Doctor Scientiae (Odontology) - DSc(Odont) / The primary function of the jaws and teeth in mammals is chewing and swallowing. In man there are additional functions of speech, non-verbal communication and cosmetic appeal. Chewing is a complex operation requiring both adequate skeletal structures, and a well co-ordinated muscle system. There is considerable variation in both these components of chewing within which adequate function appears to be possible, at least for a modern refined diet. For example, the dental arches may not conform to the modal arrangement and teeth may be missing, yet adequate function remains (Slagter et al 1993). There are unfortunately no baseline requirements for an adequate dentition nor the minimal chewing performance necessary to avoid indigestion. A common rule of thumb when replacing missing posterior teeth is that the extent of the prosthesis can be reduced to the premolars without seriously affecting chewing (Kayser, 1984). This arbitrary estimation has not been defined by a minimum area for functioning posterior occlusal surfaces. The same lack of quantifiable measurement is a feature of assessing orthodontic treatment goals and outcomes (Omar, McEwen and Ogston 1987). The clinical rules for correcting malocclusions, usually, have more to do with the restoration of modal tooth, arch and skeletal relationships, than with the restoration of function; if restoration of function is a concern of treatment, it is not measurable in the same way that tooth positions can be assessed on plaster casts or angles measured on a radiograph. Muscle tenderness and limited movement are both features of temporomandibular dysfunction. The boundary between normal subjects, who may have some signs of dysfunction and patients, who may not have distinctly more severe signs cannot always be made (Widmar 1992). By some definitions based on the morphology of the joint structures, even symptomless individuals could be categorised as abnormal. One of the difficulties in assessing functional incapacity of a patient with muscle pain is the absence of the same baseline data needed to assess malocclusion, or the handicap due to reduced occlusal area. It is encouraging to find that a simple test, such as measuring maximum opening, is a useful indicator of treatment progress in temporomandibular dysfunction. This sign, although simple and of limited diagnostic use, reflects the poverty of useful tests for masticatory function.

This study quantifies the mandibular movements of opening and close, laterotrusion and protrusion, obtained from 20 healthy subjects and 20 TMD subjects subdivided into 10 individuals with myopathy and 10 individuals with arthropaty, selected by Research Diagnostic Criteria (RDC) protocols. These movements of all subjects were captured and measured at maximum length, medium velocity and acceleration and deviation during your trajectories, were captured by three infrared cameras and measured by a computational system previously developed by the University Federal of Uberlândia, which, in this research was named Jaw Capture. This system receives images simultaneously from nine reflective markers and send and process this data to a computer using a firewire system through a mathematical approach to analyze and quantify in 3D (at X, Y and Z axis), the marker trajectories. The reflective markers were positioned by supporting systems fixed on vestibular face of lower incisives and skin surface of face. The movement ranges are similar among all individuals, meanwhile the deviation and the medium velocity and acceleration are very different between target and control group after statistical analysis. This system being proves reliable and efficient. / Este estudo quantifica os movimentos mandibulares de abertura e fechamento, lateralidade e protrusão, de 20 indivíduos saudáveis, e 20 indivíduos com DTM, sendo, 10 indivíduos portadores de miopatia e 10 indivíduos portadores de artropatia, triados segundo o protocolo de Research Diagnostic Criteria (RDC). Os movimentos mandibulares, de cada um deles, foram capturados e medidos em suas amplitudes máximas, velocidade e aceleração médias, bem como os desvios durante os mesmos, por um sistema de reconstrução de imagens, desenvolvido na Universidade Federal de Uberlândia, o qual foi chamado neste trabalho de Jaw Capture. O sistema recebe imagens simultâneas de nove marcadores de alta refletividade, capturadas por três câmeras de infravermelho, conectadas a um computador pelo sistema firewire, através de uma abordagem matemática para analisar e quantificar as trajetórias dos marcadores em três dimensões (3D), nos eixos X, Y e Z. Os sensores foram posicionados em suportes afixados nos incisivos inferiores e na pele do rosto, sem considerar os movimentos das cabeças da mandíbula. A amplitude dos movimentos em todos os indivíduos mostrou-se semelhante, entretanto os desvios e a velocidade e aceleração médias foram muito diferentes, após a análise estatística. O método provou ser confiável e eficiente. / Doutor em Ciências