- Email: [email protected]
Chin augmentation
Panel Discussion
Chin Augmentation
Editor’s note: My thanks to the moderator, S. Anthony Wolfe, MD (board-certified plastic surgeon and ASAPS member, Miami, FL), and to panelists Jeffery C. Posnick, DMD (board-certified plastic surgeon, oral and maxillofacial surgeon, and ASAPS member, Chevy Chase, MD); Michael J. Yaremchuk, MD (board-certified plastic surgeon and ASAPS member, Boston, MA); and Barry M. Zide, MD (board-certified plastic surgeon, New York, NY), for sharing their opinions and clinical experience. Analysis of chin deformity depends on physical examinaS. Anthony Wolfe, MD tion and, usually, appropriate radiographs such as Panorex and cephalometric examinations. In these patient analyses, certain assumptions have been made that do not completely reflect the true skeletal proportions so that the discussion could be facilitated to focus on the chin. Readers are advised to remember that the actual patient Michael J. Yaremchuk, MD evaluation may need to be more comprehensive than a physical examination alone and must involve a dental analysis and cephalometric and Panorex radiographic examinations. Dr. Wolfe: The first patient is a 27-year-old woman whose primary concern is to improve her nose, but she also feels that her chin is too large (Figure 1). She has normal occlusion. Dr. Yaremchuk, how would you approach the treatment of this patient? Dr. Yaremchuk: This is a difficult case because the patient’s chin is too large. The vertical dimension of her chin is disproportionate to her face. However, if the chin were reduced, there would be a soft-tissue envelope redundancy problem.
I would probably perform a horizontal osteotomy, removing a small wedge of 4 or 5 mm, to give her reasonable proportions. I would then wait and see whether I needed to correct any soft-tissue redundancy. An alternative approach would be to reduce the inferior border by the same small amount and treat the soft-tissue redundancy by taking an ellipse in the submental area. Dr. Wolfe: Dr. Zide, do you agree with this approach? Dr. Zide: For this patient, I think a wedge would work perJeffery C. Posnick, DMD fectly well. Generally, the difficulty of a bone wedge is that it places the nerves at risk. When you perform a vertical chin reduction from a submental approach, you must detach the digastric muscles from the posterior genial tubercles and then reattach them by means of drill holes. A soft-tissue excision, both muscle and skin, must be Barry M. Zide, MD performed. The benefit of using an external approach is that what you see is what you get; you need to drain the wound to get good tissue approximation, and an external support is helpful. There is little chance of nerve injury when one works from below. Among patients who have had a wedge removed, at least one third have sustained some nerve injury because the high part of the wedge is close to the mental foramen. Dr. Wolfe: How close to the mental foramen would you advise surgeons to work? Dr. Zide: Classically, the nerve courses down about 3 mm or a bit more from the foramen, then goes out the hole. The closest to the foramen that I would ever per-
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would be to have decompensating orthodontics followed by implant removal, sagittal split osteotomies of the mandible with advancement, and an oblique osteotomy of the chin with advancement. Dr. Wolfe: Dr. Zide, how would you proceed?
Figure 1. This 27-year-old woman is unhappy with the appearance of her chin. She has normal occlusion.
form an upper osteotomy is 5 mm. When I have gotten much closer, I have seen the nerve. I have even included the nerve in the bony segment and twice had to perform anastomosis. So I avoid the foramen by at least 5 mm.
orthognathic surgery.
Dr. Wolfe: Dr. Posnick, do you have a different way of approaching this patient’s case?
Dr. Wolfe: The next patient is a 15year-old girl who had a congenital cervical cleft and as a result has a tight, visible scar in her submental area (Figure 2). She has had 2 silicone chin implants: One was at the lower border of the chin and the other, although placed at the lower border, has ridden up over the alveolar bone and is visible in the lower sulcus. She has a class II malocclusion but is not interested in orthognathic surgery. She would simply like to have a chin. Dr. Posnick, how would you help her?
Dr. Posnick: She has multiple minor asymmetries in both the upper and lower face. Her ears and eyes are at slightly different levels, and her nose is a bit twisted. Her lower anterior facial height is excessive and horizontally she is retrusive. It is difficult to judge the relationship of the lips to the skeleton because she is pursing them closed in the photo. Dr. Wolfe: Additional information is that she has neither a vertical maxillary excess nor abnormal occlusion, and she does not wish to consider
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Dr. Posnick: An oblique osteotomy of the chin with a minimal vertical reduction and horizontal advancement would give her the best chin result.1
Dr. Posnick: I would educate her about the most effective functional and aesthetic approach, which
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Dr. Zide: Although you can ask adult patients to undergo orthodontia and orthognathic surgery, many of them will refuse. In this patient, let us concentrate on the chin and avoid discussing the midface and nasal bones. The difficulty in this patient is that the soft tissue underneath the mentum is incredibly tight. If you asked her to lift her head, a band would appear, and “clefting” would present in the chin when the band was tightened. My concern is that the bony segment, if advanced, might be pulled down by the soft tissue underneath the chin. The fact that the upper implant overrode the other is expected. When one smooth silicone implant is placed on top of the other, the upper implant migrates to sit on the alveolar bone, which tends to cause resorption. If it moves downward, it looks like a mass under the symphysis. Dr. Wolfe: Dr. Yaremchuk, do you think you could treat this patient with additional implants? Dr. Yaremchuk: I would need radiographs to properly evaluate her. The problem is not limited to the chin. She has a deficient mandible; if you just advanced her chin point, you would exaggerate the mandible disproportion. For now, I won’t focus on the
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Panel Discussion
soft-tissue problem because it is impossible to evaluate without a clinical examination. With either a sliding genioplasty or a chin implant (I like to use porous polyethylene, fixing it with a screw so that it cannot move), I would want to create an appropriate lateral transition so that she does not have a jutting chin point. The problem is that a sliding genioplasty alone exaggerates the posterior mandibular deficiency and does not create a new anatomic contour. It is an artificial, nonanatomic contour with a step-off; her small chin and mandible and thin skin would exaggerate these iatrogenic deformities. She needs either a sliding genioplasty with lateral alloplastic augmentation or central alloplastic augmentation with more lateral augmentation. Too much augmentation, however, would make her look masculine.
Figure 2. This 15-year-old girl had, at birth, a congenital band associated with a midline cervical cleft. She underwent 2 operations on her chin, one at age 9 and one at age 12, that involved the placement of one implant and the stacking of another. One implant is riding fairly high over the softer alveolar bone.
