Korean J Orthod.  2005 Aug;35(4):251-261.

Three-dimensional CT image study on the correction of gonial angle width enlarged on frontal cephalogram

Affiliations
  • 1Department of Orthodontics, School of Dentistry, Dental Science Research Institute, Chonnam National University, Korea. hhwang@chonnam.ac.kr
  • 2Department of Orthodontics, School of Dentistry, Chonnam National University, Korea.
  • 3Korean Adult Occlusion Study Center, Korea.

Abstract

Enlargement is an inherent property of X-rays which occurs when straight lines diverge from small a focal spot. The purpose of the present study was to evaluate the validity of the correction of gonial angle width enlarged on frontal cephalogram, using frontal and lateral cephalograms taken orthogonally from each other. In 40 adult individuals, frontal and lateral cephalograms were taken at a 90 degrees angle using the Head Posture Aligner. The angle width was measured on the frontal cephalogram and subsequently, the corrected angle width was calculated using the magnification rate of two cephalograms. Measured and corrected angle widths were compared with the measurement from the 3D CT image. The measurement on the frontal cephalogram showed a 9.10 mm of enlargement on average, ranging from 7.92 to 11.31 mm. Corrected angle width measurement showed a 0.14 mm difference with the 3D CT image measurement, which was not statistically significant. The results of the study indicate that actual angle width can be approached through calculation using frontal and lateral cephalograms taken orthogonally with the help of the Head Posture Aligner. The study also showed that the magnitude of correction error did not show a significant correlation with the amount of menton deviation, and it suggests that the present correction method is valid even in individuals with severe facial asymmetry.

Keyword

Frontal cephalogram; Angle width; Enlargement; Correction

MeSH Terms

Adult
Facial Asymmetry
Head
Humans
Posture
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