TI : The study of apical changes on the orthopantomograph

 AU : Ahn HK
 AD : Dept. of Dental Radiology, Seoul Dentistry Seoul National University.
 SO : JKAMFR. 1979;9(1):19-23
 ISSN : 1225-049X
 LA : KOREAN
 CP : KOREA

 AB : A study was made primarily to investigate vertical and horizontal distortion of the image at the apical region of the dental roots in orthopantomographs. The subjects consisted of two dry skulls with radiopaque materials attached to root surface. Measuring of the width and length of each predetermined point at 23 teeth was performed in dry skulls and radiographic films.
 The results obtained were as follows;
 1. There was overall magnification of image in the vertical dimension. And anterior portion had greater magnification rate than posterior portion, while lower anterior portion had less magnification rate than upper anterior portion.
 2. There was reduction of the image in the horizontal dimension of the teeth, because of the position relation between dry skull and image layer of the orthopantomograph.
 3. There was a significant difference in distortion rate between the opposite teeth.
 4. Cervical portion of the tooth had more decreased rate of horizontal distortion than apical portion.