Orientador: Pedro Duarte Novaes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-10T09:21:31Z (GMT). No. of bitstreams: 1 Neves_JulianadosSantos_M.pdf: 17773747 bytes, checksum: 861f7b8b208320f769d2c3c3c20302c5 (MD5) Previous issue date: 2008 / Resumo: Nos incisivos de ratos a face do alvéolo relacionada ao esmalte é continuamente reabsorvida do lado interno e neoformada no lado externo. Estudo realizado em nosso laboratório mostrou que em incisivos de ratos contidos por um período de 18 dias, há uma substituição de reabsorção óssea na face do alvéolo relacionada ao esmalte por neoformação óssea, onde osteoclastos foram substituídos por osteoblastos. CSF-1 e RANKL estimulam a proliferação e diferenciação de osteoclastos enquanto a OPG possui potente atividade inibitória da osteoclastogênese. O objetivo deste estudo foi analisar a distribuição e a intensidade do CSF-1, RANKL e OPG nos tecidos periodontais relacionados ao esmalte (PRE), de incisivos inferiores de ratos em erupção normal e após período de 18 dias de contenção, utilizando método imunohistoquímico e associando a análise quantitativa de osteoclastos. Quinze ratos Wistar machos tiveram seu incisivo inferior esquerdo imobilizado por meio de um fio de aço preso ao 1° molar inferior esquerdo por 18 dias. Quinze ratos com o incisivo esquerdo em erupção normal foram utilizados como controle. A taxa de erupção foi medida por meio de uma marca feita na face labial da coroa. No 18º dia de experimento os animais foram sacrificados e a região da crista alveolar do incisivo foi separada. Os incisivos de 12 ratos (6 controles e 6 contidos) foram fixadas e processadas para inclusão em Paraplast e reação imunohistoquímica foi realizada utilizando anticorpos primários anti-CSF-1, OPG e RANKL. A intensidade de marcação do folículo dentário foi quantificada através de medida da densidade óptica, utilizando o ¿software¿ de análise de imagens Leica QWin (Leica imaging systems, Cambridge, UK ) e ambos os grupos foram comparados pelo test t não-pareado. Para verificar a atividade osteoclástica, os incisivos de 18 ratos (9 controles e 9 contidos) foram fixadas e processadas para inclusão em Historesina e foram realizadas a evidenciação da fosfatase ácida resistente ao tartarato (TRAP) e a contagem de osteoclastos TRAP positivos presentes em toda a extensão do osso alveolar que circunda o esmalte. A contenção com fio de aço mostrou-se eficiente em imobilizar o incisivo. A diferença na quantidade de osteoclastos entre os grupos foi significante (p<0.001), sendo que no incisivo normofuncional a quantidade destes foi aproximadamente três vezes maior que no contido. Para o CSF-1 e OPG não houve, no folículo dentário, diferença estatisticamente significante na intensidade de marcação entre os grupos (p>0.05). Para RANKL o grupo contido apresentou-se com intensidade de marcação menor do que o normofuncional (p<0.01). As moléculas estudadas estavam presentes no PRE, da região da crista de incisivos inferiores de ratos, em erupção normal e contida, sendo que na condição contida houve uma diminuição na intensidade de RANKL e da quantidade de osteoclastos. Diante desta observação, podemos concluir que alterações nos tecidos que compõem o PRE no incisivo contido, modificam o balanço na relação RANKL/OPG alterando o metabolismo das células que participam da remodelação óssea / Abstract: In the rat incisors the face of the socket related to the enamel is resorpted continually on the inner side and formed on the outer side. A study accomplished at our laboratory showed that in rat incisors immobilized by a period of 18 days, there is a replacement of bone resorption in the face of the socket related to the enamel by bone formation, where osteoclasts were substituted by osteoblasts. CSF-1 and RANKL stimulate the proliferation and osteoclast differentiation while OPG has a potent osteoclastogenesis inhibitory activity. The aim of this study was to analyze the distribution and intensity of CSF-1, RANKL and OPG in periodontal tissues related to the enamel (PRE) of rat lower incisors, in normal eruption and after the period of 18 days of containment, using immunohistochemical technique and associating the quantitative analysis of osteoclasts. Fifteen male Wistar rats had their left lower incisor immobilized by means of a steel wire attached to the first left lower molar for 18 days. Fifteen rats with the left lower incisor in normal eruption were used as control. The eruption rate was measured using landmarks in the labial face of the crown. The animals were killed on day 18th and the region of the alveolar crest of the incisor was split. The incisors of 12 rats (6 control and 6 immobilized) were fixed and processed for embedding in Paraplast and immunohistochemical assay was