Experimental study for development of rabbit masticatory system depending on the style of sucking

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To investigate the difference of developmental degree of masticatory function depending on sucking style such as breast or bottle feeding with elastic nipple, four infant rabbits in each group, had been fed for three weeks in this study.EMG of masseter muscle, digastric, styloglossus, genioglossus, mylohyoid and geniohyoid muscles with breast and bottle feeding, and x-ray movie when eating solid food for evaluating the tongue and jaw movement had been carried out simultaneously. Whole data gathered had been analyzed and discussed.The summary of results are as follows.1.The diference of developmental degree of feeding function1)Muscle activity :(1)Cycle length of muscle activity was longer in bottle feeding group than in breast feeding group.(2)Time lags activity : Time lags of activity onsets of digastric muscle from masseter muscle, and that of geniohyoid muscle from mylohyoid muscle were shorter in bottle feeding group.Muscle activity integration : Integration of masseter muscle was … More higher in breast feeding than in bottle feeding, on the other hand, digastric muscle was lower in breast feeding than in bottle feeding. Genioglossus and mylohyoid muscles were higher in bottle feeding group than in breast feeding group.2)Tongue and jaw movement : The bertical dimension of jaw movement were longer in breast than in bottle feeding. The horizontal dimension of tongue movment were longer in bottle feeding than in breast feeding.2.The difference of developmental degree of masticatory function1)Muscle activity :(1)Cycle length of muscle activity was linger in bottle feeding group than in breast feeding group.(2)Muscle activity integration : Integration of masseter muscle was higher in breast feeding than in bottle feeding. The reciprocity of digastric, masseter, styloglossus, gemioglossus muscles activity were lower in bottle feeding than in normal feeding.2)Jaw and tongue movment : The length of intake phase was shorter with small amount of jaw movement in normal feeding group than in bottle feeding group, on the contrally, the length of chewing phase was longer with large amount of jaw movement in normal feeding group than in bottle feeding group.These results that the difference of developmental degree of rabbit masticatory function and jaw movement depending on the style of sucking had existed which represents the deficiency of functional development of masticatory organ in case of bottle feeding rabbit. Less