Atrophy and infection of the tongue mucosa contribute to dysgeusia resulting from changes in lingual papillae. However, influences of the changes of lingual papillae on oral mechanoreceptive sensation is unclear. Previous studies have suggested that filiform papillae function as a unit of the mechanoreceptive system and play an important role in somatosensation. We hypothesized that lingual papillae including filiform papillae participate in intraoral texture sensation. The aim of present study was to investigate the relationship between morphometric characteristics of lingual papillae and the texture sensation in tongue-hard palate. Sensory evaluation was performed in 10 healthy participants to evaluate the sensitivity of the tongue-hard palate to granularity. The sample food was an aqueous suspension containing crystalline cellulose, with an average particle diameter of 50 μm, and a concentration of 0 to 6.4 wt%. The participants were divided into high- or low-sensitivity groups (n=6 vs. 4) by evaluating the sensitivity to the granularity of the suspension. To assess the quantitative and morphometric parameters of lingual papillae, the surface roughness defined by JIS was measured by using X-ray micro-CT for image analysis of the surface configurations, which were recorded by silicone rubber impressions taken from the anterior region of the tongue. A concentration of the sample for determining the granular sensitivity threshold ranged from 0.4 to 3.2 wt%. Comparison of the high- and low-sensitivity groups revealed that the root mean square deviation (Rq) and arithmetical mean deviation (Ra) were significantly larger in the high-sensitivity group. In contrast, the lowest valley (Rv) was significantly larger in the low-sensitivity group. These results suggest that the morphometric characteristics of lingual papillae, evaluated in terms of surface roughness, may play a role in intraoral texture sensation.

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 Various factors influence a food's palatability, including elements related to the individual taster, the food itself, and the cuisine environment. The food-related elements include taste, smell, color, temperature, and texture. Food texture is an important factor involved in its tastiness.
 This study aimed to examine the influence of dry, crumbling food texture on the electromyographic (EMG) activity of the masseter and suprahyoid muscles during mastication and swallowing. Ag-Cl surface electrodes were used to record the EMG activity of the masseter and suprahyoid muscles on the habitual masticatory side. A ground electrode was secured to the skin in the posterior neck region. The following EMG parameters of the masseter and suprahyoid muscles were calculated: the peak value, onset time, offset time, peak time, burst duration, integrated EMG value, and root mean square value.
 There were no constant change tendencies in the number of masticatory cycles, the total duration of mastication, or the frequency of mastication; these parameters showed almost constant values regardless of the hardness of the dried and crumbling food texture. There were no significant differences in any of the EMG parameters during mastication of food of different textures. The texture of the food did not affect the onset times of the masseter or suprahyoid muscles. In contrast, the offset times of the masseter and suprahyoid muscles tended to be delayed as the food texture became increasingly dry and crumbling. Integrated EMG activity of the masseter and suprahyoid muscles did not change significantly. Integrated EMG activity of the masseter and suprahyoid muscles and the burst duration of the masseter muscle during swallowing did not change significantly. In contrast, the burst duration of the suprahyoid muscles increased significantly. The findings of the present study suggest that dry and crumbling test food texture influences the burst duration of the suprahyoid muscles.

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The final goal of this study was to develop a clinical procedure to accurately examine occlusal facets caused by sleep bruxism and to objectively assess their severity. A two-layered occlusal splint with soft surfaces and an occlusal guidance, adjusted for a full-balanced occlusion, was developed. A quantitative measurement system was constructed for evaluating wear facets on the surface of the splint, which consisted of the two-layered occlusal splint and a 3D dental scanner. The occlusal splint was scanned, before and after wear, using the 3D dental scanner. The scanned datasets were objectively compared to analyze the location and direction of the wear facets and the surface loss of the splint. Accuracy verification, using gauge blocks, revealed that the relative error was less than 2.0 % and no significant measurement-error differences. There were significant differences in the registration error among registration datasets. The digital imaging technique employed has the potential to detect more than 0.05 mm thickness changes of occlusal surface. After two bruxers (45-year female and 77-year male) wore the occlusal splint for 14 days during sleep, the wear facets on the surface of splint could be detected. The result of the study shows that this system has the potential to objectively evaluate the distance, area, volume, and direction of the surface change of the splint after short-term use.

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