Quantification of three-dimensional facial asymmetry for diagnosis and postoperative evaluation of orthognathic surgery

Cao, Hua-Lian,Kang, Moon-Ho,Lee, Jin-Yong,Park, Won-Jong,Choung, Han-Wool,Choung, Pill-Hoon Korean Association of Maxillofacial Plastic and Re 2020 Maxillofacial Plastic Reconstructive Surgery Vol.42 No.-

Background: To evaluate the facial asymmetry, three-dimensional computed tomography (3D-CT) has been used widely. This study proposed a method to quantify facial asymmetry based on 3D-CT. Methods: The normal standard group consisted of twenty-five male subjects who had a balanced face and normal occlusion. Five anatomical landmarks were selected as reference points and ten anatomical landmarks were selected as measurement points to evaluate facial asymmetry. The formula of facial asymmetry index was designed by using the distances between the landmarks. The index value on a specific landmark indicated zero when the landmarks were located on the three-dimensional symmetric position. As the asymmetry of landmarks increased, the value of facial asymmetry index increased. For ten anatomical landmarks, the mean value of facial asymmetry index on each landmark was obtained in the normal standard group. Facial asymmetry index was applied to the patients who had undergone orthognathic surgery. Preoperative facial asymmetry and postoperative improvement were evaluated. Results: The reference facial asymmetry index on each landmark in the normal standard group was from 1.77 to 3.38. A polygonal chart was drawn to visualize the degree of asymmetry. In three patients who had undergone orthognathic surgery, it was checked that the method of facial asymmetry index showed the preoperative facial asymmetry and the postoperative improvement well. Conclusions: The current new facial asymmetry index could efficiently quantify the degree of facial asymmetry from 3D-CT. This method could be used as an evaluation standard for facial asymmetry analysis.

하악골 전돌증을 동반한 안모비대칭의 유형 분석

윤규식(Kyu-Sik Yoon),정영수(Young-Soo Jung),강군철(Goon-Chul Kang),박형식(Hyung-Sik Park) 대한구강악안면외과학회 2004 대한구강악안면외과학회지 Vol.30 No.2

Object : Patients with facial asymmetry accompanying mandibular prognathism have various causes and clinical features. So, it is difficult to find a satisfactory treatment method functionally and esthetically. Every traditional classification and interpretation to find etiopathogenesis and/or to establish ideal surgical modality has many limitations because it can’t be applied simply to various conditions of patients with facial asymmetry accompanying mandibular prognathism. Therefore, we employ a new classification to interpret more details of the morphologic change of mandible and the spatial change of mandible and maxilla. Materials and Methods : Using panoramic X-ray films, PA cephalograms and submentovertex films of 126 patients diagnosed with facial asymmetry accompanying mandibular prognathism as resources, the following results were gathered after analyzing each characteristics through distributing the patterns according to the morphological mandibular asymmetry and mandibular and maxillary spatial asymmetry. Results : Almost frequency of morphological mandibular asymmetry was shown. In case of condyle-ramus elongation and body elongation group, it’s frequency was the highest. Higher frequency of compensating vertical growth was shown on the side of over growing maxilla in case of vertical length difference between left and right condyle-ramus. On the other hand, higher frequency of no compensating vertical growth difference between left and right side was shown in case of no vertical length difference in condyleramus. Spatial mandibular asymmetry generally occurred when there was no morphological mandibular asymmetry. Correlation between condyle length difference and condyle-ramus length difference between left and right side was very high, but correlation between condyle length difference and body length difference, and correlation between condyle length difference and body vertical length difference was low. Conclusion : In case of patients with facial asymmetry accompanying mandibular prognathism, it is suggested that various pattern of facial asymmetry is occurred by the independent growth of each unit rather than dependent growth of other unit by major growth unit abnormality. Due to the untypical pattern and the various asymmetry occurring according to the changes of each mandibular growth unit, it is considered that an appropriate surgical method should be searched based on the accurate recognition of the each pattern for patients with facial asymmetry accompanying mandibular prognathism.

