Maxillofacial Prosthetics and the Radiation Oncology Patient

Given that the treatment of head and neck neoplasms often involves radiation therapy alone or in combination with surgical ablation or chemotherapy, it is useful for the maxillofacial prosthodontist to become involved in patient care during the diagnostic phase of any proposed intervention. Because the risk for osteoradionecrosis is increased when a poor dentition is allowed to remain within irradiated maxillary or mandibular alveolar bone, a thorough evaluation of the dentition and periodontium is extremely useful in establishing dental prognoses before the initiation of radiation therapy. Additionally, because the xerostomia induced by a majority of head and neck radiation fields requires an increased diligence respecting home care and follow-up during and after radiation therapy, the maxillofacial prosthodontist’s early consultation can help prevent dental disease that could later contribute to added debility, possibly including osteoradionecrosis.

Because many head and neck cancers are treated by surgical ablation followed by radiation therapy, the maxillofacial prosthodontist’s diagnostic efforts should be performed preoperatively so that any necessary oral surgical interventions can be accomplished in conjunction with the otolaryngologist’s surgical encounter. This allows a sufficient amount of time for mucosal and alveolar bone healing before the initiation of radiation therapy, which usually occurs 6 weeks later. Patients whose dentoalveolar evaluations are accomplished after ablative surgeries are sometimes fast approaching a juncture in their care when radiation therapy should expeditiously commence in the interest of controlling local and regional oncologic disease, and delays associated with healing oral surgical wounds may be unacceptable. Likewise, the maxillofacial prosthodontist must consider similar delays in the initiation of radiation therapy when treatment plans call for primary radiation therapy or radiation therapy to be delivered concurrently with chemotherapy in the absence of an ablative surgical encounter.

Dental Diagnoses and Oral Surgical Management Preceding Radiation Therapy

Any dentoalveolar evaluation in preparation for radiation therapy should include a thorough assessment of the periodontium, as well as the dentition, and should be done with the intent of establishing lifelong prognoses for those teeth likely to be included in radiation therapy fields anticipated to receive doses in excess of 5000 cGy.

Extractions are indicated for teeth with poor prognoses meeting the criteria listed in Box 98-1.^1–13 Although the assessment is accomplished in the interest of preventing osteoradionecrosis, it is also done considering the potential for any prosthetic rehabilitation that may become necessary. Because this assessment requires consideration of primary tumor size and location, as well as regional lymph node status, diagnostic information gleaned through participation in multidisciplinary head and neck tumor board conferences supplements decisions made in the dental clinical setting where medical imaging is limited and endoscopy is not typically available.

In addition to an evaluation of the dentoalveolar structures, the maxillofacial prosthetic assessment includes intraoral and extraoral palpation and visualization of hard and soft head and neck tissues, panoramic radiography, and intraoral radiography of those teeth thought to be sound enough to retain vis-à-vis imminent radiation therapy. Although the intraoral radiography generally includes routine bitewing and periapical exposures, occlusal radiographs are sometimes helpful for primary tumor staging by affirming bony erosion associated with oral cavity lesions affecting gingivae, buccal or palatal mucosa, or the floor of mouth.

With respect to the periodontium, teeth with periodontal sulci equal to or greater than 5 mm in depth may be assigned poor prognoses and should be considered candidates for extraction before radiation therapy. Likewise, teeth with mucogingival defects or furcation involvement should be given similar prognoses and should be considered for extraction. Although prior successful endodontic treatment should not necessarily condemn a tooth for extraction, the unpredictability of endodontically treating active periapical or pulpal pathoses in the usually limited time available before radiation therapy should give rise to enough caution that the extraction of endodontically involved teeth should be strongly considered. Although gingival recession is not in itself a definite indication for exodontia in the absence of deep periodontal sulci, consideration must be given to the maintenance of radicular surfaces exposed to the xerostomic oral environment as a result of recession, because cementum is more prone to the development of inoperable carious lesions than is the more mineralized coronal enamel.