Dr. Wolfe: Do any of the panelists advocate a microvascular procedure that would bring in bone and soft tissue? Dr. Yaremchuk: I think that the iatrogenic deformities accompanying a composite bone/soft-tissue flap would be too disfiguring for the correction of a cosmetic problem. Dr. Wolfe: The next patient is a 19year-old man who has undergone no previous surgery. Although he has a minor malocclusion (really more of a maxillary cross-bite), I would like to focus on his chin (Figure 3). Dr. Yaremchuk, what would be your treatment approach? Dr. Yaremchuk: He has a severe
Chin Augmentation
Figure 3. This 19-year-old man has a bilateral crossbite because of shifted maxilla, a mandible that appears adequately midline, a hypoplastic chin, and a great deal of submental fat.
chin-bone deficiency and overall facial asymmetry. For sufficient chin projection to be achieved, he would
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probably need a 2-tiered genioplasty through a submental approach and extensive soft-tissue submental and
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anatomy of his bony chin as seen on radiographs. Dr. Wolfe: He actually has a long chin.
Figure 4. This 36-year-old woman complains that when she smiles, the muscles in front of her chin bunch up and create a noticeable deformity. She had a chin implant that became infected and was removed.
submandibular defatting. Then I would augment his lateral mandible to correct the “cowcatcher” look caused by his lateral deficiency and chin advancement. Dr. Wolfe: When you palpate the lower border of his chin, it is almost halfway down the straight line, as you can see on the photograph. Dr. Posnick, how would you improve his chin? Dr. Posnick: He appears to have a fair amount of upper-face asymmetry and lower-face disproportion. Even if his occlusion is normal, I would need to see a lateral cephalometric radiograph. I do not think you can achieve a satisfactory result by focusing on his chin alone, and I would also consider other soft tissue procedures. What I would suggest for his chin partially depends on the
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Dr. Posnick: He does have an unattractive chin, but he also has facial disproportion related to the upper and lower jaw. His A-point (anterior maxilla) extends much farther forward than his B-point (anterior mandible). He needs a Le Fort I osteotomy and bilateral sagittal split osteotomies of the mandible with counterclockwise rotation of the occlusal plane. This would reposition the A-point and B-point in better proportion with each other.2 I would also perform an oblique osteotomy of the chin for horizontal advancement. A significant component of his aesthetic problems are in the maxilla and mandible. He also needs soft tissue work. Dr. Wolfe: Dr. Zide, what would be your approach? Dr. Zide: Because we are focusing on the chin instead of an overall evaluation, I would work in 2 stages: First I would do the chin, and second I would augment his mandible to improve the sides of his jaw. The submental approach should be aggressive, including subplatysmal defatting, digastric removal (probably three-quarters), and partial removal of the submaxillary gland. He will need a radical debulking in the submental region to produce an acceptable neck contour. I would first need to get the bone as far forward as necessary (augmentation genioplasty), augment the sides of the mandible, and, in a sec-
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ond procedure, defat the subplatysmal and the submental regions to create a suitable contour for a cervicomental angle. Dr. Wolfe: Would any of you use a face lift incision as well as the submental incision in this young patient? Dr. Yaremchuk: I would consider that. I have used a face lift incision in similar patients to gather and redrape some excess skin. Dr. Wolfe: The next patient is a 36year-old woman who had a chin implant that became infected and was removed (Figure 4). A capsule formed around this implant, and now the implant is out but the capsule is contracted. When she smiles, a ball develops in her chin area, which she finds distressing. Dr. Zide, how would you help her? Dr. Zide: There are several approaches. This woman has actually had some of the mentalis muscle removed. Usually, with a capsule, you get fasciculation and “balling,” but you usually do not get a dent right in the center. Somehow, when the implant was removed, some of the mentalis muscle was also removed. Otherwise, you would not be seeing this extent of muscle loss. Fasciculation, if it’s in the lower portion of the chin pad, can be handled with muscular injections of Botox (Allergan, Inc., Irvine, CA). However, if you wish to open the capsule, you have to perform an osteotomy, release the capsule, and fill the space or insert an implant to fill the space. You must expand the capsule so that it does not contract again.
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There are other ways to do that, such as placing an Endotine device (Coapt Systems, Palo Alto, CA)— Endotine is usually used for forehead support. Or you could suture the capsule down in multiple areas. This is a difficult case, and results will never be perfect; the lost mentalis will not come back. There is no way to get it completely relaxed on both sides so that it is uniform. Dr. Wolfe: Dr. Posnick, how would you proceed? Dr. Posnick: I would like to build out her bony chin, which would then stretch out the soft-tissue envelope. But from this single view, I don’t know whether her facial aesthetics would tolerate it. This is a situation in which a lateral cephalometric radiograph would be helpful.
contracture of the pocket. It is really not a good thing.
Dr. Wolfe: Her chin is recessive even with that capsule.
Dr. Wolfe: Dr. Yaremchuk, how would you approach this problem?
Dr. Posnick: With that in mind, I would consider performing an oblique osteotomy with horizontal advancement and a vertical lengthening. Block hydroxylapatite can be placed in the interpositional defects.
Dr. Yaremchuk: We are looking at the consequences of a “button” implant that was probably placed subcutaneously, with the effect of scar contracture. She has lost soft tissue, and she has lost mentalis. Surgery should reexpand and fill the soft-tissue envelope. You can use an implant placed against the bone or perform an osteotomy with some advancement. It appears to me that the capsule is very close to the skin. If you excise the capsule, you must be very careful; there will be dermis close to your dissection. Ongoing Botox administration might have a role in the treatment of the fasciculation problem. Because a soft-tissue deficiency exists, fat injections could be
Dr. Wolfe: What would you do with her capsule? Dr. Posnick: I would excise it conservatively, taking care to avoid injuring the soft tissues further. Dr. Zide: Can I interject? The original Friedland3 paper stated that if you remove a chin implant, you maintain some of the projection. What he did not realize was that this projection is actually the capsular
Chin Augmentation
Figure 5. This 26-year-old woman underwent a chin reduction in 1976 that resulted in contour deformity. In 1980, a chin implant was placed on the left side to fill out the contour.
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helpful as a secondary procedure to replace missing soft tissue. Note that fat injections do not give the same visual effect as skeletal augmentation or advancement. Dr. Wolfe: The next patient is a 26year-old woman who underwent a chin reduction in which the lower border of the left side of her mandible was cut off (Figure 5). It was an asymmetric cut that entered the mental foramen, transecting the nerve and resulting in residual numbness. A second surgeon placed a silicone chin implant against the lower border of the now-osteotomized mandibular symphysis, which can now be palpated and moved. Some soft tissue has bunched up in her neck, resulting in an iatrogenic witch’s chin. Dr. Posnick, how would you treat this problem? Dr. Posnick: I do not know what I
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the fat in the bottom part of the chin pad and in the submental region. My goal is to make the chin look less droopy, and that could probably be achieved by working from below. I would not do it using an intraoral approach. Dr. Wolfe: What about reattaching the geniohyoid or genioglossus muscles that normally attach to the bottom of the symphysis?
