had lived during the Roman occupation of Lincoln, almost 2,000 years ago. The skull had unusual black “metallic” staining on the occlusal surfaces of the teeth. As this kind of staining is relatively uncommon, it was investigated to determine the possible cause. An individual tooth was subjected to two elemental analyses: inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX). A small sample (n=21) of modern teeth was also analysed for comparison to determine “normal” ranges of certain elements. Analysis of the ancient tooth shows very high levels of manganese (275 µg/g) and iron (1540 µg/g) compared to modern teeth values (1.90 µg/g Mn and 40.81 µg/g Fe). These results were consistent with the black staining arising from iron and manganese infiltrating bone and dental tissue from the depositional environment, and not a consequence of diet, pathological process or cultural practices.
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Cui, Xuanyou, Naiyu Cui, Xuehan Li, Xin Du, ShuXin Zhang, Changchun Wu, Dong-Hyuck Kim, Ho-Kyung Lim y Eui-Seok Lee. "Effect of Root Canal Therapy on the Success Rate of Teeth with Complete Roots in Autogenous Tooth Transplantation". Scanning 2021 (14 de abril de 2021): 1–7. http://dx.doi.org/10.1155/2021/6675604.
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Background. Autogenous tooth transplantation is a reliable method for repairing missing teeth. Although it recently became a recognized and feasible treatment method in dentistry, the long-term efficacy of root canal therapy (RCT) has not been well confirmed. This study is aimed at determining whether RCT has a good effect on the success rate of teeth with complete roots in autogenous tooth transplantation. Materials and Methods. Data were collected from the Korea University Guro Hospital. Data of patients who underwent autogenous tooth transplantation within 9 years were collected. We selected 29 teeth with complete roots as the research subjects in our study. None of the patients had any systemic diseases. All cases in this study were obtained with patient permission. Results. According to the tooth vitality test, the autogenous teeth tested negative in dental pulp test and function. Nine of the 29 teeth with autogenous tooth transplantation were treated with RCT and survived throughout the observation period. However, 20 autogenous teeth were not treated with RCT, and eight of them did not survive. All statistical analyses were performed using IBM SPSS 20.0. The null hypothesis was rejected ( p < 0.05 ). Conclusion. For complete root teeth, the success rate after autogenous tooth transplantation after RCT is higher than that of teeth not treated with RCT.
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Bendrey, R., D. Vella, A. Zazzo, M. Balasse y S. Lepetz. "Exponentially decreasing tooth growth rate in horse teeth: implications for isotopic analyses". Archaeometry 57, n.º 6 (15 de diciembre de 2014): 1104–24. http://dx.doi.org/10.1111/arcm.12151.
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Santoro, Valeria, Piercarlo Lozito, Nunzio Mastrorocco, Antonio De Donno y Francesco Introna. "Personal Identification by Morphometric Analyses of Intra-Oral Radiographs of Unrestored Teeth". Journal of Forensic Sciences 54, n.º 5 (septiembre de 2009): 1081–84. http://dx.doi.org/10.1111/j.1556-4029.2009.01106.x.
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Gulson, Brian y David Wilson. "History of Lead Exposure in Children Revealed from Isotopic Analyses of Teeth". Archives of Environmental Health: An International Journal 49, n.º 4 (agosto de 1994): 279–83. http://dx.doi.org/10.1080/00039896.1994.9937480.
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R, Suma, KK Shashibhushan, ND Shashikiran y VV Subba Reddy. "Progression of Artificial Caries in Fluorotic and Nonfluorotic Enamel. An in vitro Study". Journal of Clinical Pediatric Dentistry 33, n.º 2 (1 de diciembre de 2008): 127–30. http://dx.doi.org/10.17796/jcpd.33.2.y5837p7227x62813.
