下颌角

下颌骨的相邻结构
面动脉：下颌骨下缘
咬肌前缘进入面部 平下颌角下缘平面，距G点2.8±0.3cm

下颌骨的相邻结构
面神经下颌缘支：
穿出腮腺：过G点垂线，距升支后缘1cm →行于下颌骨下缘 ：上(76%)下(23.4%) 各1.5cm →与面A相交：距升支后缘4cm（92.6%浅，7.4%深）

下颌骨的相邻结构
咬肌：颧弓——咬肌粗隆，从外侧包绕下颌角 面动脉、面横动脉肌支；上颌动脉咬肌支 下颌神经肌支 翼内肌：从内侧包绕下颌角
历史演变
1947，Gumay：口外，咬肌部分切除 1948, Adams：口外，下颌角截骨 1951, Converse：口内，下颌角截骨

1989, Baek：口内，下颌角截骨 1989, Whitaker：口内，下颌角外板截骨 1991, Yang：口内，下颌角弧形截骨
------ Han KH, et al. 2001 : measure the mandibular plane-sella-nasion (MP-SN) angle →determining whether curved ostectomy is need
mandibular plane-sella-nasion (MP-SN) angle: Although partly reflects its posterior height, not reflect the anteriorposterior length
-the MA itself does not represent the width of the mandible as seen from the front.
Mandible
Angle Measuring(2)
Reduction mandibuloplasty: Ostectomy of the lateral cortex
Bony
spurs
result from new ossification , by the activities of the masseter muscle. always reappear after all mandible reductions. ——insufficiently slender appearance after mandible reduction because of bony spurs？ ——insufficiently slender appearance does not result from recurrences of bony spurs, but from insufficient reduction of mandible thickness.
---MAO and MASO: J. Cui, et al.: Aesth Plast Surg 15: 53-60, 2007
MAO lower face width ↓10.4 mm
MASO lower face width ↓6.2 mm
---MAO and MSAO can effectively reduce lower face width, but brings about some different aesthetic results.
发展方向

面部轮廓整体塑形：
下颌骨整形+颧突颧弓整形+颏成形+颊脂垫摘除

内窥镜
视野清晰，截骨位置准确，损伤风险小 可准确切除咬肌内层

专用器械设备 粉碎式去骨：小切口，
避免取骨操作及相关发症； 去骨量难以准确估计
激光截骨：新
谢谢！
并发症： 1，出血：面动脉及其分支、升支后静脉 2，神经损伤：面神经损伤
下齿槽神经损伤
3，意外骨折：髁状突骨折、升支纵裂 4，下颌骨形态不佳及不对称：常见 5，咀嚼功能影响：咬合力、开口度（3个月内）
存在问题
Botox
or Mandibuloplasty MAO or MASO Mandible Angle Measuring Bony spurs

MAO or MASO
MAO (mandibular angle ostectomy): Baek SM, et al.: Plast Reconstr Surg 83:272-280, 1989 Yang DB, et al.: Aesth Plast Surg 15: 53-60, 1991 Baek SM, et al.: Aesth Plas Surg 18: 283-289, 1994 ---MAO became the first choice MASO(mandibular angle-splitting ostectomy): Deguchi M, et al.: Plast Reconstr Surg 99:1831-1839, 1997 Han KH, et al.: J Craniofac Surg 12: 314, 2001 ---MASO is the main procedure. MAO is not effective to make the lower face more slender in front view
Botox
or Mandibuloplasty
H. Jin: Aesth. Plast. Surg. 29:317-324, 2005
1.the effect is temporary, the cost is high. 2.the effect is much less than that of the MA reduction, which itself reduces the masseter muscle（5%）. 3, Reducing the thickness of the muscle, the shape of the bone is more plainly exposed, which makes the asymmetry more prominent. ---Botox may be good for the income of the doctors, but not for the patients.
器械摆放角度较自由； 有瘢痕
口内切口：
无可见瘢痕； 视野不足，器械摆放角度受限—— 截骨的立体空间位置不易掌握（不对称、不足或过度） 误伤（口角、神经、血管）
口内、外联合切口（颌底、耳后？） ：
保留口外切口的优点； 通过口内切口将瘢痕减至最小
2，截骨方式选择 下颌角截骨：直线→弧形 下颌角外板截骨：范围扩大的趋势

临床现状
病理、病因、诊断及分类 术式 并发症

病理：下颌骨异常发育 咬肌肥大 病因：遗传？咬肌过度工作？ 诊断：无公认的统一标准 分类：Baek——1，下颌角下突、后突 2，下颌角外翻 3，综合型

术式 1，切口位置选择 2，截骨方式选择

1，切口位置选择 口外切口（颌底、耳后）：
Mandible
Angle Measuring(3)
女性下颌角肥大截骨范围的量化 及手术方法的选择 ------ 张余光. 2007 :
头颅正、侧位片测量亚洲成年女性下颌骨相关数据 →相关数据的正常范围值 →对不同特征的个体 选择合适的术式和术中截骨参数
G-G/Z-Z＝1:1.30±0.14
Mandible
Angle Measຫໍສະໝຸດ Baiduring(1)
Pitfalls and management of mandible angle reduction.
------Lee SS,2002: measured the MA of adult women →the range of ideal mandibular angles. →guidelines for operation to each patient.
Mandibuloplasty
濮哲铭
解剖基础 历史演变 临床现状 存在问题 发展方向

解剖基础
下颌骨的形态测量 下颌骨的相邻结构

面动脉 面神经下颌缘支 咬肌、翼内肌

下颌骨的形态测量 ( mm, °)
升支长
水平长
下颌角
男 54.3±4.1 86.5±3.7 123.5±5.9 女 49.6±3.9 76.7±4.0 122.2±4.2
G-G/Z-Z＞1:1.30±0.14 ——Extraversion
-术前评估数据较为全面 -对手术有直接指导意义 L-G/L-C ＝ 1:2.0±0.3 PRA＝10 ±2°
L-G/L-C ＞ 1:2.0±0.3 ——excess ramus
PRA＜10 ±2° ——retro-protrusion
MA alone : enough in planning the operation?
-even if the MA is identical, the postoperative results look different according to the posterior height or the anteriorposterior length