Figure 6. This 30-year-old man had 2 chin implants placed at different dates for the correction of retrogenia. Both implants are mobile and in the wrong position.
would do for her. She does not look too bad. I would not necessarily intervene. Dr. Yaremchuk: In this view she is asymmetric, with the implant inferiorly displaced. She is too young to have such a soft tissue redundancy. When the surgeon resected the chin point, were her geniohyoid muscles disinserted? Dr. Wolfe: Yes, you can see that the muscles have retracted. Dr. Yaremchuk: I would probably make a submental incision, remove the implant, reattach the muscle, and observe the result, but my impression is that if you removed the implant, her chin would be too short. I might even reverse the operation and elongate her chin, which would correct her chin pad and neck distortion. I would reattach the muscles to the bone and, perhaps, perform submental lipectomy.
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Dr. Wolfe: Dr. Zide, what would your treatment plan be? Dr. Zide: When you look at the line, the inclination from her lower lip to the labiomental fold, consider that she would look worse if the line were straight and appeared as a vertical drop. What saves her from looking unattractive is that the line is angled posteriorly. However, because the chin implant is sitting unattached in the soft tissue, it has to come out. If she has a functional, workable sulcus and good lip position, and if she is comfortable maintaining her current lip position, I would use a submental incision to excise that depression, remove some fat in the submental region, and replace the implant with Porex (Porex Corp., Fairburn, GA), screwed in, to maintain projection. She has a droopy chin, and I would try to straighten the groove in the submental region by reducing
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Dr. Zide: I do not know what to attach these muscles to; the muscles are probably in a ball. My goal would be to get the chin positioned correctly, repositioning the fat underneath and the submental region and chin pad in a straight line. Dr. Wolfe: The next patient is a 30year-old man who has undergone 2 previous chin implants to correct a retrogenia (Figure 6). He has normal occlusion. The last implant, which was long and wrap around style, was placed in an effort to lengthen his chin. It is evident in the front view that the implant contour rests beneath the lower border of his symphysis. Dr. Zide, how would you correct this chin? Dr. Zide: The problems with the wraparound implant, such as an implant that sits along the inferior border, is that implants are not made to wrap around the inferior border. Unless they are well stabilized, they will just drop in time. This patient either has a tremendous chin pad deficiency or the chin pad is just missing. I think that if the implant were removed and an advancement genioplasty or another type of implant were used to provide proper chin pad shape, he would
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look a lot better. The current implant must be removed. Dr. Wolfe: What kind of genioplasty would you perform? He has a fairly long chin. Dr. Zide: I would have to look at a radiograph to see how big his chin is. If his chin were long, I would “jump” it; (eg, “jumping genioplasty”) if his chin were not long, I would perform a straightforward advancement. Dr. Wolfe: Assuming that you would jump it, would you perform another genioplasty later? Dr. Zide: I don’t know; I would have to see how he looked. Dr. Posnick: I would be concerned that with this approach, the chin would project too far forward compared with the base position of the mandible and the teeth. 4 It would not look good. Dr. Wolfe: Then where would you place the anterior point of the chin? Without using cephalometric films but using good clinical photographs, what is your desired position? Dr. Posnick: This patient’s A-point is far in front of his B-point. He appears to have excessive vertical length in the lower anterior face and poor horizontal projection. To improve his appearance, you cannot just focus on his chin. Dr. Wolfe: Dr. Yaremchuk, what are your ideas for this patient? Dr. Yaremchuk: How much has the implant elongated his chin?
Chin Augmentation
Figure 7. This 34-year-old man would like to improve his chin. He has relatively normal occlusion.
Dr. Wolfe: The implant was about 6 to 7 mm, like a long cigar, extending from gonial to gonial angle. Now it sits below the lower border of his chin. He has more of a retrogenia than a pure microgenia. A retrogenia is a moderate length of bone that is headed back toward the hyoid. Two of the panelists have mentioned performing a jumping genioplasty. 5 I think this is a good procedure when bone stock is adequate. Dr. Yaremchuk: His whole jaw is too small. He needs mandibular implants to widen his face and increase his ramus height. Almost any technique you would use on his chin alone would make him look worse. Dr. Wolfe: The next patient is a 34year-old man who is concerned about the lower third of his face: He feels that his chin is too short
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(Figure 7). He has relatively normal occlusion. Dr. Zide, would he be a good candidate for a properly executed chin implant? Dr. Zide: He has a skeletal deep bite. If you asked him to move his lower jaw forward and put his teeth edge to edge, he would look perfect. He needs a sagittal split osteotomy. But if he were unwilling to have orthognathic surgery and wear braces, I would use 1 of 2 techniques: either an osteotomy to bring his chin forward and down or a chin implant to augment the lower border alone. His labiomental fold is very deep, and if you put in a large implant, you would decrease his labiomental angle. It would look too acute, and you would make the chin look too big. Dr. Wolfe: For panelists who use implants, what do you consider the ideal chin-implant material?
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could do nothing and the gap would fill with bone and scar tissue anyway. Dr. Wolfe: Dr. Posnick, would you turn him away if he did not want his minor malocclusion corrected?
Figure 8. Dr. Yaremchuk’s technique for alloplastic chin augmentation. The striped area denotes the area of subperiosteal dissection. Note that a pocket larger than the implant is dissected for ease of implant insertion and to provide a panoramic view of the area to be augmented. The porous polyethylene implant consists of a right and a left side so that it can parallel the border of the mandible. The implant is immobilized with screws to obliterate any gaps between the posterior surface of the implant and the anterior surface of the mandible. “In place” contouring provides an imperceptible implant skeleton transition. (Used with permission of Dr. Yaremchuk and the Journal of Plastic and Reconstructive Surgery.)
Dr. Posnick: If his other facial views and radiographs are as I suspect, I would not object to performing a “camouflage” vertical lengthening and horizontal-advancement genioplasty. It will be important to educate this patient about his overall facial disproportion. He can then make an informed decision about treatment of the chin. Dr. Wolfe: What would you interpose in the space? Dr. Posnick: Block hydroxylapatite.
Dr. Yaremchuk: I like to use 2-piece porous polyethylene implants inserted through a submental incision. I fix them with screws to immobilize them, to obliterate dead space, and to allow final contouring with a shaping base (Figure 8).