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Background and objectives: Fluorosis is an important clinical and public health problem in several parts of the world. Although the relationship of fluoride level in drinking water to dental caries and dental fluorosis is known, relationship of fluorosis with the caries is not clear. This study was conducted to evaluate and compare the thickness of enamel and depth of lesion after inducing artificial caries in fluorotic and nonfluorotic teeth. Methods: Study group included 15 fluorosis affected and 15 normal teeth. Artificial caries was induced and teeth were sectioned to 150 microns and observed under polarized light microscope to measure the enamel thickness and depth of lesion in microns. Results: Statistical analyses of the measurements were made using student's unpaired t-test. Thickness of the enamel of nonfluorotic teeth was found to be significantly more when compared with the fluorotic teeth(p-value 0.0404) and depth of lesion was significantly more in fluorotic teeth when compared with the nonfluorotic teeth(p-value 0.0218). Conclusion:Although fluoride is acknowledged as an essential factor in the prevention of dental caries there has to be careful balance in the amount consumed to ensure that fluorosis does not occur.
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Kapcia, Jerzy, Kazimierz A. Orlowski y Roman Wasielewski. "Mechatronic System for Automatic Inspection of Circular Saw Teeth". Solid State Phenomena 164 (junio de 2010): 73–78. http://dx.doi.org/10.4028/www.scientific.net/ssp.164.73.
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The paper presents a mechatronic system for automatic inspection of circular saw teeth. The described system, based on numerical processing of recorded tooth images, has been implemented in the automatic vision controller system WKOPTar. The applied mechatronic system for the automatic spindle control positioning guarantees for the circular saw blade teeth a proper position enabling to grab and record tooth images even for non-uniform pitches in the examined circular saw blade. Some examples of measurements and geometry analyses of circular saw teeth were provided in order to illustrate the diagnostic usability of the apparatus. The system allows the user to determine up to 32 parameters for one tooth. However, the direct interpretation of physical parameter is sometimes partially limited by the software because the same parameter might have different meaning. Thus, in some cases a proper interpretation of the results may be feasible after recorded tooth screen analyses.
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Dewake, Nanae, Yasuaki Ishioka, Keiichi Uchida, Akira Taguchi, Yukihito Higashi, Akihiro Yoshida y Nobuo Yoshinari. "Association between Carotid Artery Calcification and Periodontal Disease Progression in Japanese Men and Women: A Cross-Sectional Study". Journal of Clinical Medicine 9, n.º 10 (20 de octubre de 2020): 3365. http://dx.doi.org/10.3390/jcm9103365.
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Objective: To evaluate the association between alveolar bone loss (ABL) detected on panoramic radiographs and carotid artery calcification (CAC) detected on computed tomography (CT). Methods: The study subjects included 295 patients (mean age ± SD: 64.6 ± 11.8 years) who visited the Matsumoto Dental University Hospital. The rate of ABL and the number of present teeth were measured on panoramic radiographs. Univariate analyses with t-tests and chi-squared tests were performed to evaluate the differences in age, gender, history of diseases, number of present teeth, and the ABL between subjects, with and without CAC. Moreover, multivariate logistic regression analysis, with forward selection and receiver operating characteristic curve (ROC) analysis, was performed. Results: The number of subjects without and with CAC was 174 and 121, respectively. Univariate analyses revealed that CAC was significantly associated with age, hypertension, osteoporosis, number of present teeth, and ABL. Multivariate logistic regression analysis adjusted for covariates revealed that the presence of CAC was significantly associated with ABL (OR = 1.233, 95% CI = 1.167–1.303). In the ROC analysis for predicting the presence of CAC, the the area under the ROC curve was the highest at 0.932 (95% CI = 0.904–0.960) for ABL, which was significant. Conclusions: Our results suggest that the measurement of ABL on panoramic radiographs may be an effective approach to identifying patients with an increased risk of CAC.
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Quaglio, Juliana Maria, Marcela Bernardes Sousa, Thiago Machado Ardenghi, Fausto Medeiros Mendes, José Carlos Pettorossi Imparato y Sérgio Luiz Pinheiro. "Association between clinical parameters and the presence of active caries lesions in first permanent molars". Brazilian Oral Research 20, n.º 4 (diciembre de 2006): 358–63. http://dx.doi.org/10.1590/s1806-83242006000400014.
