Temporal Changes in Swallowing Function Caused by a Palate Covering

Purpose: The purpose of this study was to elucidate the temporal relationship between habituation to a palate covered by a prosthesis and swallowing function.Materials and methods: Ten healthy adults were selected as subjects. Tongue pressure on an experimental palatal plate with four pressure sensors was recorded simultaneously with surface electromyography measurements of suprahyoid muscles during swallowing of 3 ml of water. Measurements were performed 6 times: immediately after placement of the experimental palatal plate (Day 0), and on Day 1, Day 3, Day 7, Day 10, and Day 14. Temporal changes were analyzed in terms of the order of EMG activity and tongue pressure, and the duration for total swallowing (DTS), oral preparatory stage (DOPS), oral stage (DOS), and pharyngeal stage (DPS).Results: Onset of activity of the suprahyoid muscles was observed significantly earlier in all regions compared to onset of tongue pressure. Onset of tongue pressure in the posterior region was significantly delayed compared to onset of tongue pressure in another region. These results remained constant over the measurement period. DTS and DOS were significantly shortened on and after Days 3 and 7, respectively, compared to the respective values on Day 0. DOPS was significantly shortened on Day 7, compared to Day 0 and 1. DPS showed no significant change over time.Conclusion: The time required for swallowing shows a tendency to decrease over time as a subject becomes accustomed to a palate covering. This was mainly due to shortening of the oral stage.