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How to Achieve a Balanced and Delicate Lower 3rd of the Face in Orientals by Mandibular Contouring
Tao Chen DDS, Ashish Khadka DDS, Yuchun Hsu DDS, Jing Hu MD, DDS,Dazhang Wang MD, DDS, Jihua Li MD, PhD*The State Key Laboratory of Oral Diseases and Orthognathic Surgery, West China College of Stomatology, Sichuan University, Chengdu, P.R. China, 610041.*Corresponding author. Telephone: +86 28 8550 2334E-mail addresses: leejimwa6698@sohu.com(Jihua Li) AbstractIntroduction: For East Asians, correction of square jaw has become one of the commonly performed procedures in aesthetic surgery. While reviewing unsatisfactory cases of mandibular reduction, the authors discovered that failure was largely due to surgeons generally focusing too much on treatment of the posterior part of mandible, and ignoring the esthetic significance of the harmonious and smooth overall curve from the anterior mandible to the inferior margin of the mandible. Thus, our group proposes that a coordinated, balanced, and smooth jawline is considered a key factor in Oriental mandibular contouring.Patients and Methods: Methods: 128 patients accepted jawline reshaping by “V-line” ostectomy, mandibular outer cortex split ostectomy, narrowing and /or sliding genioplasty, and porous polyethylene implantation to achieve the desired cosmetic effects.Results: All patients obtained satisfactory cosmetic results, and their square jaw was corrected. After the operation, a natural, harmonized, and balanced jawline was achieved. Lower third of the facial contour was significantly improved.Conclusion: Based on different facial features of square jaw deformity, a variety of plastic surgical methods for mandibular contouring were integrated and applied to achieve a balanced and delicate jawline.Keywords: square jaw; jawline; mandibular contouringAmong some East Asians, lower third of the faces are overly wide, with/without accompanying chin hypertrophy, resulting in a square facial contour 1. Although this contour is not a pathological as such, but as per Oriental standards of beauty it is considered to be unattractive. Currently, there is no consensus on the diagnostic criteria for square jaws. The degree of the squareness is also varied and is affected by the esthetic views of the patients and the subjective judgment of esthetic surgeons, as well as of different regional cultures. At present, due to the influence of movies and the fashion industry, more and more people are undergoing cosmetic surgery to improve their facial contour. Therefore, mandibular contouring has become an important procedure in the field of modern facial plastic surgery.Based on the reviews of correction cases of square jaw that yielded unsatisfactory results, the authors have found that in addition to congenital disproportionality, some unnatural jawlines are also created because surgeons generally focus too much on the treatment of the posterior part of the mandible without fully considering the esthetic significance of the harmonious and smooth overall curve from the anterior part of mandible to the inferior margin of the mandible, leading to an obvious chin nodule or the formation of a second gonial angle. Thus, the research group proposes that after the treatment, the surface projection of the gonion should be 2 cm below the earlobe, and 1 cm in front of the earlobe. A gradually sloping smooth curve from the gonion to the gnathion should be achieved thus the lateral chin shape and size can meet the aesthetic requirements. In facial contour surgery, a coordinated, balanced, and smooth jawline is considered a key factor in facial cosmetology, as well as the most important feature of a delicate face. On this principle, the author integrated mandibular outer cortex split ostectomy(MOSCO), mandibular “V-Line” ostectomy(MVO), narrowing or/and sliding genioplasty(NSG), and the porous polyethylene implanted to increase the gonial angle (Ar-Go-Me) and the mandibular plane angle (MP-HP) to achieve a balanced and delicate jawline.PATIENTS AND METHODS PatientsFrom January 2006 to December 2010, 128 patients (including 94 first-time patients and 34 patients undergoing second treatment) had square jaw and/or unnatural jawlines. Their facial features were as follows: from the frontal view, the lower face was overly wide and the lower front mandible was overly hypertrophied, showing eversion. From the lateral