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The aim of the present study was to evaluate the association between clinical parameters and the presence of active caries lesions on the occlusal surface of first permanent molars. Forty eight children (5.8-13.8 years-old) with at least one first permanent molar present were selected. The clinical parameters evaluated were gender, age, DMF-T and dmf-t, presence of active white spots in other teeth, general plaque index, tooth's dental arch (upper or lower), tooth's side (right or left), presence of visible plaque and eruption degree of the first permanent molars. The first permanent molars were evaluated through visual inspection by two examiners in order to assess the presence of active or inactive caries lesions on the occlusal surface. Univariate and multivariate analyses for determination of the association between clinical parameters and the presence of active caries lesions in these teeth were performed. The presence of active white spots in other teeth was associated with the presence of active caries lesions in the first permanent molars, in both univariate and multivariate analyses (Odds ratio = 8.8 and 1.9, respectively). The presence of abundant visible plaque on the occlusal surface of the first permanent molars (Odds ratio = 3.5 in the univariate analysis, and 3.9 in the multivariate one) also presented a significant association. In conclusion, the presence of active white spots in other teeth and the presence of considerable visible plaque were associated with the presence of active caries lesions on the occlusal surfaces of first permanent molars.
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Bladowski, M., A. Kotowicz-Gears, D. Choszcz, M. Pawelec y J. Wojtkiewicz. "Prosthetic reconstruction of broken canine teeth in dogs with use of cast metal posts". Polish Journal of Veterinary Sciences 16, n.º 2 (1 de junio de 2013): 399–402. http://dx.doi.org/10.2478/pjvs-2013-0056.
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Abstract Prosthodontic treatment, especially restorations of fractured teeth in small animals, has been the subject of many veterinary dental analyses in relation to techniques of endodontic treatment, preparation and cementation, as well as the general principles of prosthodontic treatment. The purpose of this paper is to present a previously undescribed method of all-in-one crown and root prosthetic restoration of fractured teeth in large dogs, together with a thorough analysis of the drawbacks, which may help veterinary dentists to use an evidence-based approach when deciding on the type of treatment for their patients with tooth fractures.
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Tapanila, Leif y Jesse Pruitt. "Unraveling species concepts for the Helicoprion tooth whorl". Journal of Paleontology 87, n.º 6 (noviembre de 2013): 965–83. http://dx.doi.org/10.1666/12-156.
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The genus Helicoprion (Chondricthyes, Euchondrocephali) is preserved primarily by a continuous spiral root that forms the base for more than 130 teeth. Helicoprion is found globally in Lower Permian marine rocks and at least 100 specimens exist in public collections worldwide. Ten species of the genus are reviewed in the context of new morphometric analyses conducted on dozens of specimens. Helicoprion whorls share a common inner spiral geometry that results in exponential growth of tooth and root dimensions. Novel growth equations permit calculation of whorl diameter, volution number and tooth count from incomplete specimens. The results of meristic and geometric analyses identify taxobases that distinguish three emended species concepts. Differentiation of form is evident among specimens only after the second volution or roughly the 85th tooth. Helicoprion davisii has widely spaced, stout teeth with tall cutting surfaces and is distinguished from H. bessonowi, which has narrow, closely spaced teeth with short cutting surfaces. Helicoprion ergassaminon is an intermediate form, having narrow, closely spaced teeth with tall cutting surfaces. Several large specimens in the study are too dissimilar to place in the new emended species concepts.
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Abdulhade Ganem, Atheer, N. C. Sandeepa, Afnan Hassan Alkhayri y Yosra Mohammed Mousa. "Impact of Tooth Loss and Other Risk Factors on Cognitive Impairment in Saudi Female Population". Neuroscience Journal 2019 (24 de julio de 2019): 1–9. http://dx.doi.org/10.1155/2019/6086515.
