Bibliografías temáticas / Teeth analyses

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Literatura académica sobre el tema "Teeth analyses"

Autor: Grafiati
Publicado: 4 de junio de 2021
Última modificación: 16 de febrero de 2022

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Artículos de revistas sobre el tema "Teeth analyses"

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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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7

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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Tesis sobre el tema "Teeth analyses"

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Calleberg, Kerstin. "The Victims at Sandby Borg : Tracing mobility and diet usingstrontium analyses". Thesis, Stockholms universitet, Arkeologiska forskningslaboratoriet, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-170731.

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Sandby borg, an Iron Age ringfort on Öland, Sweden has been and is still at the center of attention in media and archaeological research. The massacre uncovered at the site during recent years opens many doors for analyses on the Migration Period (c. 400-550 AD) Iron Age skeletal remains. Eighteen teeth (molars) from 12 individuals and three rodent teeth were chosen for strontium (87Sr/86Sr) analyses. This was done to establish whether these individuals were locals or non-locals to Öland. The analyses displayed a, for the most part, local 87Sr/86Sr ratio. Two non-locals were identified, as well as a pattern of higher 87Sr/86Sr peaks on numerous of the individuals during a certain age span, which could indicate a local weaning process with a special food.
Sandby borg
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Wiener, R. Constance. "Epipathogenesis of caries| Analyses of family structure, fear, and fatalism upon World Health Organization decayed, missing, and filled teeth severity in Appalachia West Virginia and Pennsylvania". Thesis, West Virginia University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3538200.

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Appalachian has many social, economic, and biologic factors impacting dental health over the life-course.

Purpose: This study examined dental caries experience and family structure, dental fear, and fatalism in West Virginia and Pennsylvania.

Method: Using a cross-sectional study design, 2002-2009 Center for Oral Health Research in Appalachia data were analyzed utilizing the World Health Organization definitions for caries experience, dichotomized into low and high. Three groups were studied: 1) children, 11-13 years (N=237); 2) adolescents, 14-17 years (N=191); and 3) adults, 18 years and above (N=1125). For multivariable model development, generalized estimating equations with exchangeable working structures accounted for family clusters.

Results. For children, family (second biological child vs. first biological child and niece/nephew/step-/grandchild/other vs. first biological child) Fatalism Scale, Dental Fear Survey, and Short Form Fear of Pain Questionnaire failed to reach a significant difference with caries experience. There were 38.0% reporting fear on the Dental Fear Survey, and 80.2% on the Short Form Fear of Pain Survey. There were 62.0% reporting fatalism. There were 44.7% first biological children, 32.1% second biological children, and 23.2% with other family relationships.

Overall, for adolescents, family (single parent vs. both parents, same home; and second biological child vs. first biological child and niece/nephew/step-/grandchild/other vs. first biological child) failed to reach a significant difference with caries experience. However, in gender sub-group analysis, living with a single parent was protective for males, with an adjusted odds ratio (AOR) of 0.08 (95% Confidence Interval [CI]: 0.01, 0.42; p = 0.0249). The Fatalism Scale failed to reach a significant difference with caries experience in the overall model. For females, there was an AOR of 6.60 (95% CI: 1.89, 9.64; p = 0.0076). Although the Short Form Fear of Pain Questionnaire failed to reach a significant difference with caries experience in the overall model, for males, the AOR was 12.86 (95% CI: 1.71, 96.59; p = 0.0130) and for females, the AOR was 0.08 (95% CI: 0.01, 0.55; p = 0.100). There were 36.1% reporting fear on the Dental Fear Survey; 63.9% on the Short Form Fear of Pain Survey; and 43.5% reporting fatalism on the Fatalism Scale. There were 54.6% first biological children; 20.6% second biological children, and 24.8% with other family relationships; 53.5% lived in single parent homes.

For adults, a high Dental Fear Survey score was associated with a high caries experience. The AOR was 1.76 (95% CI: 1.29, 2.40; p = .0003). It remained significant for females (AOR= 2.11[95% CI: 1.41, 3.14; p = 0.0003]). For males, those never married, divorced, widowed, separated, or had other living arrangements vs. married/domestic partnering had an AOR of 0.12 (95% CI: 0.04, 0.36; p = .0002).

Conclusion: Caries is a complex disease with many influences. Gender differences exist in age categories in terms of family relationships, fear, and fatalism. Further exploration of these factors is needed to aid in the development of successful interventions to decrease caries severity.

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Hägglund, Eric. "Hogging Wealth : Dental analyses and an interdisciplinary study of the importance of pigs in prehistoric economies". Thesis, Uppsala universitet, Institutionen för arkeologi och antik historia, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-324728.