accomplished using primary antibodies anti-CSF-1, OPG and RANKL. The immunostaining of the dental follicle was quantified by measure of the optical density, using the image analysis software Leica QWin (Leica imaging systems, Cambridge, UK) and both groups were compared by test t. To verify osteoclast activity, the incisors of 18 rats (9 control and 9 immobilized) were fixed and processed for embedding in Historesin and to make the tartrate resistant acid phosphatase (TRAP) evident. Osteoclasts TRAP positive in the whole length of the alveolar bone surrounding the enamel were counted. The incisor immobilization with steel wire was efficient. The difference in the number of osteoclasts between both rat groups was significant (p<0.001). In the normal incisor, the number of osteoclasts was threefold greater than in the immobilized tooth. In the dental follicle, there wasn't significant difference in the immunostaining intensity for CSF-1 and OPG between the groups (p>0.05). The immobilized incisor group showed immunostained intensity smaller than the normal incisor group (p <0.01). The studied molecules were present in PRE, in the region of the alveolar crest of rat lower incisor, in normal and immobilized eruption. There was a decrease in the intensity of RANKL immunostaining and in the number of osteoclasts in the immobilized condition. Hence, we concluded that changes in tissues of PRE, in the immobilized incisor, modify the RANKL/OPG ratio altering the metabolism of cells that participate in the bone remodeling / Mestrado / Histologia e Embriologia / Mestre em Biologia Buco-Dental

Orientadores: Livia Maria Andalo Tenuta, Jaime Aparecido Cury / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-15T10:27:51Z (GMT). No. of bitstreams: 1 Catani_DaniloBonadia_D.pdf: 3182260 bytes, checksum: 1cbcbeff9370ac4ee3fd869799aca3fe (MD5) Previous issue date: 2010 / Resumo: O efeito do fluoreto (F) no desenvolvimento de fluorose dental em animais expostos a doses crônicas constantes é bem conhecido, mas não há informações sobre o efeito de doses crônicas oscilantes, o que foi estudado neste trabalho. Além disso, não há estudos comparando diferentes métodos de quantificação de defeito de esmalte induzido pelo F, o que também foi avaliado. O estudo foi composto por três trabalhos. Foram utilizadas ratas fêmeas da linhagem Wistar com idade de 35 dias, as quais receberam água e ração ad libitum durante um período suficiente para permitir o completo crescimento dos incisivos (70 a 78 dias). Após, os animais foram anestesiados, o sangue foi coletado e os incisivos, mandíbulas e fêmures, removidos após a morte por hemorragia. A concentração de F no plasma, nos incisivos e nos ossos foi determinada usando um eletrodo íon específico. No primeiro estudo, 20 ratas foram divididas casualmente em 5 grupos: quatro grupos receberam água com concentrações constantes de F (0; 12,5; 25 ou 37,5 µg F/mL) e o outro grupo recebeu água contendo 12,5 e 37,5 µg F/mL, alternados a cada 72 h (média de exposição igual a 25 µg F/mL). Não foi observada diferença nas variáveis metabólicas e na gravidade de fluorose dental entre o grupo que recebeu doses oscilantes e o grupo que recebeu dose correspondente à média das oscilações (p > 0,05). No segundo estudo, foram utilizadas 58 ratas, as quais foram divididas casualmente em grupos expostos a diferentes concentrações de F na água (0 a 75 µg F/mL) constantes ou alternantes (12,5 e 75 µg F/mL) por períodos assimétricos (2 ou 8 dias). A exposição a doses oscilantes de F resultou em concentrações de F no sangue e ossos e fluorose dental semelhantes às observadas nos animais expostos à média das oscilações em função do tempo utilizado. No terceiro estudo, foram utilizadas 35 ratas, divididas casualmente em 7 grupos de 5 animais cada, que receberam água em concentrações crescentes de F: 0; 12,5; 25; 50; 62,5; 75 ou 100 µg F/mL. Os incisivos foram utilizados para avaliar 5 métodos de quantificação de fluorose: radiomicrografia, microdureza, microscopia de luz polarizada, análise de fluorescência e análise da imagem da superfície do esmalte segundo o padrão de bandas claras e escuras presentes na superfície do esmalte fluorótico de ratos. Radiomicrografia, microdureza e microscopia de luz polarizada só foram capazes de detectar fluorose sob altas concentrações de F (= 50 µg/mL) e a análise de fluorescência não permitiu diferenciação entre os grupos. A análise da imagem da superfície do esmalte foi satisfatória para quantificar fluorose, mesmo nas menores concentrações de F utilizadas nesse estudo, e foi utilizada para quantificar fluorose nos estudo subsequentes. Os resultados dos estudos sugerem que o efeito biológico da exposição crônica a doses oscilantes de F reflete a média do efeito das doses oscilantes