Abstract
To study the fundamental aspects of normal mastication, we investigated changes in water content, particle size distribution and the texture of a food bolus.
Electromyography (EMG) activity record from the skin over the masseter and mylohyoid muscles during mastication was also measured. Six adults with normal dentition chewed until just before swallowing. The chewing time of the one mouthful of food for each subject was divided into three parts, and the analysis of food bolus and EMG were done at the time of 1/3,2/3 and 3/3 parts for the chewing time of one mouthful of food.
The value of one mouthful of food and the chewing time for each subject were regularly changed, and the fluctuation of these values was small. The pulverization increased regularly during mastication and it depended on the activity of the mylohyoid muscle. The water contents of the food bolus also increased with time, and the mean water content of the boluses for each subject at the swallowing showed regular values. The textures property, hardness, adhesion and gumminess changed drastically at 2/3 chewing time of one mouthful of food, and showed regular values at swallowing irrespective of the sample of food mastication.
These results suggested that pulverization and water contents of the food bolus affect the change in the textural property, and it seemed the measuring of the textural property was one of the important factors in the decision to swallow.