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Studies in zoo-archaeological Neolithic contexts is the study of early animal domestication in relation to humans transitioning into a more sedentary species. Research and documentation are vital for reconstructing the mechanisms behind the threshold event. In this thesis, teeth of Suidae have been documented, analysed and compared osteologically and interpreted cross-culturally. In addition, aDNA, isotope, coat colour and physical mammal size affecting factor studies are presented to contextualise this thesis. Primary osteological methods are Mandibular Wear Stage (MWS), Linear Enamel Hypoplasia (LEH) recordings and lower jaw third molar (M3) length measurement. These methods can detect biometric domestication markers. The analysed Suidae teeth are from the Middle Neolithic site of Ajvide, Gotland, Sweden. A collection of modern wild boar act as Control sample. These teeth are compared primarily with known domestic pig teeth sample statistics from the British Late Neolithic site of Durrington Walls, Wiltshire, United Kingdom. Results indicate that the Middle Neolithic Pitted Ware culture (PWC) on Gotland hunted during winter and kept limited numbers of captive wild boars as totemic animals (pets) possibly bound to land and ancestry. However, an exact reconstruction of the PWC pig pet keeping practices are uncertain due to human-pig relationships being highly dynamic. Intensified pig hunting, not pet keeping should be considered early domestication. Domestication carries with it detectable biometric markers, which seem to be rare in the Neolithic. The cross-cultural comparisons on traditional pig ‘low-intensity husbandry’ can attest to a human-pig relationship of hunter-gatherers keeping captive wild animals. The pig was not a staple food for the PWC and thus not intensively hunted, rather pigs were rare ritualistic commodities and likely highly praised. Perpetuating this human-pig relationship could have been maintained by PWC ‘big men’ that engaged in socio-political lavish giveaways at festivities and funerals, thus ‘hogging wealth’, but never domesticated the pig.
Studier i neolitiska zoo-arkeologiska sammanhang är undersökningar av tidig domesticering av djur i förhållande till mänsklighetens övergång till en mer stillasittande art. Forskning och dokumentation är avgörande för att rekonstruera mekanismerna bakom övergången. I denna uppsats har svintänder dokumenterats, analyserats och jämförts osteologiskt och tolkats tvärkulturellt. Studier i aDNA, isotop, pälsfärg och fysiska storleksfaktorer hos däggdjur presenteras också för att kontextualisera denna uppsats. Primära osteologiska metoder är tandslitage i underkäke (MWS), linjär emaljhypoplasi (LEH) och underkäkens tredje molar (M3) mätningar. Dessa metoder kan finna biometriska domesticeringsmarkörer. De analyserade svintänderna kommer ifrån den mellanneolitiska lokalen Ajvide, Eksta socken, Gotland. En samling moderna vildsvin agerar kontrollmaterial. Dessa tänder jämförs i första hand med kända domesticerade stenåldersvin från den Brittiska senneolitiska lokalen Durrington Walls, Wiltshire, Storbritannien. Resultaten indikerar på att den mellanneolitiska gropkeramiska kulturen (GRK), jagade på Gotland under vinterhalvåret och tog tillfånga ett begränsat antal svin som husdjur (totemdjur). Troligen togs svin tillfånga av olika ’hus’ till följd av att svinet var bundet till land och förfäder. En exakt rekonstruktion av GRKs svinhållningspraktik är dock osäkert på grund av att människo-svin relationer är dynamiska. Intensifierad svinjakt, inte tillfångatagandet av enstaka djur bör betraktas som tidig domesticering. Domesticering medför speciella biometriska markörer som är ovanligare i neolitisk tid. De tvärkulturella jämförelserna i traditionell "lågintensiv svinhållning" kan intyga på ett sådant förhållande mellan jägare-samlar grupper och vildsvin. Även om svinet inte var en basföda åt GRK, och därmed inte intensivt jagade, var svinen sällsynta ritualistiska handelsvaror och troligen högt värdesatta. Gropkeramiska "stormän" kan ha varit de drivande bakom denna praktik. Dessa ”stormän” engagerade sig i sociopolitiska aktiviteter, festligheter och begravningar, och därmed hade "hamstrat välstånd", men domesticerade aldrig svinet.
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Franzon, Renata. "Eficácia da remoção parcial de tecido cariado em dentes decíduos : ensaio clínico controlado randomizado". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/143682.

