Thesis (M.Orth.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 104-110). Also available in print.

Thesis (M.Orth.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 122-127). Also available in print.

Thesis--Göteborg. / Extra t.p. with thesis statement inserted. Includes bibliographical references (p. 43-44).

Includes bibliographical references. Aims to develop a suitable method to measure friction generated under various orthodontic appliance simulations.

Made available in DSpace on 2014-06-11T19:27:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-03-27Bitstream added on 2014-06-13T19:36:11Z : No. of bitstreams: 1 sakima_cgp_me_arafo.pdf: 875892 bytes, checksum: 0b407b85b7e24386d401869c06430798 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A possibilidade de usar fios superelásticos retangulares com níveis de força mais leves (biológicos) permitiria simultâneo alinhamento, nivelamento e torque, o que resultaria em um menor número de fios utilizados, reduzindo custos e tempo de tratamento. Existe uma tendência, principalmente na ortodontia lingual, de se dobrar fios superelásticos (manualmente ou com tratamento térmico/elétrico) para adequar o fio à forma do arco. O objetivo deste trabalho foi avaliar as propriedades mecânicas de fios de NiTi de quatro marcas comerciais diferentes (0,017 x 0,025) após dobras e tratamento elétrico. Os fios foram dobrados com alicates elétricos (sistema DERHT) e com alicate 139 e depois foram comparados com fios retos sem nenhum tratamento (grupo controle) e fios retos com tratamento elétrico sem dobras (grupo controle tratamento elétrico). Na tentativa de simular uma situação clínica, todos os fios foram testados a 36oC na máquina de testes FSI (Sistema Identificador de Forças). Foram testados usando-se braquetes autoligáveis tipo Damon, simulando ativações em segunda ordem de 0 mm a 2 mm. Foram analisadas as seguintes variáveis: força e deslocamento no ponto do limite elástico, força máxima, energia total, energia dissipada, energia perdida, força e deslocamento no início e no fim do platô, inclinação e comprimento do platô. As diferenças estatísticas para os diferentes fios, nos diferentes testes, foram avaliadas pela ANOVA. Os resultados mostraram que: (1) o tratamento elétrico afetou as propriedades mecânicas de todos os fios de maneira geral, existindo uma tendência de diminuição nos níveis de força; (2) quando os fios receberam dobras, todos perderam os platôs de superelasticidade; (3) se o uso de forças leves e constantes é desejável no tratamento ortodôntico, os fios termodinâmicos deveriam ser recomendados na seguinte ordem: Copper NiTi 400, Neo Sentalloy 100 e Copper NiTi 270. / The possibility of using superelastic rectangular Nickel-Titanium wires in early stages of treatment with light forces, could allow more three-dimensional control, a small number of wires, lowering costs and treatment time. There is a tendency, especially in lingual orthodontics of bending superelastic wires (manually or with heat treatment) to adequate the wire in the arch anatomy. The aim of this study was to evaluate the mechanical properties of four commercially available 0.017 x 0.025 inch NiTi archwires after bending and heat treatment. The wires were bent with electrical pliers (DERHT System) and with standard bird beak plier and then compared with straight wires as a control group and another electrical treatment control group. All the wires were tested at 360 C in an orthodontic wire-testing device, a so called Force System Identification (FSI) apparatus. In the FSI a two-bracket system using self ligating Damon brackets simulated second order displacements up to 2 mm. The following variables from the activation/deactivation curves were calculated: force and displacement at yield point, maximum force level, total energy up to maximum displacement, energy loss after deactivation, force and displacement at the beginning and at finish of the plateau, and the slope and length of the plateau. Any statistically significant differences in these variables for the different brands and tests were analyzed using one-way analysis of variance. The results showed that: (1) the electrical treatment affected the characteristics of all the wires tested in a different way but with a tendency of lowering the force levels. (2) When the wires were bent they all lost activation and deactivation plateau of superelasticity. (3) If the use of low and constant force levels are desirable in orthodontic treatment, the thermodynamic wires should be recommended in the following order: Copper Niti 400 , NeoSentalloy 100 and Copper Niti 270.

