The Mentalis Muscle: An Essential Component of Chin and Lower Lip Position

Abstract

A person who undergoes cosmetic surgery and gets only a fair result becomes a complainer. A person who looks worse after cosmetic surgery than before becomes depressed and toxic to those who will listen. The negativity will last until the problem is solved. This article, about such a problem, was directed at surgeons who operate on the chin and warned them about being too cavalier in this area. In the past, few people cared about the mentalis muscles, and fewer still knew what these muscles did. Surgeons now know that these elevators of the central lower lip cause dimples in the chin prominence at their insertion points. Removal or detachment of these muscles results in specific consequences. An article about iatrogenic chin ptosis may provide surgeons with a method to fix something that they had previously been unprepared to do. In this case, however, my office became the repository of a myriad of chin problems. Some were related to these muscles; many were not; most patients had already had multiple procedures. Some I could help, and many I could not. When the muscle itself had been resected, injured, or contracted after implant removal, the problems were not totally remediable. When the chin pad ptosis was associated with descension of the lip, the elevation procedure was curative, but it often had to be done twice (about 1 year apart). The important technical points are mentioned below. Chin pad ptosis can be iatrogenically acquired or it can occur normally. Some normal people smile in a way that effaces the soft tissue chin against the bones as the chin mass moves caudally. Some people have mandible denture resorption, so as the mentalis origin, and thus its insertions, are pushed down, some of the lower dermal insertions and skin descend below the menton. Some people have droopy chins purely from gravitational movement or even a relative ptosis because of a deficient soft-tissue configuration behind the submental fold. This article, however, solely addressed the iatrogenic ptosis associated with coincidental lower lip descension and excess lower incisor show at rest. All of the operations had been performed by using an intraoral route, and common to them all, the mentalis origin at the sulcus had been disrupted. Without the true mentalis origin holding the chin pad in proper position, the pad fell, and with it, the lip. As lower incisor showing at rest looks unattractive, so the lip had to be brought up; the ptosis could not be dealt with wholly from a submental approach. As stated, ancillary procedures (i.e., touch-ups to thicken the lip volume, adjust the submental fold, and reduce the tightness of the vestibule) were not uncommon. Over the years, I have learned that doctors sell chin surgery as a minor procedure, because patients rarely see their chin as the main issue. A woman with a large nose and small chin sees only her large nose. A face lift patient with extra submental skin doesn’t realize that an implant may help.

After seeing at least 125 problem chin cases, I can state:

1. Chin implant surgery (and sometimes) osteotomies previously heralded as simple may lead to problems, especially when an intraoral approach is used. An extraoral insertion provides better access for placement of the implant wings. The scar results are excellent.

2. Chin implant removal from any approach may cause changes in chin pad configuration that are difficult to fix. This is due to contraction of the pocket. A smaller implant for replacement may be a better choice to prevent pocket contraction.

3. The mentalis muscle origins must be regained when an intraoral route for any surgery is used. Leaving a vestibular wound open for drainage of infection or just sewing mucosa may be harmful.

4. Chin pad and lip ptosis can be helped in certain iatrogenic cases, but the procedure may need to be repeated because of the effects of gravity or lack of postoperative compliance, e.g., not wearing the chin support for at least 2 weeks or too-early dental work.

5. These paired muscles, which usually fuse as they reach the chin pad, often do not fuse; when they do not there is a cleft in the chin or some forme fruste of it.

6. Many people get neuropathies, i.e., changes in lip/chin sensation, after allopathic implantation or multiple procedures. Neuropathies may be problematic, for example, for women who are fearful of drooling and cannot put on lipstick without a mirror. Postoperative lip numbness after implant insertion should be dealt with early to prevent nerve resorption. If lip numbness presents beyond 2 weeks, the implant should be adjusted. The proposed procedure in this article dealt specifically with patients whose mentalis origins (usually at the sulcus) dehisced or were not sewn. The now deeper sulcus caused ptosis of the chin and, therefore, the lip. The procedure was aimed at reefing the origins, thus bringing the distal mentalis insertions back up.

The procedure works, but some caveats should be reported:

1. The chin pad must be released subperiosteally to below menton, and laterally. Some soft tissue must be left to sew onto at the height of the normal sulcus, just below the drill holes.

2. The Kirschner wire holes between the central and the lateral incisors must be as high as possible; that is, at the height of the original sulcus, high into the alveolar bone. It is inconsequential if these sutures become exposed sometime in the future.

3. Occasionally, a patient may require a root canal if the teeth are crowded and the pulp of a tooth is contacted during surgery (I have experienced this twice).

4. Permanent sutures are required for the mentalis muscles. I pass a 2-0 polypropylene from the buccal to lingual direction, then pass the suture through a spinal needle passed from the buccal direction. I then use a free needle for the muscle suturing. Mitek anchors might also work here.

5. Old hardware or wires from previous osteotomies (if available) should be sutured to for supporting the chin elevation.

6. A chin support garment for 2 to 3 weeks is crucial.

7. Aim for overcorrection (even lip eversion) and know, as with medial canthopexy, that it is impossible to overcorrect permanently.

8. The results will be two-thirds of that desired. The patient should be told that the procedure might have to be repeated for better results. The effects of gravity work against this procedure.

9. The entire procedure can be done in the office under local anesthesia using inferior alveolar blocks and local infiltration.

After seeing well over 125 chin surgery problems, I can only repeat:

1. Intraoral route procedures for chin implantation yield many more problems than extraoral placement. Intraorally, it is harder to get both implant wings exactly along the inferior border on both sides. The implant tends to be placed higher; that is, the lower edge is not exactly at the lower pogonion. The mentalis origins are always traversed. Although not problematic, per se, wound dehiscence and secondary procedures may affect the region of the origin.

2. Unless treating a tumor, never excise the mentalis muscle or lower the vestibule. Ptosis will occur.

3. Removal of a chin implant, although a no-brainer surgically, puts the final configuration of the chin pad at risk. The capsule will contract, and perhaps a smaller implant is better than total removal. As long as surgeons put medium or large implants in woman with high labiomental folds, they will continue having to remove them because the chin pads look too big.

4. Burring reduction of the prominent bony chin cannot be done safely from an intraoral route because soft tissue ptosis will occur. The submental approach with full-wedge soft-tissue excision is a better choice.

Full text available upon request.