view, the curve from the gonion (Go) to gnathion (Gn) showed an abrupt rise or was overly flat at the anterior one-third of the inferior mandibular margin. The inferior margin of the bilateral mandible was asymmetrical and exhibited a square jaw; some patients also had square chins and/or gnathion displacement. The objective of the treatment was to form a smooth sloping curve from the gonion (Go) to the gnathion (Gn) so the jawline can meet the aesthetic requirements. Before the surgery, consultations with the patients were conducted to discuss their personal requirements based on specific facial details. Preoperative frontal and lateral cephalometric radiographs and panoramic radiographs were taken. The patients were also photographed to rule out any pathological bony changes or tumors, and to analyze the mandibular symmetry, the degree of the gonial angle, and the shape of the mandible. The condition of the chin was also analyzed to determine the required amount of osteotomy. This process was conducted to fully understand the mandibular curve arc and symmetry of the patients.Operative TechniqueAll procedures were performed under general anesthesia using naso-tracheal intubation. All surgical procedures were performed intraorally. Four different operative procedures were performed depending on patients’ needs and facial contours:Categorization and surgical design:Categorization of square jaw would be helpful to delineate the preferred treatment option out of available treatment for mandibular contouring. Basic categorization and surgical design for square face was thus based on the combination of features the patients presented with. The division of the patients is shown in Table I. Thus a treatment plan was formulated keeping in mind the patients’ facial characteristics and their demands, with special attention paid to vital structures present in that vicinity. Some of the clinical cases have been presented below for better comprehension.A. The mandibular outer cortex split ostectomy (MOCSO)A MOCSO, using methods similar to those described by Kun Hwang, Han and Kim 2,3, was performed with a reciprocating saw, bur, and osteotome. The resected mandibular inferior margin and mandibular outer cortex were harvested for future inlay grafting（Fig.1）.B. Mandibular “V-Line” ostectomy (MVO) The “V- line” ostectomy was designed according to the appearance of the patient, and this surgical technique has been described in detail by our group previously4. The key point in this procedure is to determine the line of ostectomy. The forward slanting nature of the ostectomy lines is determined by the location of mandibular canal, shape of mental region, and the adjustment of lower mandibular plane angle. Thus new gonial angle is formed by the posterior edge of the ascending ramus and ostectomy line. The point of ostectomy line on the posterior edge of the ascending ramus determines the distance from lower edge of auricular lobule to gonial angle postoperatively. Generally speaking, the newly formed gonial angle should be 2 cm below the lower edge of the auricular lobule, and 1 cm in front of the earlobe on a body-surface projection(Fig.2).C. Narrowing and/or sliding genioplasty(NSG) and Inlay bone graft（IBG）The sliding and narrowing genioplasty has been described in detail by our group previously5,6. For sliding genioplasty, after completion of osteotomy; the ostectomised segment was advanced forward and fixed with miniplate and screws to correct the deficient chin. For narrowing genioplasty, the muscular attachment was stripped off after resecting the central segment. Two segments were then approximated medially and fixed with microplate and screws. Vertical height was also increased where deemed necessary by placing the graft obtained from MVO or MOSCO. Finally, to obtain a more natural sloping curvature of the lower border of the mandible from gonion to gnathion and to avoid hour glass effect, bony edges at the lateral border were trimmed using an oscillating saw and burs(Fig.3).D: The porous polyethylene（Medpore） implantChin vertical height was also increased where deemed necessary by implanting the porous polyethylene implant without MVO or MOSCO. Finally, to obtain a more natural curvature of the lower border of the mandible and to avoid hour glass effect, bony edges at the lateral border were trimmed using an oscillating saw and burs(Fig.4).A watertight closure was obtained with absorbable