Thesis (M.S.)--University of Michigan, 1971.

Thesis (M.S.)--University of Michigan, 1983.

Thesis (M.S.)--University of Michigan, 1990.

Thesis (M.S.)--University of Michigan, 1983.

Thesis (M.S.)--University of Michigan, 1984.

Thesis (M.S.)--University of Michigan, 1986.

Thesis (M.S.D.)--Indiana University School of Dentistry, 2009. / Title from PDF t.p. (viewed Aug. 11, 2009) Advisors: Mychel Vail, Chair of the Research Committee, Susan Zunt, Ted Parks, Kenneth Sponik, Joseph Legan. Curriculum vitae. Includes abstract. Includes bibliographical references (leaves 103-119).

Made available in DSpace on 2014-06-11T19:28:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-03-06Bitstream added on 2014-06-13T19:57:18Z : No. of bitstreams: 1 mata_ac_me_arafo.pdf: 2416610 bytes, checksum: 9bdfde5af83d681b15e0d7f7fbd1fde9 (MD5) / O objetivo deste trabalho foi avaliar, in vitro, a capacidade do cloridrato de tetraciclina, na remoção da smear layer radicular formada após raspagem e aplainamento, em diferentes concentrações, tempos e modos de aplicação. Amostras foram obtidas das superfícies radiculares de dentes extraídos de humanos, sendo submetidos à instrumentação rotatória e raspagem e aplainamento radicular previamente a aplicação do agente condicionante. O cloridrato de tetraciclina foi aplicado por contato ou por fricção com bolinhas de algodão trocadas a cada 30 segundos, em diferentes concentrações: 50, 125, 250 e 500 mg/ml e em diferentes intervalos: 1, 2 e 3 minutos. O grupo controle consistiu de aplicação de soro fisiológico nos mesmos modos e tempos dos grupos testes. Concluímos que: -as concentrações de 125 e 250 mg/ml de tetraciclina foram as que apresentaram os melhores resultados na remoção da smear layer; - a aplicação por fricção mostrou ser mais eficiente na remoção da smear layer; - os resultados não foram tempo-dependentes. Quando verificou-se as variáveis conjugadas, a concentração de 50 mg/ml sob fricção por 1 minuto e a concentração de 125 mg/ml sob fricção por 1 minuto foram as que apresentaram os melhores resultados. / The goal of this study is to assess the capacity of tetracycline HCl in removing -in vitro, in different concentrations, during different intervals and according to different modes of application-radicular smear layer resulting from scaling and planing root surfaces of human extracted teeth, which had been, previously, submitted to rotary instrumentation. Cotton pellets, soaked in a solution of tetracycline HCl, in concentrations of 50, 125, 250, or 500mg/ml, were either gently placed or rubbed on the prepared root surfaces for either one, two or three minutes. Pellets were changed every 30 seconds. The control group consisted of applying physiological serum during the same intervals and according to the same modes of application of those used for the testing-groups. As a conclusion, the strongestly recommended concentrations of tetracycline for removing radicular smear layer were the ones of 125 and 250 mg/ml; that rubbing root surfaces proved to be the most efficient on the removal of radicular smear layer; and that the results reached in the present study were not time-dependent. When all assessment criteria were simultaneously applied, the best results derived not only from rubbing the prepared surfaces in a concentration of 50 mg/ml of tetracycline HCl, during one minute, but also from rubbing them in a concentration of 125 mg/ml of tetracycline HCl, during one minute.