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A remoção parcial de tecido cariado (RPTC) em lesões profundas de cárie em dentes decíduos tem demonstrado excelentes resultados clínicos, radiográficos e microbiológicos. No entanto, o desempenho das restaurações com resina composta em dentes que tiveram esse tratamento ainda merece esclarecimentos. O objetivo desse trabalho foi investigar a taxa de manutenção de restaurações sobre tecido cariado através de uma revisão sistemática de literatura e de um ensaio clínico controlado randomizado. Métodos: Cinquenta e uma crianças de 3 a 8 anos de idade (28 meninos e 23 meninas) portadoras de ao menos um molar com lesão profunda de cárie foram incluídas no estudo. Os dentes foram aleatoriamente divididos de acordo com os seguintes tratamentos: Grupo controle: Remoção total de tecido cariado (RTTC) e teste: Remoção parcial de tecido cariado (RPTC). Nos casos em que ocorreu exposição pulpar foi realizada pulpotomia. Três Odontopediatras realizaram os procedimentos que foram acompanhados em 3, 6,12, 18 e 24 meses. Todos os procedimentos foram realizados sob anestesia local e isolamento absoluto. No início e no final do procedimento as crianças reportaram sua ansiedade através de duas escalas: Venham Picture Test (VPT) e Facial Image Scale (FIS). O comportamento da criança durante o atendimento foi avaliado através da escala de Sarnat. Em todos os momentos experimentais foram avaliados os aspectos clínicos e radiográficos dos tratamentos e as restaurações foram analisadas por um examinador cego e calibrado através do USPHS modificado.Para determinar as taxas de sucesso clínico e radiográfico e das restaurações de resina composta foram geradas curvas de sobrevida com o estimador Kaplan-Meyer. A distribuição dos indivíduos cooperativos e não cooperativos de acordo com diferentes variáveis independentes, assim como as comparações das escalas FIS e VENHAM entre os três tratamentos, foram avaliadas utilizando-se o teste de Qui-quadrado. Resultados: Quarenta e oito crianças e 120 dentes foram incluídos na análise. Dentre as variáveis analisadas, apenas o tempo de atendimento afetou significativamente o comportamento das crianças (p=0,018). No grupo RTTC ocorreram 15 casos de exposição pulpar (27,5%), enquanto que no grupo RPTC apenas 1 caso (2%). As taxas de sucesso clínicoradiográfico após RPTC e RTTC foram 92% e 98%, respectivamente (p=0,14). Foi observada uma tendência a menor taxa de sucesso clínicoradiográfico em cavidades oclusoproximais (92%) em comparação com cavidades oclusais (100%), porém não estatisticamente significante (p=0,08). Não houve diferença significativa entre os operadores. A taxa de sobrevida das restaurações foi de 66%, 85% e 92%, para os grupos RPTC, RTTC e pulpotomia, respectivamente, após 24 meses, (p=0,09). Quando a taxa de sobrevida das restaurações foi avaliada de acordo com o tratamento e o tipo de cavidade, foi observada taxa de sobrevida significativamente menor (p=0,007) para restaurações do tipo oclusoproximais após RPTC (52%).Por outro lado, os maiores percentuais 10 de sobrevida das restaurações foram observados em cavidades oclusais após RPTC (95%). A revisão de literatura demonstrou que o sucesso das restaurações aumenta quanto menor o número de superfícies envolvidas, assim, cavidades classe I apresentaram em torno de 90% de sucesso e diminui para 50% quando mais de uma superfície foi restaurada. Conclusões: As restaurações de resina composta sobre tecido cariado necessitam de proservação em curtos períodos de tempo para manutenção e reparo.
Partial caries removal in deep carious lesions of primary teeth has been demonstrated excellent clinical, radiographs and microbiological results. However, the clinical performance of composite resin restorations placed over the demineralized dentin need more information. The objective of this work was to investigate the restoration performance over carious tissue trough a literature systematic review and a randomized controlled clinical trial. Methods: Fifty-one children aged from 3 to 8 years old (28 boys and 23 girls) with, at least, one molar with deep carious lesion were included in this clinical trial. The teeth were randomly divided according to the following treatments: Control group - total caries removal (TCR); and Test - partial caries removal (PCR). In case of pulp exposure during dentinal excavation, pulpotomy was performed. Three Pediatric Dentist made the procedures that were followed-up by 3, 6, 12, 18 and 24 months. All procedures were performed under local anesthesia and rubber dam isolation. At the beginning and right after the procedure the children reported their anxiety through two scales: Venham Picture Test (VPT) and Facial Image Scale (FIS). The children behavior during the attendance was valued through Sarnat scale. During the time course follow-up clinical and radiographic aspects of the treatments were evaluated and the restorations analyzed by a calibrated and blinded examiner through modified USPHS. To determine the clinical and radiographic outcomes of composite restorations the groups were statistically analyzed using Kaplan-Meier survival followed by Log Rank. The distribution of cooperatives and non-cooperatives subjects in accordance with different independent variables as well as FIS and VENHAM comparisons between the tree treatments were availed using Qui-square test. Results: The final sample was comprised by forty-eight children and 120 teeth. Among all the analyzed variables, only the time spent for the procedure significantly affected the children behavior (p=0.018) The total caries removal procedure produced 15 pulp exposures (27.5%), while the same event occurred only in one case for the PCR group (2%). The clinical- radiographic success rate after PCR and TCR were 92% and 98%, respectively (p=0.14). It was observed a tendency to lower clinical-radiographic success rate in oclusoproximal cavities (92%) in comparison with oclusal (100%) but without statistic significance (p=0.08). The restorations survival rate was 66%, 85% and 92% to PCR, TCR and pulpotomy groups, respectively after 24 months follow-up (p=0.09). When the restorations survival rate was evaluated in accordance with type of treatment and the type of cavity was observed a significant lower survival rate (p=0.007) to oclusoproximal restoration after PCR (52%). On the other hand, the highest restorations survival was observed in oclusal cavities with partial caries removal (95%). The literature review shows that success rate increases with the decrease of involved surface at the restoration, thus class I restorations presented around 90% of success and it decreases below to 50% if more than one surface are restored. Conclusions: The composite resin restorations placed over caries tissue need shorter follow-up time to evaluate the necessity of being repaired or replaced.
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Bailey, Lillian Amanda. "The Bolton Analysis revisited". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0005/MQ34333.pdf.