de acordo com o tempo de exposição. A análise da imagem da superfície do esmalte se mostrou um método adequado para quantificar fluorose em incisivos de ratos. / Abstract: The effect of fluoride (F) on the development of dental fluorosis in animals chronically exposed to constant F doses is well known, but there is no information about the effect of chronic oscillating doses, and this was evaluated in the present study. Moreover, there are no studies comparing different methods of quantification of enamel defects induced by F, which was also evaluated. The study comprised of three experiments. Wistar female rats, aged 35 days, received water and food ad libitum during enough time to allow the full growth of the incisors (70 to 78 days). After, the animals were anesthetized, blood was collected and femurs, mandible bones and incisors were removed after their death by bleeding. F concentration in the blood plasma, bones and teeth was determined using ion-specific electrode. In the first study, 20 rats were randomly divided into 5 groups: four groups received water with constant F concentration at 0, 12.5, 25 or 37.5 µg F/mL and the other group received water containing 12.5 and 37.5 µg F/mL, which were alternated at each 72 h (mean exposure equals to 25 µg F/mL). No difference in metabolic variables and in severity of dental fluorosis between the group which received oscillating doses and the group receiving 25 µg F/mL was observed (p > 0.05). In the second study, 58 rats were randomly divided into groups which were chronically exposed to different F concentration in the water (0 to 75 µg F/mL), constant or oscillating (12.5 and 75 µg F/mL) for different periods of length (2 or 8 days). Exposure to oscillating F doses resulted in F concentrations in blood plasma and bones and enamel fluorosis similar to those observed in groups receiving F concentrations equal to the means of the oscillating range, according to the period length. In the third study, 35 rats were randomly divided into 7 groups of 5 animals, which received water at increasing F concentrations: 0, 12.5, 25, 50, 62.5, 75 or 100 µg F/mL. Incisors were used to assess fluorosis using five quantification methods: transverse microradiography, cross-sectional microhardness, polarized bright microscopy, quantitative light-induced fluorescence and image analysis of the enamel surface based on the pattern of white and dark bands present on rat fluorotic enamel. Transverse microradiography, cross sectional microhardness and bright field microscopy were only able to detect the fluorotic defect in the rat incisor when high F concentrations (= 50 µg F/mL) were used and quantitative ightinduced fluorescence analysis did not allow the differentiation among the groups. The image analysis method of the enamel surface was satisfactory to quantify dental fluorosis, even at low F concentrations, and was used to evaluate fluorosis in the subsequent studies. The present study suggests that the biological effect of F when an animal is exposed chronically to oscillating F doses may reflect the effect of the mean of the oscillating doses, according to exposure length. The image analysis of the enamel surface was a suitable method to quantify enamel fluorosis in rat incisors. / Doutorado / Saude Coletiva / Doutor em Odontologia

A thesis submitted to the College of Dental Medicine of Nova Southeastern University of the degree of Master of Science in Dentistry. Objective: This study was conducted to examine the changes in the inclination of mandibular incisors and their alveolar bone dimensions between pre- and post- non-extraction orthodontic treatment, measured using cone beam computed tomography (CBCT) images. The study measured the association of the pre- and post- labial and lingual bone measurements with the pre- and post- treatment incisor inclination by comparing the incisor-mandibular plane angle (IMPA). Background: Teeth move through bone by extensive osseous adaptation within the alveolar process. It is a common belief in orthodontics that alveolar bone follows tooth movement. As a tooth moves, bone will remodel around the alveolar socket usually in a 1:1 ratio of bone resorption to bone apposition. However, conflicting evidence in the orthodontic literature questions whether the anterior alveolar bone is able to remodel and follow the direction and quantity of tooth movement. Many studies have shown that the width of the alveolar bone and the lingual and labial cortical plates set limitations on how much anterior tooth movement can be accomplished without negative effects such as periodontal problems, root resorption or fenestrations. Methods: Pre- and post- non-extraction orthodontic treatment CBCT scans of twenty Class I molar patients with mild to moderate