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Archive for the ‘chin implants’ Category

Technical Strategies – Vertical Chin Cleft Creation with Chin Implant Augmentation

Sunday, December 3rd, 2017

 

The chin has few topographic features on an otherwise round convex shape as it covers the projecting chin bone. Chins can have either a dimple or cleft. A chin dimple is a circular central indentation of the soft tissue chin pad. A chin cleft is a vertical indentation through the lower half of the chin pad that extends to the inferior border. While many perceive that these chin indentations are caused by the bone underneath them (particularly a vertical cleft), they are actually anomalies in the soft tissue and not the bone.

The vertical chin cleft is the easiest to understand since the lower jaw is formed by the paired brachial arches that meet in the middle in the embryo. Failure to have a complete meeting in the middle can result in a ‘cleft’ of the overlying soft tissues. Or more likely the union of the tissues developed a very slight separation that resulted in a very minor soft tissue cleft.

When surgically trying to make a chin cleft, making a vertical defect in the bone alone will not work. Or in the case of placing a chin implant, a ‘cleft’ chin implant will also not create the desired effect. It requires soft tissue manipulation, preferably from a submental incision, to make an effective external cleft appearance.

When doing a combined chin implant and vertical cleft creation, the bigger the chin implant the more likely it will be effective. Whether the chin implant is round or square does not matter, it can be done equally well in either one. The key technical points are two-fold. First a wedge of cleft must be made through the center of the implant to create a channel for the soft tissue anchoring. In so doing the implant will need to be secured with screws on each side so it remains positionally stable. Secondly a vertical wedge of soft tissue (muscle and fat)is removed from its underside up to the dermis of the skin. Sutures can then be placed to pul the skin down into the implant cleft. This will create a resultant vertical indentation of the overlying external chin.

A vertical chin cleft can also be created in patients who are not undergoing chin implant augmentation. The technique is the same with the exception that a vertical groove is made into the lower edge of the bone as opposed to that of an implant.

Dr. Barry Eppley

Indianapolis, Indiana

The Role of Mandibular Ligaments in Chin Implant Surgery

Sunday, December 3rd, 2017

 

Chin augmentation using an implant is the common form of aesthetic facial augmentation. Putting an implant on the front edge of the chin bone has been done for over fifty years using a variety of materials. Silicone chin implants dominate the materials used for chin augmentation and are available in a variety of styles. The extended chin implants, or an implant style that has long wings that go back along the sides of the chin into the jawline, is the basic concept of most chin implant designs today.

While chin implants are effective for increasing the horizontal projection of the chin, they are not complication free. The most common adverse aesthetic issue with their use is malposition. With the extended implant design the risk of such malpositions are magnified as it doesn’t take much less than a perfect horizontal leveling of the implant to have wing asymmetry.

The longer wings of extended chin implants requires that a complete subperiosteal elevation of the tissues is done along the lower edge of the chin. If the tissues are not adequately released the wing of the implant will to be allowed to extend back as it was designed. Because the wing of these implants is very thin it is quite easy for their tips to bend with little detention that it has happened.

In executing the subperiosteal dissection along the inferolateral rim of the chin and anterior jawline, firm attachments are always encountered. These are the key anatomic structures that must be released for good pocket creation. These ligaments are the mental ligament and has been described as occurring about 1 cm to the midline and just superior to the inferior border of the mandible. Further back is the medial mandibular ligament located about 3 cms from the midline. (I prefer to call this the Ligament of Binder by the surgeon who first described its significance in surgically placing chin implants) A third mandibular osteocutaneous ligament also located about 5 cms to the midline and his has greater relevance in custom chin and jawline implants which go much further back along the jawline.

The release of these mandibular ligaments is the key in chin implant placement regardless of whether it is done through a submental or intraoral approach. Failure to do can result in chin implant malposition and external asymmetries.

