Research of the occlusal phase during the masticatory movement

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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.