Abstract
For securing better permanent dentition, proper guidance and care of the occlusion of primary dentition in children is essential. A study model detection system was newly developed in our department, permitting observation of the arch form on a computer CRT. The purpose of the study was to investigate the method and accuracy of the system.
The main system consists of a CCD camera (PX-390A, PIAS), positioned and standardized at a right angle 350 mm apart from the measuring plane, an image analyzer (LA525MS, PIAS), a personal computer (PC-9801RX, NEC), digitizer (D3110, PIAS), and sampling images managed and displayed on a CRT.
In the first investigation, the strain of the camera lens was studied by measuring a standarized graph paper via the system. It was disclosed that the results obtained by the image analyzer tended to reflect smaller values at the edges of the CRT than in the center of the CRT (maximum measured error -2.97%, mean measurement error -0.45 %) than the real distance.
In the second investigation, the length and width of three upper study models were examined and the differences between measuring methods; i. e. image analyzer and slide calipers measurement were evaluated. As a result, the mean measurement error of the study model by using an image analyzer were -4.01 % compared to the measurements of the slide calipers. However, the values of the coefficient variation of the image analyzer measurements were very low compared to the slide caliper measurements.
In conclusion, since a study model detection system by using the image analyzer showed high dimensional accuracy, it could be useful to examine a study model for the diagnosis of occlusion.
