Korean J Orthod.  2007 Oct;37(5):319-330.

Correction of mandibular ramus height with frontal and lateral ramal inclinations in cephalograms and its effects on diagnostic accuracy of asymmetry

• Hwang HS
• Kim HM
• Lee KH
• Lim HJ

Abstract

OBJECTIVE
Defining right and left side differences in mandibular ramus height is one of the key elements in the diagnosis of facial asymmetry. The purpose of the present study was to evaluate the effect of correction of ramus height with frontal and lateral ramal inclinations (FRI and LRI) in 2-dimensional cephalograms and observe how this affects the diagnostic accuracy of asymmetry.
METHODS
Frontal and lateral cephalograms were obtained in 40 individuals with chin deviation. FRI and LRI were measured on each side and ramus height measurement was corrected with these inclinations using Pythagorean's theorem. The results of diagnosis before and after correction on cephalograms were compared with the results in 3D CT images.
RESULTS
Both FRI and LRI showed greater values in the contralateral side than in the chin-deviated side and these contributed to an increase in the right and left side ramus height differences. After comparison of diagnostic results before and after correction on cephalograms with the results on 3D CT images, the sensitivity increased significantly (from 74 to 94 %) whereas the specificity decreased (from 44 to 22 %). Overall accuracy increased from 68 to 78 % with the correction using FRI and LRI.
CONCLUSIONS
The results of the present study indicate that correction of ramus height with FRI and LRI is useful for an accurate diagnosis of facial asymmetry on frontal cephalograms.

Keyword

Frontal cephalogram; Correction of ramus height; Ramal inclination; Accuracy

MeSH Terms

Chin
Diagnosis
Facial Asymmetry
Sensitivity and Specificity