Dr. Wolfe: Do you have resorption under the implant? Dr. Yaremchuk: I have very little; 1 or 2 mm is the most I have seen with porous polyethylene. I do see more with silicone, but it depends where the implant is.
Dr. Zide: I use both porous polyethylene and silicone. It is rare that I do not contour the implant; I adjust each implant by reducing size or projection or by changing the shape before I insert it. For porous polyethylene, I use screws. For silicone implants, I use 2 sutures into the periosteum, one on each side, so that the implant does not ride up. I have actually put holes in the bone, going right through the implant, then through the hole in the bone, and all the way around the inferior border.
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Dr. Zide: If it is a “high rider,” you will get resorption. If it is right on the lower mandibular bone and is a soft implant, you will get much less. Dr. Wolfe: Considering this patient (Figure 7), Dr. Zide, would you interpose material of some sort? Dr. Zide: My choice is to use either hydroxylapatite or bone cement. You could use a regular bone graft, if it is less than 3 or 4 mm, or you
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Dr. Wolfe: Dr. Yaremchuk, how would you help this patient? Dr. Yaremchuk: I would lengthen and slightly advance his chin. Through a submental approach, I would perform a horizontal osteotomy with slight advancement and probably 8 to 10 mm of elongation. I would fix it with plates and screws. I would interpose a piece of porous polyethylene to maintain that height, and I would make sure that it extended sufficiently laterally to smooth the transition at the lateral osteotomy site. Dr. Wolfe: The next patient is a 22year-old woman who is displeased with her chin (Figure 9). Dr. Yaremchuk, what treatment would you propose? Dr. Yaremchuk: Her chin is reces-
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sive, too long, and her mandibular plane looks rather steep. I would perform an advancement genioplasty. I like to use a submental approach to avoid problems with the mentalis muscle. Dr. Wolfe: Dr. Hofer 6 and Sir Harold Gillies7 both approached the chin that way. What kind of osteotomy would you perform? Dr. Yaremchuk: I would need to increase her projection and decrease her vertical height. The obliquity of my cut would have to accomplish those goals. She is already narrow; if you just extended her chin point, you would need to do something to soften the lateral transition. I would place an implant laterally to effect a good transition so that the mandible will have an appropriate size and contour instead of appearing “stuck on.” Another option would be to decrease the vertical chin height and place an implant to provide anterior projection. Dr. Wolfe: Dr. Zide, looking at this photograph we see, midway between her labiomental crease and the lower border of her chin, a little mound that is actually the mentalis muscle. She has evident lip strain and works to achieve lip seal. Do you think that rearranging the bone would help this? Dr. Zide: I do not think that rearranging the bone would make her lips better. Reducing the inferior border and inserting an implant would work well if you wanted to use a submental approach. Dr. Wolfe: If you are going to reduce it, why not jump it?
Chin Augmentation
Figure 9. This 22-year-old woman has satisfactory occlusion, considerable retrogenia, and some underdevelopment of the lower border of the body of the mandible.
Dr. Zide: You could. When you look at most of these patients, there is more than 1 way of treating them. Dr. Wolfe: Dr. Posnick, what would you do to improve her chin? Dr. Posnick: A lateral cephalometric radiograph would likely confirm that she has increased vertical chin length and horizontal retrusion. I would perform an intraoral oblique osteotomy of the chin with vertical shortening and horizontal advancement.4 Dr. Wolfe: Would you lift the lower border and jump it, or would you slide it forward and fix it? Dr. Posnick: I would reduce the vertical height by removing a small wedge and then horizontally advancing the chin. I would use titanium micro plates and screws for fixation.
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Dr. Wolfe: What do you think about the issue of lip seal? Dr. Posnick: She has problems with lip seal because of the increased vertical height in the lower face. The mentalis muscle rides up with attempts at lip closure. If you decrease the vertical height of the bony chin, you will decrease lip strain. Dr. Wolfe: It is notable that patients may experience functional improvement as a result of chin surgery in addition to the aesthetic improvement.
References 1. Posnick JC. Aesthetic alteration of the chin: evaluation and surgery. In: Posnick JC, ed. Craniofacial and maxillofacial surgery in children and young adults. Philadelphia, PA: Saunders; 2000:1113–1124. 2. Posnick JC. Maxillary excess with or without mandibular deficiency. In: Posnick JC, ed. Craniofacial and maxillofacial surgery in children and young adults. Philadelphia, PA: Saunders; 2000:1025–1056.
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Bibliography
3. Friedland JA, Coccaro PJ, Converse JM. Retrospective cephalometric analysis of mandibular bone absorption under silicone rubber chin implants. Plast Reconstr Surg 1976;57:144–151.
1. Guyuron B, Michelow BJ, Willis L. A Practical Classification of Chin Deformities. Columbus OH: The Ohio Valley Society for Plastic and Reconstructive Surgery:1993.
4. Posnick JC. Mandibular deficiency with or without maxillary deformity. In: Posnick JC, ed: Craniofacial and maxillofacial surgery in children and young adults. Philadelphia, PA: Saunders; 2000:981–1003.
2. Guyuron B, Michelow B, Willis L. Practical Classification of Chin Deformities. American Socity of Craniofacial Surgery and American Cleft Palate-Craniofacial Association:1994.
5. Wolfe SA, Berkowitz J. Plastic Surgery of the Facial Skeleton. Boston MA: Little, Brown Medical Division;1989.
3. Yaremchuk MJ. Improving aesthetic outcomes after alloplastic chin augmentation. Plast Reconstr Surg 2003;112:1422–1432.
6. Hofer O. Die operative Behandlung der aloveolären Retraktion des Unterkiefers und ihre Anwendungsmöglichkeit für Prognathie und Mikrogenie. Dtsch Z Mund Kieferheilk 1942;9:130.
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7. Zide BM, McCarthy J. The mentalis muscle: an essential component of chin and lower lip position. Plast Reconstr Surg 1989;83:413-420. Reprint request: S. Anthony Wolfe, MD, 1444 N.W. 14th Avenue, Second Floor, Miami, FL 33125; e-mail: [email protected]. Copyright © 2004 by The American Society for Aesthetic Plastic Surgery, Inc. 1090-820X/$30.00 doi:10.1016/j.asj.2004.02.002
4. Yaremchuk MJ. Mandibular augmentation. Plast Reconstr Surg 2000;106:697–706. 5. Zide BM, Bontros S. Chin surgery III: revelations. Plast Reconstr Surg 2003;Il: 1542-1550.
7. Gillies H, Millard R Jr. The principles and art of plastic surgery, vol II. Boston, MA: Little, Brown; 1957:361.
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tial component of chin and lower lip position. Plast Reconstr Surg 2000;105:1213–1215.
