J Korean Assoc Oral Maxillofac Surg.  2011 Feb;37(1):21-29. 10.5125/jkaoms.2011.37.1.21.

The change of frontal ramal inclination (FRI) after orthognathic surgery with laterognathism: posteroanterior cephalometric study

• Yu SJ

• KMID: 2189802
• DOI: http://doi.org/10.5125/jkaoms.2011.37.1.21

Abstract

INTRODUCTION
To compare the change in frontal ramal inclination (FRI) in laterognathism after orthognathic surgery.
MATERIALS AND METHODS
Twenty four patients (10 men, 14 women; mean age, 22.8+/-5.2 years) with minimal facial canting (< or =2 mm) and apparent menton deviation (5.9+/-2.4 mm) who had been operated on to correct facial asymmetry and skeletal CIII malocclusion, were selected. On a preoperative posteroanterior (PA) cephalogram, the FRI of the deviated side and non deviated side, L1 deviation amounts and menton deviation amounts were measured. The FRI differences between both sides were compared, and the correlations between the measured deviated elements and the FRI differences were analyzed. On a postoperative PA cephalogram, the shifting amount of L1, shifting amount of L7 and FRI of both sides were measured, and the correlations between the shifting elements and the change in FRI were analyzed.
RESULTS
On the preoperative PA cephalogram, the FRI of the non deviated side was significantly greater than those of the deviated side. The differences in FRI, with a menton deviation amount showed a significant correlation. On the postoperative PA cephalogram, the FRI differences between the deviated and non deviated side were decreased significantly and mandibular transverse movement toward central position was noted. The mean shifting amounts of L7 were associated with the amount of change in the deviated side of FRI.
CONCLUSION
Transverse shifting of the mandible through orthognathic surgery decreases the FRI difference, which showed laterognathism, and improves the facial contour.

Keyword

Frontal ramal inclination (FRI); Laterognathism; Mandibular transverse movement; Orthognathic surgery; Cephalogram

MeSH Terms

Facial Asymmetry
Humans
Male
Malocclusion
Mandible
Orthognathic Surgery

Figure

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  Fig. 1. Cephalometric landmarks and measurements used in this study: FRI of deviated side, FRI of non deviated side, amount of menton deviation, amount of U1 deviation, amount of L1 deviation, linear L7 of deviated side, linear L7 of nondeviated side.(FRI: frontal ramal inclination)

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  Fig. 2. Diagram of FRI change after parallel shifting of mandibular body.(FRI: frontal ramal inclination)

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  Fig. 3. Superimposition of 3-dimensional computed tomography of preoperation and postoperation.

Reference

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