Dr. Barry Eppley

Indianapolis, Indiana

Case Study – Correction of Custom Chin Implant Malposition with Lag Screw Fixation

Sunday, October 29th, 2017

 

Background: Chin augmentation with implants has a long successfully history. While standard chin implants work for many patients, significant chin deformities do not fare as well. The shape and size of off-the-shelf implants are made for more modest to moderate aesthetic deficiencies primarily in the horizontal direction.

In the more severe horizontally deficient chin, which in many cases is really a manifestation of a mandibular growth deformity, the chin often has a dimensional deficiency that is not just in the forward dimension. As the ramus of the mandible fails to grow vertically long enough the jaw angles remain high and the mandibular body tilts downward. This creates a short but vertically long chin. Placing a standard implant on the front part of the chin will bring its projection forward and downward…not an ideal aesthetic change.  While the implant can be placed higher up on the front edge of the chin, this can create an exposed lower edge of the chin bone. This is why a sliding genioplasty is usually favored in this type of chin deformity as it can vertically shorten the chin  as it is brought forward.

Very horizontally short chins in females poses a unique challenge for implants.  Large chin implants have long extended wings which end up widening the chin significantly in the front view…an aesthetic problem that most women will find unacceptable. Women prefer more narrow chin widths and there are not standard implants that can offer enough projection but with a narrow base width.

Case Study: This female had a chin implant history of five previous surgeries over the years to find an acceptable chin augmentations result. She had a very short lower jaw, a class II malocclusion, and previous standard chin implants which were modified to try and give enough horizontal projection but not be overly wide. Her fifth and last surgery involved a custom chin implant made from a 3D CT scan. It had an uncommon design with a lot of horizontal projection, a narrow base and an almost cone-like shape.

She reported that this custom implant produced a satisfactory aesthetic change right after surgery. But with the first week after its placement, the chin shape changed and her chin become vertically long and lost its horizontal projection. She had a CT scan which showed that the implant had become displaced, basically falling of the chin and rotating 90 degrees. This gave her a ‘pharoah’s chin or false beard look.

Under general anesthesia and through her existing submittal incision, the displaced implant was removed through a thin overlying soft tissue coverage. A capsulectomy was done on the bone and releasing capsulotomies were done on the surrounding soft tissue pocket lining. The implant was reinserted and positioned as it was designed and secured with two 2.0mm screws through the implant into the bone. A capsular flap was raised from the inferior side of the soft tissue pocket and added as another tissue layer over the implant prior to skin closure.

Her immediate result showed how the chin was designed to look from the custom implant design.

Screw fixation of facial implants in general, and chin implants in particular, has often been debated. But it is important to remember that an implant over the front edge of the chin is not particularly stable. This can become more so based on the implant’s dimensions. While a custom chin implant ensures that the desired shape and size is achieved, there is no assurance it will stay where it is designed to be placed. In implants that look less positionally secure, double lag screw fixation ensures this will not be a postoperative problem. Repositioning of any chin implant malposition probably merits screw fixation to prevent recurrence.

Highlights:

1) A custom chin implant is as prone to malposition as a standard chin implant.

2) Any form of a chin implant completely falling off the chin bone is rare but in a high horizontal:vertical base ratio implant that risk is accentuated.

3) Screw fixation of chin implants prevents postoperative malpositioning and should be used in ‘high risk’ facial implants.

Dr. Barry Eppley

Indianapolis, Indiana

OR Snapshots – Double Stacking Chin Implants

Wednesday, September 27th, 2017

 

Chin implants are the original and still today the most common form of facial skeletal augmentation. Having been around for over fifty years in various forms, chin implants have undergone many evolutionary changes in their shapes to satisfy a wide variety of aesthetic chin needs. Because of its history and frequent use, they have the greatest number of different styles and sizes off any type of facial implant.

But even with such a diversity of standard options, not every patient will do well with an off-the-shelf implant shape. This is where the role of custom implants comes into play where any dimensional need can be addressed through patient specific designing for unique chin dimensional augmentations. While extremely effective custom facial implants come at an increased cost over standard ones that may be a limiting factor for some patients.