6. Zide BM. The mentalis muscle: an essen-
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Volume 24, Number 3
Chin Augmentation
Editor’s note: My thanks to the moderator, S. Anthony Wolfe, MD (board-certified plastic surgeon and ASAPS member, Miami, FL), and to panelists Jeffery C. Posnick, DMD (board-certified plastic surgeon, oral and maxillofacial surgeon, and ASAPS member, Chevy Chase, MD); Michael J. Yaremchuk, MD (board-certified plastic surgeon and ASAPS member, Boston, MA); and Barry M. Zide, MD (board-certified plastic surgeon, New York, NY), for sharing their opinions and clinical experience. Analysis of chin deformity depends on physical examinaS. Anthony Wolfe, MD tion and, usually, appropriate radiographs such as Panorex and cephalometric examinations. In these patient analyses, certain assumptions have been made that do not completely reflect the true skeletal proportions so that the discussion could be facilitated to focus on the chin. Readers are advised to remember that the actual patient Michael J. Yaremchuk, MD evaluation may need to be more comprehensive than a physical examination alone and must involve a dental analysis and cephalometric and Panorex radiographic examinations. Dr. Wolfe: The first patient is a 27-year-old woman whose primary concern is to improve her nose, but she also feels that her chin is too large (Figure 1). She has normal occlusion. Dr. Yaremchuk, how would you approach the treatment of this patient? Dr. Yaremchuk: This is a difficult case because the patient’s chin is too large. The vertical dimension of her chin is disproportionate to her face. However, if the chin were reduced, there would be a soft-tissue envelope redundancy problem.
I would probably perform a horizontal osteotomy, removing a small wedge of 4 or 5 mm, to give her reasonable proportions. I would then wait and see whether I needed to correct any soft-tissue redundancy. An alternative approach would be to reduce the inferior border by the same small amount and treat the soft-tissue redundancy by taking an ellipse in the submental area. Dr. Wolfe: Dr. Zide, do you agree with this approach? Dr. Zide: For this patient, I think a wedge would work perJeffery C. Posnick, DMD fectly well. Generally, the difficulty of a bone wedge is that it places the nerves at risk. When you perform a vertical chin reduction from a submental approach, you must detach the digastric muscles from the posterior genial tubercles and then reattach them by means of drill holes. A soft-tissue excision, both muscle and skin, must be Barry M. Zide, MD performed. The benefit of using an external approach is that what you see is what you get; you need to drain the wound to get good tissue approximation, and an external support is helpful. There is little chance of nerve injury when one works from below. Among patients who have had a wedge removed, at least one third have sustained some nerve injury because the high part of the wedge is close to the mental foramen. Dr. Wolfe: How close to the mental foramen would you advise surgeons to work? Dr. Zide: Classically, the nerve courses down about 3 mm or a bit more from the foramen, then goes out the hole. The closest to the foramen that I would ever per-
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would be to have decompensating orthodontics followed by implant removal, sagittal split osteotomies of the mandible with advancement, and an oblique osteotomy of the chin with advancement. Dr. Wolfe: Dr. Zide, how would you proceed?
Figure 1. This 27-year-old woman is unhappy with the appearance of her chin. She has normal occlusion.
form an upper osteotomy is 5 mm. When I have gotten much closer, I have seen the nerve. I have even included the nerve in the bony segment and twice had to perform anastomosis. So I avoid the foramen by at least 5 mm.
orthognathic surgery.
Dr. Wolfe: Dr. Posnick, do you have a different way of approaching this patient’s case?
Dr. Wolfe: The next patient is a 15year-old girl who had a congenital cervical cleft and as a result has a tight, visible scar in her submental area (Figure 2). She has had 2 silicone chin implants: One was at the lower border of the chin and the other, although placed at the lower border, has ridden up over the alveolar bone and is visible in the lower sulcus. She has a class II malocclusion but is not interested in orthognathic surgery. She would simply like to have a chin. Dr. Posnick, how would you help her?
Dr. Posnick: She has multiple minor asymmetries in both the upper and lower face. Her ears and eyes are at slightly different levels, and her nose is a bit twisted. Her lower anterior facial height is excessive and horizontally she is retrusive. It is difficult to judge the relationship of the lips to the skeleton because she is pursing them closed in the photo. Dr. Wolfe: Additional information is that she has neither a vertical maxillary excess nor abnormal occlusion, and she does not wish to consider
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Dr. Posnick: An oblique osteotomy of the chin with a minimal vertical reduction and horizontal advancement would give her the best chin result.1
Dr. Posnick: I would educate her about the most effective functional and aesthetic approach, which
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Dr. Zide: Although you can ask adult patients to undergo orthodontia and orthognathic surgery, many of them will refuse. In this patient, let us concentrate on the chin and avoid discussing the midface and nasal bones. The difficulty in this patient is that the soft tissue underneath the mentum is incredibly tight. If you asked her to lift her head, a band would appear, and “clefting” would present in the chin when the band was tightened. My concern is that the bony segment, if advanced, might be pulled down by the soft tissue underneath the chin. The fact that the upper implant overrode the other is expected. When one smooth silicone implant is placed on top of the other, the upper implant migrates to sit on the alveolar bone, which tends to cause resorption. If it moves downward, it looks like a mass under the symphysis. Dr. Wolfe: Dr. Yaremchuk, do you think you could treat this patient with additional implants? Dr. Yaremchuk: I would need radiographs to properly evaluate her. The problem is not limited to the chin. She has a deficient mandible; if you just advanced her chin point, you would exaggerate the mandible disproportion. For now, I won’t focus on the
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soft-tissue problem because it is impossible to evaluate without a clinical examination. With either a sliding genioplasty or a chin implant (I like to use porous polyethylene, fixing it with a screw so that it cannot move), I would want to create an appropriate lateral transition so that she does not have a jutting chin point. The problem is that a sliding genioplasty alone exaggerates the posterior mandibular deficiency and does not create a new anatomic contour. It is an artificial, nonanatomic contour with a step-off; her small chin and mandible and thin skin would exaggerate these iatrogenic deformities. She needs either a sliding genioplasty with lateral alloplastic augmentation or central alloplastic augmentation with more lateral augmentation. Too much augmentation, however, would make her look masculine.
Figure 2. This 15-year-old girl had, at birth, a congenital band associated with a midline cervical cleft. She underwent 2 operations on her chin, one at age 9 and one at age 12, that involved the placement of one implant and the stacking of another. One implant is riding fairly high over the softer alveolar bone.