Facial asymmetry: a case report of localized linear scleroderma patient with muscular strain and spasm

Kim, Jae-Hyung,Lee, Suck-Chul,Kim, Chul-Hoon,Kim, Bok-Joo Korean Association of Maxillofacial Plastic and Re 2015 Maxillofacial Plastic Reconstructive Surgery Vol.37 No.-

Facial asymmetry is found in patients with or without cosmetic facial alterations. Some patients have facial asymmetry that manifests underlying skeletal problems, while others have only limited soft-tissue facial asymmetry. Orthognathic surgery brings about a dermatic change, as soft tissue covers underlying bones. Limited soft-tissue asymmetry, meanwhile, is difficult to correct. The treatment modalities for the creation or restoration of an esthetically pleasing appearance were autogenous fat grafts, cartilage graft, and silicon injections. A young female patient had right-side facial asymmetry. The clinical assessment involved visual inspection of the face and palpation to differentiate soft tissue and bone. Although the extra-oral examination found facial asymmetry with skin atrophy, the radiographic findings revealed no mandibular atrophy or deviation. She was diagnosed as localized scleroderma with muscle spasm. In conclusion, facial asymmetry patients with skeletal asymmetry can be esthetically satisfied by orthognathic surgery; however, facial atrophy patients with skin or subdermal tissue contraction need treatment by cosmetic dermatological surgery and orthodontic correction.

안면비대칭 평가를 위한 Nottingham Grading System의 문제점 개선

이민우(M. W. Lee),장민(M. Jang),김진아(J. A. Kim),신상훈(S. H. Shin) 한국재활복지공학회 2017 재활복지공학회논문지 Vol.11 No.2

안면 비대칭은 다양한 원인에 의해 발병되기 때문에 원인 분석이 중요하고, 평가하는데 있어서 정량적인 지표가 필요하다. 본 연구에서는 웹켐을 이용하여 얻은 영상을 영상처리 및 연산부를 거쳐 마커를 추적하고 마커 간의 거리를 계산하여 안면 마비를 평가하는데 정량적인 지표로 사용하던 Nottingham Grading System을 안면 비대칭을 평가하는데 적용해 보았다. 기존 Nottingham Grading System은 표정 변화에 따른 안면부의 특징점들간의 거리변화를 합산하여 좌, 우를 비교하기 때문에 특정 케이스의 경우 측정 오류를 불러일으키는 문제점이 있었다. 기존 Nottingham Grading System과 문제점을 보완하여 개선시킨 평가지표를 이용하여 안면비대칭인 피실험자와 정상의 피실험자를 비교하였다. 기존 Nottingham Grading System에서는 안면 비대칭의 경우 99.0%, 정상의 경우 95.0%로 둘 다 정상 범위 속에 포함되었다. 하지만 개선시킨 Nottingham Grading System에서는 안면 비대칭의 경우 74.0%, 정상의 경우 93.2%의 결과가 나왔다. 본 연구의 결과로 인해, 개선시킨 Nottingham Grading System은 각 부위별 상세한 평가 및 진단이 가능하고, 기존 Nottingham Grading System의 `문제점을 보완하였음을 보여주었다. Because facial asymmetry is caused by various causes, the cause analysis is important and quantitative index is needed to the evaluation. In this study, we applied the Nottingham Grading System that was used as a quantitative index to evaluate the facial paralysis by tracking the markers through the image processing and calculating the distance between the markers with images obtained by using the webcam, to evaluate facial asymmetry. The existing Nottingham Grading System has a problem of causing a measurement error in the specific case because the left and right are compared by summing the distance change between the feature points of the face part according to the change of the facial expression. We compared the case of the facial asymmetry and case of normal subject by using the existing Nottingham Grading System and the improved Nottingham grading system. In the existing Nottingham Grading System, case of facial asymmetry and case of facial symmetry were 99.0% and 95.0% respectively in the normal range, but the improved Nottingham Grading System showed facial asymmetry case was 74.0% and facial symmetrical case was 93.2%. The results of experiment show that the improved Nottingham Grading System allows detailed evaluation of each site and improved the problem of the Nottingham Grading System for specific cases.

