published_or_final_version / Dentistry / Master / Master of Orthodontics

Thesis (M.Orth.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 74-95). Also available in print.

published_or_final_version / Dentistry / Doctoral / Doctor of Philosophy

Orientador: João Roberto Gonçalves / Banca: Ary dos Santos Pinto / Banca: Dirceu Barnabé Raveli / Banca: Daniel Gamba Garib / Banca: Terumi Okada Ozawa / Resumo: A estabilidade do tratamento cirúrgico da classe III tem sido uma preocupação com relatos de pequenas ou significativas alterações mandibulares pós-cirúrgicas, Alguns pacientes afetados pela instabilidade do tratamento podem manter relação oclusal aceitável com compensações ortodônticas pós-cirúrgicas, mas outros irão desenvolver alterações oclusais e esqueléticas de forma significativa, necessitando de intervenção adicional ortodôntica e cirúrgica gerando custo adicional e aumento da morbidade. Muitas variáveis têm sido apontadas como preditoras da instabilidade do tratamento, mas poucos estudos sugerem a hiperplasia condilar (HC) como um fator de risco para a correção cirúrgica da Classe III. 51 pacientes classe III foram selecionados consecutivamente de uma população de pacientes operados entre 1996 e 2007 por um único cirurgião. Telerradiografias em norma lateral foram selecionadas nas seguintes fases: diagnóstico inicial, imediatamente antes da cirurgia, imediatamente após a cirurgia e com pelo menos um ano de acompanhamento pós-cirúrgico. Um total de 19 pontos de referência foram identificados e digitalizados através da utilização do software DFPlus (Dentofacial Software Inc, Toronto, Ontario, Canada). Estes pontos de referência foram utilizados para calcular 21 medidas lineares e/ou angulares e 10 medidas horizontais e verticais. A amostra que apresentava classe III associada a hiperplasia condilar obteve maior taxa de crescimento mandibular total pós puberal (2,6 mm) e maior comprimento do corpo (2,2 mm). Diante de uma má oclusão esquelética de classe III associada a HC, a adoção de uma abordagem de tratamento diferenciada é de fundamental importância para a obtenção de resultados estáveis, embora os tratamentos que envolvam a manipulação da articulação temporomandibular... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Class III surgical treatment stability has been a concern with reports of minor or significant post-surgical mandibular change. Most of the patients affected by treatment instability may retain acceptable oclusal relation while some of the skeletal position changes. Other affected patients have to undergo further treatment generating additional cost and increased morbidity. Many variables have been identified as predictors of treatment instability, but few reports suggest condylar hyperplasia as a risk factor for class III surgical correction. 51 class III patients records were consecutively selected from the patient population operated between 1996 and 2007 by the senior author. Lateral cephalometric radiographs were selected at the following periods: initial, immediate before surgery, immediate after surgery and at least one year follow-up). A total of 19 landmarks were identified and digitized using DFPlus software (Dentofacial Software Inc, Toronto, Ontario, Canada). These landmarks were used to compute 21 traditional linear and/or angular measurements and 10 horizontal and vertical measurements. During the observational period in the present sample condylar hyperplasia promoted higher post pubertal total mandibular growth rate (2.6 mm) and higher corpus length (2.2 mm). Appropriate condilar hyperplasia diagnosis and customized approach are mandatory in order to obtain stable results for Class III surgical treatment. Although treatments that involving manipulation of the temporomandibular joint to be viewed with caution by many professionals in the field of surgery, for some articular pathologies, such as condylar hyperplasia, it is necessary to approach the TMJ together with orthognathic surgery so that stable long... (Complete abstract click electronic access below) / Doutor

Master of Science / Most studies of condylar movement are based on the movement of an arbitrary condylar point. As the condyle is a 3-dimensional body which undergoes complex rotations and translations in function, the movement of one point in the vicinity of the condyle may not accurately represent condylar movement. The aims of this investigation were to determine in human subjects, during open-close and excursive jaw movements, the movement patterns of arbitrary and anatomical condylar points; and whether the trajectory of a single selected point can accurately reflect the movement of the condyle. In 44 subjects, condylar point movements were recorded with an opto-electronic tracking system (JAWS3D), which recoded the position of three light-emitting diodes attached to each dental arch. The primary point, selected to represent movement of the condyle, was 15 mm medial to the palpated lateral condylar pole, parallel to the Frankfort horizontal plane. Additionally, four points were selected along orthogonal axes in the sagittal plane, and four in the horizontal plane: each was 5 mm from the primary point. In two subjects, the mandibular condyles were imaged by computerised tomography (CT) and the lateral and medial poles, most superior, anterior and posterior points of their condyles were selected. The trajectories of each point were compared for each subject for the mandibular movements listed above. Variability in both path form and dimension was noted between the subjects for all mandibular movements. For example, in an open-close mandibular movement the condylar point translation varied in the antero-posterior direction between 1.8-22.8 mm, and in the supero-inferior direction between 4.5-12.1 mm. For each subject, the pathway of each point was different in form and dimension from that subject’s other condylar points for the open-close, and ipsilateral lateral mandibular movements. For the open-close movement, in only four of the 44 subjects were the arbitrary point traces similar in form within a subject; and the tracings of each subject’s condylar points showed, on average, a 3.2 mm difference in maximal horizontal (i.e. antero-posterior) translation and 2.9 mm in maximal vertical (i.e. supereo-inferior) translation. For contralateral lateral mandibular movements, the path form and dimension in the sagittal plane of the condylar points were similar within a subject; however the lateral component showed variability in path length for the different points within a subject. The pathways of the condylar points for a protrusive movement displayed the most similarity within a subject, with an average of 0.4 mm variation in maximal horizontal or vertical displacement between each subject’s arbitrary condylar points’ tracings. The anatomical condylar points of the two subjects showed variability between and within each subject. For these two subjects the trajectories of the arbitrary condylar points moved in directions similar to the anatomical points of all movements except for the ipsilateral lateral mandibular movement, where in one subject, the arbitrary condylar points moved posteriorly, inferiorly and laterally whereas the anatomical points moved anteriorly, inferiorly and laterally. There is much variability in both form and dimension for mandibular condylar movement between human subjects. There is also considerable variability within subjects in the form and dimension of condylar point movement, whether arbitrary or anatomical, depending on the point selected. By inference therefore, a single condylar point cannot accurately reflect the movement of the mandibular condyle, except perhaps for a protrusive mandibular movement. Multiple mandibular points are therefore required to describe the motion of the condyle. In an ipsilateral lateral mandibular movement, for example, an arbitrary point may move in a completely different direction to the mandibular condyle, and so anatomically derived condylar points should be utilised to assess accurately condylar movement.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 163-189). Also available in print.

Thesis (M. Orth.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 178-189).

published_or_final_version / Dentistry / Master / Master of Orthodontics

published_or_final_version / Dentistry / Master / Master of Orthodontics

published_or_final_version / Dentistry / Master / Master of Orthodontics