Research of the occlusal phase during the masticatory movement

本研究的目的是：1)建立能够观察功能性咀嚼运动中咬合接触和滑动长度的系统；2)研究咀嚼运动中咬合相的特征。该系统已建立并报告于2000年（J Dent Res, 79: 1890-1895）。在2000年、2001年和2002年，用该系统比较了具有健康恒牙列的儿童的咀嚼运动特征（J J J口腔口腔功能，38,1025- 1033,2000；J J口腔康复，28,328- 334,2001；J J口腔康复，29,64- 71,2002）。为了阐明儿童咬合期的特征，本文研究了1)咬合滑动长度，2)咬合滑动长度的稳定性，3)最小开口位置位置的稳定性，4)最大尖间位置的稳定性，5)咀嚼周期闭合和闭合路径矢状面和额面投影角，以及6)打开和关闭路径之间的相关性。结果表明：(1)初生牙列儿童在几乎所有变量上的差异都较小；(2)两组咀嚼方式不相同；(3)与儿童相比，成人在开闭路径上的相关性相对较高。这些结果可能是由于1)相对平坦的咬合形态（包括牙列和颞下颌关节）和2)即使在有初级牙列的儿童中也可能存在印迹吸吮行为。一些研究结果表明，这些特征会随着它们的生长发育而减弱。本研究为初生牙列儿童的咬合期特征提供了良好的信息。然而，需要进一步的研究来获得下颌骨功能诊断的线索。

The purposes of this study were 1) to establish the system, which could observe the occlusal contacts and the length of the glide during functional masticatory movements, and 2) to investigate the characteristics of the occlusal phase during chewing movements. The system has been built and reported in 2000 (J Dent Res, 79: 1890-1895). Also several characteristics of chewing movements in children with primary dentition compare with adults with healthy permanent dentition has been reported in 2000, 2001 and 2002 by means of this system (J Jpn Soc Stomatognath Funct, 6: 153-161, 2000; Jpn J Ped Dent, 38, 1025-1033, 2000; J Oral Rehabil, 28, 328-334, 2001; J Oral Rehabil, 29, 64-71, 2002). To elucidate the characteristics of occlusal phase in children, 1) the length of occlusal glides, 2) the stability of this length, 3) the stability of the position of the minimum opening position, 4) the stability of the maximum intercuspal position, 5) the sagittal and frontal projected angles both on the closing and opening pathway of masticatory cycles, and 6) correlations between the opening and closing pathways were examined.As results, 1) children with primary dentition had less variability on almost all variables, 2) chewing pattern was not the same between two groups, and 3) adults had relatively high correlations between the opening and closing pathway compared with children. These results might be caused by 1) relatively flat occlusal morphology including dentitions and TMJ, and 2) imprinted sucking behavior might exist even in children with primary dentition. Some finding suggested that these characteristics would be decreasing with their growth and development.This study could provide good information for the characteristics of the occlusal phase in children with primary dentition. However, further investigation will be required to obtain the clues for the functional diagnosis of the mandible.