With regard to the dentition, mobile primary teeth should be extracted from alveolar bone to be irradiated, as should any unrestorable teeth. If no plan is or can be made to restore the occlusion of unopposed posterior teeth that will be irradiated, consideration should be given to their extraction, because subsequent supraeruption can contribute to expansive gingival embrasures that are difficult to maintain free of plaque and food debris, possibly resulting in localized periodontitis or radicular carious lesions that are difficult or even impossible to repair. Although extracting impacted teeth from alveolar bone soon to be irradiated is meritorious, consideration should be given to the length of healing time often required of associated surgical sites. This is particularly true of impacted third molars that carry an increased risk for developing acute alveolar osteitis. When deciding whether an impacted tooth should be extracted before radiation therapy, the impacted tooth’s likelihood of erupting enough to gain exposure to the oral environment should be considered. If a bony impacted tooth is unlikely to erupt permucosally, the relative risk of it contributing to a future osteoradionecrosis should be judged low and the tooth should be allowed to remain in situ, unless of course there is a pathosis associated with the tooth that overrides a conservative approach. Conversely, an impacted tooth within a proposed radiation field whose anatomic position suggests a potential for intraoral eruption should be deemed a candidate for extraction before radiation therapy.

The presenting or oftentimes soon to be rendered edentulous or partially edentulous condition of many newly diagnosed head and neck cancer patients also demands evaluation of maxillary or mandibular exostoses, tori, and tuberosities primarily in preparation for removable, but sometimes fixed, prosthodontic rehabilitation after the completion of oncologic care. Preprosthetic surgery to include the removal of tori and exostoses and the reduction of tuberosities that could prove obtrusive relative to future prosthetic considerations should coincide with any necessary exodontia as far in advance of radiation therapy as possible. The reduction of these anatomic structures can improve prosthetic-bearing areas and reduce the risk of prosthetic-induced mucosal violations that could contribute to the development of osteoradionecrosis. Although the completion of such preprosthetic surgery before radiation therapy is paramount for those structures lying within proposed radiation fields, the extended mucogingival flaps required for removing bony prominences require consideration for the removal of such prominences even if their juxtaposition to the primary field does not lend to an anticipated dose exceeding 5000 cGy.

Patients using removable prostheses should be advised to minimize prosthetic use during and immediately after radiation therapy to diminish the risk of exacerbating mucositis underlying intaglio prosthetic surfaces, particularly when prostheses are ill fitting and radiation therapy fields directly encompass the oral cavity. Even small prosthesis-related mucosal ulcerations could result in the exposure of alveolar bone and the initiation of osteoradionecrosis. When oral cavity mucositis is anticipated, restorative dental care of high priority should be expeditiously undertaken considering the fact that compromised patient comfort will make restorative dental care difficult or impossible after as little as 1000 to 2000 cGy of radiation. Routine dental prophylaxes should also be sought before head and neck radiation therapy because the relative attenuation of plaque and calculus could diminish the severity of gingival mucositis induced by direct oral cavity irradiation and could decrease the potential for cariogenic dental colonization associated with xerostomia. Additionally, a hiatus in orthodontic care could be considered for those whose radiation therapy coincides with orthodontia because the removal of bands, brackets, and wires could lend to a diminution of trauma to inflamed mucosal surfaces.

For patients retaining a full or partial natural dentition whose head and neck radiation therapy will induce xerostomia, it is important to institute a daily and lifelong regimen of topical fluoride gel use to concur with the initiation of radiation therapy.¹–⁷,⁹,¹²,¹⁴–¹⁸ This is true for patients whose retained dentition is or is not encompassed by radiation therapy fields. Dental casts generated from clinical impressions recorded before radiation therapy but subsequent to any oral surgical procedures in preparation for radiation therapy should be used to fashion thermoplastic vinyl fluoride gel carriers (Fig. 98-1) into which topical fluoride gel can be applied. After routine brushing and flossing, patients should be instructed to place pharmacy-prescribed 1.1% neutral sodium fluoride or 0.4% stannous fluoride gel into the dental aspects of the fluoride gel carriers for 5 to 10 minutes every day indefinitely before applying them to their dentition. The topical fluoride gel application should be followed by expectoration of excess gel and a period of 30 minutes during which the patient is encouraged not to rinse, eat, or drink.

