두부 위치 변화에 따른 파노라마 방사선사진상의 치축각도의 왜곡

Abstract

The purpose of this study was to evaluate the effect of head position changes on the root parallelism between adjacent teeth on the panoramic radiographs. The model with normal occlusion was constructed in the SolidWorks program, and then RP (rapid protyping) model was fabricated. The model was repeatedly imaged and repositioned five times at each of the following nine positions: ideal head position, 5°, 10° up, 5°, 10° down, 5°, 10° right up, and 5°, 10° right rotation. Panoramic radiographs were taken by Planmeca ProMax and the angle between the long axes of adjacent teeth was directly measured in the monitor. The results showed that there were statistical differences between tooth angulations measured from the panoramic radiograph taken at ideal head position and tooth angulations measured from the panoramic radiographs taken at various head positions. Axes of adjacent teeth tended to converge toward the occlusal plane when head tilted up and converge toward opposite of the occlusal plane when head tilted down. Anterior teeth showed the most notable differences. When one side of head tilted up 5° and 10° along anteroposterior axis (Y axis), tooth axes of the same side tended to converge toward the occlusal plane and tooth axes of the opposite side tended to converge toward opposite of the occlusal plane. When the head rotated to one side along the vertical axis (Z axis), canine and lateral incisor of same side converged toward opposite of the occlusal plane and canine and lateral incisor of the other side converged toward the occlusal plane. The above results suggest that panoramic radiographs should be taken at correct position. When assessing the root parallelism on the panoramic radiographs, occlusal plane cant (anteroposterior or lateral) or asymmetry of dental arch should be considered because these can cause distortion of tooth axes in the panoramic radiographs.