Abstract
WinJaw® systems record jaw movements by using ultrasonic waves. The sensor is very light and the data is obtained without physical contact. The condylar analyzing system must be able to analyze small movements because the functional movements of the condyle are usually small, typically less than 1 mm. The purpose of this study was to confirm the precision of the WinJaw® EPA for evaluating condyle position, and to compare two types of sensor, 3 Maker+3 Microphone (3 MK) and 4 Maker+4 Microphone (4 MK).
In this study we made simulators which were designed to simulate the micro movement of the condyle. The accuracy and resolution were measured for each sensor and the results were compared statistically.
Next, we used signal processing to improve the resolution. Smoothing from 3 to 6 points was tried for each resolution and its effect was then estimated.
The results were as follows. Average resolution was 3 MK: 51.9∼53.9μm and 4 MK: 44.9∼45.6μm, average error was 3 MK: -0.45∼5.31% and 4 MK: 0.46∼4.27%, and overall accuracy was 3 MK: 98.9μm and 4 MK: 90.9μm. The differences between the two sensors were not significant, but there were some differences in the results depending on the direction.
The signal processing results revealed that the 6-points smoothing could improve the resolution by less than 50%. Consequently, by using this smoothing technique, the overall accuracy can be 68.6μm in 3 MK and 71.0μm in 4 MK, which is sufficient for analyzing condylar micro movements. Thus we conclude that the WinJaw® EPA is adequate for objectively analyzing condylar position in treatment rooms.