While chin implants can be modified by hand carving them during surgery, adding to them is a different matter. There is no recognized method for increasing the size or shape of a standard chin implant. In some situations I have found it effective to marry together two different implant styles to get the desired effect. This is an example where a prejowl implant is added to an anatomic implant to get wider wings for more prejowl augmentation. By suturing the implants together in multiple locations, shifting or one implant sliding off of the other is prevented.

It is acknowledged that the use of 3D imaging and implant designing is best for most unique chin augmentation needs. But in the right circumstances it is possible to create a ‘semi-custom’ chin implant using standard implants in a stacking technique with suture fixation.

Dr. Barry Eppley

Indianapolis, Indiana

The Mentalis Muscle and Chin Augmentation

Monday, September 18th, 2017

 

The mentalis is a well known muscle of the chin. Any chin surgery procedure involves manipulation of this muscle no matter what type of dimensional chin change is being done or how it is being done. (implant vs. osteotomy vs osteotomy) Since it is the only muscle that has attachments to the anterior surface of the chin bone, postoperative problems with its function can occur. While many chin procedures are done successfully with the return of normal muscle function, mentalis muscle dysfunction is not rare and is a frequent source of after surgery chin problems. Given the frequent misunderstanding of the mentalis muscle anatomy and function amongst patients and even some surgeons, its role and relevance in chin augmentation surgery merits review.

The mentalis is a paired central muscle of the chin that runs vertically over the chin bone. It actually has two halves and is separated by a fat pad that is most prominent near its bony origin underneath the labiomental fold below the lower lip. The relevance of this central fat pad in the muscle is not clear. The muscle is attached to the bone at the depth of the internal vestibule superiorly and runs down vertically to insert into the soft tissues of the lower submental chin pad. It is important to appreciate that the point of firm fixation is at its origin to the bone but its insertion is into the soft tissue inferiorly. The primary function of the muscle is contraction of the chin pad superiorly and inward (towards the lower lip) which will concurrently raise the lower lip creating a pout type facial expression. It is innervated by the marginal mandibular branch of the facial nerve which crosses over the jawline laterally to reach the muscle’s surface.

In chin augmentation surgery incisional access is either intraoral through the mucosa or submental through the skin. In sliding genioplasty the only choice is intraoral. But implant placement can be done both ways. Both incisional approaches cut through the mentalis muscle but they do so through different areas of the muscle. (origin or insertion. This is more than just an anatomic distinction, it can have a significant influence on muscle tension and function after surgery.

Cutting through the insertion of the muscle with an intraoral approach does so at the point of its maximal muscle thickness and tension. It is extremely important to leave an adequate cuff of muscle attached to the bone with this maneuver, otherwise there will be nowhere to attach the released inferior bulk of the muscle bellies. Without a reattachment the muscle will contract down, the labiomental fold will get deeper and the chin pad will pull down off of the bone. (chin ptosis)

With a retained muscle cuff onto which the released muscle can be reattached, one is essentially re-establishing muscle length at the thickest part of the muscle. But it is easy to see how the muscle length is changed when the soft tissue chin pad is stretched out by an implant or an advanced bony chin segment. The larger the chin pad displacement the tighter the muscle closure will be. This accounts for many a patient’s complaints of prolonged chin tightness and stiffness after a sliding genioplasty, particularly in large advancements. It can also occur with chin implants and is most commonly seen when the implant rides up high and pressures the resutured muscle origin.

In the submental approach for chin implants, it is the insertion of the muscle that must be cut and lifted up to reach the bone. Since this is not a firm bony attachment, muscle elevation and closure is done at the thinner lower portion of the muscle and has a much lower risk of adversely affecting muscle tension and postoperative function. This is why there are far fewer complaints of chin stiffness and tightness from submentally placed chin implants as re-establishing muscle length is much easier as opposed to pulling the muscle back up to its original bony attachment.

Mentalis muscle anatomy and its function is just one issue to consider in chin augmentation and is most relevant with implants where both incisional options are in play. When the patient prefers an intraoral approach for a standard chin implant I use the muscle splitting approach through its septum rather than cutting the muscle’s bony attachment.

