Analysis of masticatory movements in children using three-dimensional dynamic simulation model

为了探讨口颌功能的发育阶段，我们对正常儿童下颌运动、咀嚼肌活动、咬合面和咬合力进行了研究。说明儿童口颌功能具有不同于成人的特点。然而，为了评估生长期儿童咬合功能的生物力学发展，错牙合畸形的功能障碍，以及通过治疗从咀嚼功能障碍中恢复的过程，三维下颌运动的视觉估计在这方面的研究中必须给我们带来更多的好处。计算机仿真技术在工业领域中被广泛应用于固体结构的运动分析。该方法对牙齿、下颌牙列和牙齿接触情况的分析也有一定的应用价值，但要将该方法应用于口腔医学领域，必须获得各种精确的参数，以建立牙列实体模型，并获得咀嚼过程中下颌骨和头部的动力学特性。通过本研究，可以获得乳牙列的三维精确结构，咀嚼时咀嚼肌的肌肉活动平衡，下颌开闭运动时头部运动的特点，以及早期前牙反牙合儿童下颌运动的特点。利用这些参数建立了三维实体动力学模型，对咬合接触情况进行了分析。然后，利用计算机图形学技术直观地显示出乳牙列侧向移动过程中咬合接触面积的变化，量化了每颗牙齿的咬合接触面积，以及侧向移动过程中工作侧和非工作侧乳第二磨牙的咬合接触情况，并对计算机模拟下颌运动的效果进行了进一步的研究。

In order to investigate the developmental steps of stomatognathic function, we have researched into mandibular movement, masticatory muscle activity, occlusal facet and occlusal force of children with of normal occlusion. These results clarified that children showed the different characteristics in stomatognathic function from adults. However, to estimate biomechanical development of occlusal function in growing children, dysfunction of malocclusion, and recovery process from the masticatory dysfunction through the treatments, the visual estimation of mandibular movements in three-dimensions must bring us much more benefits in this research aspect. The computer simulation technology is widely used for analyzing movements of solid structures in the industrial world. This method is also thought to be useful for analyzing teeth, mandibular dentition and teeth contact situation, however to apply this method into the field of dentistry, various and accurate parameters must be obtained to make solid dentition models, and dynamic characteristic of mandible and head during mastication. In this study, we could gain the three-dimensional precise structure on primary dentition, the muscle activity balance of masticatory muscles during chewing, the characteristics of head movement during open-close movement of mandible, and the characteristics of mandibular movement in children with primary anterior reverse bite. These parameters were used for making the solid dynamic models to analyze the situation of occlusal contact. Then, computer graphics were used to visually display changing occlusal contact area during lateral excursions in the primary dentition, the occlusal contact area of each tooth was quantified, and occlusal contact occurred at the primary second molars on both the working and non-working sides during lateral excursion.Further studies are needed to evaluate the mandibular movements using computer simulation.