**6. Implants in reconstruction**

space, and provide acceptable soft tissue contouring and aesthetic results. The pectoralis major flap is used to reach the orbital region, but it must be exteriorized to reach this site, thus adding a second operation. The latissimus dorsi muscle flap can access the orbit without a subsequent exteriorization procedure, but the patient must be repositioned for its harvest. A trapezius flap is also available, but its use must be carefully assessed in a previously irradiated patient or one in whom a radical neck dissection was performed. Again, this technique requires repositioning of the patient. In larger defects, free tissue transfer provides a well-vascularized, bulky tissue, without the restrictions of a pedicle. The most frequently used is the rectus abdominis free flap; simultaneous ablation of the tumor and flap harvest by two surgical teams reduces operative time and patient mortality. Region II defects essentially include the boundaries of the middle cranial fossa. It comprises the infratemporal and pterygomaxillary fossae and the overlying segment of the skull base. Tumors of this area include basal and squamous cell carcinoma of the external ear and scalp, invasive parotid tumors, and tumors of the middle ear. Access to the middle cranial vault is primarily through an infratemporal approach but may also be combined with a mandibulotomy, lateral mandibulotomy, anterior mandibulot‐ omy with swing, or anterior displacement of the mandible. Also, via a hemicoronal incision, a transtemporal approach can provide access to the tumor. The location and the size of the defect dictate which reconstructive option is used. Historically, large scalp rotation flaps [152] and deltopectoral flaps have provided adequate restoration. Smaller defects can be repaired with temporalis muscle flaps. However, when larger defects may be inadequately treated with these local flaps-that is, when communications between the nasopharynx and dura persists-

694 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

free flaps become the procedure of choice, specifically, the rectus abdominis free flap.

Region III includes the posterior segment of the middle cranial fossa, as well as the entire posterior section. The most common tumors encountered here are glomus tumors and schwannomas. Through a transtemporal approach, tumors are readily excised, and small defects can be closed with local flaps such as temporalis, deltoid, and sternocleidomastoid. Larger defects are more definitively reconstructed with latissimus dorsi flaps or the rectus abdominis free flap. Eye socket reconstruction requires not only a mucosal lining but also supportive tissue to mimic the tarsus. Traditionally, full- or split-thickness skin grafts without any supportive tissue failed owing to severe contracture formation. Millard [153] in 1962 used a composite nasal cartilage-mucosa graft. In 1985, Siegel [154] discussed the use of the palatal mucosa for reconstruction of the eyelid. The palatal mucosa is thick and rigid tissue that has been used for the reconstruction of the lip, gingiva, nasal vestibular lining, and tracheal wall defects. The "socket plasty" described by Yoshimura and coworkers [155] uses a palatal mucosa graft to maintain the dimensions of the socket to accept an orbital prosthesis. The palatal mucosa is sutured to deepen the fornix and keep the maximal dimensions of the graft for at least 10 to 14 days. An artificial eye or Silastic rubber ball is inserted to maintain the newly formed socket during the initial healing period. The donor site usually heals unremarkably, with little patient discomfort. Orbital floor defects have been treated with many materials, including autografts, allografts, xenografts, and alloplasts. The ideal material is fresh autoge‐ nous bone, but this requires a second surgical procedure. Harvested auricular cartilage provides an excellent source of autogenous tissue for repairing orbital floor defects. This fresh cartilage maintains adequate structure and volume many years after transplantation [156] In