Orientador: Eduardo César Almada Santos / Banca: Liliana Ávila Maltagliata / Banca: Francisco Antonio Bertoz / Resumo: Estabilidade da colagem dos acessórios ortodônticos durante o tratamento pode ser influenciado por vários fatores, dentre eles, o sistema de colagem eleito e o0 tipo de bráquete. Frente à importância de se elucidar ao máximo possível a respeito destas variáveis, esta pesquisa foi encetada com o propósito de comparar in vitro a resistência ao cisalhamento de bráquetes metálicos ortodônticos (AbZIL-LANCER) com bases em malha convencional e bráquetes com bases em malha pré-tratadas industrialmente com jateamento de óxido de alumínio. Para a realização deste trabalho, duzentos e quarenta incisivos bovinos foram selecionados e divididos aleatoriamente em seis grupos de quarenta cada (n = 40), segundo o tipo de base do bráquete e o material de colagem utilizado. Os acessórios (AbZIL.LANCER) foram diretamente colados nos dentes bovinos com três sistemas adesivos: Sistema A - resina fotopolimerizante Transbond XT convencional (3M - Unitek, St Paul, Mn, U.S.A.); Sistema B - TransbondTM Plus Self Etching Primer (SEP) + Transbond XT (3M - Unitek, St Paul, Mn,U.S.A.) e Sistema C - cimento de ionômero de vidro resinoso Fuji ORTHO LC em cápsulas (GC Corp., Tokyo, Japan). Os testes de cisalhamento foram realizados 24 horas após a colagem dos bráquetes, utilizando uma máquina universal de ensaios DL-3000 (EMIC - Equipamentos e Sistemas de Ensaio Ltda.), utilizando célula de carga de 200 Kgf e velocidade de 1mm/min. Os resultados obtidos foram submetidos aos testes estatísticos ANOVA a dois critérios e TUKEY, ambos em nível de significância a 5%. A análise estatística demonstrou não haver diferenças estatisticamente significante entre os resultados dos testes de cisalhamento das bases comparadas. Contudo, os valores encontrados revelaram diferenças espressivas no desenpenho dos sistemas de colagem, tendo o Sistema A - (14,92MPa) apresentado os resultados mais satisfatórios...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Despite of the high-quality materials for orthodontic bonding have, an ideal bonding system has not been developed yet. The aim of this study was to test shear bond strength of two types of brackets bases. Two hundred and forty bovine incisors were randomly divided into 6 groups, according to the type of foil mesh (sandblasted or not) and the bonding materials. Brackets (AbZIL.LANCER) were directly bonded to teeth with 3 different bonding systems: System A - light-cured resin TransbondTM XT conventional XT (3M-Unitek, St Paul, Mn, U.S.A.); System B -TransbondTM XT + TransbondTM Plus Self Etching Primer (3M-Unitek, St Paul, Mn, U.S.A.) and System C - reinforced glass ionomer orthodontic cement Fuji ORTHO LC in capsules (GC Corp., Tokyo, Japan). The tests were performed 24 hours after bonding procedure in a DL 3000 (EMIC) testing machine, with a load cell of 200 Kgf in a 1mm/min speed. Results were analyzed by ANOVA and TUKEY tests at 5% of significance level. There were no statistical differences between the two types of brackets. However, there were statistical differences related to the bonding materials. Tukey's test revealed that System A presented the best shear bond strength (14,92MPa), followed by Systems B (10,66MPa) and C (13,24MPa), but there were not significantly differences between Systems A... (Complete abstract, click electronic address below) / Mestre

Doctor Educationis / The need for in-depth knowledge of dental emergence and calcification in orthodontic diagnosis and treatment planning cannot be disputed. Serial extractions, treatment timing, bite opening and closing, expansion and various other orthodontic procedures cannot be successfully executed without an in depth knowledge of the calcification and eruption of teeth. Besides its orthodontic implications, dental calcification and eruption plays a significant role in physical anthropology, forensic odontology, endocrinology and nutrition (Demirjian, 1978). Forensic scientists are agreed that teeth constitute the most important and reliable means for determining age from approximately 10 week in utero to old age (Altini, 1983). It is a generally accepted fact that there is no correlation between biological age and chronological age (Prahl-Andersen and Van der Linden, 1972; Demirjian, 1978), an aspect, which will be discussed in further detail later in the review of the literature. Biological age is seen to be a more accurate indicator of an individuals maturity than chronological age (Moorees et al, 1963; Prahl-Andersen and Van der Linden, 1973; Oemirjian et al, 1973). However, allocating a biological age to an individual is not an easy exercise as no definite consensus has, to date, been reached regarding the best method of determining biological age (Moorees et al, 1963; Garn et al, 1967; Demirjian, 1978). Today, many different methods are being used to establish this, for example bone age, height, menarche, circumpubertal growth and dental age.