Facial Flap Repositioning in Posttraumatic Facial Asymmetry Perfect

변일환,변단,백우열 대한두개안면성형외과학회 2016 Archives of Craniofacial Surgery Vol.17 No.4

Perfect facial and body symmetry is an important aesthetic concept which is very difficult, if not impossible, to achieve. Yet, facial asymmetries are commonly encountered by plastic and reconstructive surgeons. Here, we present a case of posttraumatic facial asymmetry successfully treated with a unique concept of facial flap repositioning. A 25-year-old male patient visited our department with severe posttraumatic facial asymmetry. There was deviated nasal bone and implant to the right, and the actual facial appearance asymmetry was much more severe compared to the computed tomography, generally shifted to the right. After corrective rhinoplasty, we approached through intraoral incision, and much adhesion from previous surgeries was noted. We meticulously elevated the facial flap of both sides, mainly involving the cheeks. The elevated facial flap was shifted to the left, and after finding the appropriate location, we sutured the middle portion of the flap to the periosteum of anterior nasal spine for fixation. We successfully freed the deviated facial tissues and repositioned it to improve symmetry in a single stage operation. We conclude that facial flap repositioning is an effective technique for patients with multiple operation history, and such method can successfully apply to other body parts with decreased tissue laxity.

안면부 비대칭을 동반한 하악전돌증 환자의 수술 후 비대칭의 교정과 재발

윤상엽,박상훈,윤근철,박인권 대한성형외과학회 2003 Archives of Plastic Surgery Vol.30 No.6

The purpose of this study is to evaluate the amount of correction and relapse after orthognathic surgery in patients with facial asymmetry and prognathism by means of the frontal cephalogram. Out of twenty prognathism patients who had been diagnosed as having skeletal facial asymmetry in need of orthognathic operation at our institute during last 6 years, only thirteen patients with pre- existing pre-operative(T0), immediate postoperative (T1) and long term follow up(T2) frontal cephalograms were included in the study. The population was divided according to the kind of surgical operation and severity of asymmetry. The midline sagittal reference line (MSR) was drawn and four basic landmarks were marked on the frontal T0, T1 and T2 cephalograms. Radiographic facial asymmetry was found most obviously in the lower jaw(Deviation from MSR: 2.21mm at ANS, 8.34mm at menton). Facial asymmetry was corrected to minimal degree(1.34 at menton) with orthognathic procedures. On long-term follow up, the correction of deviation was maintained as 1.98mm. The relapse rate was 24.1% at menton. The contributing factor was searched and the amount of asymmetry correction and the amount of prognathism correction proved to have statistical significance (p<0.05). In conclusion, asymmetry could be corrected with orthognathic procedures, which could be maintained with minimal degree of relapse. However, in preoperative planning, the degree of relapse should be considered to maximize the aesthetic outcome.

Factors contributing to the perception of facial asymmetry in dentists and laypersons

Sung-Kwon Choi,강경화 조선대학교 치의학연구원 2019 Oral Biology Research (Oral Biol Res) Vol.43 No.3

The aims of this study were to find differences in how dentists and laypersons evaluate facial asymmetry and to identify factors contributing to the perception of asymmetry. Photographs of young male and female faces were transformed according to lower facial height, lower facial width, the direction of chin deviation, and the angle of chin deviation. Thirty dentists (mean age, 28.0 years; 16 males, 14 females) and 50 laypersons (mean age, 22.2 years; 24 males, 26 females) answered a questionnaire evaluating the asymmetry in 24 photographs (12 males and 12 females) using visual analog scale. The individual t-test and logistic regression analysis were used for statistical analysis. There was no difference between dentists and laypersons in evaluating photographs with a 5° chin deviation angle. Compared with laypersons, dentists evaluated photographs with 10° chin deviation angle as more asymmetric. Faces with a long lower facial height, left deviation of the chin, and a large chin deviation angle were considered to be more asymmetric than those with normal lower facial height, right deviation of the chin, and a small chin deviation angle, respectively ( p <0.05). There was no consistent relationship between lower facial width and the perception of facial asymmetry in both the groups. The perception of facial asymmetry was affected by lower facial height, the direction of chin deviation, and the amount of chin deviation.