Figure 98-1. Thermoplastic vinyl fluoride gel carriers and the models on which the gel carriers are made.

Prosthodontic Support of the Radiation Oncologist

The maxillofacial prosthodontist may be called on to lend support to the radiation oncology team in their efforts to manage dosimetry by way of patient posturing,^19–22 anatomic displacement or shielding,^3,6,19,23,24 fabrication of brachytherapy appliances,^3,25 or construction of devices capable of mimicking normal tissues.^3,19,24 Although the devices should be constructed following any oral surgical procedures that are done in preparation for radiation therapy, they must be manufactured before radiation therapy simulation appointments in that they must be positioned at the time of simulation.

The undulating topography of head and neck cutaneous structures makes the uniform delivery of radiation difficult at best without the use of boluses constructed of materials considered more or less to be tissue equivalent in terms of their relative resistance to photon or electron penetrance. Consequently, the radiation oncologist may call on the maxillofacial prosthodontic team to assist with facial moulage recording and bolus fabrication when evaluating the physics associated with treating malignant head and neck skin lesions. A facial moulage cast with a gypseous dental stone can aid the radiation oncology team’s delineation of a proposed treatment field and prescription of an appropriate bolus thickness before a bolus is constructed of dental baseplate wax or polymethylmethacrylate. Boluses can be particularly useful for providing more even dose distributions for nasal (Fig. 98-2) or orbital malignancies.

Figure 98-2. A, Basal cell carcinoma of the nasal bulb to be treated with external electron beam radiation therapy. B, Facial moulage being recorded. C, Facial moulage prepared for casting. D, Model on which the wax bolus was fabricated. E, Frontal view of the bolus. F, Lateral view of the bolus. G, Intaglio surface view of the bolus.

Although Aquaplast masks are routinely used to immobilize patients throughout the course of head and neck radiation therapy,¹⁹ customized intraoral devices can be used to provide a stable maxillomandibular relationship when attempts are made to precisely localize an external photon or electron beam relative to oral cavity anatomy. The use of intraoral positioning devices is particularly useful when there is a desire to shield all or part of the maxilla or the mandible from radiation when the opposing jaw is to be included in an external beam field. By positioning the mandible in a prescribed open position with the use of a polymethylmethacrylate appliance that prevents deviation from an arranged spatial relationship to the maxilla, the radiation oncology team can make shielding possible by way of replicable daily positioning of patients from the time of simulation to the completion of radiation therapy. This strategy is helpful when mandibular structures are to be spared from sinonasal or maxillary radiation or when maxillary structures are to be excluded from fields involving the floor of mouth, oral tongue, or other sites encompassing the mandible. In addition to stabilizing the maxillomandibular relationship, the incorporation of radiopaque materials such as orthodontic wire, ball bearings, or gutta percha into such devices can lend support to the radiation oncology team’s efforts to identify structures for inclusion in proposed radiation fields at the time of simulation (Fig. 98-3).

Figure 98-3. A, Panoramic radiograph of a patient’s status after segmental mandibulectomy, total glossectomy, floor of mouth resection, and microvascular fibula free flap reconstruction for a squamous cell carcinoma. B, Models of the maxillary and neomandibular structures articulated in relation to one another. C, Wax pattern of the proposed positioning device before its completion. The wax pattern covers the microvascular free flap tissues in the area of the floor of mouth once occupied by the oral tongue. Bilateral pillars engage the maxillary model to maintain a consistent maxillomandibular relationship during each radiation therapy fraction. D, Clinical view of the anterior aspect of the polymethylmethacrylate positioning device. A segment of orthodontic wire placed within the midsagittal plane of the positioning device identifies the dorsum of the microvascular free flap structures during radiation oncology simulation and ensures its inclusion in proposed radiation therapy fields. E, Simulation radiograph exposed with the positioning device positioned intraorally.