Indiana University-Purdue University Indianapolis (IUPUI) / A study was made to ascertain the effect of heat treatment, at a time-temperature ratio of three minutes at 900 F., on orthodontic 18-8 and Elgiloy steel wire with respect to the followings a) the ability of a vertical loop to resist permanent deformation when subjected to a tensile load; b) the effect of heat treatment on ductility of a steel orthodontic wire; c) the effect of heat treatment on the warpage of a orthodontic wire which has previously been formed. A standardized nine millimeter vertical loop was incorporated in the wire. Weights in increments of 100 grams were suspended from one end of the wire while the other end was firmly held in a vice. Permanent deformation as a result of a given load was determined by the amount of permanent opening of the vertical loop. The force just necessary to produce a permanent opening of the vertical loop is defined as the proportional limit. The ability of Elgiloy to resist permanent deformation due to heat treatment is enhanced as much as 66 percent. On the other hand, Elgiloy heat treatment produces the undesirable side effect of reducing ductility i.e., as high as 77 percent reduction in ductility following heat treatment. Therefore a Elgiloy steel wire cannot be altered in shape to any great extent after heat treatment. Eighteen-eight type 304 steel wire, when subjected to the same treatment, shows an increased ability to resist permanent deformation i.e. a 39 percent increase in proportional limit following heat treatment. It is significant that ductility, as determined by the cold bend test, is not significantly affected by heat treating 18-8 steel wire. The latter phenomena supports the claim of many investigators that 18-8 steel is not capable of a true heat treating transformation and therefore any improvements in elastic properties as a result of heat treatment can be considered to be due to a stress-relieving process. Ductility, as determined by the cold bend test, was found to be a highly variable property. Large variations in ductility were even found in the same feet-length of wire. Both 18-8 and Elgiloy steel wire exhibit this phenomena. Following heat treatment of Elgiloy a reduction in the variability of ductility was noted in all the wires tested. The effect of heat treatment on warpage of a previously shaped orthodontic steel wire was studied by incorporating a right angle bend in the center of a four inch section of wire. After a three week storage at a constant temperature of 98.6m to simulate mouth conditions, the angles were again measured. Any alteration in degrees from the right angle was considered to be indicative of warpage. Heat treated wires were compared to non-heat treated. Heat treatment appears to increase warpage in orthodontic steel wires; however, because of large variations no conclusive results were obtained with respect to this problem.

Indiana University-Purdue University Indianapolis (IUPUI) / The object of this study was the determination of the amount of force exerted by some of the simpler widely-used orthodontic appliances. More specifically, interest was centered on the rate of force delivery, as well as upon the nature of the stresses induced in the various parts of the wires. By using experimentally determined values of the modulus of elasticity and the appliance dimensions the forces and corresponding deflections of these simpler orthodontic structures may be calculated. Theoretical force determinations according to the methods employed in the science of strength of materials were made on the following appliance forms: the finger spring; the simply supported wire; the semicircular wire form; and the U-Shaped arch. Force values and corresponding displacement measurements were made on samples of various sizes of round and rectangular wires. Comparison of these measurements with the calculated values indicated very good agreement.

Indiana University-Purdue University Indianapolis (IUPUI) / This investigation was designed to compare the force (grams) required to overcome a simulated cuspid retraction assembly capable of three dimensional control during the retraction process. It was hypothesized that a significant difference in the mean retraction values exists between the newer orthodontic alloys of Nitinol, Beta-Titanium, as well as Stainless Steel. One hundred eighty bracket and archwire combinations were examined as follows: Sample # Wire Cross-section Wire Material 30 .016”x.022” Stainless Steel 30 .017”x.025” ” 30 .016”x.022” Nitinol 30 .017”x.025” ” 30 .016”x.022 Beta-Titanium (TMA) 30 .017”x.025” ” A statistically significant difference was shown to exist between all six groups examined regarding the variables of wire size and wire material. The statistical analysis revealed that increasing rectangular archwire cross-sectional size from .016"x.022" to .017"x.025” rectangular wire when simulating canine retraction using an .018" slotted Lewis bracket will lead to significantly greater functional forces. The analysis of wire materials indicated that a significant difference (p=.01) exists between rectangular Beta-Titanium (TMA), Nitinol, and stainless steel during simulated cuspid retraction utilizing a narrow .018" Lewis bracket ligated with A-lastik ligatures. The least frictional force was observed with the .016"x.022" stainless steel test cells. The largest frictional force was found in the .017”'x.025" Beta-Titanium retraction specimens. Nitinol revealed force data intermediate between stainless steel and Beta-Titanium. The maximum resistance assembly developed 2.3 times the minimum frictional force observed. The mean grams of frictional force within these test cells ranged from 55.03 grams for the .016"x.022" retraction assembly to 132.68 grams for the .017"x.025" Beta-Titanium assembly. A topographical scanning electron microscope survey of the brackets and archwires utilized was included to provide qualitative insights into the quantitative results described.