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Lam, Raymond Hiu-wai. "Artificial teeth : dental biofilm analysis on a chip". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62525.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references.
In this thesis, an "artificial teeth" microfluidic device is developed that provides unprecedented control over the conditions required to simulate the growth of complex dental biofilm. Dental plaque formation is not only a precursor to tooth decay, but also induces more serious systemic health problems such as cardiovascular disease, pre-term labor, and diabetes. Therefore, understanding the conditions promoting colonization and subsequent biofilm development involving complex bacteria coaggregation is particularly important. The requirement of the continuous culture and analysis systems for large quantities of growth media and reagents has pushed the move toward microfluidics - the miniaturization and chip-based control of fluidic operations. Microfluidic oxygenation is necessary to regulate the cellular gas condition of culture medium, especially for mixed population biofilms consisting of both anaerobic and aerobic cell populations. A double-layer gas perfusion network structure fabricated above the cell culture regions is developed for culture oxygenation. Throughout the modeling and analysis of the oxygen transfer in microfluidic oxygenators, design strategies for such devices are proposed for different configurations. Various designs of oxygen-nitrogen mixer networks providing parallel oxygenation with differential or tunable oxygen concentrations are described and verified experimentally to test the corresponding applicability in microbiological culture. The microfluidic "artificial teeth" platform, integrated with the microfluidic oxygenators, functions as an effective and inexpensive analysis tool to dynamically adjust critical growth parameters such as bacteria population, growth medium composition, medium flow rate and dissolved oxygen levels. The first single-chamber "artificial tooth" chip is developed for long-term dental biofilm culture with better medium handling, such as mixing, humidification and automated growth medium replenishment. This device is also compatible with different analysis techniques using optical microscopy in order to determine the biofilm thickness, the ratio between viable and dead cells, and the visualization of spatial distribution of different dental bacteria in the biofilm. Furthermore, the single-chamber design is extended to a device containing up to 128 chambers. This "artificial teeth" chip is developed to achieve high-throughput parallel biofilm culture and analysis with a matrix of different growth conditions that can contribute to the quantitative studies of the physiology of dental biofilms. The artificial teeth device is applied to investigate the response of two key dental bacteria, Streptococci sp. and Fusobacterium nucleatum, in the biofilm under different microenvironments, including their growth under different gas conditions and their adherence properties with different sucrose concentrations. This work demonstrates a successful application of microfluidics to long-term biofilm culture applications.
by Raymond H. W. Lam.
Ph.D.
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Steiner, Alexis K. "3D Digitization and Wear Analysis of Sauropod Teeth". Bowling Green State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1525990888624381.

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Whitenack, Lisa Beth. "The biomechanics and evolution of shark teeth". [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002678.

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Benazzi, Stefano <1977&gt. "Image analysis in the morphological and morphometric study of teeth". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/326/.

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The subject of this doctoral dissertation concerns the definition of a new methodology for the morphological and morphometric study of fossilized human teeth, and therefore strives to provide a contribution to the reconstruction of human evolutionary history that proposes to extend to the different species of hominid fossils. Standardized investigative methodologies are lacking both regarding the orientation of teeth subject to study and in the analysis that can be carried out on these teeth once they are oriented. The opportunity to standardize a primary analysis methodology is furnished by the study of certain early Neanderthal and preneanderthal molars recovered in two caves in southern Italy [Grotta Taddeo (Taddeo Cave) and Grotta del Poggio (Poggio Cave), near Marina di Camerata, Campania]. To these we can add other molars of Neanderthal and modern man of the upper Paleolithic era, specifically scanned in the paleoanthropology laboratory of the University of Arkansas (Fayetteville, Arkansas, USA), in order to increase the paleoanthropological sample data and thereby make the final results of the analyses more significant. The new analysis methodology is rendered as follows: 1. Standardization of an orientation system for primary molars (superior and inferior), starting from a scan of a sample of 30 molars belonging to modern man (15 M1 inferior and 15 M1 superior), the definition of landmarks, the comparison of various systems and the choice of a system of orientation for each of the two dental typologies. 2. The definition of an analysis procedure that considers only the first 4 millimeters of the dental crown starting from the collar: 5 sections parallel to the plane according to which the tooth has been oriented are carried out, spaced 1 millimeter between them. The intention is to determine a method that allows for the differentiation of fossilized species even in the presence of worn teeth. 3. Results and Conclusions. The new approach to the study of teeth provides a considerable quantity of information that can better be evaluated by increasing the fossil sample data. It has been demonstrated to be a valid tool in evolutionary classification that has allowed (us) to differentiate the Neanderthal sample from that of modern man. In a particular sense the molars of Grotta Taddeo, which up until this point it has not been possible to determine with exactness their species of origin, through the present research they are classified as Neanderthal.
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Sathorn, Chankhrit. "Factors affecting fracture susceptibility of tooth root : a laboratory and finite element analysis (FEA) study /". Connect to thesis, 2004. http://eprints.unimelb.edu.au/archive/00001600.

