The purpose of this study was to investigate the cause of taste disorders of denture wearers. In this study, the following experiments were performed for twenty normal subjects with intact dentition and without taste disorders.
Five kinds of experimental plate were made; they were “Basic plate” covering the whole hard palate and “Half-covered plate” covering the anterior half of palate (thickness of both plates were 1.5 mm), “A-plate”(thickness of the plate covering the whole hard palate was 3.0 mm), “B-plate”(thickness of only front area of the plate was 3.0 mm), and “C-plate”(thickness of only around the posterior teeth area of the plate was 3.0 mm). After producing each palatal plate, the gustatory responses of salt and bitter tastes shown by the threshold of judgment were investigated by the chewing method. The gustatory test, masticatory efficiency and mandibular movement (Mandibular Kinesiograph, K 5 AR) during chewing gumi-jelly were investigated with and without each plate. The results were as follows:
1. The area of the plate was large or the thickness of the plate was not regular (B-plate and C-plate), the threshold of judgment was high and masticatory efficiency was low.
2. When wearing the plate, the opening phase time and cycle time were long and the stability of mandibular movement was disordered. These changes became notable when the area of the plate was large or the thickness of the plate was not regular (B-plate and C-plate).
These results suggested that masticatory movement and gustatory response could vary by change of shape and thickness of the palatal plate.