[Studies evaluating measurement accuracy of CMS-JAW, a jaw motion tracking device with six degrees of freedom using an ultrasonic recording system].

PURPOSE: For diagnoses of temporomandibular dysfunction, reports indicate the importance of analyzing jaw movements using a jaw motion tracking device with six degrees of freedom. However, such devices are not widely applied in clinical practice, due to difficulty of use. To determine whether CMS-JAW (a newly developed six degrees of freedom jaw motion tracking device that features easy analysis of jaw movements) offers the measurement accuracy required for clinical use, we evaluated the device by measuring condyle translation and rotation during jaw movement. METHODS: In this study, we evaluated measurement accuracy by comparing measurements of condyle movements obtained from the Win Jaw System, a comparable jaw motion tracking device with six degrees of freedom based on an ultrasonic recording system; the Gnathohexagraph II, a device based on a different measurement principle; and the CMS-JAW. In the experiment, we confirmed the condyle translations and rotations obtained by each device by measuring distances and angles, respectively, with a micro slider for three-dimensional measurements (to an accuracy of 0.01 mm and 0.02 mm) and a digital protractor (to an accuracy of 0.1 degrees). RESULTS: No significant distortions were observed in the space replicated based on the range of condyle translations obtained with CMS-JAW. Deviations from theoretical values were greatest along the z-axis, with a maximum error of 0.20 mm and root mean square (RMS) error of 0.10 mm. The maximum error for angles of condyle rotation was 0.50 degrees; RMS errors ranged from 0.05 to 0.30 degrees. CONCLUSION: Our analysis of condyle movement demonstrates that the CMS-JAW provides acceptable measurement accuracy for clinical applications.

[Reliability of the measurement of current perception thresholds in the palatal mucosa].

PURPOSE: The purpose of this study was to investigate the possibility of applying measurement of the Current Perception Threshold (CPT) to the oral mucosa. METHODS: Forty healthy volunteers (20 males and 20 females; mean age, 29.5 +/- 5.1 years) were recruited for the study. CPT measurements were performed over the nasopalatine nerve area and greater palatine nerve area with 5,250 and 2000 Hz electrical stimulation using the Neurometer NS3000. The CPTs were measured on three separate days, and each measurement was carried out once a day by a single operator. RESULTS: Each of the electrical stimulations of 5,250 and 2000 Hz had a specific CPT. There were no significant differences in the CPT values measured over the three days. The CPTs were lower in the females than in the males. There were no significant differences in the CPTs in the greater palatine nerve area between the right and the left side. No order effect was observed on the CPTs in the greater palatine nerve area of either side in the first and second measurements. The intraclass correlation coefficient of the CPT measurements was as high as 0.80. CONCLUSION: It was concluded based on the high reliability of the measurements obtained, that CPT measurement can be applied to the oral mucosa.