Dr. Barry Eppley

Indianapolis, Indiana

The Role of Custom Chin Implants

Sunday, June 18th, 2017

 

Alloplastic chin augmentation is the oldest facial implantation procedure. As a result, many different styles and sizes of chin implants have been used over the five decades of the procedure being performed. While in the vast majority of patients standard preformed chin implants work just fine, they do not always achieve the patient’s aesthetic lower facial reshaping goals. It is important to remember that current chin implants styles are based on historic patient’s aesthetic needs and surgeon experiences as well as what is economically feasible for the manufacturer. (they can’t produce endless styles of chin implants that end up having few commercial sales)

It is also relevant that today’s patients may have different aesthetic goals than that of what was popular ten or twenty tears ago. Patients are also becoming increasingly sophisticated as to the nuances of their facial aesthetics and, in some ways, are becoming more ‘3D’ in the desire for their facial changes. There is also the patient who has had a standard chin implant and is dissatisfied with the result due to shape issues.

As a result, there is an increasing role for custom chin implants. Even though the chin implant is the ‘simplest’ of all facial augmentation procedures that does not mean it is always easy to get a pleasing chin augmentation outcome. Contrary to popular perception the revision rates of chin implant surgery is not as low as most patients and surgeons believe. I have seen many patients who are on their second or third chin implant seeking an improved result.

Customizing a chin implant design can achieve several shape improvements over standard chin implants. First and foremost it can provide a horizontal projection versus width ratio that is not available in standard styles. Secondly, it can create a vertical lengthening increase with horizontal and transverse widths that is not currently available. Third, the wings of the implant can be designed to blend in better along the inferolateral borders of the lower jaw. Lastly, features such as a vertical chin cleft can be added.

Dr. Barry Eppley

Indianapolis, Indiana

Case Study – Chin Implant Asymmetry Correction

Sunday, May 21st, 2017

 

Background: Chin implants are well known to induce a variety of tissue reactions around the implant site. A surrounding encapsulation of scar tissue is always seen as occurs in every synthetic implant placed in the body. ‘Bone resorption‘ is often cited as an adverse reaction to chin implants but this is a misinterpretation of the actual biologic response that has occurred. It is more accurately described as a limited and passive bone remodeling as a response to the recoil of the expanded tight chin pad tissues now overlying the implant. It is, in effect, a pressure relief.

Some limited bone overgrowth around the edges of the implant is also not uncommonly seen. This occurs because the implant is placed in a subperiosteal location from which a limited osteogenic response is seen from the disturbed periosteal layer. It is actually rather remarkable that bone would grow up over portions of the implant given that it is a synthetic material. But this speaks to the osteogenic potential of the periosteum. But when such a bony overgrowth is seen it is limited to just the edge of the implant, usually the lower edge.

Case Study: This 35 year female had an anatomic chin implant placed eight years previously. While she liked the general chin augmentation effect, there were several aesthetic issues that developed from it that she didn’t like. The implant had some asymmetry to it with the left wing higher than that of the right. There were also multiple indentations that had developed over the soft tissue chin pad that were present at rest and became magnified when she smiled.

Under general anesthesia and through her existing submental incision, dissection was carried down to the chin bone. Initially the chin implant could not be found as only bone could be seen.Tapping on the chin bone had a hollow sound to it. It was suspected that bone had overgrown the bottom edge of the implant and its outer layer was chipped off with an osteotome over a small area to reveal the implant underneath. Continuing to remove the bone overgrowth eventually revealed that the entire implant was completely encased in bone including over the small lateral wings of the implant. The total bony ovegrowth was removed and the implant extracted. All edges of the bony overgrowth down to normal bone was removed. The implant was re-inserted and position in a midline neutral position and secured with double microscrew fixation to prevent implant rotation and recurrent asymmetry.

