eMedicine Specialties > Plastic Surgery > Facial Augmentation

Facial Alloplastic Implants, Mandibular Angle: Treatment

Author: Lily Love, MD, Staff Physician, Department of Otolaryngology, Mount Sinai Medical Center
Coauthor(s): R Edward Newsome, MD, Program Director and Chief of Plastic Surgery, Henderson Chair in Surgery, Assistant Dean for Graduate Medical Education, Tulane University School of Medicine; Moises Salama, MD, Staff Physician, Department of Surgery, Jackson Memorial Hospital, University of Miami School of Medicine; John N Kent, DDS, Head, Boyd Professor, Department of Oral and Maxillofacial Surgery, Louisiana State University Medical Center; David A Jansen, MD, FACS, Private Practice, Surgical Associates LLC
Contributor Information and Disclosures

Updated: Nov 24, 2008

Treatment

Surgical Therapy

The deficiencies that require implantations usually are either vertical or lateral. Two basic approaches exist for implantation. The extraoral approach is advantageous because it allows for accurate placement of the implant and access is easy. The intraoral approach is liked because no visible scar is created but it is associated with a higher rate of infection.

In general, the implant should lie in healthy tissue away from areas of irradiation or excessive scar formation. The placement should be deep in the supraperiosteal pocket directly on the bone if the implant has porous or osteophilic properties. This accuracy of placement can be attained if preoperatively determined landmarks, measurements, and 3-dimensional imaging is obtained. The implant should be in firm contact with the tissues, and compression of the implant pores should be avoided.

Apply antibiotics before and after surgery by soaking the implant or through vacuum impregnation if the implant is porous. The implant should be screwed, wired, or sutured into position, and compressive dressings should be used to minimize dead space and avoid hematoma formation. The success of the procedure depends on many factors, including the implant's physical traits, the biologic response, proper handling, the surgeon's operative experience and technique, and postoperative care. Patient compliance must be ensured through proper patient selection and informed consent.

Preoperative Details

Ample evidence exists that the composition of the alloplastic material transplanted clearly affects biocompatibility. However, the surgical technique and location of placement clearly have a critical role in long-term clinical success. The quality of tissue (eg, vascularity, the thickness of the tissue covering the implant) into which the implant is to be placed must be critically inspected. Patients who previously have had radiation to the area may have decreased vascularity, which impedes the body's ability to mount an inflammatory response to microbial invasion should the implant become inoculated or infected.

Placement of the implant in or through an infected bed of tissue greatly increases the chances of implant failure. Most implants can tolerate host tissue vascular ingrowth. Therefore, a lack of vascular supply compounded upon the surface affinity of many alloplastic implants for bacterial adhesion and overgrowth makes anything less than strict aseptic technique and clean healthy tissue planes unacceptable. The tissue over the implant should be as thick as possible because if the tissue is thin, the chance of wound dehiscence, exposure, or extrusion of the implant is increased. If a thin layer of subcutaneous tissue or dermis is placed over the implant, these layers thin because of pressure from the underlying avascular implant.

Kent et al have described the characteristics of the ideal facial implant material as follows:⁴

• The material is readily available in block and precarved forms and is easily carved.
• It can be steam autoclaved readily.
• It can be molded or bent to improve bone interface and overlying facial contour.
• The material should be malleable, allowing for deformation, but should not have memory characteristics, which may lead to mobility, extrusion, or resorption.
• Its surface should be porous to allow tissue ingrowth and immediate stabilization on bone and surrounding soft tissues.
• Resorption or deformation of bone underneath implants from soft tissue or muscle tension should be clinically insignificant.
• Redistribution of soft tissues overlying the face of the implant should be minimal so that the implant size should be determined predictably.
• The healed tissue implant matrix should have gross characteristics approaching bone with plenty of overlying soft tissue and skin.
• The material should be osteophilic and osteoconductive for calcified tissue ingrowth and stabilization.
• The material should have no objectionable color, especially when scant tissue or skin coverage is available.
• The implant material should be easy to remove if the result is not satisfactory.
• The material should allow for additional augmentation if necessary.
• It should exert no local or distant cytotoxic effects and should be highly compatible.

