**6. Implant placement**

reconstruction. PMMA is well tolerated without significant inflammatory foreign body reactions. Being able to create customized implants unique to each patient's needs is one of its

ePTFE known as ''Gore-Tex'' (W.L.Gore and Associates, Flagstaff, AZ), is a fibrillated polymer of polytetrafluoroethylene, with pores between the fibrils averaging 22 microns in diameter which allows limited soft tissue ingrowth while creating only a mild chronic inflammatory response, providing early stabilization and permitting removal when necessary [39]. ePTFE is spongy in consistency, inert, and does not change shape or resorb with time. It also has been found to be non-carcinogenic and is rarely allergenic [28, 40]. Because ePTFE is hydrophobic,

Calcium hydroxyapatite is mixed in a fashion similar to methylmethacrylate to form a cement that can be contoured to each individual patient's needs. Because it forms the synthetic, inorganic constituent of bone, it can induce osseointegration. Mixing does not result in an

The surgeon must be able to make a decision regarding the selection of an implant based on chemical composition, physical structure, and planned site for application. Characteristics of an ideal implant include biocompatibility, chemical inertness, lack of elicitation of foreign body or hypersensitivity reaction, non-carcinogenicity, and ease of shaping and carving [42].

Common implant materials include expanded PTFE, methyl methacrylate, porous polyethy‐ lene, and silicone rubber. Porous polyethylene and silicone rubber implants are the most commonly used. Silicone rubber implants can be easily trimmed, being flexible, conform well to underlying anatomy and become well encapsulated. They can be easily be removed or

The structure of porous polyethylene implants allows better tissue integration, but this can also be extremely problematic when attempting to remove or replace an implant. Significant

Most patients, as they age, lose volume in the submalar region. The submalar area includes the hollow area of the infraorbital, anterolateral maxillary region, and canine fossa regions. Most of these patients have a hollow submalar region. They usually have adequate and welldefined zygomatico-malar esthetics and adequately projected cheekbones. These patients are best treated with only submalar augmentation, as their problem is loss of submalar volume.

tissue injury, defects or implant fragmentation can occur with removal.

exothermic reaction. It is now used more commonly as an injectable implant.

main advantages.

**4.8. Hydroxyapatite**

**5. Implant selection**

replaced if necessary.

**4.7. Expanded polytetrafluoroethylene**

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it does not absorb antibiotic solutions [41].

#### **6.1. Malar and submalar augmentation**

The placement of midfacial implants is a simple surgical procedure for experienced maxillo‐ facial surgeons. The implants are always placed in the subperiosteal plane. With the exception of the infraorbital neurovascular bundle, there is little vulnerable anatomy in the midface region, when dissecting in the subperiosteal plane. The implants can also be placed concomi‐ tantly with other esthetic or orthognathic procedures.

With the patient in the sitting position, the atrophic submalar area is marked and the zygomatic arch is outlined. The patient is prepared and draped. Several approaches to the malar and submalar region exist including subciliary, transconjunctival, and intraoral. The intraoral approach if preferred. The procedure is begun by injecting about 5 mL of 2% lidocaine with 1:100,000 epinephrine in the subperiosteal plane along the anterior maxilla, malar region, and the anterior zygomatic arch region. An incision is made just below the maxillary vestibule, approximately 1 cm above the canine tooth (Figure 3). The mucosa and soft tissues are incised in the canine fossa region and through the periosteum. Subperiosteal dissection is performed (Figure 4).

**Figure 3.** Intraoral approach for malar implant placement

**Figure 4.** Subperiosteal dissection for malar implant placement

The borders of this dissection pocket are the lateral portion of the inferior orbital rim, superi‐ orly, the zygomatic arch superolaterally and the masseteric fascia laterally. The buccal fat pad must be avoided. The extent of the dissection is dictated by the shape and size of the implant. The combined submalar and shell implants require more dissection over the malar and zygomatic regions. The dissected pocket should be just slightly larger than the actual implant size. As the subperiosteal dissection is begun in the anterior maxillary region, it is important to protect the infraorbital neurovascular bundle. After the anterior maxilla is dissected, the periosteal elevator is angled and the remainder of the dissection is primarily in an oblique vector over the malar region and extends over the anterior portion of the zygomatic arch. After the implant pocket is dissected, the area is checked for hemostasis (Figure 5). The pocket is then irrigated with antibiotic solution (300 mg of clindamycin and or gentamicin mixed with 30 mL of sterile water) and the implant is placed. The implants are also soaked in antibiotic solution. This is especially important for porous implants (Figure 6).

