Rumiko Maeda1,2, Eri Takei1, Kayoko Ito3, Jin Magara1, Takanori Tsujimura1, Makoto Inoue1. 1. Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata, 951-8514, Japan. 2. Department of Rehabilitation, Faculty of Health Science, Kansai University of Welfare Sciences, 3-11-1 Asahigaoka, Kashiwara-shi, Osaka, 582-0026, Japan. 3. Oral Rehabilitation, Niigata University Medical and Dental Hospital, 1-754 Asahimachi-dori, Chuo-ku, Niigata, 950-8510, Japan.
Abstract
BACKGROUND: There is a wide variation of chewing behaviors even in healthy humans. The present study was aimed to clarify how the rheological properties of the bolus during chewing is different among individuals. We also investigated if the swallowing threshold was consistent among the individuals and if the difference in the bolus properties at the swallowing affected swallowing movement. METHODS: Twenty-nine healthy volunteers were asked to ingest 8 g of steamed rice. Based on the chewing duration defined by the time until first swallow, participants were asked to chew the food, then either spit it out, or swallow it, at 50%, 100% and 150% of chewing duration. In seven volunteers, the maximum bite force was measured. RESULTS: The hardness of the bolus gradually decreased throughout recording. Although the chewing duration varied widely, there was a significant negative correlation between time and hardness, regardless of the difference in individual chewing duration. The cohesiveness of the bolus was unchanged at the 100% time point, followed by a slight but significant increase. There was no significant correlation between the chewing duration and adhesiveness of the bolus. Swallowing-related bursts of Supra and Infra EMGs were not related to the chewing duration or bolus properties, and chewing duration did not affect swallowing function. CONCLUSION: The current results suggest that the bolus properties such as the hardness and cohesiveness during chewing is just dependent on the chewing duration and the difference in the bolus properties does not affect the swallowing initiation and movement. This article is protected by copyright. All rights reserved.
BACKGROUND: There is a wide variation of chewing behaviors even in healthy humans. The present study was aimed to clarify how the rheological properties of the bolus during chewing is different among individuals. We also investigated if the swallowing threshold was consistent among the individuals and if the difference in the bolus properties at the swallowing affected swallowing movement. METHODS: Twenty-nine healthy volunteers were asked to ingest 8 g of steamed rice. Based on the chewing duration defined by the time until first swallow, participants were asked to chew the food, then either spit it out, or swallow it, at 50%, 100% and 150% of chewing duration. In seven volunteers, the maximum bite force was measured. RESULTS: The hardness of the bolus gradually decreased throughout recording. Although the chewing duration varied widely, there was a significant negative correlation between time and hardness, regardless of the difference in individual chewing duration. The cohesiveness of the bolus was unchanged at the 100% time point, followed by a slight but significant increase. There was no significant correlation between the chewing duration and adhesiveness of the bolus. Swallowing-related bursts of Supra and Infra EMGs were not related to the chewing duration or bolus properties, and chewing duration did not affect swallowing function. CONCLUSION: The current results suggest that the bolus properties such as the hardness and cohesiveness during chewing is just dependent on the chewing duration and the difference in the bolus properties does not affect the swallowing initiation and movement. This article is protected by copyright. All rights reserved.