Prediction of frontal soft tissue changes after mandibular surgery in facial asymmetry individuals

Hyeon-Shik Hwang; Jessica J. Lee; Chung Hyon Hwang; Hak-Hee Choi; Hoi-Jeong Lim

doi:10.4041/kjod.2008.38.4.252

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Hwang, Lee, Hwang, Choi, and Lim: Prediction of frontal soft tissue changes after mandibular surgery in facial asymmetry individuals

Original Article

Korean Journal of Orthodontics

Korean Journal of Orthodontics 2008; 38(4): 252-264.

Published online: 31 August 2008

DOI: https://doi.org/10.4041/kjod.2008.38.4.252

Prediction of frontal soft tissue changes after mandibular surgery in facial asymmetry individuals

Hyeon-Shik Hwang, DDS, MSD, PhD^a, Jessica J. Lee, DDS^b, Chung Hyon Hwang, DMD, MPH^c, Hak-Hee Choi, DDS, MSD^d, Hoi-Jeong Lim, MS, PhD^e

^aProfessor, Department of Orthodontics, 2nd Stage of Brain Korea 21, School of Dentistry, Dental Science Research Institute, Chonnam National University, Korea.

^bAssistant Professor, Department of Oral and Maxillofacial Surgery, School of Dentistry, University of Washington, USA.

^cResearch Scientist, Korean Adult Occlusion Study Center, Korea.

^dGraduate Student, Department of Orthodontics, School of Dentistry, Chonnam National University, Korea.

^eProfessor of Biostatistics, Department of Orthodontics, School of Dentistry, Chonnam National University, Korea.

Corresponding author: Hyeon-Shik Hwang. Department of Orthodontics, School of Dentistry, Chonnam National University, 8, Hak-dong, Dong-gu, Gwangju 501-757, Korea. +82 62 220 5486; hhwang@chonnam.ac.kr

Received 4 May 2007 Revised 2 November 2007 Accepted 5 November 2007

Abstract

Objective

To aid the development of a frontal image simulating program, we evaluated the soft tissue frontal changes in relationship to movement of hard tissue with orthognathic surgery of facial asymmetry patients.

Methods

Preoperative and postoperative frontal cephalograms and frontal view photographs of 45 mandibular surgery patients with facial asymmetry were obtained in a standardized manner. Vertical and horizontal changes of hard tissue and soft tissue were measured from cephalograms and photographs, respectively. Soft tissue change in result to hard tissue change was then analyzed.

Results

Both vertical and horizontal correlation analysis showed a weak relationship between the changes. Hard tissue points that were picked for 1:1 mean ratio with soft tissue points did not show any significant relevance. For each soft tissue change, regressive equation was formulated by stepwise multiple regression analysis, and the equation for soft tissue Menton was most reliable in predicting changes. Both vertical and horizontal hard tissue changes were used together in prediction of vertical or horizontal soft tissue change.

Conclusions

The results suggest that computerized image simulation using regression analysis may be of help for prediction of soft tissue change, while 1:1 mean ratio method is not useful.

Keywords: Prediction of soft tissue change, Frontal cephalogram, Frontal photo, Facial asymmetry, Image simulation

Figures and Tables

Fig 1

Cephalometric landmarks to represent hard tissue change. Detailed description of landmarks is in Table 2.

Fig 2

Photometric landmarks to represent soft tissue change. Detailed description of landmarks is in Table 3.

Table 1

Description of the subjects used in this study and summary of orthognathic surgery performed

^*The number in the surgery column indicates the amount of operation (unit; mm); ^†The degree of chin deviation before and after surgery is expressed as the angle formed by Cg-ANS and ANS-Me lines (unit: °). Mn, mandible; Genio, genioplasty; Vt, vertical; AP, anteroposterior; Rt, right; Lt, left.

Table 2

Description of frontal cephalometric landmarks used in this study

Table 3

Description of photometric landmarks used in this study

Table 4

Correlation coefficient between hard tissue change and soft tissue change in the horizontal direction

^*p < 0.05; ^†p < 0.01.

Table 5

Correlation coefficient between hard tissue change and soft tissue change in the vertical direction

^*p < 0.05; ^†p < 0.01.

Table 6

Mean ratio between soft tissue and hard tissue change in the horizontal direction

^*p < 0.05; ^†p < 0.01.

Table 7

Mean ratio between soft tissue and hard tissue change in the vertical direction

^*p < 0.05; ^†p < 0.01.

Table 8

Results of stepwise multiple regression analysis for the horizontal change of soft tissue points

Table 9

Results of stepwise multiple regression analysis for the vertical change of soft tissue points

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