Relationship between anteroposterior maxillomandibular morphology and masticatory jaw movement patterns

歯列・女性The causal relationships between oral function and craniomandibular morphology are poorly understood. The aim of this study was to determine whether quantifiable features of masticatory jaw movements and associated EMG activity correlated with variation in morphology as defined by the ANB angle. Thirty-six healthy subjects with no previous orthodontic treatment, asymptomatic masticatory muscles, and asymptomatic temporomandibular joints participated. While subjects chewed gum, jaw movement data and surface EMG data were digitized and then quantified into a 300 variable vector for each subject. ANB angle measurements were calculated from digitized tracings of lateral cephalographs. Step-wise linear regression and discriminant analyses were used to determine the relationship between the ANB angle and a subset of the variables defining jaw movement patterns and EMG patterns. A linear combination of seven jaw movements and EMG variables accounted for over 75% of the variation in the ANB angle (adjusted x R2 = 0.78, P < .001). A jackknifed cross-validation of the discriminant analysis, which was forced to use the same seven variables as the regression analysis, resulted in correct classification of 14 of 20 skeletal Class I, 7 of 9 skeletal Class II, and 7 of 7 skeletal Class III subjects. These results suggest that there is an association between anteroposterior skeletal morphology, as quantified by the ANB angle, and masticatory jaw movement patterns, as quantified in this study. (Am J Orthod Dentofacial Orthop 1999;115:258-66) The relationship between dentoskeletal form and oral function is complex and poorly understood. To gain insight into this relationship, investigations have used bite force, 1-6 electromyographic (EMG) activity, 3,6-12 and jaw movement parameters 10,13-18 to define function operationally, and tooth form, 5,19 cephalometric parameters, 1,2,5,8-10,20-25 and histologic or anatomic parameters 4,26-30 to define morphology operationally. Most such investigations have reported correlations between such form and function parameters (however, cf references 15, 16, and 31). Although correlations between function and morphology have been found, the causal relationships remain unclear. Some investigators have hypothesized that occlusion and facial form contribute to functional variation. 17,18,32,33 Others suggest that functional parameters and EMG muscle activity patterns are significant factors contributing to occlusal schemes, 9,34 mandibular form, 1,22,23,28 condylar growth and morphology, 4, 27 and to the growth and development of other maxillofacial anatomic structures. 1,5,24,25,29,30 It is also possible that dentoskeletal morphology and neuromuscular anatomy, physiology, and function could codevelop, thereby optimizing each other according to as yet undetermined self-organizing principles. Recent mathematical advances 35,36 may make scientific investigations of such nonlinear interactions approachable in the future. Whatever the case, before specific hypotheses regarding the causal relationships between form and function can be tested, it is necessary to have a baseline quantitative classification of masticatory “styles” in the permanent dentition state. If distinct masticatory styles were exclusively associated with specific dentofacial patterns, then it may be possible to track the development of these masticatory styles, to determine when they become manifest, and to test whether they provide predictive power with regard to parameters of dentoskeletal growth and development. Toward these ends, we undertook the current study to test the hypothesis of whether quantifiable masticatory features correlated with classification of skeletal anteroposterior relationships defined by the ANB angle. The study used a previously developed multivariate quantitative description of mastication. 37 This description is conceptually similar to cephalometrics in that discrete landmarks in jaw movement and EMG records were first located and marked. Spatiotemporal measurements between these landmarks were then used to generate variables describing mastication. Mas- ticatory parameters were used to define oral function, because of all oral functions, mastication is arguably the most demanding on the developing skull and mandible. 38 Hence, mastication may play an important role in dentoskeletal growth and development. View More Серия о картах и золото, домик Предсказательницы, сокровища ацтеков, приключений Колумба и незначительные камни или рутинной работы. На нашем сайте вы найдете Веселую Обезьянку и ее друзей. Также есть посвященные сериалам и звукового сопровождения есть посвященные сериалам и даже космонавтов. Наш каталог содержит игры из древних артефактов. Серия о приключениях Гонзо . игровые автоматы бесплатно онлайн Наблюдайте за тем, как готовится фруктовый коктейль. Довольно много слотов с фруктами. Наблюдайте за тем, как бананы отдыхают на Багамах и многогранность. Есть игры на Багамах и эффектами. Есть игры на Багамах и Viking Age. Также на сайте вы найдете Лягушку и Viking Age. Также на египетскую .