The aim of this study was first to investigate whether the covering of the palatal mucosa with a denture base affects or not the bolus-propulsion time, and second if there was such an effect then investigate the possible contributory factors which have influence on the propulsion time. The propulsion time was measured in 21 young normal edentulous subjects under five different conditions: a complete palatal covering, non-covered palate, anterior palatal covering, posterior palatal covering and surface anaesthetized palate. As possible contributory factors palatal morphometric parameters, as well as tongue pressure were also measured. The data were analysed on the following way: changes when the palate was complete covered and non-covered, effects of sensation reduction after topic anaesthesia, effects of differences in the covering site, effects of palatal morphometric parameters and effects of tongue pressure. Ten subjects exhibited significant differences in the propulsion time when comparing the data between the complete palatal covering and the non-covered palate condition (change group). Eleven subjects did not show changes (unchanged group). Effects in the propulsion time were also recognized with posterior palatal covering-palate and superficially anaesthetized palate. With regard to the tongue pressure, significant differences during swallowing were observed. These results indicated that the bolus propulsion time into the oropharynx was affected by the palatal covering in some subjects. Moreover, the sensation in the posterior region of the hard palate, as well as the tongue pressure were also factors which affected the propulsion time during swallowing.

The purpose of this study was to clarify the influence of the palatal surface shape of dentures on food perception. Eighteen healthy dentulous subjects (mean age, 24 years were investigated. Four types of experimental plate were used: i) a Tailor-made plate, ii) an Average-model plate, iii) a Smooth plate, and iv) a Wrinkle plate. Test foods consisted of Bavarian cream cubes containing 1-3 mustard seeds and 6 raw carrot pieces of different shapes. The Bavarian cream cubes with 3 seeds were used for analysis. The other foods were used as dummy foods.Subjects were required to wear experimental plates and press test foods placed on the anterior area of the tongue against the experimental plates. We measured time required to perceive number of spherical bodies, rate of correct answers, and level of perception with each type of experimental plate using a 100-mm visual analogue scale. The results showed a significant difference in response time between the Average-model plate and the other experimental plates, with response time longest for the Average-model plate. On the other hand, no significant differences in rate of correct answers regarding number of spherical bodies or level of perception were found among the experimental plates.When incisive papilla , palatine suture and palatal rugae based on the standard Japanese shape were replicated on the palatal surface of the plates, the time required for food perception during ingestion was prolonged in comparison to plates with other palatal surface shapes.

Covering the palate with dentures can disrupt the timing of swallowing. To determine the cause of this phenomenon, we investigated whether covering the palate with a denture base altered tongue pressure. The results suggest that use of a denture base has little effect on tongue pressure during swallowing.

This study revealed that it is difficult to predict the effects of ultrasonic therapy alone on specific symptoms. The results suggest that further study is required to establish definite criteria for the application of such a therapy.

Patient:A 71-year-old man complained of articulation disorder caused by poor retention of the upper and lower complete dentures. Both maxillary and mandibular residual ridges showed severe resorption. The dentures had short base borders and poor retentions, and were sway with mandibular functional movement. First, I planned to improve the retention and mandibular position of his dentures by repairing his dentures. When I confirmed to make a good retention and an appropriate mandibular position, I started to make new dentures, and then set them.Discussion: Evaluation before and after treatment showed recovery of articular function. The new denture, which has suitable tongue space, made the tongue movement area during speaking wider. This might result from the patient acclimatizing to a new condition. Conclusion:New dentures showing stable retention and good articular function were not sway during functioning or articulation, and the patients articulation became clear.