**Figure 5.** The subperiosteal pocket is checked for hemostasis

**Figure 3.** Intraoral approach for malar implant placement

556 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

**Figure 4.** Subperiosteal dissection for malar implant placement

The borders of this dissection pocket are the lateral portion of the inferior orbital rim, superi‐ orly, the zygomatic arch superolaterally and the masseteric fascia laterally. The buccal fat pad must be avoided. The extent of the dissection is dictated by the shape and size of the implant. The combined submalar and shell implants require more dissection over the malar and zygomatic regions. The dissected pocket should be just slightly larger than the actual implant size. As the subperiosteal dissection is begun in the anterior maxillary region, it is important

**Figure 6.** The implants are also soaked in Gentamicin solution

A well-conforming implant in a tight pocket does not generally need fixation. If the pocket is considerably larger than the implant and there is increased mobility of the implant, a single fixation screw can be placed. The fixation screw is best placed in the thicker bone of the buttress area (Figure 7). Finally, the incision is closed with interrupted 4-0 absorbable suture (Figure 8).

**Figure 7.** Implant fixation

**Figure 8.** Incision closureChin augmentation

There are two main approaches to chin augmentation; one with an intraoral incision, and one with an incision in the submental crease. The main advantage of the intraoral incision is the avoidance of an external scar. The submental incision is preferred because the external scar is well camouflaged in the submental crease and there is no need to divide the mentalis muscle.

A well-conforming implant in a tight pocket does not generally need fixation. If the pocket is considerably larger than the implant and there is increased mobility of the implant, a single fixation screw can be placed. The fixation screw is best placed in the thicker bone of the buttress area (Figure 7). Finally, the incision is closed with interrupted 4-0 absorbable suture (Figure 8).

558 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

**Figure 7.** Implant fixation

**Figure 8.** Incision closureChin augmentation

A 2-cm incision is made in the submental crease centered about the midline. Sharp and blunt dissection is used to reach the periosteum of the lower edge of the mandible in the midline. A sharp incision is made through the periosteum laterally. A subperiosteal dissection is per‐ formed to create a pocket for the implant. Dissection laterally should be performed as close to the mandibular border as possible to avoid injuring the mental nerve. After the implant is inserted a stabilizing stitch or screws may be used. The incision is then closed in two layers.

When using an intra-oral approach, a 2 to 3-cm incision is made in the mandibular labial sulcus about 10 to 15-mm away from mucogingival junction (Figure 9). Then the mentalis muscle and periosteum are transected and a subperiosteal dissection is performed (Figure 10). Care must be taken not to injure the mental nerve.

The implant is inserted over the chin bone and screws are used for fixation (Figures 11 and 12). Then the mentalis muscle portions are aligned and sutured together. The mucosa is closed with absorbable sutures.

**Figure 9.** Intra-oral approach for chin implant placement

**Figure 10.** Subperiosteal dissection for chin implant placement

**Figure 11.** Implant placement

**Figure 12.** Implant fixation

**Figure 10.** Subperiosteal dissection for chin implant placement

560 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

**Figure 11.** Implant placement

### **7. Postoperative sequelae**

The patient must be warned that during the first 1 to 2 weeks he or she will experience abnormal animation when smiling and talking. The tissue dissection violates the orbicularis oris and lip elevator muscles, which heal uneventfully with the return of normal animation. Significant edema is not uncommon, especially with larger implants and in the early postoperative period. Cold packs and steroids are routinely used. Severe swelling may indicate hematoma formation and, if necessary it must be drained. This can usually be done by opening the incision and suctioning the blood or clot from under or around the implant without compromising the result. Minor hematomas will usually heal uneventfully without treatment. Occasionally, subconjunctival or periorbital ecchymosis is seen but remains a rare occurrence and heals uneventfully.

#### **8. Post operative care**

No dressings are required and the postoperative care includes analgesics, antibiotics, and steroids if desired. The patient is instructed to avoid significant talking and animation for the first 48 hours and is asked to follow a liquid or soft diet for the same period. Ice packs are used for the first 24 hours.