Complete bony overgrowth of an extended chin implant is a tissue reaction that I have not seen occur. Partial bony overgrowth occasionally occurs  but never complete bony encasement. Such a bony reaction to the implant could be the source of the overlying soft tissue chin pad indentations due to tethering into the tissues. It remains to be seen if removal of the bone improves these indentations.

It is important in treating chin implant asymmetry that any impedance to the wings of the implant be released/removed to allow the total implant to have achieve a completely horizontal orientation. Usually this involves a release of the surrounding scar capsule. In this case it involved all raised bony edges.

Highlights:

  1. Chin implants often induce local tissue reactions including bone overgrowth.
  2. Complete bony encasement of a silicone chin implant is not an implant reaction that I have seen previously.
  3. Chin implant asymmetry correction requires that all surrounding bony overgrowth must be removed.

Dr. Barry Eppley

Indianapolis, Indiana

Square Chin Implants

Sunday, April 2nd, 2017

 

While chin implants has historically been viewed as a critical component of profile enhancement for some patients, this is a limited view of what it can aesthetically do. A more complete assessment of chin implants, 3D chin augmentation, takes into account what changes are needed or will occur in the frontal and three quarter views as well. Such changes take on great gender significance as what men and women want in the frontal view of their chin can be very different.

Some men prefer a more square shape to their chin and this can be one of the desirous changes of placing a chin implant. Increasing the angularity creates a stronger and more defined shape to the lower face at the front edge of the jaw. This is well illustrated in many male celebrities and model who have very defined jawlines and are often referred by men seeing chin and jaw augmentation.

The desire for a more square chin look is probably represented by those men that wear goatees that are specifically cut to create a square chin look. Underneath the facial hair may lie a rounder less angular chin.

The one style of facial implant that is designed to create more angularity is that of the square chin implant style. Its obvious more square shape is in contrast to every other chin implant style which is rounder and is designed to augment the natural curve of the front edge of the chin. It is available in several different styles. What separates the two basic square chin implants is the width that is created. A style 1 is 45mm wide while a style 2 is 55 wide from corner to corner.

Careful inspection of naturally square chins shows that the chin width should not exceed a vertical line dropped down from the corner of the mouth or not much beyond that line. This should be the guide as to whether a style 1 or style 2 square chin implant is used. Going significantly beyond the corners of the mouth with chin squareness can take on a cartoon-like appearance and make the overall face too square.

The other square chin implant style is the extended version. This has long wings that go way back along the jawline. This would be a good square chin implant style to use if one is also getting jaw angle implants for a total jawline augmentation. Such an approach may avoid the need for a custom wrap around jawline implant in some cases that do not involve any vertical jawline increase.

Dr. Barry Eppley

Indianapolis, Indiana

Case Study – Chin Implant after Sliding Genioplasty

Saturday, August 6th, 2016

 

Background: The sliding genioplasty is a well known chin augmentation procedure that is often viewed as a substitute for a chin implant. While this is certainly true in some patients, for other patients it is a better alternative as both an autologous operation and because it can offer some dimensional chin changes that an implant has historically not been able to do.

One dimensional limitation of this bony genioplasty operation is that the amount of horizontal augmentation obtainable is controlled by the thickness of the bone. To ensure bony healing as well as survival of the downfractured chin segment, bone contact must be maintained. This means that the maximal amount of horizontal bone movement is that the back cortex of the mobilized chin segment must stay in contact with the front cortex of the intact chin bone above it.

Because of this anatomic limitation not every sliding genioplasty can achieve ideal chin projection. This leaves the role of a chin implant to achieve an even better chin augmentation result.

Chin Deficiency after Sliding GenioplastyCase Study: This 25 year-old female had previously undergone a sagittal split mandibular advancement with a sliding genioplasty. Even with these two combined lower jaw movements, her chin projection remained aesthetically deficient.

Chin Implant after Sliding Genioplasty intraop Dr Barry Eppley IndianapolisUnder general anesthesia an intraoral approach was used to access her chin. A extended medium chin implant was placed below the existing metal plate from her prior sliding genioplasty. The implant was positioned lower on the chin bone to help create some vertical lengthening as well. (8mms forward and 3mm down) The implant was secured in its position with two 1.6mm screws at the superior aspect of the implant.

