2021 Volume 25 Issue 1 Pages 11-21
Introduction: In swallowing, oral sensation plays an important role in shape recognition, smooth mastication, and transportation of the bolus. Oral stereognosis, which is the ability to recognize the shape of objects inside the oral cavity without visual information, is also one of the oral sensations. However, objects (pieces) used in previous studies were not uniform in terms of material, type, and method. Therefore, the DF8 kit was developed in Japan for oral sensation research; it includes 10 test pieces (TPs) with different shapes. However, no reports have examined oral stereognosis using this kit. In this study, we used the DF8 kit to measure oral stereognosis and examine the differences in the number of correct responses and age for each TP, oral stereognosis and static tongue haptic threshold, and the relationship between oral stereognosis and oral motor function.
Method: Eighty-four healthy subjects (18 to 79 years old) were included in this study. Oral stereognosis, static tongue haptic threshold, and oral motor function were measured using the DF8 kit.
Results and Discussion: No evident relationship was observed in terms of age. The correct response rate for the DF8 kit was not lower in the older adult group than in the adolescent group. The results showed that oral stereognosis was retained in the older adult group (69.6±16.5 years old). Furthermore, the number of correct responses varied with TP shape. Several correct responses were reported for the asymmetric TP. When TP shape could not be determined, subjects tended to provide incorrect responses for TPs with a similar shape. However, no significant correlation was found between oral stereognosis and oral motor function/articulatory function. The static tongue haptic threshold increased with age but had no evident relationship with the correct response rate for the DF8 kit. Static perception was good, but there were still some cases with a low number of correct responses for the DF8 kit. This result suggests that the static tongue haptic threshold alone may not be enough to estimate the state of oral stereognosis. Our results highlight the need for further studies on the relationship between oral stereognosis and the static tongue haptic threshold and oral motor function/articulatory function.