chromic gut suture. Negative pressure drainage was applied. Antibiotics were prescribed for three to four days and bulky compressive dressing was applied for five days postoperatively in all cases.3. RESULTSThe mandibular contouring procedures were performed successfully in all cases. No severe complications and unexpected fractures were observed. Postoperative recovery was uneventful, and all wounds healed by primary intention without local infections. No facial paralysis or trismus was observed in any of the patients. Transient sensory disturbance of the skin around the mental nerve area was observed in 37 cases but all recovered without sequelae within 6 months.On completion of the surgical procedure, the preoperative and postoperative photographs of each patient were compared in the 6~40 months follow-up period. Postoperatively,the lower facial contour of all patients significantly improved from both frontal and lateral views, showing coordinated and symmetrical shape without a second gonial angle. The chin surface also conformed to the esthetic plane. Meanwhile, the mandibular contour line formed a smooth and gradually sloping curve from gonion to gnathion. Out of 128 patients, both the operating surgeon and the patient were satisfied in 124 cases. Only in 4 cases the patients were not fully satisfied with the results, which deviated from their preoperative expectations.Clinical CasesCase 1Facial appearance Feature: From the frontal view, square jaw was apparent. From the lateral view, the gonial angle (Ar-Go-Me) and the mandibular plane angle (MP-HP) were normal; the surface projection of the gonion was 2.5 cm from the lower end of the earlobe, and 1.3 cm in front of the earlobe; the contour line of the inferior margin of the mandible sloped gradually from the gonion to the point vertically below the angulus oris, then rising gradually from the angulus oris to gnathion, causing an unnatural and unattractive contour. But, the lower 1/3 of the face was not shorter than the middle third of the face in frontal view. And the chin was meet the requirement of Ricketts's E-line in lateral view.Therapeutic Schedule: After MOCSO, the square jaw significantly improved. The effect seen from the frontal view was relatively desirable. Yet, due to slight eversion of anterior mandibular inferior margin, the contour of the inferior margin of the mandible as seen from the lateral view was not entirely satisfactory(Fig.5).Improvement Schedule:Through the partial inferior margin ostectomy to solve the sinking margin, a gradually sloping smooth jawline from the gonion to the gnathion should be achieved thus the lateral view can meet the aesthetic requirements.Case 2:Facial appearance Feature: From the frontal view, the lower 1/3 of the face was shorter than the middle third of the face by 5 mm. The posterior mandible was naturally contoured, whereas the chin was square and wide. From the lateral view, the chin was horizontally normal but vertically short with deep mentolabial sulcus. The jawline of the inferior mandibular margin sloped gradually from the gonion to the part vertically below the angulus oris, then gradually becoming flat from the gonion to the gnathion, giving off an unnatural contour.Therapeutic Schedule: The broad square chin was medially approximated by 5 mm, shifted downward by 3 mm, and then fixed. The corrected Medpor(porous polyethylene) implant was then implanted over the mental region to achieve the satisfactory results from both frontal and lateral views(Fig.6).Case 3Facial appearance Feature: In anterior view, the lower face was square and short, chin was short and stunted. The gonial angle(Ar-Go-Me) was 105, lower mandibular plane angle(MP-HP) was 15, and chin was severely retrusive that failed to meet the requirement of Ricketts's E-line in lateral view. The lower 3rd of face compared to the middle 3rd was shorter by 6mm.Therapeutic Schedule:After mandibular “V-Line” ostectomy combined with mandibular outer cortex ostectomy, sliding genioplasty was accomplished with downward movement of 6 mm and forward movement of 6 mm, and bone graft was placed within the space produced by downward sliding, using the trimmed mandibular “V-Line” ostectomy segment. One-year postoperative, the appearance showed that the lower face was tapering, the mental region was slick, and the facial proportion was suitable. The patient was very satisfied with her new facial contour (Fig.7).Case 4: Facial appearance Feature: From the frontal view, patient had a relatively wide lower face and relatively short lower one-third of the face. Patient also had facial asymmetry: the inferior border of the mandible was slightly higher on the left side; chin was wide and inclined towards right; the genion was shifted towards right from the midline by 5 mm. From the lateral view, the gonial angle (Ar-Go-Me) and the mandibular plane angle (MP-HP) were normal. The surface projection of the gonion was 2.3 cm below the earlobe, and 1.1 cm in front of the earlobe. The chin was horizontally normal but vertically short. The contour line of the right inferior margin of the mandible sloped gradually from the gonion to the gnathion, yet the mandibular contour was unsatisfactory due to asymmetry. The right lateral inferior margin of the mandibular body was sinking.Therapeutic Schedule: After MOCSO the square jaw significantly improved. The effect seen from the frontal view was relatively desirable. The “V-line” ostectomy of the inferior margin of the right mandible was then used to solve the sinking margin and left-right asymmetry. Meanwhile, the chin was narrowed by 6 mm and shifted downward by 4 mm. The resected outer cortex was embedded in the gap and fixed with microplate and screws to achieve satisfactory effects from both frontal and lateral views(Fig.8).DiscussionGiven the differences between Eastern and Western cultures, facial features and esthetic preferences, an oval face is preferred by Asians. Moreover in recent times, due to the influence of television, movies, and the fashion industry, more and more people prefer their face to be slender and oval with smooth curves and outlines. Thus contour reshaping of the mandible has become popular in the field of facial plastic surgery in Asia in recent years1,2,8.Thus far, the contour reshaping of the mandible has made great progress in both esthetic concepts and surgical modalities. In 1951, Converse9 first introduced an intraoral approach for an osteotomy in a case prominent jaw with master hypertrophy. However osteotomy advocated by Converse was a linear one which could easily result in formation of second gonial angle. Likewise, the contour of the inferior mandibular margin after the osteotomy also exhibited an unnatural transition from posterior half to anterior half at the inferior border.. Baek10 et al. on 1989 reported a second-arc osteotomy, and later Yang8 et al. proposed a three- or four-arc osteotomy. The two methods not only could overcome the undesired effects of linear osteotomy but also could result in remarkable resemblance to a natural contour. However, the surgery is performed intraorally in multiple steps, which adds to the complexity of the operation and also increases the risk for asymmetry. Gui11 et al. then proposed an intraoral one-stage curved ostectomy to avoid the formation of a second gonial angle and to overcome the complexity associated with multiple steps in two/three/four arc osteotomy. However, the method is very demanding with regards to surgical skills, operation techniques and surgical equipment, and also has a high risk for jaw asymmetry. Around the same time, Han3 et al. proposed the mandibular outer cortex splitting ostectomy. From the frontal view, this method can result in considerable reduction of the mandibular width (Go-Go), however it is unable to change the gonial angle (Ar-Go-Me) or overly flat inferior margin of the mandible. Additionally, it cannot correct the sinking gonial angle. Therefore, on lateral view, the effects thus obtained from mandibular outer cortex splitting ostectomy are often unsatisfactory. In 2010, Hsu4 et al. proposed that the mandibular outer cortex ostectomy can be integrated with “V-line” osteotomy to naturalize the contour of the mandible as a whole. This combination method can effectively reduce the mandibular width on frontal view, increase the gonial angle and increase the slope of mandibular plane on lateral view thus reshaping the mandible to a desirable contour .Therefore this method is best suited for square jaw deformity presenting with a low gonial angle. Besides the time-tested surgical ostectomies that we have mentioned here as well as previously, we have advocated the usage of Medpor (Porous polyethylene) to be able to better control the mandibular contour. Technically, it is easy to work and can easily be carved and contoured with a surgical scalpel. It is