There is no reason that an implant can not be placed on top of a prior sliding genioplasty. This would be the simplest way to improve a prior bony chin augmentation procedure. With the many styles of chin implants now available many alloplastic options exist to change the shape of the prior remodeled chin bone.

Highlights:

1) A sliding genioplasty does not always create the ideal horizontal position of the chin particularly in significant lower jaw deficiences.

2) A chin implant can be a secondary addition to a prior sliding genioplasty.

3) The extended wings of a chin implant can help camouflage any bony irregularities along the jawline from the prior sliding genioplasty.

Dr. Barry Eppley

Indianapolis, Indiana

Volume Comparison of Chin Implants and Injectable Fillers

Sunday, May 29th, 2016

 

Chin Implant Augmentation Indianapolis Dr Barry EppleyChin augmentation is a common aesthetic facial reshaping procedure that is second only to rhinoplasty. It has been traditionally performed by the placement of a preformed implant. While many different chin implant styles have been used over the years, the basic concept of an alloplastic chin augmentation is the same.

The emergence of injectable methods for facial augmentation using a variety of injectable fillers and fat has now become an accepted treatment approach for chin augmentation. While no injectable material offers an assured and permanent outcome as that of an implant for chin augmentation, it does provide an opportunity for patients to non-surgically ‘wear’ the result for awhile to determine if it suits them.

An interesting but relevant issue when using injectable fillers for chin augmentation is how do they compare volumetrically. To create an injectable chin augmentation effect, what volume of injectable filler is needed to compare to what a chin implant does? It is not a fair comparison if one is ‘testing’ an injectable filler and the volume injected does not equal what that of the effect that a chin implant does.

Volume Displacement of Facial Implants Dr Barry Eppley Indianapolisextended-anatomical-chin-implantComparing facial implants and injectable fillers is done using volumetric displacement. Based on the Archimedes principle of displacement, volume of displaced water would equal to the volume of the implant. (provided that they sink in water and all chin implants do) Using the most commonly used extended anatomic chin implants (Implantech) of small, medium, large and extra large, their weights in grams and volume displacement were as follows:

Small Chin Implant        2.1 grams     1.3cc

Medium Chin Implant   2.7 grams      1.7cc

Large Chin Implant      3.4 grams     2.2cc

X Large Chin Implant  4.0 grams     2.7cc

The volume displacement of all injectable fillers is on the syringe so the comparison to chin implants is straightforward. It shows that a 1cc syringe of any of the hyaluronic acid-based fillers (e.g., Juvederm) would be less than even a small chin implant. A small anatomic chin implant more favorably compares to 1.5cc of Radiesse. Larger chin augmentation effects requires up to 3ccs of injectable filler regardless of the type.

There are other variables that affect how any of these materials create an external facial augmentation effect. The most significant would be how well does the material push on the overlying soft tissues or push off of the bone to create their effect. This is known as G Prime Force or their elastic modulus. It is quite clear that implants are stiffer than any liquid material and would have a higher resistance to deformation. (thus creating more outward effect given a similar material volume) Therefore it is probable that comparing volume displacements alone overestimates the effect of injectable fillers compared to that of chin implants.

Dr. Barry Eppley

Indianapolis, Indiana


Dr. Barry EppleyDr. Barry Eppley

Dr. Barry Eppley is an extensively trained plastic and cosmetic surgeon with more than 20 years of surgical experience. He is both a licensed physician and dentist as well as double board-certified in both Plastic and Reconstructive Surgery and Oral and Maxillofacial Surgery. This training allows him to perform the most complex surgical procedures from cosmetic changes to the face and body to craniofacial surgery. Dr. Eppley has made extensive contributions to plastic surgery starting with the development of several advanced surgical techniques. He is a revered author, lecturer and educator in the field of plastic and cosmetic surgery.

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