Furthermore, intraoral polymethylmethacrylate appliances can be constructed that harbor Lipowitz’s alloy.^19,21,26 Being the same metal used by radiation oncology teams to create the portals and shields suspended from frames situated between patients and linear accelerator collimators that fashion conventional three-dimensional (3D) conformal radiation therapy fields, Lipowitz’s alloy, a low-fusing combination of lead, bismuth, tin, and cadmium, can suitably shield intraoral anatomy when electron beam therapy is indicated. These devices typically serve the dual purposes of shielding and maxillomandibular positioning because their interocclusal construction also stabilizes the maxillomandibular relationship. These alloy-containing intraoral appliances are often fabricated for lip (Fig. 98-4) and ipsilateral parotid gland (Fig. 98-5) fields. The protective intent of these appliances is supplemented when they are constructed in such a fashion as to physically displace soft tissues away from the source of an electron beam. When parotid gland shielding devices are used, patients are instructed to position the tongue anteriorly during treatment. Doing this while occluding on the interocclusal appliance forces the bulk of the tongue into a contralateral position where less radiation is encountered. When parotid gland malignancies are treated with a combination of photons and electrons, radiation oncologists sometimes find it helpful to use two appliances, one with Lipowitz’s alloy and one lacking metal. The use of the appliance devoid of alloy during the delivery of photons offers the advantages of consistent day-to-day maxillomandibular positioning and soft tissue displacement without the electron backscatter potentially associated with an appliance that harbors a large volume of metal.

Figure 98-4. A, Clinical frontal view of a Lipowitz alloy-containing shielding device used during external electron beam radiation therapy for a squamous cell carcinoma of the lower lip. The device was held in its interocclusal position during fractionation and served not only to shield normal anatomy but also to anteriorly displace the labial tissues being treated from posterior structures to be spared of radiation. B, Clinical frontal view of a Lipowitz alloy-containing shielding device with the patient’s lips retracted. C, Extraoral view of the shielding device.

Figure 98-5. A, Shielding device positioned on the articulated models on which it was constructed. The device was fashioned for use during radiation therapy for a left parotid gland adenoid cystic carcinoma. The device extends as far into the oropharynx as the patient will allow without gagging. Lateral view demonstrates that portion of the polymethylmethacrylate intended to displace buccal tissues in an ipsilateral direction to further separate tissues to be treated from those that should not be treated. B, Clinical verification of the fit of the device before it is filled with Lipowitz’s alloy. C, The device is hollowed from the medial side before being loaded with Lipowitz’s alloy.

The radiation oncologist’s desire for tissue equivalence is not limited to the application of surface boluses because postoperative tissue voids can give rise to an uneven distribution of radiation resulting in suboptimal dosing or overdosing of tissue peripheral to cavernous surgical defects such as those resulting from a maxillectomy. Unfortunately, however, the rigidity of wax and polymethylmethacrylate does not solely allow the dependable use of these materials as intracavitary tissue mimicking materials by virtue of soft tissue and bony undercuts usually associated with these defects. Consequently, filling an intracavitary void with tissue-equivalent material in the interest of improving radiation therapy dose distribution often requires the use of pliable materials that assist daily insertion and removal without unduly traumatizing surrounding tissue. The combination of an inflexible customized intraoral device that stabilizes the maxillomandibular relationship with a pliable material that fills an intracavitary void can, however, overcome the limitations posed by the complex nature of a maxillectomy defect. This combination can be achieved by constructing an intraoral positioning device that incorporates a shelf of polymethylmethacrylate immediately inferior to the maxillectomy defect. The device is capable of supporting a balloon that can be inflated with a tissue-equivalent mixture of radiopaque liquid and water before radiation therapy simulation and each fraction (Fig. 98-6).

Figure 98-6. A, Anterior view of articulated maxillary and mandibular models and the wax pattern used to generate an intraoral device that serves to repetitively position the mandible and oral tongue and support a diaphragm to be filled with water during radiation fractionation. The water-containing diaphragm thus occludes maxillectomy defects and serves as a tissue-equivalent material. B, Inferior view of the wax pattern demonstrating an axial shelf to inferiorly confine and exclude the oral tongue from the radiation fields. C, Anterior view of the finished intraoral device. D, Anterior view of the positioned intraoral device demonstrating the diaphragm-supporting shelf situated immediately inferior to the maxillectomy defect.