biocompatible and its porous nature allows ingrowth of bony and fibrous tissues12. It has long-term stability, high tensile strength, and does not resorb or disintegrate. It has excellent handling properties and can be adapted and fixated using screws to obtain a precise, three-dimensional construct7.Although the above mentioned surgical methods can help achieve significant improvement of the mandibular contour, especially the gonion, the individual, isolated application of the above methods can only improve the posterior part of the mandible. For some patients with defective contour in the anterior part of the mandible, these methods are insufficient in improving the overall mandibular contour. Meanwhile, in addition to inherent disproportionality, some unnatural jawlines are also iatrogenic resulting in transportation of gonion towards the anterior edge of osteotomy line causing a second gonial angle or a formation of chin nodule. This results because the surgeons generally focus too much on the treatment of the posterior part of the mandible without fully considering the esthetic significance of the harmonious and smooth overall sloping curve of the inferior margin of the mandible from gonion to gnathion.. Thus if the surgeon fails to fully appraise the overall mandibular contour, post-surgery, the sloping curve from the gonion to the gnathion may show an abrupt rise or be overly flat anteriorly, leading to a sharp contour line. To solve this problem, Satoh13 and Li5,14 et al. proposed that the mandible contour should be considered as a whole in the surgery design. In our previous papers we have stated the significance of ramus length, gonial angle and chin dimension and their impact on the choice of surgical techniques5,14. Here we have further extended our observation, wherein we noticed the importance of sloping smooth mandibular inferior margin contour and its impact on overall facial esthetics. We have highlighted the importance of sloping inferior mandibular margin by showing a case (Case 1,2) where the surgeon failed to notice the unpleasing mandibular contour. Thus in subsequent cases, we have shown how a wholesome approach to patient complaining of a square jaw deformity results in the best treatment results. We reemphasize that the surgery design for a square jaw deformity should cover the area from the lateral ramus, the body of the mandible, the inferior margin of the mandible, to the chin. Thus, from our observation, our group proposes that the surface projection of the gonion should be 2 cm below the earlobe, and 1cm in front of the earlobe. The chin shape should be of appropriate size and meet the esthetic requirements. Likewise, a gradually sloping smooth curve from the gonion to the gnathion should be created to achieve a coordinated, balanced, and smooth jawline.Mandibular contour is an important component of overall beauty. Thus, in the design of facial contour plastic surgery, apart from the anatomical structures of the face and its coordination with the body; patient requirements, aesthetic views, cultural qualities, occupation, age, mental state, and other factors of the patients should also be considered. Therefore, on the premise of an overall beauty, a customized design should be made based on the results of thorough discussions between the patient and surgeon. The most appropriate surgery method/combination should be selected based on the original facial contour so as to achieve most significant improvement6. For different types of jaw deformities, different methods and combinations should be integrated to achieve an ideal outcome. One essential aspect while contouring the inferior margin of the mandible is to make a smooth transition between the anterior and the posterior half of the mandible, leaving no bony stepoff or protuberance. Some people might worry that this procedure might create jowls. But due to vertical movement and advancement of the chin combined with bone grafting or augmentation by Medpor implant in the mental region; there was hardly any evidence of jowls after surgery. However numbness of the lower lip was a common complaint postoperatively in most of the cases. The numbness thus resulting from stretching of mental nerves was transient and none resulted in permanent numbness.AcknowledgementsDisclosure: None of the authors has a financial interest in any of the products, devices, or drugs mentioned in this article.References1. Kim SK, Han JJ, Kim JT. Classification and treatment of prominent mandibular angle. Aesth Plast Surg 2001;25:382-7.2. Cui J, Zhu S, Hu J, Li J, Luo E. The effect of different reduction mandibuloplasty types on lower face width and morphology. Aesth Plast Surg 2008;32:593-8.3. Han K, Kim J. Reduction mandibuloplasty: ostectomy of the lateral cortex around the mandibular angle. J Craniofac Surg. 2001;12:314-25.4. Hsu YC, Li J, Hu J, Luo E, Hsu MS, Zhu S. Correction of square jaw with low angles using mandibular “V-line” ostectomy combined with outer cortex ostectomy. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;109:197-202.5. Li JH, Hsu YC, Khadka A, Hu J, Wang DZ, Wang QS. Contouring of a Square Jaw on a Short Face by Narrowing and Sliding Genioplasty Combined with Mandibular Outer Cortex Ostectomy in Orientals. Plast Reconstr Surg 2011;127: 2083-92.6. Khadka A, Hsu YC, Hu J, Wang QS, Zhu SS, Luo E, Li JH. Clinical observations of correction of square jaw in East Asian individuals. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;111:428-347. Cenzi R, Farina A, Zuccarino L, Carinci F. Clinical outcome of 285 Medpor grafts used for craniofacial reconstruction. J Craniofac Surg 2005;16: 526-30.8. Yang DB, Park CG. Mandibular contouring surgery for purely aesthetic reasons. Aesth Plast Surg 1991;15:53-60.9. Converse JM. Deformities of the jaws. Reconstructive plastic surgery. Philadelphia: Saunders; 1977. p. 1406-11.10. Baek SM, Kim SS, Bindiger A. The prominent mandibular angle: preoperative management, operative technique and results in 42 patients. Plast Recontr Surg 1989;83:272-80.11. Gui L, Yu D, Zhang Z, Changsheng LV, Tang X, Zheng Z. Intraoral one-stage curved osteotomy for the prominent mandibular angle: a clinical study of 407 cases. Aesth Plast Surg 2005;29:552-7.12. Park JY, Kim SG, Baik SM, Kim SY. Comparison of genioplasty using Medpor and osteotomy. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;109:e26-3013. Satoh K. Mandibular contouring surgery by angular contouring combined with genioplasty in Orientals. Plast Reconstr Surg 2004;113;425-30.14. Li JH, Hsu YC, Khadka A, Hu J, Wang QS, Wang DZ. Surgical designs and techniques for mandibular contouring based on categorisation of square face with low gonial angle in orientals. J Plast Reconst & Aesth Surg2012;65:e1-8Fig.1 The lateral illustration of mandibular outer cortex split ostectomy (MOCSO). Fig.2 The lateral illustration of mandibular “V-line” ostectomy (MVO).Fig.3 The illustrations of MOCSO + MVO + Narrowing and/or sliding genioplasty (NSG) and Inlay bone graft (IBG).Fig.4 The illustration of Medpor implant placed over the mental region and fixed with screws.Fig.5 Preoperative views of a 25-year-old woman in Case 1(a, c). 11 months postoperative views after MOCSO (b, d). Postoperative frontal views showed that the facial proportion was suitable and the lower face was narrow and symmetrical.However, the contour of inferior mandibular margin was slightly everted at the anterior part of the mandible leading to unaesthetic appearance on lateral view.Fig.6 Preoperative views of a 22-year-old woman in Case 2 (a,c). Note the square chin with deep mentolabial sulcus.13 monthes postoperative views after NSG and Medpor implantation(b,d). NSG was accomplished by downward shift of 3 mm and narrowing by 5 mm. Medpor implant was then placed over the mental region. Postoperatively, the lower face was tapering with slender mental region and facial proportion was balanced and harmonious (b,d).Fig.7 Preoperative views of a 20-year-old woman in Case 3 (a,c). Postoperative views after MVO+MOCSO + SG+ IBG(b,d). SG was accomplished with downward movement of 6 mm and forward movement of 6 mm, and bone graft was placed within the space produced by downward sliding, using the trimmed MVO segment.12 months postoperative, the appearance showed that the lower face was tapering, the mental region was slick, and the facial proportion was suitable (b,d).Fig.8 Preoperative views of a 20-year-old woman in Case 4 (a,c). Note the slight facial asymmetry.9 monthes postoperative views after MOCSO, NSG, BG and the right lateral MVO(b,d). NSG was accomplished by downward shift of 4 mm and narrowing by 6 mm, and bone graft was placed within the space produced by downward sliding, using the trimmed MOCSO segment. Postoperatively, the lower face was symmetric tapering, the mental region was slick, and the facial proportion was suitable (b,d).