crowding were used to observe the buccal and lingual width and incisor inclination of each of the patient's four mandibular incisors. The labial and lingual alveolar bone dimensions were measured pre-treatment and post-treatment at 6 mm apical to the CEJ and at the apex of each tooth. The inclination of the incisors (using IMPA) of both time points was also documented. Results: A Fisher's exact test and a Cramer's V test were performed. The results showed statistical significance between the change in bone of the incisors and the change in their inclination at the buccal 6mm, buccal apex, lingual 6mm and lingual apex. There was also statistical significance found between the change in bone between the buccal apex and lingual apex of the LR1, LR2, LL1, and LL2. Conclusion: Our results showed that the change in bone of the lower incisors is correlated to the change in their inclination. This suggests that incisors were tipped within the confines of the mandibular anterior alveolar process, or the alveolar process bent and remodeled around the incisors in the same direction of tooth movement or a combination of the two.

Syfte: Att utvärdera reliabiliteten för bedömning av infraposition av implantatförankrade incisiver i överkäken för två tidigare beskrivna metoder och en ny metod. Material och metod: I studien ingick 11 implantatstödda singelkronor i överkäkens framtandsområde från 10 patienter. Studiematerialet omfattade studiemodeller, intraorala kliniska fotografier periapikala röntgenbilder från baseline och uppföljning. En radiologisk metod, ett estetiskt index och en ny metod som använde kliniska fotografier och studiemodeller, användes för att utvärdera infraposition. Sex observatörer, en oral radiolog, en parodontolog/protetiker och fyra tandläkarstudenter utförde bedömningar med samtliga metoder vid två tillfällen. Inter- och intraobservatörs-överensstämmelsen analyserades med hjälp av Cohen’s kappa, viktat kappa, IRR och ICC. Resultat: Högst intra-observatörsöverensstämmelse erhölls då nya metoden användes (ICCmin-max 0,760-0,910) och lägst med radiologiska metoden (ICCmin-max 0,073-0,830). Inter-observatörsöverensstämmelsen var högst då den den nya metoden användes (ICC 0,67) och lägst avseende estetiskt index (viktat kappa 0,234). Utifrån vårt resultat hade specialisterna högre överensstämmelse med varandra jämfört med studenterna för den radiologiska metoden medan studenterna hade högre överensstämmelse med det estetiska indexet. För den nya metoden var jämförelse mellan observatörsgrupperna ej möjlig pga att data saknades.Slutsats: Vårt resultat indikerar att de tidigare beskrivna metoderna har låg reliabilitet, framförallt mellan observatörerna. Dock visar den nya metoden hög reproducerbarhet och därmed är reliabiliteten mycket god. Därför kan nya metoden passa för att mäta graden av infraposition hos implantatförankrade maxillära incisiver. Huruvida uppmätt infraposition är sannolik kan inte säkerställas med mindre än att en referensmetod finns att tillgå. / Aim: To evaluate reliability of two previously described methods and one newly developed method in assessment of infraposition of implant supported maxillary incisors. Material and method: A retrospective material consisting of periapical radiographs, study casts and intraoral photographs from baseline and follow-up from 10 patients with 11 implant-supported crowns in maxillary incisor position, was used. Six raters: one oral radiologist, one prosthodontist/periodontist and four dental students, independently assessed infraposition with three methods (radiographic method, aesthetic index and a new method based on clinical photographs and study casts). Reevaluation was performed after at least two weeks. Inter-and intrarater agreement was calculated with Cohen’s kappa, weighted kappa, IRR and ICC.Results: The highest intrarater agreement was achieved using the new method (ICCmin-max 0.760-0.910) and the least with the radiographic method (ICCmin-max 0.073-0.830). Highest interrater agreement was achieved using the new method (ICC 0.67) and the least with the aesthetic index (weighted kappa 0.234). According to our findings specialists had higher agreement than students in the radiographic method whereas students had higher agreement in the aesthetic index. In the new method this comparison was not possible due to missing data.Conclusions: Our findings indicate a low reliability for the two previously described methods. However, assessments with the new method are reproducible which imply a very good reliability. Therefore the new method may be suitable for evaluating infraposition of implant supported maxillary incisors. Whether observed infraposition is close to the truth cannot be evaluated until a reference method has been proposed.

