Ken'ichi Kobayashi

Measurement in vivo of Masticatory Mucosal Thickness with 20 MHz B-Mode Ultrasonic Diagnostic Equipment

Analysis of the movement of the denture foundation under function is very important for construction of a denture. For this analysis, the thickness of the masticatory mucosa gives the required quantitative information. The thickness measurements were taken from 21 oral sites in 100 edentulous patients, by means of 20 MHz B-mode ultrasonic equipment. The average thickness of the masticatory mucosa ranged from 1. 92 mm to 2.38 mm at the upper edentulous ridge and from 1.45 mm to 1. 58 mm at the lower edentulous ridge. The center of the palate had the thinnest mucosa and the lateral area of the palate had the thickest among all the measuring points. Contrary to what is often believed, a decrease in mucosal thickness with age was not observed by one-way analysis of variance. Furthermore, as the degree of ridge reduction increased, a decrease in the mucosal thickness was found by one-way analysis of variance at only two of the 14 measuring sites on the ridges. At four of the 21 measuring sites, male patients had significantly thicker mucosa than did females, and the correlation coefficients of the thickness of mucosa between right and left sides in the palate were higher than those in residual ridges.

Development of a recording system for saliva pH with a complete denture by telemetry

A new system for measuring saliva pH by radio telemetry was developed. The system was built into a lower complete denture and could operate for about 19 h. The maximum error in the range pH 5-8 was 0.15 pH, and the correlation when values were compared with those from a glass-electrode pH meter was 0.99. That this system operates successfully was confirmed in a clinical experiment.

The Movement of the Chin during Mastication.

The purpose of this study was to evaluate suitability of the soft tissue on the chin as a reference point in measuring masticatory movements. The movements of the chin and a lower incisor during mastication were measured simultaneously using a real-time measuring system for three-dimensional movements of soft tissues (3-D Auto Tracking System).The results were as follows1. Computer-based analysis was developed to divide the whole-chewing period into single stroke and determine the beginning of the opening, closing, occluding phase.2. The chin movements were 1/60 sec slower than lower incisor movements at the beginning of the opening phase.3. The chin movements were 1/60 sec faster than lower incisor movements at the beginning of the occluding phase.The results obtained in this study indicate that the soft tissue on the chin was suitable as a reference point in measuring masticatory movements.

[Measurement of facial form using stereo-photogrammetry system].

We have been developing a three dimensional measurement system by 35mm non-metric SLR camera and have been applying this system to the measurement of complete denture base surface area and edentulous cast model surface. The purpose of this study was to apply this system to the measurement of the facial form. The subjects head was fixed and 15 control points were arranged around his face. In order to make the process of stereo-matching easier, we projected mesh on the subjects face and took stereoscopic photographs. These photographs were measured by the digitizer and the 3-D coordinates of about 5000 measuring points were calculated by a personal computer. The geometric model of the face was displayed in three dimensional computer graphics. And the model of the face was carved out from the acrylic resin by the NC milling machine from these data.