After extensive ablation of maxillofacial tumors, reconstruction of the head and neck region is attempted to restore the external cosmetic and functional deficits. However, masticatory function continues to be a problem in the rehabilitation of these patients. Without dental implants, the area of reconstruction does not allow placement of a dental prosthesis. Implants eliminate the requirement for adjacent natural soft tissue support for the prosthesis. Endo‐ sseous implants placed in bone grafts have been shown to stimulate bone growth and minimize its resorption. Therefore, when one reconstructive option is chosen over another, not only the quantity but also the quality of the bone that will ultimately receive endosseous implants should be a consideration [20]. Implants can be placed after a reconstruction has been per‐ formed or at the time of immediate reconstruction [159] Stoler and Hill [160] were the first to report a case in which oromandibular reconstruction was performed for a patient who had undergone ablative surgery for fibrous dysplasia using a combination of both free cranial and microvascular iliac crest grafts, as well as osseointegrated implants placed in vitro and then grafted onto the reconstructed mandible. The advantages of immediate placement are the ease of access and ability to avoid any adjacent alloplastic materials, such as bone plates and screws. One possible problem associated with immediate placement is improper position of the implant. A delayed placement has the advantage of providing better control for placement in the correct position. However, disadvantages of the delayed technique are the necessity for a secondary surgical procedure, the need to deal with abnormal intraoral soft tissues, and the need to be aware of the position of the vascular pedicle as it relates to the reconstructed mandible [161]. Moscoso and associates [162] analyzed the effect of osseointegration in various donor sites for vascularized bone used for oromandibular reconstruction. The results of the study confirmed that the iliac crest is the most uniform implantable source of vascularized bone for the reception of osseointegrated implants. This was followed by scapula, fibula, and radius. They also pointed out some gender differences. Male fibulas were statistically equiv‐ alent to the iliac crest in terms of implantability. In females, however, only one third of proximal scapulas and 50% of proximal to midfibulas would allow implant placement. The long-term stability of a successfully osseointegrated implant is dependent on implant dimension, the structural integrity of the bone to withstand functional loading, and allowances for loss of marginal bone height [163] In cases in which the iliac crest is not accessible owing to previous bone grafting attempts or disruption of vascular anatomy from previous groin vascular surgery, or when the excessive tissue bulk associated with the osteomyocutaneous iliac flap is not desired, an alternative is to use osseointegrated implants in free vascularized radial bone grafts. The radial bone graft provides the ideal mucosal replacement tissue from the associated forearm skin paddle. Radial bone was previously reported as being too thin to accept implants. Mounsey and Boyd [164] reported their experiences using implants placed in vascularized radial bone flaps.

They showed that for small, straight, bony defects, the radius is a good alternative. In larger defects, the contoured iliac crest is a better option. However, the radial bone may be osteo‐ tomized to attempt to create the desired mandibular contour. They reported excellent results following implant placement in small- to moderate-size lateral defects, as well as small anterior or anterolateral defects. Further reports using radial bone and dental implants were made by Martin and colleagues [165], with similar success. They do not advocate one-stage reconstruc‐ tion and primary implant placement because of the possibility of jeopardizing its periosteal blood supply. The microvascular free fibular transfer is an excellent option for reconstruction of large mandibular defects. Its bicortical nature mimics that of the native mandible and seems to be ideal for inserting implants as primary stabilization is achieved [166]. However, dental restoration with traditional removable oral appliances has failed owing to diminished denturebearing regions as tongue dysfunction. Zlotolow and associates [167] studied the use of the fibular free flap with osseointegrated implants. They reported seven successful cases and concluded that with microvascular bony reconstruction with osseointegrated implants, the quality of life is greatly enhanced by bringing the patient closer to the predisease state.

In 1994, Donovan and coworkers [168] described a new technique combining calvarial onlay bone grafts with osseointegrated implants-more specifically, the Branemark system. The use of such membranous grafts stemmed from previous reports stating that less resorption is seen with membranous bone grafts, compared with endochondral onlay grafts [169]. After har‐ vesting the outer cortical table of calvarial-parietal bone in strips, two grafting techniques are used. The vertical technique is used primarily in the atrophic maxilla, and the graft is secured to the lateral aspect of the remaining maxillary bone or alveolar processes with a rigid screw system. This is followed by a period of healing, approximately 6 to 8 months, before definitive placement of dental implants. They reported an 86% success rate with this onlay procedure, attributing possible failures to varying degrees of soft tissue ingrowth, as well as the cortical strip of bone being further away from its source of blood supply. The horizontal technique, which enjoyed a 98% success rate, places the calvarial bony strips in a horizontal fashion in the anterior maxillary region, where the nasal spine is separated from its most inferior bony attachment. The cortical struts are then placed in a horizontal fashion superiorly at the level of the nasal floor as well as inferiorly, augmenting the height of the maxillary ridge. The "sandwiched" maxilla is then stabilized with its grafts with the placement of osseointegrated implants from one canine eminence to the other. These implants, in contrast to those used in the vertical technique, have bicortical stabilization and are placed close together to aid in stress load distribution. These success rates are comparable to those seen when reconstructing the anterior mandible. All patients were restored with implant-supported prostheses, resulting in good function, a stable prosthesis, lack of donor site morbidity, early ambulation, and a short hospital stay.