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Libros sobre el tema "Teeth analyses"

1

Mafart, Bertrand-Yves y Djillali Hadjouis. Paléo-odontologie: Analyses et méthodes d'étude. Paris: Editions Artcom', 2001.

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Litvin, F. L. Topology of modified helical gears and tooth contact analysis (TCA) program. Cleveland, Ohio: Lewis Research Center, 1989.

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Litvin, F. L. Topology of modified helical gear and tooth contact analysis (TCA) program. [Washington, DC]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Division, 1989.

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Glasgow), British Combinatorial Conference (10th 1985 Universityof. Surveys in combinatorics 1985: Invited papers for the Tenth British Combinatorial Conference. Cambridge: Cambridge University Press, 1985.

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Collins, E. Analysis of costs for the treatment of dental fluorosis. Cincinnati, OH: U.S. Environmental Protection Agency, Water Engineering Research Laboratory, 1987.

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Handschuh, Robert F. Experimental and analytical assessment of the thermal behavior of spiral bevel gears. [Washington, D.C.]: National Aeronautics and Space Administration, 1995.

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Handschuh, Robert F. Experimental and analytical assessment of the thermal behavior of spiral bevel gears. [Washington, D.C.]: National Aeronautics and Space Administration, 1995.

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Handschuh, Robert F. Experimental and analytical assessment of the thermal behavior of spiral bevel gears. [Washington, D.C.]: National Aeronautics and Space Administration, 1995.

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Kumar, A. A procedure for 3-D contact stress analysis of spiral bevel gears. [Washington, DC]: National Aeronautics and Space Administration, 1994.

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Kumar, A. A procedure for 3-D contact stress analysis of spiral bevel gears. [Washington, DC]: National Aeronautics and Space Administration, 1994.

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Capítulos de libros sobre el tema "Teeth analyses"

1

Kisailus, David y Michiko Nemoto. "Structural and Proteomic Analyses of Iron Oxide Biomineralization in Chiton Teeth". En Biological Magnetic Materials and Applications, 53–73. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-8069-2_3.

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Lieberman, Daniel E. "Cementum Increment Analyses of Teeth From Wadi Judayid (J2) And Tor Hamar (J431): Estimations of Site Seasonality". En Prehistoric Cultural Ecology and Evolution, 391–98. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4757-2397-7_18.

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Meneghini, Fabio y Paolo Biondi. "Lips, Teeth, Chin, and Smile Analysis". En Clinical Facial Analysis, 107–24. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-27228-8_8.

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Schmidt, Christopher W., Robin Quataert, Fatma Zalzala y Ruggero D'Anastasio. "Taphonomy of Teeth". En Taphonomy of Human Remains: Forensic Analysis of the Dead and the Depositional Environment, 92–100. Chichester, UK: John Wiley & Sons, Ltd, 2017. http://dx.doi.org/10.1002/9781118953358.ch7.

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Miyazaki, Lucas K., Rogério Y. Takimoto, André K. Sato, Hiromasa Suzuki y Marcos S. G. Tsuzuki. "Teeth Mesh Segmentation Through Curvature Analysis". En Advances in Intelligent Systems and Computing, 235–43. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-63403-2_21.

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Anand, Sekar, Arunachalam Dharmalingam Srikeshav, Baskar Sharran y Lokavarapu Bhaskara Rao. "Design and Analysis of Helical Teeth Harmonic Drive". En Lecture Notes in Mechanical Engineering, 507–19. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-7557-0_42.

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Frejlichowski, Dariusz y Robert Wanat. "Extraction of Teeth Shapes from Orthopantomograms for Forensic Human Identification". En Computer Analysis of Images and Patterns, 65–72. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-23678-5_6.

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Klukkert, Zachary S., John C. Dennis, Francis M’Kirera y Peter S. Ungar. "Dental Topographic Analysis of the Molar Teeth of Primates". En Methods in Molecular Biology, 145–52. Totowa, NJ: Humana Press, 2012. http://dx.doi.org/10.1007/978-1-61779-977-8_9.

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Bruja, A., M. Dima y C. Francu. "Meshing Forces Distribution Analysis on Gearing Teeth with Precession Movement". En SYROM 2009, 267–73. Dordrecht: Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-90-481-3522-6_21.

