2010 Volume 14 Issue 1 Pages 27-32
[Purpose] Bolus preparation is important to reduce the risk of aspiration. We previously reported that it is possible to evaluate bolus preparation for swallowing in the pharynx using videoendoscopy. In other previous studies, which evaluated the bolus outside of the mouth or pharynx, it has been reported that the number of chewing strokes influenced bolus preparation. This study examined the relationship between the number of times the bolus was chewed and the swallow threshold bolus observed in the pharynx using videoendoscopy.
[Methods] Thirty healthy dentulous adults participated in this study. Rice in two colors （white and green） was used as the examination foods. The subjects were instructed to eat mouthfuls of the rice with two colors in their usual manner. We evaluated the bolus in the pharynx using videoendoscopy from the perspective of grindability, mixing and aggregation and counted the number of chewing strokes before swallowing the bolus.
[Results] The bolus immediately before swallowing showed a high degree of aggregation and relatively low degrees of grindability and mixing. The degrees of grindability and mixing increased in association with the increase in the number of times the rice was chewed. There were correlations between the number of chewing strokes and the grindability or mixing. The degree of aggregation was high despite the number of times the rice was chewed. There was no correlation between the number of chewing strokes and the aggregation.
[Conclusion] These findings indicated that the number of chewing strokes influences grindability and mixing of bolus similar to the findings of the previous studies. At the swallow threshold, the bolus showed a high degree of aggregation even when there were poor degrees of grindability and mixing due to a low number of chewing strokes. These results suggested that the swallow threshold depends on the degree of aggregation, not the degrees of grindability and mixing.
