Change in tooth length and angulation on panoramic radiographs taken at different labiolingual and buccolingual inclinations

Choi, Gab Lim; Lim, Sung Hoon; Kim, Kwang Won; Kim, Jae Duck

Abstract

OBJECTIVE
The purpose of this study was to examine how the mesio-distal angulation and the length of each tooth changes on panoramic radiograph at different bucco-lingual inclinations.
METHODS
After constructing an acrylic model based on the mean arch of 30 adults with normal occlusion, the wire was placed in the center of the teeth on the acrylic model. First, the wire was implanted in normal angulation and inclination and a panoramic radiograph taken. After changing the inclination from I-15 degrees to I+15 degrees by 5 degrees a panoramic radiograph was taken again and the mesio-distal angle and wire length on the panoramic radiograph were assessed.
RESULTS
When the wire was implanted at the normal angulation and inclination, the length measured in the panoramic radiograph was magnified 111 ~ 117% from the original length in the anterior region and 121 ~ 125% in the posterior region. Only the central and lateral incisors showed significant length differences when the inclination was changed from I-15 degrees to I+15 degrees at fixed angulation. When the inclination was changed from I-15 degrees to I+15 degrees, the angulation of most teeth on panoramic radiograph appeared to be more disto-angulated than in reality, and the lateral incisor and canine showed the largest difference. Only I-15 degrees, I+15 degrees groups of premolars and I+15 degrees group of molars showed more mesio-angulation than in reality. As the labio(bucco)lingual inclination of all teeth were decreased, tooth angulation in the panoramic radiograph appeared to be more disto-angulated.
CONCLUSION
The labio-liugual inclination of teeth should be considered because it affects panoramic image of teeth, such as length of incisors and angulation of other teeth.