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Introduction. It is known that cognitive impairment is linked to aging and neurobiological, psychological, and social factors. Recently, however, mastication and the number of teeth has also attracted attention, with a previous case control study reporting a correlation between the loss of teeth and Alzheimer’s disease. Objective. To investigate possible relationships between cognitive function and various demographic variables, stress, medical history, and number of natural teeth in a specified female population. Materials & Methods. A sample of the Saudi female population, 40–65 years of age, who visited the King Khalid University College of Dentistry (Abha, Saudi Arabia), was studied. Education, occupation, perceived stress, and medical history, along with the number of remaining teeth, were assessed. The Mini-Mental State Examination (MMSE) was used to assess cognitive performance and the results were statistically analyzed. Results. Subjects were divided into those with mild, moderate, and severe impairment based on MMSE score; the association between age, education, occupation, medical history, and cognitive function demonstrated statistically significant results. Fifty percent of subjects with 0–16 teeth exhibited severe cognitive impairment. Of the cognitive abilities, attention, recall, and language skills were linked to the number of remaining teeth. When subjects were categorized into only high and low cognitive impairment based on MMSE score, regression analysis did not reveal a significant correlation between any of the studied variables and cognitive impairment. Conclusion. Results of the present study add to the recent data and head towards the theory of likely connection between the number of teeth and hippocampus-dependent cognitive functioning. Results of regression analysis revealed an absence of conclusive relation in the latter part of study. Longitudinal analyses including comprehensive clinical dental data with brain-imaging will shed further light on probable causal relationship(s).
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Duailibi, S. E., M. T. Duailibi, W. Zhang, R. Asrican, J. P. Vacanti y P. C. Yelick. "Bioengineered Dental Tissues Grown in the Rat Jaw". Journal of Dental Research 87, n.º 8 (agosto de 2008): 745–50. http://dx.doi.org/10.1177/154405910808700811.
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Our long-term objective is to develop methods to form, in the jaw, bioengineered replacement teeth that exhibit physical properties and functions similar to those of natural teeth. Our results show that cultured rat tooth bud cells, seeded onto biodegradable scaffolds, implanted into the jaws of adult rat hosts and grown for 12 weeks, formed small, organized, bioengineered tooth crowns, containing dentin, enamel, pulp, and periodontal ligament tissues, similar to identical cell-seeded scaffolds implanted and grown in the omentum. Radiographic, histological, and immunohistochemical analyses showed that bioengineered teeth consisted of organized dentin, enamel, and pulp tissues. This study advances practical applications for dental tissue engineering by demonstrating that bioengineered tooth tissues can be regenerated at the site of previously lost teeth, and supports the use of tissue engineering strategies in humans, to regenerate previously lost and/or missing teeth. The results presented in this report support the feasibility of bioengineered replacement tooth formation in the jaw.
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Santos, Luciane Geanini Pena dos, Luiz Alexandre Chisini, Camila Guerner Springmann, Beatriz Dulcineia Mendes de Souza, Fernanda Geraldo Pappen, Flávio Fernando Demarco, Mara Cristina Santos Felippe y Wilson Tadeu Felippe. "Alternative to Avoid Tooth Discoloration after Regenerative Endodontic Procedure: A Systematic Review". Brazilian Dental Journal 29, n.º 5 (septiembre de 2018): 409–18. http://dx.doi.org/10.1590/0103-6440201802132.
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Abstract This systematic review aimed to evaluate whether alternative materials to conventional triple antibiotic paste (TAP - metronidazole, ciprofloxacin, and minocycline) and grey mineral trioxide aggregate (GMTA) could avoid tooth discoloration in teeth submitted to Regenerative Endodontic Procedure (REP). It was also investigated if dental bleaching is able to reverse the color of darkened teeth due to REP. The search was conducted in four databases (Medline via PubMed, Scopus, ISI Web of Science and BVS - Virtual health library), following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The retrieved papers were uploaded in the software EndNoteTM and two reviewers independently selected the studies and extracted the data. Only studies in humans (case reports, case series, clinical trials) were included in the review. From 1,122 potentially eligible studies, 83 were selected for full-text analysis, and 38 were included in the review. The included studies were mainly case reports (76.3 %). The studies described a total of 189 teeth submitted to REP. From these, about 54% of teeth presented some degree of discoloration. Most teeth presenting color alteration were treated with TAP, especially when combined with GMTA. Only three studies performed dental bleaching to restore the color of teeth and neither bleaching technique was able to restore the original color of the crowns. The use of alternative materials to TAP and GMTA, such as double antibiotic paste or Ca(OH)2 pastes and white mineral trioxide aggregate or BiodentineTM, reduces the occurrence of tooth discoloration.
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Tihacek-Sojic, Ljiljana y Slobodan Saulic. "Justification of forming active prosthetic segments". Serbian Dental Journal 51, n.º 3 (2004): 153–57. http://dx.doi.org/10.2298/sgs0403153t.