Dr. Wolfe: Do any of the panelists advocate a microvascular procedure that would bring in bone and soft tissue? Dr. Yaremchuk: I think that the iatrogenic deformities accompanying a composite bone/soft-tissue flap would be too disfiguring for the correction of a cosmetic problem. Dr. Wolfe: The next patient is a 19year-old man who has undergone no previous surgery. Although he has a minor malocclusion (really more of a maxillary cross-bite), I would like to focus on his chin (Figure 3). Dr. Yaremchuk, what would be your treatment approach? Dr. Yaremchuk: He has a severe
Chin Augmentation
Figure 3. This 19-year-old man has a bilateral crossbite because of shifted maxilla, a mandible that appears adequately midline, a hypoplastic chin, and a great deal of submental fat.
chin-bone deficiency and overall facial asymmetry. For sufficient chin projection to be achieved, he would
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probably need a 2-tiered genioplasty through a submental approach and extensive soft-tissue submental and
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anatomy of his bony chin as seen on radiographs. Dr. Wolfe: He actually has a long chin.
Figure 4. This 36-year-old woman complains that when she smiles, the muscles in front of her chin bunch up and create a noticeable deformity. She had a chin implant that became infected and was removed.
submandibular defatting. Then I would augment his lateral mandible to correct the “cowcatcher” look caused by his lateral deficiency and chin advancement. Dr. Wolfe: When you palpate the lower border of his chin, it is almost halfway down the straight line, as you can see on the photograph. Dr. Posnick, how would you improve his chin? Dr. Posnick: He appears to have a fair amount of upper-face asymmetry and lower-face disproportion. Even if his occlusion is normal, I would need to see a lateral cephalometric radiograph. I do not think you can achieve a satisfactory result by focusing on his chin alone, and I would also consider other soft tissue procedures. What I would suggest for his chin partially depends on the
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Dr. Posnick: He does have an unattractive chin, but he also has facial disproportion related to the upper and lower jaw. His A-point (anterior maxilla) extends much farther forward than his B-point (anterior mandible). He needs a Le Fort I osteotomy and bilateral sagittal split osteotomies of the mandible with counterclockwise rotation of the occlusal plane. This would reposition the A-point and B-point in better proportion with each other.2 I would also perform an oblique osteotomy of the chin for horizontal advancement. A significant component of his aesthetic problems are in the maxilla and mandible. He also needs soft tissue work. Dr. Wolfe: Dr. Zide, what would be your approach? Dr. Zide: Because we are focusing on the chin instead of an overall evaluation, I would work in 2 stages: First I would do the chin, and second I would augment his mandible to improve the sides of his jaw. The submental approach should be aggressive, including subplatysmal defatting, digastric removal (probably three-quarters), and partial removal of the submaxillary gland. He will need a radical debulking in the submental region to produce an acceptable neck contour. I would first need to get the bone as far forward as necessary (augmentation genioplasty), augment the sides of the mandible, and, in a sec-
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ond procedure, defat the subplatysmal and the submental regions to create a suitable contour for a cervicomental angle. Dr. Wolfe: Would any of you use a face lift incision as well as the submental incision in this young patient? Dr. Yaremchuk: I would consider that. I have used a face lift incision in similar patients to gather and redrape some excess skin. Dr. Wolfe: The next patient is a 36year-old woman who had a chin implant that became infected and was removed (Figure 4). A capsule formed around this implant, and now the implant is out but the capsule is contracted. When she smiles, a ball develops in her chin area, which she finds distressing. Dr. Zide, how would you help her? Dr. Zide: There are several approaches. This woman has actually had some of the mentalis muscle removed. Usually, with a capsule, you get fasciculation and “balling,” but you usually do not get a dent right in the center. Somehow, when the implant was removed, some of the mentalis muscle was also removed. Otherwise, you would not be seeing this extent of muscle loss. Fasciculation, if it’s in the lower portion of the chin pad, can be handled with muscular injections of Botox (Allergan, Inc., Irvine, CA). However, if you wish to open the capsule, you have to perform an osteotomy, release the capsule, and fill the space or insert an implant to fill the space. You must expand the capsule so that it does not contract again.
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There are other ways to do that, such as placing an Endotine device (Coapt Systems, Palo Alto, CA)— Endotine is usually used for forehead support. Or you could suture the capsule down in multiple areas. This is a difficult case, and results will never be perfect; the lost mentalis will not come back. There is no way to get it completely relaxed on both sides so that it is uniform. Dr. Wolfe: Dr. Posnick, how would you proceed? Dr. Posnick: I would like to build out her bony chin, which would then stretch out the soft-tissue envelope. But from this single view, I don’t know whether her facial aesthetics would tolerate it. This is a situation in which a lateral cephalometric radiograph would be helpful.
contracture of the pocket. It is really not a good thing.
Dr. Wolfe: Her chin is recessive even with that capsule.
Dr. Wolfe: Dr. Yaremchuk, how would you approach this problem?
Dr. Posnick: With that in mind, I would consider performing an oblique osteotomy with horizontal advancement and a vertical lengthening. Block hydroxylapatite can be placed in the interpositional defects.
Dr. Yaremchuk: We are looking at the consequences of a “button” implant that was probably placed subcutaneously, with the effect of scar contracture. She has lost soft tissue, and she has lost mentalis. Surgery should reexpand and fill the soft-tissue envelope. You can use an implant placed against the bone or perform an osteotomy with some advancement. It appears to me that the capsule is very close to the skin. If you excise the capsule, you must be very careful; there will be dermis close to your dissection. Ongoing Botox administration might have a role in the treatment of the fasciculation problem. Because a soft-tissue deficiency exists, fat injections could be
Dr. Wolfe: What would you do with her capsule? Dr. Posnick: I would excise it conservatively, taking care to avoid injuring the soft tissues further. Dr. Zide: Can I interject? The original Friedland3 paper stated that if you remove a chin implant, you maintain some of the projection. What he did not realize was that this projection is actually the capsular
Chin Augmentation
Figure 5. This 26-year-old woman underwent a chin reduction in 1976 that resulted in contour deformity. In 1980, a chin implant was placed on the left side to fill out the contour.
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helpful as a secondary procedure to replace missing soft tissue. Note that fat injections do not give the same visual effect as skeletal augmentation or advancement. Dr. Wolfe: The next patient is a 26year-old woman who underwent a chin reduction in which the lower border of the left side of her mandible was cut off (Figure 5). It was an asymmetric cut that entered the mental foramen, transecting the nerve and resulting in residual numbness. A second surgeon placed a silicone chin implant against the lower border of the now-osteotomized mandibular symphysis, which can now be palpated and moved. Some soft tissue has bunched up in her neck, resulting in an iatrogenic witch’s chin. Dr. Posnick, how would you treat this problem? Dr. Posnick: I do not know what I
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the fat in the bottom part of the chin pad and in the submental region. My goal is to make the chin look less droopy, and that could probably be achieved by working from below. I would not do it using an intraoral approach. Dr. Wolfe: What about reattaching the geniohyoid or genioglossus muscles that normally attach to the bottom of the symphysis?