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Janžura, Martin. "Statistical Analysis of Gibbs Random Fields". En Transactions of the Tenth Prague Conference, 429–38. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-3859-5_45.

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Actas de conferencias sobre el tema "Teeth analyses"

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Bassani, Roberto, Enrico Ciulli, Enrico Manfredi, Salvatore Manconi, Alessandro Polacco y Giovanni Pugliese. "Experimental Study on Wear and Fracture in Aeronautical Gear Transmissions". En ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95720.

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This work presents some of the results obtained from an extensive experimental test campaign performed at the Department of Mechanical Nuclear and Production Engineering (DIMNP) of Pisa University with the partnership of Avio Propulsione Aerospaziale S.p.A. This test campaign, that is still being performed, is concerned with the characterization of teeth damage in high performance gear transmissions, such as aeronautical ones, characterized by high levels of velocity and load. Damage detection and monitoring have been pursued during all the tests in order to achieve a better understanding of causes and evolution of teeth damage. Moreover, to investigate the effects of different parameters on teeth damage, tests with different load, velocity, teeth geometry, materials and surface finishing, have been performed. The surface conditions of the gear teeth have been investigated using in particular two different instruments: a computer-controlled stylus profilometer able to perform 3D investigations and a scanning electron microscope (SEM) recently provided by a software for surface reconstruction. Qualitative and quantitative changes in surface roughness have been detected. Besides the experimental activity, numerical analyses have been also started for finding theoretical criteria for surface damage prediction; some few obtained results are presented. Due to the vastness of the work performed, only a survey of the main results obtained till now is presented in the paper.
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Dogu, Yahya, Mustafa C. Sertçakan, Koray Gezer, Mustafa Kocagül, Ercan Arıcan y Murat S. Ozmusul. "Leakage Degradation of Straight Labyrinth Seal due to Wear of Round Tooth Tip and Acute Trapezoidal Rub-Groove". En ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57928.

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In this paper, labyrinth seal leakage is numerically quantified for an acute trapezoidal rub-groove accompanied with a rounded tooth, as a function of rub-groove sizes and tooth-groove axial positions. Analyses parameters include clearance, pressure ratio, number of teeth, and rotor speed. Labyrinth seals wear during engine transients. Radial incursion and axial movement of the rotor-stator pair cause the labyrinth teeth to rub against the unworn stator surface. The labyrinth teeth and/or stator wear depending on their material hardness. Wear damage in the form of material loss or deformation permanently increases seal clearance, and thus, leakage. This leakage is known to be dependent on the shape and geometry of the worn tooth and the stator rub groove. There are two types of reported tooth tip wear. These can be approximated as a mushroom shape and a round shape. The stator rub-groove shapes can be approximately simulated in five forms: rectangle, trapezoid (isosceles and acute), triangle, and ellipse. In this paper, the acute trapezoidal rub-groove shape is specifically chosen, since it is the most similar to the most commonly observed rub-groove form. The tooth tip is considered to be rounded, because the tooth tip wears smoothly and a round shape forms during rub-groove formation. To compare the unworn tooth, the flat stator is also analyzed as a reference case. All analyzed parameters for geometric dimensions (groove width, depth, wall angle, tooth-groove axial position,) and operating conditions (flow direction, clearance, pressure ratio, number of teeth, rotor speed) are analyzed in their practical ranges. CFD analyses are carried out by employing a compressible turbulent flow solver in a 2-D axi-symmetrical coordinate system. CFD analyses show that the rounded tooth leaks more than an unworn sharp-edged tooth, due to the formation of a smooth and streamlined flow around the rounded geometry. This smooth flow yields less flow separation, flow disturbance, and less of vena contract a effect. The geometric dimensions of the acute trapezoidal rub-groove (width, depth, wall angle) significantly affect leakage. The effects of clearance, pressure ratio, number of teeth, and rotor speed on the leakage are also quantified. Analyses results are separately evaluated for each parameter.
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Doğu, Yahya, Mustafa C. Sertçakan, Ahmet S. Bahar, Altuğ Pişkin, Ercan Arıcan y Mustafa Kocagül. "CFD Investigation of Labyrinth Seal Leakage Performance Depending on Mushroom Shaped Tooth Wear". En ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43607.