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The aim of this paper was to examine the justification of forming active prosthetic segments on the abutment teeth for the incline of the elements of removable partial denture. Methods. The investigation was performed during 3-years observational period, at the Prosthodontic Clinics of Belgrade University Dental School, and the Military Medical Academy (MMA). During the mentioned observation period two groups of 200 patients with different kinds of edentulousness were analyzed, indicated for the design of metal frame removable partial dentures (MFRPD) with cast clasps. A total of 400 patients represented 50% of the sample chosen by random choice method for the determined observational period and dental institutions. Results. The evaluation of justification of the abutment teeth preparation was done during the analysis of the requirement of forming: guide planes, planes for occlusal rests, vestibular under cut, oral under cut. Conclusion. Upon the evaluation of the performed analyses the following can be concluded: during the composition of every MFRPD it is necessary to use at least two or more guide planes, depending on the type edentulousness of patients' teeth; formation of guide planes is performed in excessively high number of the abutment teeth (over 95%); during the composition of each particular MFRDP it is necessary to use as more occlusal rests as possible, at least 3, or more, which also depends on the type of patients' edentulousness; composition of the planes for occlusal rest has to be performed in almost all the patients (over 95% of the abutment teeth); vestibular planes of the abutment teeth should be prepared in over 50% of the used teeth; oral planes are prepared within the preparation of the abutment teeth for other active prosthetic segments. Conclusion. It is necessary to perform the composition of active prosthetic segments according to the plan established for the study models, both if the preparation of teeth for the adoption of MFRDP elements with clasps represents the use of an uninvasive, or an invasive dental method.
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Feeney, Robin N. M. "An investigation of ultrasound methods for the assessment of sex and age from intact human teeth". Dental Anthropology Journal 18, n.º 1 (3 de septiembre de 2018): 2–11. http://dx.doi.org/10.26575/daj.v18i1.128.
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Determining sex and age in humanremains is necessary to achieve positive identificationof individuals in forensic settings, and to provide datarequired for demographic analyses in archaeologicalsamples. Due to their denser mineralization, teeth maybe better preserved than other skeletal elements, whichare often fragmentary and poorly preserved. This workis the first to investigate the use of ultrasound methodsto accurately, objectively, and non-destructively assesssex and estimate age of human skeletal remains fromintact teeth. An ultrasound imaging system usingpulse-echo technique and nominal frequency (3.5 MHz)longitudinal waves was developed for applicationon teeth. Mechanical and acoustic properties of teethwere examined to explore their relationship withthe interaction of ultrasound wave propagation.Experiments were conducted to determine differencesin wave propagation in teeth from individualsof different ages and sex, both permanent anddeciduous. Consistent differences in integral acousticresponse patterns in the different teeth were found.It is concluded that pulse-echo ultrasound is a viablenon-destructive technique to yield integral acousticcharacteristic properties of teeth, potentially usefulfor assessing sex and estimating age, and resolvingminimum numbers of individuals from commingledand scattered remains. Information developed fromthis study will be significant to future research insofaras it introduces a new potential method that is nondestructive,fast, and easy to administer in situ.
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Hassunuma, RM, ACM Stipp, MTCD Heubel, TM Cestari, DS Ceolin, RSB Nakamura, PHO Rosseti y GF Assis. "Tooth morphology, implantation and replacement system of Hoplias malabaricus (Teleostei, Characiformes, Erythrinidae)". Brazilian Journal of Biology 73, n.º 4 (noviembre de 2013): 783–89. http://dx.doi.org/10.1590/s1519-69842013000400014.
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The oropharyngeal cavity of Hoplias malabaricus, an ichthyophagous freshwater fish, is anatomically adapted to predation. Macroscopic and microscopic analyses were conducted in order to study the morphology and system of implantation and replacement of teeth. The results showed that this teleost has conical and caniniform teeth, with an orthodentin crown covered by an enameloid cap and a vascularised orthodentin in the root. With regard to the implantation system, there is a junction between the tooth and the bone tissue, as a typical physiological dental ankylosis. The teeth are replaced by a resorption process of multinucleated giant cells that actively eliminate the dentin and bone tissue.