Figure 6. This 30-year-old man had 2 chin implants placed at different dates for the correction of retrogenia. Both implants are mobile and in the wrong position.
would do for her. She does not look too bad. I would not necessarily intervene. Dr. Yaremchuk: In this view she is asymmetric, with the implant inferiorly displaced. She is too young to have such a soft tissue redundancy. When the surgeon resected the chin point, were her geniohyoid muscles disinserted? Dr. Wolfe: Yes, you can see that the muscles have retracted. Dr. Yaremchuk: I would probably make a submental incision, remove the implant, reattach the muscle, and observe the result, but my impression is that if you removed the implant, her chin would be too short. I might even reverse the operation and elongate her chin, which would correct her chin pad and neck distortion. I would reattach the muscles to the bone and, perhaps, perform submental lipectomy.
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Dr. Wolfe: Dr. Zide, what would your treatment plan be? Dr. Zide: When you look at the line, the inclination from her lower lip to the labiomental fold, consider that she would look worse if the line were straight and appeared as a vertical drop. What saves her from looking unattractive is that the line is angled posteriorly. However, because the chin implant is sitting unattached in the soft tissue, it has to come out. If she has a functional, workable sulcus and good lip position, and if she is comfortable maintaining her current lip position, I would use a submental incision to excise that depression, remove some fat in the submental region, and replace the implant with Porex (Porex Corp., Fairburn, GA), screwed in, to maintain projection. She has a droopy chin, and I would try to straighten the groove in the submental region by reducing
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Dr. Zide: I do not know what to attach these muscles to; the muscles are probably in a ball. My goal would be to get the chin positioned correctly, repositioning the fat underneath and the submental region and chin pad in a straight line. Dr. Wolfe: The next patient is a 30year-old man who has undergone 2 previous chin implants to correct a retrogenia (Figure 6). He has normal occlusion. The last implant, which was long and wrap around style, was placed in an effort to lengthen his chin. It is evident in the front view that the implant contour rests beneath the lower border of his symphysis. Dr. Zide, how would you correct this chin? Dr. Zide: The problems with the wraparound implant, such as an implant that sits along the inferior border, is that implants are not made to wrap around the inferior border. Unless they are well stabilized, they will just drop in time. This patient either has a tremendous chin pad deficiency or the chin pad is just missing. I think that if the implant were removed and an advancement genioplasty or another type of implant were used to provide proper chin pad shape, he would
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look a lot better. The current implant must be removed. Dr. Wolfe: What kind of genioplasty would you perform? He has a fairly long chin. Dr. Zide: I would have to look at a radiograph to see how big his chin is. If his chin were long, I would “jump” it; (eg, “jumping genioplasty”) if his chin were not long, I would perform a straightforward advancement. Dr. Wolfe: Assuming that you would jump it, would you perform another genioplasty later? Dr. Zide: I don’t know; I would have to see how he looked. Dr. Posnick: I would be concerned that with this approach, the chin would project too far forward compared with the base position of the mandible and the teeth. 4 It would not look good. Dr. Wolfe: Then where would you place the anterior point of the chin? Without using cephalometric films but using good clinical photographs, what is your desired position? Dr. Posnick: This patient’s A-point is far in front of his B-point. He appears to have excessive vertical length in the lower anterior face and poor horizontal projection. To improve his appearance, you cannot just focus on his chin. Dr. Wolfe: Dr. Yaremchuk, what are your ideas for this patient? Dr. Yaremchuk: How much has the implant elongated his chin?
Chin Augmentation
Figure 7. This 34-year-old man would like to improve his chin. He has relatively normal occlusion.
Dr. Wolfe: The implant was about 6 to 7 mm, like a long cigar, extending from gonial to gonial angle. Now it sits below the lower border of his chin. He has more of a retrogenia than a pure microgenia. A retrogenia is a moderate length of bone that is headed back toward the hyoid. Two of the panelists have mentioned performing a jumping genioplasty. 5 I think this is a good procedure when bone stock is adequate. Dr. Yaremchuk: His whole jaw is too small. He needs mandibular implants to widen his face and increase his ramus height. Almost any technique you would use on his chin alone would make him look worse. Dr. Wolfe: The next patient is a 34year-old man who is concerned about the lower third of his face: He feels that his chin is too short
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(Figure 7). He has relatively normal occlusion. Dr. Zide, would he be a good candidate for a properly executed chin implant? Dr. Zide: He has a skeletal deep bite. If you asked him to move his lower jaw forward and put his teeth edge to edge, he would look perfect. He needs a sagittal split osteotomy. But if he were unwilling to have orthognathic surgery and wear braces, I would use 1 of 2 techniques: either an osteotomy to bring his chin forward and down or a chin implant to augment the lower border alone. His labiomental fold is very deep, and if you put in a large implant, you would decrease his labiomental angle. It would look too acute, and you would make the chin look too big. Dr. Wolfe: For panelists who use implants, what do you consider the ideal chin-implant material?
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could do nothing and the gap would fill with bone and scar tissue anyway. Dr. Wolfe: Dr. Posnick, would you turn him away if he did not want his minor malocclusion corrected?
Figure 8. Dr. Yaremchuk’s technique for alloplastic chin augmentation. The striped area denotes the area of subperiosteal dissection. Note that a pocket larger than the implant is dissected for ease of implant insertion and to provide a panoramic view of the area to be augmented. The porous polyethylene implant consists of a right and a left side so that it can parallel the border of the mandible. The implant is immobilized with screws to obliterate any gaps between the posterior surface of the implant and the anterior surface of the mandible. “In place” contouring provides an imperceptible implant skeleton transition. (Used with permission of Dr. Yaremchuk and the Journal of Plastic and Reconstructive Surgery.)
Dr. Posnick: If his other facial views and radiographs are as I suspect, I would not object to performing a “camouflage” vertical lengthening and horizontal-advancement genioplasty. It will be important to educate this patient about his overall facial disproportion. He can then make an informed decision about treatment of the chin. Dr. Wolfe: What would you interpose in the space? Dr. Posnick: Block hydroxylapatite.
Dr. Yaremchuk: I like to use 2-piece porous polyethylene implants inserted through a submental incision. I fix them with screws to immobilize them, to obliterate dead space, and to allow final contouring with a shaping base (Figure 8).
