The gonial angle stripper: an instrument for the treatment of prominent gonial angle

Analysis of incidences and types of complications in mandibular angle ostectomy in Koreans

A prominent mandibular angle is considered to be unattractive in Asians because it gives the face a square, coarse, and muscular appearance. Asian women desire to have an ovoid, reduced, and slender face by aesthetic mandibular angle resection. Mandibular angle ostectomy has been known to be effective and to satisfy both surgeons and patients. Especially in Korea, it has become as popular as facial bone contouring surgery, which reduces lower facial width. However, a narrow surgical field hinders direct view of the site, making a procedure that is rather difficult to perform. Despite thorough presurgical planning and attention, there can be many complications and unfavorable results. The purpose of this study is to find out the cause of these complications of mandibular angle ostectomy and to develop methods that could prevent these complications from occurring. A questionnaire consisting of 30 questions regarding mandibular angle ostectomy was sent to 40 Korean plastic surgeons. Data from 33 surgeons were analyzed. The total number of operations was 1251, and among them complications appeared in 124 operations, a complication rate of 9.9%. In regards to severe complications, there were 8 cases of subcondyle fracture of the mandible and 6 cases of severe bleeding. Transient facial nerve injury, infection, trismus, asymmetry, undercorrection, overcorrection, secondary angle formation, and entrapped bony segment were also noted as complications. We will report the cause and the prevention methods for each complication.

The Position of the Inferior Alveolar Nerve at the Mandibular Angle:

Mandibular angle reduction is a popular contouring surgery in Asia. Avoidance of injury to the inferior alveolar nerve is crucial during these procedures. Anatomic data regarding the position of the nerve in the mandibular angle area are sparse. The purpose of this study was to use 3-dimensional computed tomographic data to evaluate the nerve in patients with prominent mandibular angles and to compare the nerve position with a normative group. A total of 28 female and 5 male adult patients who presented with a complaint of prominent angles or a "square-face" look, as well as 20 female and 22 male adult normal subjects were included, for a total of 150 hemimandibles for extraction of the inferior alveolar nerve. The nerve and the mandible were displayed. Point O was defined on the oblique line along the anterior cortex of ramus, where it intersected with a line extending from the alveolar arch. From the O point, linear distances were defined, including horizontal distances to the posterior cortex, oblique distances to the gonion, and the vertical distances to the inferior cortex. Mandibular width was defined as the distance between the 2 gonion points. Results demonstrated significant differences mainly in the oblique distances (ie, from the O point to the nerve [O1], from the nerve to the gonion [O2], and from the O point to the gonion [O1-O2]) in both female and male patients. The O2 distance was 23.69 mm versus 20.66 mm in women and 27.30 mm versus 23.28 mm in men (square face vs norm). The mandibular width was significantly larger in the male square-face patients, but the difference was not significant between the female groups. These results provide useful information for surgeons planning mandibular angle reduction. These findings suggest that the mandibular contouring procedure should be aimed at correcting regional osseous dysmorphology in the angle area and improving the relationship to the chin, rather than merely reducing the mandibular width.