Evaluation of Masticatory and Swallowing Functions Using Videoendoscopy and Observation of Facial and Mandibular Movements.

Background It is important to observe masticatory and swallowing movements to improve the eating habits of older adults with dysphagia. Observing facial and mandibular movements can be useful for such evaluations. However, the process models that occur while eating solid foods have not been adequately considered. Objective This study aimed to clarify the differences in facial and mandibular movements before and after bolus transport to the pharynx (stage II transport; STII) during the consumption of solid food. Methods As this was conducted as a pilot study, the participants included 20 healthy young adults with normal dentition who freely ate rice crackers while their facial and mandibular movements were recorded using a small mobile device. A video endoscope was inserted nasally to observe STII, and facial and mandibular movements were analyzed before (phase 1) and after (phase 2) STII. The maximum horizontal and vertical distances from the origin, velocity, total distance of movement, and the number, duration, and frequency of mastication cycles were calculated. These variables were analyzed using the Wilcoxon signed-rank test (p < 0.05). Results The maximum horizontal distances, maximum vertical distances, velocity, and total distances of both oral commissures and the mandible were significantly decreased in phase 2 compared with phase 1. The number, duration, and frequency of mastication also significantly decreased in phase 2 (p < 0.05). Conclusion Facial and mandibular movements differed between phases 1 and 2 during the consumption of solid foods. Despite the limitation that the research participants were young adults, it is important to focus on the lateral and downward movements of both oral commissures and the mandible, as well as the chewing frequency.