Tetsuya Takamata

The Endogenous Opioids Related with Antinociceptive Effects Induced by Electrical Stimulation into the Amygdala

Pain relief is necessary and essential for dental treatments. Recently, the relationships of pain and emotion were studied, and electrical stimulation applied to the amygdala depressed the nociceptive response in the anterior cingulate cortex (ACC). Thus, the antinociceptive effects of the amygdala are elucidated, but its mechanism is not yet clarified. The present study was performed to investigate whether endogenous opioid system is related to the depression, and the quantitative changes of endogenous opioids induced by electrical stimulation to the amygdala. We investigated immunohistologically c-Fos expression to confirm the activated neurons, as well as the distribution and the amount of endogenous opioids (β-endorphin, enkephalin and dynorphin A) in the brain using male Wistar rats, when electrical stimulation was applied to the central nucleus of the amygdala (CeA) or noxious stimulation was delivered to the peripheral tissue. c-Fos expression in the ipsilateral ACC was increased by electrical stimulation to the CeA. However, only a small amount of endogenous opioids was observed in the ACC when noxious stimulation or electrical stimulation was applied. In contrast, the amount of dynorphin A in the periaqueductal gray (PAG) was increased by electrical stimulation to the CeA, and the amount of β-endorphin in the PAG was increased by noxious stimulation to the peripheral tissue. The results suggest that dynorphin A in the PAG induced by electrical stimulation to the CeA activate the descending antinociceptive system, and suggest that the nociceptive response in the ACC is depressed indirectly.

Factors Related with the Number of Chewing Strokes for Recognizing Taste

Abstract The sense of taste has been evaluated mostly by investigating the taste perception threshold of taste solutions; however, few studies have examined the spread of taste in terms of the masticatory process. We examined the factors related with the number of chewing strokes for recognizing taste. Forty-three subjects without missing teeth were instructed to chew food samples made from 3% agarose containing 2 or 5% sucrose. The number of chewing strokes needed to recognize sweetness in either a partial area or the whole area of the tongue was counted using electromyography. In addition, masticatory performance, salivary flow rate, maximum bite force and scores of oral health related to quality of life (Oral Health Impact Profile, OHIP) were assessed. Male subjects exhibited a larger number of chewing strokes to recognize taste than female subjects for the 5% sucrose sample. The number of necessary chewing strokes for the taste recognition in the whole area was larger than that in a partial area of the tongue. Moreover, some relationships between the count and experimental conditions were found, such as masticatory performance (Spearmans correlation coefficient by rank test: rs=0.49), salivary flow rate (rs= − 0.53), maximum bite force (rs= − 0.43) and scores of OHIP (rs=0.44 — 0.66). The findings suggest that the number of chewing strokes for recognizing sweetness might be affected by the aesthetic feeling against the teeth and oral conditions.

Study on Stress Analysis of Occlusion Forces Distributed in Complete Denture. Part I. Effect of Separating Elements and Loading Position on the Supporting Tissues of Lower First Moller.

The purpose of this study was to analyze the occlusal stress under complete denture base.In this study, the effect of the separating elements and loading points were performed utilizing the finite element method. The results were as follows:1. As the separation of elements decreases, the stress distribution area become limited.2. The area of the greatest stress concentration was found in mucosa under the loading point.3. The area of stress concentration of cortical bone was found on the lingual side.4. The lower bite rim model has a tendency to be displaced to the lingual side.

Color Stability of Three New Resilient Lining Materials Used for Denture Bases. Part 2. Temporal Change of Spectral Reflectance.

A temporal change of spectral reflectance for three new soft lining materials was discussed. These materials, Polyolefin, Silicone resilient materials and Polyphosphazine fluoroelastomer were immersed in four aqueous solutions and one oleaginous solution. A remarkable change was observed in the Polyolefin immersed in olive oil plus β-Carotene, and also in Silicone in turmeric and instant coffee. Polyphosphazine fluoroelastomer in turmeric and in instant coffee also caused a noticeable temporal change of spectral reflectance. These results suggested that the use of spectral reflectance was very useful for comparing with before and after evaluation for color change.