M-shaped Genioplasty: New Findings after 10 Years of Experience

Abstract

Background: This study aimed to evaluate changes of the M-shaped genioplasty in sagittal and vertical planes in a group of 34 patients and describe other indications, such as the increase of the mentolabial angle, decrease in the depth of the mentolabial fold, and the centering of the chin. Methods: A retrospective analysis was performed on 34 patients between 2010 and 2019. All studies were conducted at T0 (preoperative), T1 (a month after surgery), and T2 (1 year after surgery). The position of the bone pogonion (Pg) was measured vertically and horizontally at T0, T1, and T2; the mentolabial angle and the depth of the mentolabial fold were measured at T0 and T2. Results: The average sagittal advancement at T1 was 6.6 mm and at T2 was 6.4 mm. The inferior movement was an average of 5.6 mm at T1 and T2, showing both movements excellent stability. The mentolabial angle increased at T2 an average of 28.2 degrees (5 degrees per each millimeter of inferior movement), whereas the depth of the mentolabial fold decreased an average of 2.8 mm (decreased 49% from the initial depth and decreased 0.56 mm per each mm of inferior movement). The average increase of the lower third of the face was 5 mm. No complications were observed in any patient. Conclusions: M-shaped genioplasty is an anterior osteotomy of the mandible, which allows the chin to move forward and downward. Additionally, it allows an increase of the mentolabial angle and decreases the mentolabial fold.