Made available in DSpace on 2016-06-07T17:12:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-06-26. Added 1 bitstream(s) on 2016-06-07T17:16:54Z : No. of bitstreams: 1 000865438.pdf: 1339128 bytes, checksum: 7300f58841dc06da4c66d44d8c2fbe47 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo no presente estudo foi avaliar, in vitro, a influência do comprimento do pino de fibra de vidro na resistência à fratura de raízes submetidas a diferentes níveis de fragilização. Noventa incisivos bovinos, de dimensões semelhantes, tiveram as coroas removidas e foram instrumentados, obturados e divididos aleatoriamente em 9 grupos (n =10), de acordo com o protocolo de fragilização (SF - sem fragilização; FM - fragilização moderada; FS - fragilização severa) e o comprimento do pino utilizado (7 mm; 9 mm e 12 mm). Os canais foram preparados para o retentor e, nas raízes fragilizadas, os mesmos foram individualizados com resina composta. Foi utilizado um cimento resinoso quimicamente ativado para a cimentação de todos os pinos. Após a cimentação, foi feita reconstrução coronária com resina composta, com base em matrizes de silicone padronizadas. Para reprodução da mobilidade fisiológica, a porção radicular foi coberta com poliéter e incluída em poliuretano. A ciclagem termomecânica foi realizada sob cargas de 88 N em 1.200.000 ciclos, com frequência de 3,8 Hz. Para determinação da resistência à fratura, as amostras foram posicionadas a 45 ° em uma máquina de ensaios universal, com célula de carga de 100 Kgf e velocidade de 1 mm/min. Após o ensaio mecânico, os espécimes foram analisados em estereomicroscópio para classificação do tipo de fratura gerada (reparável/irreparável). Os valores de resistência obtidos foram submetidos a análise estatística ANOVA - dois fatores e teste de Tukey (nível de significância de 5%). As frequências dos tipos de fratura foram comparadas pelo teste qui-quadrado. Os resultados da ANOVA revelaram que a associação entre o comprimento do pino e a fragilização foi estatisticamente significante (p < 0,05). O teste de Tukey indicou que esta diferença foi entre as raízes não fragilizadas e com maior... / The aim in this study was to evaluate, in vitro, the influence of glass fiber posts of different lengths on the fracture resistance of roots submitted to different weakening protocols. Ninety bovine roots, of same dimensions, were endodontically treated and randomly distributed in 9 groups (n =10), according the weakening protocol (NW - non-weakened; MW - medium-weakened; HW - hard-weakened) and the post length (7 mm; 9 mm e 12 mm). The canals were prepared for the posts and, on the weakened roots, they were individualized with composite resin A chemically activated resin cement was used in all posts. After luting, coronary reconstruction was conducted with composite resin, based on standardized silicon matrix. To reproduce physiological mobility, root portion was covered by polyether and embedded in polyurethane. The thermomechanical cycling was realized under a load of 88 N at 1.200.000 cycles, with a frequency of 3.8 Hz. For the resistance of fracture analysis, the specimens were placed at 45 ° in a universal testing machine, with a load-cell of 100 Kgf, with speed of 1mm/min. After mechanical essay, the specimens were analyzed by stereomicroscope to classify the failure mode (reparable/irreparable). Numerical values (n = 10) obtained for specimens' fracture were subjected to statistical analysis ANOVA two-way and Tukey test (5% of significance). The frequencies of failure mode were compared by chi-square test. ANOVA showed that the association between length and weakening was statistically significant (p < 0.05). The post-hoc Tukey's test revealed that this difference was between NW and HW roots for posts of 12-mm in length. Chi-square test indicated association between failure mode and the length and weakening factors. It was concluded that highly-weakened roots with longer posts had lower fracture resistance values, as catastrophic mode was more predominant

Abstract Studies on families and individuals with sex chromosome abnormalities and 46,XY females, together with molecular research, have provided proof that both X and Y chromosome genes are expressed in human tooth crown growth. The Y chromosome promotes the formation of both permanent tooth crown enamel and dentin, whereas the effect of the X chromosome is seen mainly in enamel formation. In particular, the effect of the Y chromosome on dentin formation explains the expression of sexual dimorphism in crown size. When crown growth is complete, root dentin is formed and requires proliferation of epithelial cells in Hertwig's epithelial root sheath to initiate the differentiation of root odontoblasts. These epithelial cells determine the size, shape and number of the roots. There is a clear sex difference in tooth crown sizes, men have larger teeth than women. The aim of this research was to study completed permanent tooth root lengths in individuals with sex chromosome abnormalities and 46,XY females, an approach which might also provide some clues for a further insight into the development of sexual dimorphism in human growth. The underlying hypothesis was that the effect of the X and Y chromosomes on crown growth is also expressed in root growth. The subjects were participants of L. Alvesalo's research project, Kvantti, and comprised 45,X/46,XX females, 47,XYY and 47,XXY males and female sex reversals with insensitivity to androgens (46,XY females). The root lengths were measured from dental panoramic radiographs with a sliding digital calliper. All available teeth (except third molars) with complete root formation on both sides of the jaws were measured. The results showed longer final permanent tooth root lengths in 47,XYY and 47,XXY males, while the roots in 45,X/46,XX females were shorter compared with the values of normal men and women, respectively. The root lengths of 46,XY females were longer compared to normal women and placed on a level with normal men. The root morphology did not reveal any major deviations from normal variation. In terms of population dental developmental standards it is conceivable that changes in these study groups in final size of their permanent tooth roots become evident during a period beginning eight years after birth and continuing up to the age of 14 years, at least. It became clear that the effect of the Y chromosome on tooth root growth is greater than that of the X chromosome, and this may cause the observed sexual dimorphism, males having longer roots than females. It is suggested that root growth may be affected by the same genes on the X and Y chromosomes which promote crown growth.