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Conventional labyrinth seal applications in turbomachinery encounter a permanent teeth tip damage and wear during transitional operations. This is the dominant issue that causes unpredictable seal leakage performance degradation. Since the gap between the rotor and the stator changes depending on engine transitional operations, labyrinth teeth located on the rotor/stator wear against the stator/rotor. This wear is observed mostly in the form of the labyrinth teeth becoming a mushroom shape. It is known that as a result of this tooth tip wear, leakage performance permanently decreases, which negatively affects the engine’s overall efficiency. However, very limited information about leakage performance degradation caused by mushroom wear is available in open literature. This paper presents a study that numerically quantifies leakage values for various radii of mushroom shaped labyrinth teeth by changing tooth-surface clearance, pressure ratio, number of teeth, and rotor speed. Analyzed parameters and their ranges are mushroom radius (R=0–0.508mm), clearance (cr=0.254–2.032mm), pressure ratio (Rp=1.5–3.5), number of teeth (nt=1–12), and rotor speed (n=0–80krpm). CFD analyses were carried out by employing compressible turbulent flow in 2-D axi-symmetrical coordinate system. CFD leakage results were also compared with well-known labyrinth seal semi-empirical correlations. Given a constant clearance, leakage increases with the size of the mushroom radius that forms on the tooth. This behavior is caused by less flow separation and flow disturbance and the vena contracta effect for flow over the smoothly shaped mushroom tooth tip compared to the sharp-edged tooth tip. This leakage increase is higher when the tooth tip wear is considered as an addition to the unworn physical clearance, since the clearance dominates the leakage. The leakage affected by the number of teeth was also quantified with respect to the mushroom radius. The rotational effect was also studied as a secondary parameter.
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Karpat, F. y S. Ekwaro-Osire. "Efficiency of the High Contact Ratio Involute Spur Gears With Asymmetric Teeth". En ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-40933.

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Gears with asymmetric teeth have unique potential for application in gearboxes, particularly when uni-directional loading is applied. Most recently, gears with asymmetric teeth have received much attention for use in applications that require high performance due to increased load capacity. Such applications include aircraft and wind turbine. These gears offer flexibility to designers due to their non-standard design. In asymmetric teeth, the geometry of the drive side is not to be symmetric to the coast side. In other words, the pressure angle on the drive side is greater or smaller than that on the coast side. Asymmetry between tooth sides provide vital in obtaining key properties, such as high load carrying capacity, low weight, low wear or low vibration. In order to effectively design asymmetric teeth, it is necessary to perform analyses on the efficiency of these gears under various loading. In this study, the results obtained on high contact ratio involute spur gears with asymmetric teeth are presented and discussed. The impact of a few design parameters, such as pressure angle or tooth height, on sliding velocities and friction is investigated and illustrated with numerical examples.
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Savignano, Roberto, Sandro Barone, Alessandro Paoli y Armando V. Razionale. "FEM Analysis of Bone-Ligaments-Tooth Models for Biomechanical Simulation of Individual Orthodontic Devices". En ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/detc2014-34912.

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In the last decades, research in the orthodontic field has focused on the development of more comfortable and aesthetic appliances such as thermoformed aligners. Aligners have been used in orthodontics since the mid 20-century. Nonetheless, there is still not enough knowledge about how they interact with teeth. This paper is focused on the development of a Finite Element Method (FEM) model to be used in the optimization process of geometrical attributes of removable aligners. The presented method integrates Cone Beam Computed Tomography (CBCT) data and optical data in order to obtain a customized model of the dental structures, which include both crown and root shapes. The digital simulation has been focused on analyzing the behavior of three upper frontal teeth. Moreover, the analyses have been carried out by using different aligners’ thicknesses with the support of composite structures polymerized on teeth surfaces while simulating a 2 degrees rotation of an upper central incisor.
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Krisch, Robert. "Investigation of the Meshing Conditions of a Flat Wheel Harmonic Gear Drive". En ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34059.

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The function principle of the flat wheel harmonic gear drive is similar to the basic principle of the classical harmonic drives. The flexible and the solid gear of the drive are coaxial flat wheels. The rotating wave generator deforms periodically and elastically different portions of an annular face gear on the flexible member in axial direction into engagement with teeth on an annular face gear on the solid member. The numbers of teeth of the face gears are different. An analytical method is introduced, that investigates meshing conditions of flat-wheel harmonic drives. The numbers of the connected teeth taking part in the load-transmission and the tangential component of the acting force on them in the range of tooth engagement are calculated. It depends on the loading torque, so calculations were launched at different levels of torques in case of various parameters. The tooth flanks were approximated by planes. Results are compared with the results of calculations based on finite element analyses.
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Dogu, Yahya, Mustafa C. Sertçakan, Koray Gezer, Mustafa Kocagül, Ercan Arıcan y Murat S. Ozmusul. "Labyrinth Seal Leakage Degradation due to Various Types of Wear". En ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57944.