Although the maxillofacial prosthodontist is not likely to lend assistance in the clinical application of interstitial brachytherapy, the management of intracavitary brachytherapy often requires the combined efforts of the radiation oncology and maxillofacial prosthetic teams. The orbit and nasopharynx comprise the most common intracavitary head and neck brachytherapy sites, and the stents used for these sites are typically constructed of polymethylmethacrylate that surrounds catheters into which radioisotopic seeds are inserted. The radiation oncologist or physicist, in accord with an intended dose distribution specific for the radioisotope proposed for use, prescribes the catheter positions in consultation with the maxillofacial prosthodontic team after the generation of a master cast from an impression of the site to be treated. When the stents are positioned, they are retained for the duration of treatment by anatomic soft tissue undercuts (Fig. 98-7) or dentoalveolar structures.

Figure 98-7. A, Orbital exenteration site for a patient whose positive melanoma margins necessitated postoperative brachytherapy. B, Brachytherapy device in position demonstrating accessibility to catheters for radioisotopic seeding and treatment.

Dental Management during Radiation Therapy

Recalling patients every 2 to 3 weeks during radiation therapy is beneficial from the standpoint of identifying dental, periodontal, and mucosal pathoses that may coincidentally appear or arise secondary to radiation therapy. Such a follow-up interval is also meritorious for reinforcing the import of increased hygiene vigilance and the use of topical fluoride gel. It is not uncommon for patients with newly diagnosed life-threatening neoplasms to forget virtually everything that was discussed during an initial maxillofacial prosthodontic evaluation that may have coincided with appointments in otolaryngology, radiation oncology, diagnostic radiology, nuclear medicine, medical oncology, anesthesia, internal medicine, and oral surgery. The overwhelming nature of patients’ initial oncologic experience lends to a necessary redundancy with respect to patient communication and education.

Although restorative dental care can be accomplished during radiation therapy, procedures that potentially exacerbate mucositis should be avoided. However, particularly in cases involving oral cavity radiation, patients may reach a point—usually after 2 to 3 weeks of fractionation—where mucositis is severe enough that they do not want to be subject to dental restorative procedures. Regardless of the need for restorative dental care, a readily concocted mouthrinse to obtund mucositis consists of mixing 1 teaspoon of baking soda and 1 teaspoon of salt in a quart of water that is warmed before use. Alternatively, a compounded solution of tetracycline, diphenhydramine, nystatin, and hydrocortisone termed “magic mouthwash” can be obtained from a pharmacy. Two teaspoons of magic mouthwash swished and gargled thrice daily before swallowing serves to mollify radiation-induced stomatitis and pharyngitis.

Dental Management after Radiation Therapy

Follow-up examinations should be arranged every 4 to 8 weeks after the completion of radiation therapy with patients returning to a standard interval thereafter as long as they comply with hygiene and daily topical fluoride gel regimens. Patients can be considered routine patients in terms of their candidacy for restorative dental care after head and neck radiation therapy; however, they must understand that they should not undertake bone-exposing oral surgery within anatomic areas that received more than 5000 cGy of radiation. Such exposures could prompt the development of osteoradionecrosis that could precipitate a pathologic fracture or necessitate a bony resection.^{2,6,7,9,12,27–34} Therefore when patients complete their radiation therapy, they should be asked to inform the maxillofacial prosthodontist of any future oral treatment proposal to include a tooth extraction, the surgical placement of an endosseous titanium implant, or periodontal or endodontic flap surgery in advance so that an estimation of dosimetry can be provided to the surgeon. When these estimates indicate that a bone-exposing violation of mucosa could occur in an area that received more than 5000 cGy of radiation, the Marx hyperbaric oxygen protocol should be considered as an adjunct to the surgical procedure.^{3,6,7,9,12,27,28,32} Marx’s hyperbaric oxygen regimen involves 90-minute dives at a barometric pressure of 2.4 atmospheres while breathing 100% oxygen. Twenty dives are undertaken preoperatively, and 10 dives are completed postoperatively in the interest of stimulating an angioneogenesis that partially and irreversibly³² counteracts the hypovascularity caused by radiation therapy that is responsible for the increased risk of osteoradionecrosis.