#### **6.1. Maxillofacial prosthodontics**

grafted onto the reconstructed mandible. The advantages of immediate placement are the ease of access and ability to avoid any adjacent alloplastic materials, such as bone plates and screws. One possible problem associated with immediate placement is improper position of the implant. A delayed placement has the advantage of providing better control for placement in the correct position. However, disadvantages of the delayed technique are the necessity for a secondary surgical procedure, the need to deal with abnormal intraoral soft tissues, and the need to be aware of the position of the vascular pedicle as it relates to the reconstructed mandible [161]. Moscoso and associates [162] analyzed the effect of osseointegration in various donor sites for vascularized bone used for oromandibular reconstruction. The results of the study confirmed that the iliac crest is the most uniform implantable source of vascularized bone for the reception of osseointegrated implants. This was followed by scapula, fibula, and radius. They also pointed out some gender differences. Male fibulas were statistically equiv‐ alent to the iliac crest in terms of implantability. In females, however, only one third of proximal scapulas and 50% of proximal to midfibulas would allow implant placement. The long-term stability of a successfully osseointegrated implant is dependent on implant dimension, the structural integrity of the bone to withstand functional loading, and allowances for loss of marginal bone height [163] In cases in which the iliac crest is not accessible owing to previous bone grafting attempts or disruption of vascular anatomy from previous groin vascular surgery, or when the excessive tissue bulk associated with the osteomyocutaneous iliac flap is not desired, an alternative is to use osseointegrated implants in free vascularized radial bone grafts. The radial bone graft provides the ideal mucosal replacement tissue from the associated forearm skin paddle. Radial bone was previously reported as being too thin to accept implants. Mounsey and Boyd [164] reported their experiences using implants placed in vascularized

696 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

They showed that for small, straight, bony defects, the radius is a good alternative. In larger defects, the contoured iliac crest is a better option. However, the radial bone may be osteo‐ tomized to attempt to create the desired mandibular contour. They reported excellent results following implant placement in small- to moderate-size lateral defects, as well as small anterior or anterolateral defects. Further reports using radial bone and dental implants were made by Martin and colleagues [165], with similar success. They do not advocate one-stage reconstruc‐ tion and primary implant placement because of the possibility of jeopardizing its periosteal blood supply. The microvascular free fibular transfer is an excellent option for reconstruction of large mandibular defects. Its bicortical nature mimics that of the native mandible and seems to be ideal for inserting implants as primary stabilization is achieved [166]. However, dental restoration with traditional removable oral appliances has failed owing to diminished denturebearing regions as tongue dysfunction. Zlotolow and associates [167] studied the use of the fibular free flap with osseointegrated implants. They reported seven successful cases and concluded that with microvascular bony reconstruction with osseointegrated implants, the quality of life is greatly enhanced by bringing the patient closer to the predisease state.

In 1994, Donovan and coworkers [168] described a new technique combining calvarial onlay bone grafts with osseointegrated implants-more specifically, the Branemark system. The use of such membranous grafts stemmed from previous reports stating that less resorption is seen

radial bone flaps.