Dr. Wolfe: Do you have resorption under the implant? Dr. Yaremchuk: I have very little; 1 or 2 mm is the most I have seen with porous polyethylene. I do see more with silicone, but it depends where the implant is.
Dr. Zide: I use both porous polyethylene and silicone. It is rare that I do not contour the implant; I adjust each implant by reducing size or projection or by changing the shape before I insert it. For porous polyethylene, I use screws. For silicone implants, I use 2 sutures into the periosteum, one on each side, so that the implant does not ride up. I have actually put holes in the bone, going right through the implant, then through the hole in the bone, and all the way around the inferior border.
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Dr. Zide: If it is a “high rider,” you will get resorption. If it is right on the lower mandibular bone and is a soft implant, you will get much less. Dr. Wolfe: Considering this patient (Figure 7), Dr. Zide, would you interpose material of some sort? Dr. Zide: My choice is to use either hydroxylapatite or bone cement. You could use a regular bone graft, if it is less than 3 or 4 mm, or you
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Dr. Wolfe: Dr. Yaremchuk, how would you help this patient? Dr. Yaremchuk: I would lengthen and slightly advance his chin. Through a submental approach, I would perform a horizontal osteotomy with slight advancement and probably 8 to 10 mm of elongation. I would fix it with plates and screws. I would interpose a piece of porous polyethylene to maintain that height, and I would make sure that it extended sufficiently laterally to smooth the transition at the lateral osteotomy site. Dr. Wolfe: The next patient is a 22year-old woman who is displeased with her chin (Figure 9). Dr. Yaremchuk, what treatment would you propose? Dr. Yaremchuk: Her chin is reces-
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sive, too long, and her mandibular plane looks rather steep. I would perform an advancement genioplasty. I like to use a submental approach to avoid problems with the mentalis muscle. Dr. Wolfe: Dr. Hofer 6 and Sir Harold Gillies7 both approached the chin that way. What kind of osteotomy would you perform? Dr. Yaremchuk: I would need to increase her projection and decrease her vertical height. The obliquity of my cut would have to accomplish those goals. She is already narrow; if you just extended her chin point, you would need to do something to soften the lateral transition. I would place an implant laterally to effect a good transition so that the mandible will have an appropriate size and contour instead of appearing “stuck on.” Another option would be to decrease the vertical chin height and place an implant to provide anterior projection. Dr. Wolfe: Dr. Zide, looking at this photograph we see, midway between her labiomental crease and the lower border of her chin, a little mound that is actually the mentalis muscle. She has evident lip strain and works to achieve lip seal. Do you think that rearranging the bone would help this? Dr. Zide: I do not think that rearranging the bone would make her lips better. Reducing the inferior border and inserting an implant would work well if you wanted to use a submental approach. Dr. Wolfe: If you are going to reduce it, why not jump it?
Chin Augmentation
Figure 9. This 22-year-old woman has satisfactory occlusion, considerable retrogenia, and some underdevelopment of the lower border of the body of the mandible.
Dr. Zide: You could. When you look at most of these patients, there is more than 1 way of treating them. Dr. Wolfe: Dr. Posnick, what would you do to improve her chin? Dr. Posnick: A lateral cephalometric radiograph would likely confirm that she has increased vertical chin length and horizontal retrusion. I would perform an intraoral oblique osteotomy of the chin with vertical shortening and horizontal advancement.4 Dr. Wolfe: Would you lift the lower border and jump it, or would you slide it forward and fix it? Dr. Posnick: I would reduce the vertical height by removing a small wedge and then horizontally advancing the chin. I would use titanium micro plates and screws for fixation.
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Dr. Wolfe: What do you think about the issue of lip seal? Dr. Posnick: She has problems with lip seal because of the increased vertical height in the lower face. The mentalis muscle rides up with attempts at lip closure. If you decrease the vertical height of the bony chin, you will decrease lip strain. Dr. Wolfe: It is notable that patients may experience functional improvement as a result of chin surgery in addition to the aesthetic improvement.
References 1. Posnick JC. Aesthetic alteration of the chin: evaluation and surgery. In: Posnick JC, ed. Craniofacial and maxillofacial surgery in children and young adults. Philadelphia, PA: Saunders; 2000:1113–1124. 2. Posnick JC. Maxillary excess with or without mandibular deficiency. In: Posnick JC, ed. Craniofacial and maxillofacial surgery in children and young adults. Philadelphia, PA: Saunders; 2000:1025–1056.
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3. Friedland JA, Coccaro PJ, Converse JM. Retrospective cephalometric analysis of mandibular bone absorption under silicone rubber chin implants. Plast Reconstr Surg 1976;57:144–151.
1. Guyuron B, Michelow BJ, Willis L. A Practical Classification of Chin Deformities. Columbus OH: The Ohio Valley Society for Plastic and Reconstructive Surgery:1993.
4. Posnick JC. Mandibular deficiency with or without maxillary deformity. In: Posnick JC, ed: Craniofacial and maxillofacial surgery in children and young adults. Philadelphia, PA: Saunders; 2000:981–1003.
2. Guyuron B, Michelow B, Willis L. Practical Classification of Chin Deformities. American Socity of Craniofacial Surgery and American Cleft Palate-Craniofacial Association:1994.
5. Wolfe SA, Berkowitz J. Plastic Surgery of the Facial Skeleton. Boston MA: Little, Brown Medical Division;1989.
3. Yaremchuk MJ. Improving aesthetic outcomes after alloplastic chin augmentation. Plast Reconstr Surg 2003;112:1422–1432.
6. Hofer O. Die operative Behandlung der aloveolären Retraktion des Unterkiefers und ihre Anwendungsmöglichkeit für Prognathie und Mikrogenie. Dtsch Z Mund Kieferheilk 1942;9:130.
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7. Zide BM, McCarthy J. The mentalis muscle: an essential component of chin and lower lip position. Plast Reconstr Surg 1989;83:413-420. Reprint request: S. Anthony Wolfe, MD, 1444 N.W. 14th Avenue, Second Floor, Miami, FL 33125; e-mail: [email protected]. Copyright © 2004 by The American Society for Aesthetic Plastic Surgery, Inc. 1090-820X/$30.00 doi:10.1016/j.asj.2004.02.002
4. Yaremchuk MJ. Mandibular augmentation. Plast Reconstr Surg 2000;106:697–706. 5. Zide BM, Bontros S. Chin surgery III: revelations. Plast Reconstr Surg 2003;Il: 1542-1550.
7. Gillies H, Millard R Jr. The principles and art of plastic surgery, vol II. Boston, MA: Little, Brown; 1957:361.
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6. Zide BM. The mentalis muscle: an essen-
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