Case 2: Broad Chin
A 32-year-old woman complained about her broad, heavy lower face, especially around the lateral side of the mouth. Inverted V-shaped genioplasty and mandibular angle reduction were performed, and a 12-mm central strip was resected. The main goal of this case was not shortening but narrowing of chin at the lateral side of the mouth. Postoperatively, her lower face appeared slender and had a tapering oval shape (Fig. 5 and Table 4).
Case 3: Trapezoid and Long Chin with Asymmetry
A 27-year-old patient presented with a heavy, long, and asymmetric chin. Inverted V-shaped genioplasty and mandibular angle reduction with zygoma reduction were performed, and a 10-mm central strip was resected. For correction of asymmetry, 6 mm of the 10-mm central strip was resected on left side and 4 mm on the right side. With zygoma reduction and genioplasty, her face appears shortened and more symmetric and harmonious than before (Fig. 6 and Table 4).
To achieve ovular and slender facial features, which are especially preferred in East Asian countries, several methods have been introduced and developed. These methods used to fix a square contour generally require resection of the mandibular angle or reduction of the mandible itself; however, several authors emphasize the aesthetic significance of the harmonious and smooth overall curve from the chin and the anterior part of mandible to the inferior margin of the mandible.1 Some authors reported that the main reason why a resection of the mandible alone does not make the face appear slender is due to a wide, flat chin and a U-shaped lower facial morphology, and they performed a surgical approach to the center of the chin to excise the rectangular central bony segment and reduce the width of the chin.2 Therefore, if patients have a wide chin and symphysis, the correction of the chin area with the treatment of the posterior part of the mandible is essential to accomplish the overall smooth curve during the mandibuloplasty.1–6
Park and Noh2 performed narrowing genioplasty, which is a surgical approach to the center of the chin to excise the rectangular segment of bone and reduce the width of the chin. In another study, Park et al3 described mandibular tubercle resection to maximize the benefits of reduction mandibuloplasty. The horizontal osteotomy and central segment resection method introduced by Park et al3 suggested a new concept of narrowing genioplasty, and it has been widely used to create slender and ovular chin shapes. This method continues to be the most popular method. The basic principle of this method is to reduce the width of the chin through a horizontal osteotomy and central segment resection. However, this method has little effect on the reduction of the chin width considering the amount of central segment resection. To create a lower face that is more slender and ovular, the central segment should be resected excessively by up to 15–20 mm. Therefore, the genial musculature of the lingual side is more detached and retracted, which results in many problems including palpable mass and bulging of the submental area. Furthermore, this method does not reduce the vertical length of the chin. Many patients who want a narrowing genioplasty have a long chin and need additional horizontal bony segment resection to shorten the length of the chin (Fig. 7). Because of additional horizontal bony segment resection, the genial musculature of the lingual side is detached too excessively, thereby affecting the aesthetically natural line of the chin. Bone bleeding and swelling increase, and the recovery period is lengthened.
To improve these points, we designed an inverted V-shaped osteotomy line instead of the horizontal osteotomy line and performed simultaneous central bony segment resections. With this method, the width of chin can be reduced more than with the conventional horizontal osteotomy technique described by Park et al.3 In addition, it is a simple and effective method to shorten the vertical length simultaneously without additional horizontal bony segment resection.
Our method has several advantages compared with the conventional horizontal osteotomy technique. First, with the conventional technique, the remaining 2 lateral segments are centralized medially and horizontally after central segment resection. However, with our method, the 2 lateral segments remaining after central resection are centralized medially and superiorly due to inverted V-shaped osteotomy line. Therefore, the more lateral and proximal bony edges that remained after centralization can be excised, which reduce the width of the chin more than the conventional technique with the same amount of central segment resection (Fig. 7). Second, the inverted V-shaped osteotomy can preserve more of the genial musculature of the lingual side compared with the conventional technique, and it can decrease the rate of complications, such as a palpable mass due to the contraction of the detached genial musculature or an unnatural contour of the submental area. Third, it can shorten the vertical length without additional horizontal bony segment resection due to cephalic movement of 2 lateral segments. It can shorten 4–8 mm of length, and it may adjust the amount according to the width and apex angle of the central strip. Finally, it can easily correct the asymmetry of the mandible and symphyseal deviation by adjusting the location and apical angle of the central strip.