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Dixon, E. James y George S. Smith. "Broken Canines from Alaskan Cave Deposits: Re-Evaluating Evidence for Domesticated Dog and Early Humans in Alaska". American Antiquity 51, n.º 2 (abril de 1986): 341–51. http://dx.doi.org/10.2307/279946.
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Broken canines from two caves on the Porcupine River, Alaska are analyzed with respect to size, development, morphology, breakage pattern, and stratigraphic placement. These analyses indicate that they are deciduous bear teeth exfoliated in these caves through noncultural processes associated with dental development. Similarity of these teeth to the canines recovered from various stratigraphic levels at Trail Creek Caves 2 and 9, on the Seward Peninsula, Alaska (Larsen 1968:58), indicates that the Trail Creek specimens (including specimens from levels dating to the late Pleistocene) are also naturally exfoliated bear teeth and not dog canines (Canis familiaris) broken out by human beings, as originally suggested.
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Lee, Ko Eun, Mijeong Jeon, Seunghan Mo, Hyo-Seol Lee, Je Seon Song, Hyung-Jun Choi, Hyunsoo Cho y Chung-Min Kang. "Deferoxamine Reduces Inflammation and Osteoclastogenesis in Avulsed Teeth". International Journal of Molecular Sciences 22, n.º 15 (30 de julio de 2021): 8225. http://dx.doi.org/10.3390/ijms22158225.
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Replacement and inflammatory resorption are serious complications associated with the delayed replantation of avulsed teeth. In this study, we aimed to assess whether deferoxamine (DFO) can suppress inflammation and osteoclastogenesis in vitro and attenuate inflammation and bone resorption in a replanted rat tooth model. Cell viability and inflammation were evaluated in RAW264.7 cells. Osteoclastogenesis was confirmed by tartrate-resistant acid phosphatase staining, reactive oxygen species (ROS) measurement, and quantitative reverse transcriptase–polymerase chain reaction in teeth exposed to different concentrations of DFO. In vivo, molars of 31 six-week-old male Sprague–Dawley rats were extracted and stored in saline (n = 10) or DFO solution (n = 21) before replantation. Micro-computed tomography (micro-CT) imaging and histological analysis were performed to evaluate inflammation and root and alveolar bone resorption. DFO downregulated the genes related to inflammation and osteoclastogenesis. DFO also reduced ROS production and regulated specific pathways. Furthermore, the results of the micro-CT and histological analyses provided evidence of the decrease in inflammation and hard tissue resorption in the DFO group. Overall, these results suggest that DFO reduces inflammation and osteoclastogenesis in a tooth replantation model, and thus, it has to be further investigated as a root surface treatment option for an avulsed tooth.
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Ergün Kunt, Göknil, Deniz Kökçü, Gözlem Ceylan, Nergiz Yılmaz y Ahmet Umut Güler. "Pulpal blood flow changes in abutment teeth of removable partial dentures". Bosnian Journal of Basic Medical Sciences 9, n.º 4 (20 de noviembre de 2009): 296–300. http://dx.doi.org/10.17305/bjbms.2009.2782.
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The purpose of this study was to investigate the effect of tooth supported (TSD) and toothtissue supported (TTSD) removable partial denture wearing on pulpal blood flow (PBF) of the abutment teeth by using Laser Doppler Flowmeter (LDF).Measurements were carried out on 60 teeth of 28 patients (28 teeth and 12 patients of TTSD group, 32 teeth and 16 patients of TSD group) who had not worn any type of removable partial dentures before, had no systemic problems and were non smokers. PBF values were recorded by LDF before insertion (day 0) and after insertion of dentures at day 1, day 7 and day 30. Statistical analysis was performed by student t test and covariance analyses of repeated measurements.In the group TTSD, the mean values of PBF decreased statistically significantly at day 1 after insertion when compared with PBF values before insertion (p<0,01). There was no statistically significant difference among PBF mean values on 1st, 7th and 30th day. However, in the group TSD, there was no statistically significant difference among PBF mean values before insertion and on 1st, 7th and 30th day. In other words, PBF mean values in group TSD continued without changing statistically significant on 1st, 7th and 30th day.TTSD wearing may show negative effect on the abutment teeth due to decreasing basal PBF.