Because dosimetry is highly variable depending on primary tumor sites, regional metastases, radiation oncology philosophy, and available technology, patients and their dental caregivers cannot be expected to routinely know whether it is safe to go forward with bone-exposing oral surgical interventions after radiation therapy. Consequently, it is incumbent on the maxillofacial prosthodontist to assist this determination whether the prosthodontist personally accepts this responsibility or shares it with radiation oncology personnel. When patients have been treated with conventional 3D conformal radiation therapy, possession of simulation and portal radiographs, as well as radiation oncology records, sometimes allows the prosthodontist to establish a relative risk for surgically precipitated osteoradionecrosis without the assistance of a physician or a physicist. On the other hand, when intensity-modulated radiation therapy, the latest 3D conformal radiation modality, is used, a greater reliance on the radiation oncologist or radiation physicist, or both, may be necessary.

Oral surgical planning after conventional 3D conformal radiation therapy first involves the acquisition of simulation and portal radiographs, as well as a complete description of the radiation oncologist’s dosimetric and clinical assessments.^3,6,19 Although the possession of simulation and portal radiographs provides the dental team a mere 2D perception of the fields prescribed by the radiation oncologist, their value in determining whether dentoalveolar structures of interest lie within or without treatment fields allows for surgical treatment planning often without the need for further conference with radiation oncology personnel. When parallel opposed field simulation and portal radiographs are shown to encompass dentoalveolar structures, the dental team must take for granted the fact that an invasive procedure within that field will place the patient at risk for osteoradionecrosis if the prescribed dose to that field surpassed 5000 cGy. However, as is frequently the case in head and neck radiation oncology, the exclusion of dentoalveolar structures anterior, superior, or inferior to a field boundary allows surgical intervention in the excluded area without risking osteoradionecrosis (Fig. 98-8) because osteoradionecrosis by definition comprises a volume of necrotic bone within a radiation therapy field.³⁰ Uncertainty can arise, however, when treatment field borders bisect or tangentially appose dentoalveolar structures to be included in a proposed surgical intervention. Although dosages at the borders of conventional 3D conformal radiation therapy fields approximate only 50% of the prescribed dose, patient positioning can vary by as much as 5 mm in any given dimension despite exceptional efforts on the part of radiation oncology teams to reproducibly orient their patients on a daily basis. Considering the possibility of positioning errors during the course of daily radiation therapy sessions, such scenarios warrant erring on the side of caution with the assumption that affected field border areas could become osteoradionecrotic after a surgical insult.

Figure 98-8. A, Bilateral parallel opposed simulation radiograph for a patient who undertook radiation therapy after a total laryngectomy for a squamous cell carcinoma. The exclusion of dentoalveolar structures anterior to the field boundaries allowed for the safe extraction of the remaining carious dentition without adjuvant hyperbaric oxygen therapy. The patient’s treatment plan includes the placement of endosseous titanium implants in the parasymphyseal mandible to enhance removable prosthetic retention. B, Appositional anteroposterior simulation radiograph delineating the supraclavicular field associated with the patient’s radiation therapy.

Likewise, when ipsilateral dentoalveolar structures are found within unilateral treatment fields where photon doses exceeded 5000 cGy, it can be assumed that ipsilateral oral surgical procedures within that field would place a patient at great risk for osteoradionecrosis. Conversely, the risk for contralateral, oral, surgically induced osteoradionecrosis can be relatively low for such a patient considering the fact that only about one third of a conventionally prescribed photon dose would reach contralateral dentoalveolar structures. However, because the use of electron beams; uniform, oblique, or wedged pair multiple fields; or appositional fields can complicate dosimetric deductions made with the use of simulation and portal radiographs and a medical record narrative, it is always reasonable to confer with the radiation oncologist or physicist when questions arise before invasive oral surgical procedures. The potential debility associated with the precipitation of osteoradionecrosis merits such caution.