안모비대칭의 진단용 기준선의 유용성에 관한 연구

류성호(Sung-Ho Ryu),장현호(Hyun-Ho Chang) 대한구강악안면외과학회 2005 대한구강악안면외과학회지 Vol.31 No.3

Purpose: To assess the relationship between soft tissue reference line and hard tissue reference line using the standardized photographs and the posteroanterior cephalometric radiographs(P-A)in facial asymmetric patients and to compare the differences of angular measurement between normal group and asymmetry group. Methods: Normal group consisted of 44 persons with normal occlusion and normal facial morphology. Asymmetry group consisted of 90 patients with facial asymmetry. Standardized facial photographs and P-A were taken in all subjects. The horizontal reference lines were bipupillary line in photographs and latero-orbitale line in P-A respectively. The vertical reference line were the line from the midpoint of horizontal reference line perpendicularly. Angular measurement of otobasion canting, lip canting, nose deviation, chin deviation, and maxillary deviation were compared and analyzed in photographs. And angular measurement of mastoid canting, mandibular canting, nose deviation, chin deviation, and maxillary deviation were compared and analyzed in P-A. Results: 1. The variables of photographs and P-A were significantly related in the asymmetry group. 2. Significant differences between all variables except for PT2 and PA2 were shown in the asymmetry group and between PT1 and PA1, PT3 and PA3 in the normal group respectively. 3. Comparison measurement scores of angular difference between control group and experimental group concerning each variable showed significant difference except for PA1. Conclusions: Soft tissue components may not compensate for underlying skeletal imbalance in nose deviation and chin deviation. The horizontal reference lines in photographs were significant related with the P-A, but angular variables between the two studies show significant differences. Therefore, we do not recommend use photography in the assessment the facial asymmetry as complemented in the P-A.

안면 비대칭환자의 하악골체부의 시상 단면에 관한 연구

이재열(Jae-Yeol Lee),김용일(Yong-Il Kim),황대석(Dae-Seok Hwang),김용덕(Yong-Deok Kim),신상훈(Sang-Hun Shin),김욱규(Uk-Kyu Kim),정인교(In-Kyo Chung) 대한구강악안면외과학회 2011 대한구강악안면외과학회지 Vol.37 No.2

Introduction: To correct the facial asymmetry by mandibular jaw surgery, it is important to know the anatomy of the mandible including the mandibular canal positioning of patients with facial asymmetry. This study was performed to evaluate the differences in the cross-sectional surface in the body of the mandible between the deviated side and opposite side in patients with facial asymmetry. Materials and Methods: The study was conducted on 37 adult patients composed of 2 groups, the asymmetry group (n=20) and non-asymmetry group (n=17). Using the cross-sectional computed tomography (CT) images, the distance from the buccal aspect of the mandibular canal to the outer aspect of the buccal cortex, distance from the buccal aspect of the mandibular canal to the inner aspect of the buccal cortex, distance from the inferior aspect of the mandibular canal to the inferior border of the mandible, thickness of the mandible, and cross-sectional surface area of the mandible were measured in each side of the mandible. Results: The cross-sectional area of the mandible including the mandibular canal positioning in the deviated side was not statistically different from the opposite side in the asymmetry group. Only the distance from the inferior aspect of the mandibular canal to the inferior border of the mandible in the ramus area of the deviated side was significantly longer than opposite side. On the other hand, the bucco-lingual width of the asymmetry group was thinner than the non-asymmetry group. Conclusion: The cross-sectional area including the mandibular canal of the mandible did not appear to be modified by the facial asymmetry.

3차원 CT을 이용한 안면 비대칭의 치험 1례

최봉주,박노부,박효상 啓明大學校 醫科大學 1996 계명의대학술지 Vol.15 No.3

It is very difficult to diagnose the facial asymmetry, that is, difficult to determine what part of problem is major cause to treatment. The three dimensional CT developed recently can provide excellent three dimensional image of soft and hard tissue, thus authors decided to determine the possibility of three dimensional CT for the diagnostic means for facial asymmetry. The patient, 19 year old female, had anterior edgebite with deviated dental midline and mild concave profile and was diagnosed as facial asymmetry with skeletal asymmetry and functional displacement of mandible by using three dimensional CT. The orthodontic and orthognathic procedure were performed. The following results were obtained. The facial asymmetry was favorably corrected. The favorable facial profile was achieved. The harmonious occlusion was obtained. The three dimensional CT will provide useful guide for skeletal abnormality and will be good diagnostic means for facial asymmetry. However, the appropriate analysis method is not established, it will be further needed.