Newly developed sensor sheet for measuring tongue pressure during swallowing.

PURPOSE: The aim of this study was to develop a sensor sheet for measuring tongue pressure during swallowing and to clarify its usefulness by comparing it with a conventional pressure sensor installed in the palatal plate. METHODS: A tactile sensor system was used for the construction of the measuring system. Based on our preceding study, a T-shaped sensor sheet with 0.1mm thickness, five measuring points (three points on the median line, two points on the posterior-lateral part) and three sizes based on the morphological analysis of 60 maxillary casts was designed for application on the hard palate. To elucidate the sensing characteristics of the sensor sheet, the output level of the sensor sheet was compared with that of a conventional pressure sensor under the same load. The maximal magnitude of tongue pressure (MP) during the swallowing of 15 ml water was recorded by a sensor sheet attached to the palatal mucosa and was compared with that recorded by pressure sensors installed in the palatal plate. RESULTS: The output level of the sensor sheet was smaller than that of the pressure sensor. There was a high correlation between the output levels of the two sensors (R=0.952, P<0.001). Although MP at each sensing point of the sensor sheet was also smaller than that recorded by the pressure sensors, MP collected by the regression equation obtained in our experiment was quite similar to that for the pressure sensors. CONCLUSIONS: This system could be useful for evaluating tongue activity during oropharyngeal swallowing.

Evaluation of tongue-, jaw-, and swallowing-related muscle coordination during voluntarily triggered swallowing.

PURPOSE: The prosthodontic treatment of dysphagic patients may preclude favorable treatment outcomes due to uncoordinated or discordant oral and pharyngeal functions. Since optimal treatment requires a full understanding of the mechanism of oropharyngeal swallowing, this study seeks to describe the normal temporal pattern of tongue-, jaw-, and swallowing-related muscle coordination during voluntarily triggered swallows in healthy patients. MATERIALS AND METHODS: Tongue pressure against the hard palate at seven measuring points, swallowing sounds, and surface electromyography (EMG) activity of the masseter, anterior digastric, and infrahyoid muscles during voluntarily triggered swallowing were recorded in seven healthy male volunteers. The order of onset and offset of these parameters was analyzed by repeated-measures two-way analysis of variance. RESULTS: The onset of anterior digastric muscle activity occurred first and was significantly earlier than the onset of the masseter or infrahyoid muscles and tongue pressure. The onset of masseter muscle activity was also significantly earlier than that of the infrahyoid muscle and tongue pressure. Offset of masseter activity was almost simultaneous with the swallowing sound and was significantly earlier than the offset of the anterior digastric and infrahyoid muscles as well as tongue pressure. The EMG burst of the anterior digastric muscle continued until the offset of tongue pressure, and was followed by the offset of infrahyoid muscle activity. CONCLUSIONS: The temporal coordination patterns of the tongue, jaw, and oropharyngeal muscles during voluntarily triggered swallowing appear to agree with known safe management of a bolus and offer criteria for evaluating the function of oropharyngeal swallowing.