In contrast to conventional 3D conformal radiation therapy, in which gantry positions are limited and static, intensity-modulated radiation therapy can be delivered by way of a mobile collimator. The collimator arcs across several swaths of parallel appositional fields while two rows of tungsten leaves within the collimator (Fig. 98-9) concentrically open and close to strategically deliver radiation to targeted tissues while sparing normal structures of the highest radiation burdens.^22,35–38 In another technique that has come to be known as step and shoot intensity-modulated radiation therapy, radiation is directed from multiple stationary gantry positions that are each uniquely and statically collimated through the use of multiple layers of tungsten leaves capable of converging from the periphery of the linear accelerator’s nonadjustable port to fashion customized portal shapes in accord with the radiation oncologist’s or physicist’s treatment prescription (Fig. 98-10). In either scenario, intensity-modulated radiation therapy simulation is based on an interface between computed tomography imaging and dosimetric treatment planning software such as the CORVUS system. As such, intensity-modulated radiation therapy simulation and portal radiographs offer limited or no value for establishing surgically induced osteoradionecrosis risks after radiation therapy, and intensity-modulated radiation therapy dosimetry must be evaluated using software that is at this time almost universally unavailable to any dental team. This software, however, offers an evaluation of each computer-generated tomographic slice that is so detailed in its resolution that anatomic structures as small as individual tooth roots can be identified and dosages can be estimated at the pinpoint level of a computer mouse cursor superimposed over the area of dosimetric interest. Because CORVUS and other intensity-modulated radiation therapy software firms offer axial, sagittal, and coronal tomography sections, a comprehensive 3D depiction of dosimetry can be achieved by means of a review of computer records. This can be done without the need for assessing multiple simulation and portal radiographs that may be geometrically confusing, tattered from age, untidily drawn, of poor radiographic quality, or entirely lost or discarded.

Figure 98-9. A, MIMiC collimator showing two rows of tungsten leaves in their closed positions. B, MIMiC collimator showing the tungsten leaves in their opened positions.

Figure 98-10. Step and shoot intensity-modulated radiation therapy collimator.

Although intensity-modulated radiation therapy dosimetric evaluations performed in the interest of establishing the relative safety of proposed dental interventions are readily achieved by way of the dental team’s access to computer records when maxillofacial prosthodontic support is found in the facility in which a patient’s therapy was delivered, communicative problems can arise between dental and radiation oncology personnel when they are separated geographically. Radiation oncology personnel are not always familiar with dental anatomy and terminology or oral surgical procedures, and dental personnel are not generally knowledgeable of intensity-modulated radiation therapy computer simulation packages or the general delivery of intensity-modulated radiation therapy. It can thus benefit dental practitioners routinely involved in invasive oral procedures to personally meet a radiation oncology team involved in the delivery of intensity-modulated radiation therapy before encountering their first head and neck intensity-modulated radiation therapy patient. Conversely, dental personnel can share an oral surgical treatment plan with a patient’s radiation oncology team face-to-face when they first encounter a patient treated by way of intensity-modulated radiation therapy. Either way, an initial interdisciplinary conference at the intensity-modulated radiation therapy facility could lend clarification to each team’s needs and concerns when future patients are shared and fiscal, travel, and time constraints make it impractical or impossible to convene personally. Once dental and intensity-modulated radiation therapy providers possess a working knowledge of one another’s methodology and concerns, distant communication can be assisted. The most convenient means by which to request dosimetric data from a remote intensity-modulated radiation therapy center involves obtaining printed colorized serial computed tomograms displaying isodose information that is superimposed over imaged anatomy (Fig. 98-11). These images are generated by all intensity-modulated radiation therapy computer packages and offer a reasonable representation of dosages delivered in three dimensions. A common impediment to dental teams’ treatment planning efforts involves their receipt of black-and-white photocopied computerized tomography isodose images that are essentially illegible by virtue of the fact that intensity-modulated radiation therapy computer packages routinely rely on the use of color for the assignment of dosimetric values.