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This paper systematically presents a complete leakage comparison for various types of wear experienced by labyrinth seals. Labyrinth seals used in turbine engines are designed to work at a clearance during steady-state engine operations. The tooth tip rubs the stator and wears either itself or the stator surface during transient operations, depending on the material properties of the tooth and stator. Any type of wear that increases clearance or deforms the tooth tip will cause permanent and unpredictable leakage degradation. This negatively affects the engine’s overall efficiency, durability, and life. The teeth have been reported to wear into a mushroom profile or into a rounded profile. A rub-groove on the opposing surface may form in several shapes. Based on a literature survey, five rub-groove shapes are considered in this work. They are: rectangle, trapezoid (isosceles and acute), triangle, and ellipse. In this work, leakage degradation due to wear is numerically quantified for both mushroomed and rounded tooth wear profiles. It also includes analyses on rounded teeth with the formation of five rub-groove shapes. All parameters are analyzed at various operating conditions (clearance, pressure ratio, number of teeth, rotor speed). CFD analyses are carried out by employing compressible turbulent flow in a 2-D axi-symmetrical coordinate system. CFD analyses show that the following tooth-wear conditions affect leakage from least to greatest: unworn, rounded, and mushroomed. These are for an unworn flat stator. It is also observed that rub-groove shapes considerably affect the leakage depending on the clearance. Leakage increases with the following groove profiles: triangular, rectangular, acute trapezoidal, isosceles trapezoidal, and elliptical. The results show that any type of labyrinth seal wear has significant effects on leakage. Therefore, leakage degradation due to wear should be considered during the engine design phase.
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Chougule, Hasham H., Alexander Mirzamoghadam y Douglas Ramerth. "CFD Simulation of Single Step and Double Notched Tooth for Labyrinth Seals". En ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26286.

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A variant “Stepped Double Notched Tooth” for conventional sharp teeth of a labyrinth seal has been proposed and investigated by three-dimensional CFD numerical modeling of the flow field. The purpose is to reduce total leakage through the seal. The tooth is numerically tested with both solid and honeycomb lands. CFD assumptions and analysis were validated by comparison with leakage data from stationary labyrinth seal experiments conducted by Stocker [1]. The baseline model considered for comparison study consists of the conventional straight-through four sharp knife shaped teeth in combination with solid and honeycomb land. The variant tooth is also straight having a sharp tip but has a stepped inclined notch opposing the flow at both sides of the tip. CFD analyses revealed that this double notched tooth reduces seal leakage by ∼10.7% when used with solid land and ∼12.5% when used with honeycomb land compared to a conventional baseline tooth.
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Vinaud, Felipe J. y Thiago de A. Bosqueiro. "Non-Linear Finite Element Analysis of an Open Spline Connection". En ASME 2020 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/detc2020-22101.

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Abstract Splines are geared mechanical connections widely used for torque transmission. The analysis of splined connections follows straightforward techniques that take into account the stresses developed at the gear root and flanks. Special difficulties arise when the spline connection needs to eliminate backlash and the part’s geometry is not symmetrical. Misalignment, combined loads and differences in stiffness are responsible for causing a non even contact profile between teeth along the spline circumference. These conditions lead to dissimilar stress profiles and some teeth end up being subject to significantly higher stresses. This work analyses the stress profile of a peculiar spline component used in flight control actuation systems of EMBRAER aircraft, tailored to eliminate backlash due to the need of accurate positioning feedback. Normally, for this kind of application, the external spline has an open geometry and the backlash is avoided by means of a bolt used to tighten both sides of the open spline. There are no known analytic solutions that consider the bolt tightening effect and the contact stress distribution appearing on the gear teeth which depends on the spline geometry and local stiffness of the parts being joined. To approximate the spline local stress distributions, a non-linear finite element model was developed and the resulting stresses were compared to those from methodologies available in the literature. Finally the finite element model results were used to successfully approximate the fatigue life and damage tolerance cycles of a spline connection that broke during certification tests of the flap mechanism of an EMBRAER aircraft.
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Guagliano, Mario, Andrea Piazza y Laura Vergani. "A Weight-Functions Based Approach to Predict Rolling Contact Fatigue Sub-Surface Crack Propagation in Gears". En ASME 2003 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/detc2003/ptg-48023.

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The problem of the rolling contact fatigue crack propagation in gear teeth is dealt with. An approach based on the weight function method for the determination of KI and KII of internal cracks was developed. The effect of the contact and of the friction between the crack faces was taken into consideration by using approximate relations. The results were compared with the ones obtained by finite element analyses and the agreement was found satisfactory. By means of the determined weight function several analyses were performed and an interpolating function of KII versus the crack length were found. An approach for rolling contact fatigue crack propagation prediction based on the obtained solution and on a short crack propagation law was developed and implemented in a computational routine. The results are critically discussed.
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Informes sobre el tema "Teeth analyses"

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Guo, Runzhi. Alveolar bone changes in maxillary and mandibular anterior teeth during orthodontic treatment: A systematic review and meta-analysis. INPLASY - International Platform of Registered Systematic Review Protocols, abril de 2020. http://dx.doi.org/10.37766/inplasy2020.4.0174.

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Xie, Yirui, Yao Lin, Junbing He y Furong Lu. Revascularization Versus Apexification for the Treatment of Immature Necrotic Teeth based on periapical healing and root development outcomes：a systematic review and meta-analysis. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, septiembre de 2020. http://dx.doi.org/10.37766/inplasy2020.9.0013.

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Freund, F. Charge distribution analysis of catalysts under simulated reaction conditions. Technical progress report: Tenth quarter, January 1--March 31, 1995. Office of Scientific and Technical Information (OSTI), octubre de 1995. http://dx.doi.org/10.2172/113897.

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