Dental pulp is located in root canal of tooth. To modern root canal therapy, "Root canal preparation" is the main means to debride dental pulp infection. The shape of root canal will be changed after preparation, so, when assessing the preparation instruments and techniques, the root canal shaping ability especially the apical offset is very important factor. In this paper, a novel digital image processing and measurement system is designed and applied to quantitative analysis of simulated canal shape. By image pretreatment, feature extraction, registration and fusion, the variation of the root canals' characteristics (before and after preparation) can be accurately compared and measured, so as to assess the shaping ability of instruments. When the scanning resolution is 1200dpi or higher, the registration and measurement precision of the system can achieve 0.021mm or higher. The performance of the system is tested by a series of simulated root canals and stainless steel K-files.
The study of shaping ability is very important in assessment of instruments and preparation techniques. Using simulated canals in these studies have many advantages such as good standardization, good comparability, transparent et al. A new computer assistant measure system particularly designed for quantitative analysis of the shape of simulated canals is set up and described in this paper. This system can be used in automatic assessment of shaping ability of instruments, by image pretreatment, feature extraction, registration, fusion, and measurement. Comparing the simulated root canal shape before and after instrument in the fused image is good to reduce the errors from vision and enhance the repetition of results. The registration and measurement precision of the system can achieve 0.021mm or higher, when the resolution of original root canal image is 1200 DPI or higher. The shaping ability of stainless steel K-files is evaluated by the system.