The Safe Chin Augmentation

Goals/Purpose: Chin augmentation is the most commonly performed facial skeletal augmentation procedure in the United States. Correction of microgenia in the aesthetic patient can be achieved with an osseous or an alloplastic implant. Both methods require the surgeon to accurately predict the anatomic location of the mental foramen (MF) and the insertion of the mentalis muscle (MM) in order to avoid the postoperative sequela of lower lip parasthesia, mentalis strain, or lower lip incompetence. The purpose of this study is to predict the location of the MF and the MM insertion based on bony surface landmarks along the mandibular border.

Methods/Technique: Fourteen fresh cadaveric hemifaces were dissected with the aid of loupe magnification. Vertical distances from the inferior border of the mandible to the MF and the MM insertion were measured. A distance ratio was calculated from pre-defined anatomic landmarks to the MF along the mandibular border.

Results/Complications: The MF and the MM are 1.7 +/- 0.2 cm and 1.8 +/- 0.3 cm cephalad to the inferior border of the mandible, respectively. The MF is 0.63 the distance between the masseteric tuberosity and the mental midline, which is approximately 2/3.

Conclusion: A safe zone of dissection for a chin augmentation is identified. The strength of this study is in its applicability to implant placement through a submental or an intraoral incision. These findings are also useful for both aesthetic and reconstructive procedures of the mandible.