For the surgical plan, the factor that was considered most important was the amount of the vertical reduction. According to the amount of vertical reduction, the apical angle and the width of the central strip were taken into consideration. The amount of vertical reduction was approximately 4–8 mm in all cases. For the amount of vertical reduction, the proportion (ratio of lower face to midface) and occlusion of the patient, the request of the patient, the amount of angle resection, and operative history were considered using gross photographs and 3-dimensional computed tomography. The assessment in men was quite different from that in women because men already have a longer, wider, and more angled preoperative mandibular line, and most of them wish to have a more angled mandibular line than women. Therefore, they usually do not want a mental tubercle area that is too sharp or a mandibular angle that is too obtuse. Namely, the masculine beauty was focused on the operation to male patients in contrast with feminine beauty, just like V-line of mandible, in women. During the preoperative plan, a wider apex angle (more than 10 degrees) and more narrow width of the central strip (less than 2–4 mm) are usually needed in men than in women.
We estimated the preoperative and postoperative changes in soft tissue using the distance of the subnasale to the gnathion in the frontal view (Table 2). Eighty-two women and 15 men were verified and divided into 5 groups according the amount of vertical reduction. In evaluating soft- and hard-tissue changes, the ratio of soft-tissue reduction to hard-tissue reduction was estimated at 0.48. As the amount of bony resection was increased, the amount of soft-tissue vertical reduction was also increased; however, this result is not suggestive. Although this trial was due to obtain more objective and corrective results about soft-tissue changes, our results have several limitations. The distance from the subnasale to the gnathion was estimated only in the frontal view without the assessment of lateral cephalograms and statistics. Regarding soft- and hard-tissue changes, it is thought that additional evaluations are needed in the next follow-up series with a large data set.
Complications included a minor bony step-off at the chin-mandible junction, transient numbness of the lower lip, bunching of the chin, wound dehiscence, and wound infection (Table 3). To prevent bony step-offs at the chin-mandibular junction, meticulous trimming of the bony edges on the cutting boundary is essential with an oscillating saw and burs and the lateral end of the genial segment should be located at approximately 5 mm from the mental foramen to avoid mental nerve injury.7,8 To avoid the bunching of the chin, soft tissue around the chin area should be minimally dissected. Numbness of the lower lip was a common complaint postoperatively. The numbness which is due to stretching of the mental nerves was transient. The wound dehiscence case was treated with wound revision under local anesthesia. The wound infection case presented as heat, erythema, and tenderness on postoperative day 5 and was treated with continuous intravenous antibiotics. On postoperative days 10–14, the infective symptom had diminished, and there were no signs of severe infection, such as purulent discharge.
Various surgical procedures have been suggested to solve a squared and long contour of the lower third of the face, but correction of the chin area with the treatment of the posterior part of the mandible is essential for successful treatment of overall mandibular reduction.
Horizontal osteotomy with central segment resection, the most widely used method for narrowing genioplasty, has little effect on the reduction of the chin width proportional to the amount of central segment resection, and it cannot shorten the vertical length. In case with a considerably wide and long chin, excessive central segment resection and additional horizontal bony segment resection are required, which eventually result in an unnatural curvature of the lower mandibular border.
To improve these points, we used an inverted V-shaped osteotomy line instead of a horizontal line and performed simultaneous central segment resection. In conclusion, inverted V-shaped osteotomy and central bony segment resection technique is a simple and more effective method for simultaneously reducing the chin width and height without additional procedures.
Patients provided written consent for the use of their images.
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6. Uckan S, Soydan S, Veziroglu F, et al. Transverse reduction genioplasty to reduce width of the chin: indications, technique, and results. J Oral Maxillofac Surg. 2010;68:1432–1437
7. Warren SM, Spector JA, Zide BM. Chin surgery V: treatment of the long, nonprojecting chin. Plast Reconstr Surg. 2007;120:760–768
© 2014 American Society of Plastic Surgeons
8. Hwang K, Lee WJ, Song YB, et al. Vulnerability of the inferior alveolar nerve and mental nerve during genioplasty: an anatomic study. J Craniofac Surg. 2005;16:10–14