Patients should receive a dose of intravenous antibiotic intraoperatively and then a postoperative oral course. The antibiotic should cover Staphylococcus and Streptococcus species (1 g of a first-generation cephalosporin or 600-900 mg of clindamycin). Since some of the implants are hydrophilic, many surgeons seek additional antibiotic protection by washing or soaking the implant before insertion. Keep the implant in its sterile packing until the time of insertion and keep manual handling to a minimum. Furthermore, use sterile instruments in handling the implant. Minimize contact with the surrounding skin, soft tissues, and oral cavity to prevent bacterial inoculation of the implant's surface. Some surgeons even advocate changing gloves prior to touching the implant. Proving the effect of these precautions in actual practice is difficult; however, it makes sense to take special care to avoid contamination to improve the success and survival of the implant.

Intraoperative Details

Intraoral approach

• The intraoral approach involves a vertical vestibular incision through periosteum; a subperiosteal dissection is carried out along the lateral surface of the angle and ascending ramus. Curved elevators facilitate the release of the soft tissue attachments along the inferior border of the mandible and posterior ramus.
• Insert a well-contoured angle implant into the subperiosteal pocket and use bone screws to secure the implant to the lateral cortex of the mandible.

Extraoral technique

• The extraoral technique involves the standard submandibular approach. Make a modified Risdon incision, preferably in an existing rhytid, through subcutaneous fat down to the platysma muscle.
• Divide the platysma with blunt hemostats. Use a nerve tester to selectively test for the cervical and marginal mandibular branches of the facial nerve as they dip below the inferior border of the mandible. The platysma thus is divided superiorly and inferiorly in the surgical field, exposing the superficial layer of the deep cervical fascia.
• Take caution because the facial nerve lies in this fascia. This nerve is freed and retracted superiorly. The facial artery and vein usually are found anteriorly near the submandibular lymph nodes. These vessels usually are ligated if they are in the way of proper placement of the implant. Care must be taken not to transect or injure these vessels because even though they can be ligated, any postoperative bleeding likely causes a hematoma and possible need for further surgery.
• Then dissect the pocket along the posterolateral border of the mandibular angle under the pterygomasseteric sling. Place and fixate the implant. Usually, the pocket is sufficient to hold the implant in place, but occasionally, a screw may be used to secure the implant. Finally, perform copious irrigation with antibiotic-impregnated saline and carry out a careful layered closure with resorbable suture.
• Place a Jobst jaw bra with 4 X 4 dressings over the mandibular angle for stability and to minimize swelling. This compressive dressing also may decrease the chance of postoperative hematoma if mild venous bleeding occurs. Most patients are able to resume normal activities in 1-2 days.

Other procedures are sometimes performed in conjunction with mandibular angle augmentation to achieve a balance in the final appearance (ie, with chin, cheek, nose).

Postoperative Details

Good postoperative care is probably as essential in ensuring success as the surgery. During the postoperative period, periodically monitor the patient for early signs of complications such as infections or hematomas. If a complication is observed early, action to correct the problem has increased chance of success. Patients should maintain good oral hygiene postoperatively to lower the risk of wound infection. Also, they should avoid gum chewing, tough foods, and any activity or action that requires wide opening of the mouth. Finally, counsel patients after any aesthetic or reconstructive surgery to help them cope and adapt to their new image. Prepare them to expect some postoperative swelling and bruising.

Follow-up

Patients may schedule follow-up appointments at 6 months, 1 year, and then annually as indicated or as needed.

Complications

All surgical procedures have potential complications. However, as may be expected, the introduction of a foreign object into human tissue can produce additional complications. Still, in most studies, complications are rare.

Hemorrhage or infection can occur. Common culprits are streptococci, staphylococci, and gram-negative rods. Bleeding complications include exterior bleeding or hematomas.

Other complications include injuries to the inferior alveolar (fifth nerve) or the ramus mandibularis (seventh nerve). The mandibular branch of the facial nerve is particularly vulnerable, and special caution must be taken during surgery. For more information, see eMedicine article Facial Nerve Paralysis.

Because of contracture and tissue breakdown, the implant material can be exposed. This can be managed by reoperation or by trimming the implant and closing the exposure.

Other complications or failures include implant migration or mobility if fixation is not performed appropriately. The implant may break or rupture, requiring surgery. Finally, some other complications to consider include seromas, paresthesias, neuralgias, pain, visible scars, and, rarely, immune responses to implanted material, possibly necessitating further surgical intervention.

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