Le shoveling de l'incisive centrale maxillaire est une caractéristique dentaire non-métrique utilisée en anthropologie comme indicateur des relations entre les populations. Ce trait morphologique dentaire est défini comme le degré d'élévation des crêtes mésiales et distales marginales sur la surface linguale des incisives maxillaires avec des formes plus prononcées renfermant une fosse. Plusieurs tentatives ont été faites pour classer et évaluer les différences de shoveling entre les populations humaines modernes et fossiles, en utilisant d'abord des approches descriptives détaillées et en élaborant par la suite des systèmes de notation ordinale des traits. A ce jour, la technique gold standard pour l'analyse du shoveling est basée sur une échelle ordinale de sept grades qui a été adaptée et intégrée à un système formel de notation des traits non métriques de la morphologie dentaire: le Arizona State University Dental Anthropology System (ASUDAS). Ce protocole standard est basé sur des plaques de plâtre de référence représentant les moulages de dents sélectionnées montrant un gradient d'expression d'un trait particulier. La notation ordinale, même si elle est contrôlée par des définitions strictes des caractéristiques, des références visuelles et l'expérience de l'observateur, comprend une part inévitable de subjectivité. De plus, les supports d'information conventionnels utilisés par ASUDAS peuvent entrainer des pertes d'information dans le temps. Dans un premier temps, nous avons élaboré une nouvelle approche morphométrique quantitative pour évaluer la variation du shoveling des incisives centrales maxillaires humaines modernes (UI1). Nous avons analysé par imagerie virtuelle 87 UI1 humaines modernes (Europe, Afrique, Asie) et les 7 UI1 de la plaque de référence ASU-UI1 en utilisant la morphométrie géométrique et le positionnement de points de repères glissants. Les résultats de la répartition du shoveling en fonction des populations selon notre nouvelle méthode morphométrique sont en étroite corrélation avec la répartition du shoveling largement décrite dans la littérature. En outre, nos résultats ont mis en évidence certaines limites dans l'utilisation des plaques ASUDAS, laissant supposer qu'elles ne représentent pas nécessairement un gradient objectif d'expression de cette caractéristique dentaire non métrique. [...] / The shoveling of the maxillary central incisor is a non-metric dental characteristic frequently used in anthropology as an indicator of population relations for its taxonomic and phylogenetic relevance for many decades. This dental morphological feature is defined as the degree of elevation of the mesial and distal marginal ridges on the lingual surface of the maxillary incisors, canines and mandibular incisors, with more pronounced pit-like forms. From the 19th century until today, several attempts have been made to classify and assess the shoveling differences between fossil and modern human populations, first using detailed descriptive approaches and later developing ordinal feature notation systems. The standard gold technique for shoveling analysis is based on a seven-grade ordinal scale that has been adapted and integrated into a formal system for scoring non-metric features of dental morphology: the Arizona State University Dental Anthropology System (ASUDAS). This widely-used standard protocol is based on reference plaster plaques representing the casts of selected teeth showing a gradient of expression of a particular trait. Ordinal notation, even if controlled by strict definitions of characteristics, visual references, and observer experience, includes an inevitable element of subjectivity. Moreover, the conventional information support used by ASUDAS can lead to loss of information over time. Some researchers have attempted to reduce visual subjectivity by measuring the depth of lingual shoveling, but with little success in their results due to method accuracy problems. First, we developed a new quantitative morphometric approach to assess the shoveling variation of modern human maxillary central incisors (UI1). We analyzed by virtual imaging 87 modern human UI1 (Europe, Africa, Asia) and the 7 UI1 of the ASU-UI1 reference plaque using geometric morphometry and the positioning of sliding reference points. The results of the distribution of shoveling according to populations according to our new morphometric method are in close correlation with the distribution of shoveling widely described in the literature. In addition, our results showed some limitations in the use of ASUDAS plaques, suggesting that they do not necessarily represent an objective gradient of expression of this non-metric dental characteristic. [...]