The demand for maxillofacial prosthodontic devices for the rehabilitation of patients with postsurgical defects has intensified in recent years. The extensive surgical procedures neces‐ sary to eradicate cancer of the head and neck often leave extremely large physical defects that may not be amenable to surgical reconstruction. The prosthodontist can provide surgical stents, radiation carriers and shields, intraoral cone stents, palatal augmentation prostheses for glossectomy patients, and immediate transitional and definitive prostheses, as well as extraoral prostheses to replace ears, nose, and facial defects. Thus, the maxillofacial prostho‐ dontist must have knowledge of the disease, etiology, diagnosis, treatment, and rehabilitation in order to be a member of the team that is responsible for enhancing the patient's quality of life [170]. Prosthetic and prosthodontic appliances are required for realignment and fixation of mandibular fragments in adequate dental occlusal relationships with the teeth of the opposing jaw; as obturators for the occlusion of defects of the palatal region; for the mainte‐ nance of facial form and contour so as to prevent contracture of the tissues during the healing period; as a temporary or transitional modality before or during surgical treatment; and for the restoration of facial features, such as the nose, auricle, or orbital region [171]. The maxillary defects that result from ablative cancer surgery vary in complexity, but prosthetic rehabilita‐ tion may provide a functional and aesthetic result. The purpose of the obturator prosthesis is to re-establish the normal contour of the oral cavity to allow normal speech and swallowing. The size of the defect determines the size of the obturator, or bulb portion that closes the surgical defect. The loss of this supporting tissue can be offset by gaining retention from the peripheral tissues. The maturity of the defect also determines how the obturator is tolerated. The more mature the defect, the more readily it is tolerated. A skin graft can provide a firm tissue base that resists abrasion and reduces mucus secretion, minimizing poor hygienic environments. The opposing mandibular ridge is important to the stability of the obturator. Prosthetic rehabilitation of the maxillectomy patient is performed in three phases. Stage one starts with the placement of the surgical packing and surgical obturator, which is retained for 5 to 7 days by screw or wire fixation. This helps re-establish oral contours and allows the patient to start a liquid diet almost immediately postoperatively, bypassing the need for nasogastric feeding. In the second stage, the surgical obturator is removed and modified with a tissue conditioner. As the obturator is modified, the patient learns how to swallow less forcefully, and leakage around the prosthesis decreases. The third stage can be anywhere from 3 months to over a year after maxillectomy, when the definitive obturator prosthesis is fabricated [172]. In maxillectomy patients, osseointegrated implants may be placed in the residual alveolar ridge or horizontal palate. An edentulous maxillectomy defect has the poorest prognosis for accepting an obturator. It is impossible to achieve retention of a complete maxillary denture. Thus, endosseous implants may aid in retention, stability, and support of the obturator prosthesis; a bar and clip, magnet, and ball-0-ring gasket-type keeper are widely used in these situations. The bar and clip assembly provides the obturator prosthesis with improved stability and retention. For patients with significant extraoral tissue loss, the facial prosthesis also has limitations related to retention and stability. The extraoral application of implants has been a significant advance in maxillofacial prosthetics (Figure 32).

**Figure 32. Orbit prosthesis Figure 32.** Orbit prosthesis

51

For example, implants placed in the mastoid bone or the temporal bones allow an auricular implant to be fixated via bar splinting. A nasal prosthesis can use a similar retention technique and have its fixtures placed in the floor of the nose. And in situations in which tumor ablation included the orbit, implants can be placed in the supraorbital rim region [173]. As with intraoral dental implants, extraoral sites require proper hygiene practices to ensure tissue health. For example, implants placed in the mastoid bone or the temporal bones allow an auricular implant to be fixated via bar splinting. A nasal prosthesis can use a similar retention technique and have its fixtures placed in the floor of the nose. And in situations in which tumor ablation included the orbit, implants can be placed in the supraorbital rim region [173]. As with intraoral dental implants, extraoral sites require proper hygiene practices to ensure tissue health.

of pediatric orofacial defects following extensive tissue losses.

Mandibular reconstruction and rehabilitation in a 7-year-old with osteosarcoma were recently reported by Richardson and Cawood [174]. They made every effort to maintain the functional matrix so as not to disturb the normal growth processes of the face. After tumor ablation with a partial mandibulectomy, immediate reconstruction with a titanium mesh tray was performed without bone graft. This technique allowed the tray to function as a space maintainer. When the patient approached the onset of puberty, the tray was removed and a composite circumflex iliac crest free flap was used to restore the continuity and soft tissue deficiencies. Microvascular anastomosis of the donor and recipient sites was used. Two years later, osseointegrated implants were placed, with a subsequent vestibuloplasty with a split-thickness skin graft. They concluded that the multidisciplinary approach to the care of this patient, along with the introduction of revascularized free tissue transfer with osseointegrated implants, revolutionized the reconstruction

The postoperative care and management of complications require an understanding of osseous wound healing and the potential causes of failure. Loss of skeletal stability as a result of loss of fixation allows for motion at the wound interface, with secondary impairment of vascularization. Early recognition of flap compromise is associated with improved chances of flap salvage. The ideal flap monitoring technique should be reliable, reproducible, easily interpretable, inexpensive, noninvasive, rapidly responsive to changes in microcirculation, and able to provide continuous monitoring in the immediate postreconstructive period. The clinical examination should focus on capillary refill time (>3 seconds is the cutoff), which provides information on the adequacy of the arterial supply. Early venous outflow obstruction results in capillary refill that is too brisk. The color of a flap can also provide information about arterial insufficiency. A pale flap signifies poor flap perfusion, whereas one with outflow obstruction is congested and hyperemic. Skin temperature can assess the adequacy of circulation in digits but is of little use when applied to

**Pediatric Reconstruction** 

**Postoperative Evaluation** 