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Some African mole-rats of the family Bathyergidea have dramatically different ecological niches which may cause selective anatomical adaptations. Bathyergus suillus lives in sandy soil and eats a wide range of food whereas Georychus capensis is restricted to the mountainous hard soil and eats mainly geophytes. Georychus capensis is considered a chisel-tooth digger in that it uses its incisors to dislodge soil while Bathyergus suillus is a scratch-digger that uses both its incisors and large front paws to dislodge soil. The purpose of this study was to compare certain aspects of the masticatory anatomy of Bathyergus suillus and Georychus capensis. In particular the question that drives this study is: Do the differences in ecology of the two species reflect in the anatomical adaptation of their masticatory apparatus? Nine whole body specimens of each species were obtained for this study. The masticatory apparatus of each specimen was dissected, examined and analysed.Selected bones of their skulls were investigated to determine their gross morphology. Digitalized images were captured by a high-resolution Olympus digital camera and were analysed by DOCU analysis software, in order to determine the morphometric parameters. In addition, the cleaned skulls of each species were weighed with a chemical balance. In order to make the comparison of the four muscles of mastication more effective than when using only their linear measurements, the mass (in grams) of each skull was divided by the length of each metric traits squared in order to yield their respective indices. Various statistical tests were used.This study has thus revealed some dissimilarities between the two species.Comparison of the two species reveals that one of the more distinguishing differences between the two is their upper incisors. There are also significant differences in the morphology and dimensions of their angular plates. And the external pterygoid muscle is significantly larger in Georychus capensis than in Bathyergus suillus, there are no significant differences between the others of the masticatory muscles of the two species.The feeding and foraging activities of Bathyergus suillus as well as Georychus capensis have close relationship with their lifestyles (digging abilities and adaptations). Bathyergus suillus is predisposed to dig with its incisors as well as its large front paws, and the range of food is large, whereas Georychus capensis uses its incisors only to dig, and the range of food is limited. Subsequently the skull of Bathyergus suillus is bigger than Georychus capensis. But, due to the environment of the latter, strong incisors are needed to perform its feeding and digging activities. The investigation thus reveals that the two selected species have successfully adapted their anatomical masticatory elements to their environments.

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Ce mémoire présente une analyse tracéologique, c’est-à-dire l’analyse fonctionnelle d’un objet à partir des microtraces d’usure, appliquée à une collection d’incisives de castor issue des sites iroquoiens de la région de Saint-Anicet: McDonald, Droulers et Mailhot-Curran. L’objectif est de mieux comprendre la fonction de ces objets fréquents sur les sites archéologiques iroquoiens, étant donné que la fonction précise est soit inconnue, soit présumée de façon spéculative. Pour répondre à cette question de recherche, l’analyse se déploie en trois volets : expérimental, analytique et comparatif. Le premier permettra d’éclairer la relation entre différentes matières travaillées et les traces laissées sur les outils en incisives de castor, ainsi que les mouvements effectués et la durée d’utilisation. Le deuxième volet aborde la tracéologie des incisives de castor de nos trois sites à l’étude, à partir des résultats des expérimentations. Le troisième volet de l’étude est dédié à la comparaison inter-sites. Ce projet permet de déterminer à quelles activités les outils sur dents de castor des collections ont servi, puis de comprendre les choix qui les sous-tendent. Cela permet donc de mieux comprendre l’humain derrière l’objet. Les résultats des analyses ont permis de démontrer l’utilisation des incisives de castor iroquoiennes comme outils servant à travailler le bois, mais plus spécifiquement comme outils servant à travailler des bois verts, tendres et mi-durs. De plus, il a été confirmé que les incisives de castor à double fonction, ciseau-racloir, sont le résultat d’outils recyclés ou réutilisés qui servaient à des usages divers. / This dissertation presents a traceological analysis, that is to say the functional analysis of an object based on microtraces of wear, applied to a collection of beaver incisors from Iroquoian sites in the Saint-Anicet region. : McDonald, Droulers and Mailhot-Curran. The goal is to better understand the function of these common objects at Iroquoian archaeological sites, given that the precise function is either unknown or speculated speculatively. To answer this research question, the analysis is deployed in three parts: experimental, analytical and comparative. The first will shed light on the relationship between different materials worked and the traces left on beaver incisor tools, as well as the movements made and the duration of use. The second part addresses the traceology of beaver incisors from our three sites under study, based on the results of the experiments. The third part of the study is dedicated to the inter-site comparison. This project makes it possible to determine what activities the beaver tooth tools in the collections were used for, then to understand the choices behind them. This therefore allows us to better understand the human behind the object. The results of the analyzes demonstrated the use of Iroquoian beaver incisors as tools for working wood, but more specifically as tools for working green, soft and semi-hard wood. Furthermore, it was confirmed that the double-function beaver incisors, chisel-scraper, are the result of recycled or reused tools that were used for various purposes.

The purpose of this research was to investigate the influence of height, crosssection and metal alloy in the mechanical act of teardrop loops used in incisors retraction and in en masse retraction of incisors and canines, aiming analyze the mechanical behavior of these loops in relation to optimum forces presented in the literature. Two hundred and forty loops were submitted to a tensile load on the testing machine considered heights of 6mm, 8mm and 10mm; cross-sections of 0.018in.x 0.025in and 0.019in.x 0.025in and wire materials of stainless steel and beta-titanium alloys. It was obtained magnitudes of horizontal force (N) and load-deflection (N/mm) for each loop across activations of 0.5mm, 1mm, 1.5mm, 2mm and 2.5mm. The results showed that height (p<0.01), cross-section and metal alloy (p<0.05) were considered significant factors with reference to horizontal force and load-deflection. There was no influence of one factor but a combination of these trying to achieve very light forces. This study suggest that is necessary a large orthodontic biomechanics knowledge with respect to loops design used in incisors retraction and in en masse retraction of incisors and canines, selecting adequate height, crosssection and metal alloy. / O objetivo desta pesquisa foi investigar os efeitos da altura, secção transversal e tipo de liga no desempenho mecânico de alças confeccionadas em forma de gota, indicadas para a retração de incisivos e para a retração em massa de incisivos e caninos, buscando avaliar o comportamento das mesmas em relação às magnitudes de força ótima existentes na literatura. Foram submetidas a um ensaio mecânico 240 alças, considerando as alturas de 6mm, 8mm e 10mm; as seções transversais de 0.018 x 0.025 e de 0.019 x 0.025 e as ligas de aço inoxidável e beta-titânio (TMA). Foram obtidos valores de força horizontal (N) e carga-deflexão (N/mm) para cada alça mediante ativações de 0.5mm, 1mm, 1.5mm, 2mm e 2.5mm. Os resultados mostraram que a altura (p<0.01), a secção transversal e a liga (p<0.05) foram consideradas fatores significativos na força horizontal e cargadeflexão gerada. Não houve influência de um fator sobre os demais, mas sim, uma combinação destes, buscando atingir forças muito leves. Este estudo sugere que é necessário amplo conhecimento da biomecânica ortodôntica na confecção de alças direcionadas para a retração dos dentes anteriores, selecionando adequadamente a altura, a secção transversal e a liga.