Figure 98-11. A, Computed tomography illustration of intensity-modulated radiation therapy isodose lines for a patient treated for a left tonsillar squamous cell carcinoma. The development of a second primary squamous cell carcinoma in the area of the right maxillary palatal mucosa after intensity-modulated radiation therapy necessitated a right inferior maxillectomy. The subsequent development of osteoradionecrosis in the area of the maxillectomy is substantiated by the cumulative dose of radiation in the area of the posterior right maxilla. The axial image demonstrates dosages delivered to the dentoalveolar structures at a level midway between the crestal alveolar bone and the periapices of the right maxillary molars. B, The patient’s left tonsillar tumor bed was boosted during the administration of intensity-modulated radiation therapy. The computed tomography axial image delineates the additional dosages that were received during the boost in the area of the right posterior maxilla. The collective dose to the right posterior maxilla in the area of subsequent postoperative osteoradionecrosis approximated 7000 cGy and warranted a hyperbaric oxygen therapy regimen that indeed mitigated the osteoradionecrosis.

Overview of Maxillofacial Prosthodontic and Radiation Oncology Interactions

The maxillofacial prosthodontic team’s involvement in the care of head and neck cancer patients who will receive radiation therapy is initially focused on treatment planning in the interest of preventing osteoradionecrosis and the preparation for any prosthetic rehabilitation necessitated by that treatment planning or a patient’s comprehensive oncologic management. The maxillofacial prosthodontist also participates in decision making intended to diminish the risk of osteoradionecrosis for patients obliged to undertake oral or maxillofacial surgical procedures after radiation therapy. Because these efforts are usually multidisciplinary to the extent that decisions made by any of those involved in the treatment of an oncology patient could affect the maxillofacial prosthodontic team’s treatment options, participation in multidisciplinary head and neck tumor board conferences is constructive. Additionally, with support from the general dental and oral hygiene communities, the maxillofacial prosthodontist contributes to preventive dental health education and care from the outset of the oncologic experience through what should become a lifelong follow-up relationship. Furthermore, maxillofacial prosthodontic personnel can assist the radiation oncology team with intraoral and extraoral devices that repeatedly position and shield anatomy, serve as tissue-equivalent material to allow a more even dose distribution of external radiation beams, or situate radioisotopic sources for intracavitary brachytherapy. Finally, the participation of maxillofacial prosthodontic team members at the commencement of any head and neck oncologic treatment is meritorious in that the often complex intraoral and extraoral rehabilitation of anatomic deficits acquired before, during, or after that treatment is germane to the traditional role of maxillofacial prosthodontists.

Surgical Obturation

Resection of maxillary tumors that involve the oral cavity is dedicated to total eradication of disease. Similarly, preservation of anatomy conducive to prosthetic rehabilitation should be considered. Preoperative assessment of the patient by the maxillofacial prosthodontist is integral to overall treatment success by the head and neck treatment team (Fig. 98-12). Clinical examination with panoramic radiography may assist with decisions to extract diseased teeth at the time of surgical resection (Fig. 98-13). In this way, if adjunctive radiotherapy is necessary, a 4- to 6-week healing time offers a distinct advantage (Fig. 98-14). Preoperative assessment also aids to plan osteotomy planes through the existing tooth sockets in dentate patients to preserve the support of adjacent teeth.⁴⁰ These teeth, also called abutments, may be strategic for retention of a prosthesis. In fact, the more arch curvature formed by remaining teeth, the more favorable retention may be for a prosthesis of this type.

Figure 98-12. Preoperative assessment of patient with squamous cell carcinoma of the anterior maxilla. The maxillectomy was planned to include removal of six teeth with split-thickness skin graft to buccal aspect of cheek flap and defect.

Figure 98-13. Panoramic radiograph of patient with mucoepidermoid carcinoma of the left posterior maxilla. Anterior osteotomy site is to be made through socket of the upper left first premolar. Note the impacted third molar, left side.

Figure 98-14. Postoperative panoramic radiograph of patient in Figure 98-13. Note removal of maxillary segment and impacted lower third molar with ample healing time before radiation therapy.

Arches planned for maxillectomy should be approached with the thought of disease eradication. As a secondary thought, preservation of structures vital for support should be kept in mind for maximum potential of successful rehabilitation. The first of these preserves as much of the hard palate as possible, which is the primary stabilizing structure of a maxillary prosthesis. Second is grafting of the cheek flap with epidermis or split-thickness skin (discussed further later). Third comes removal of the inferior conchae, which, if not eliminated, frequently obstruct proper obturation. This is most evident with posterior and some lateral resections that involve the oral cavity. Finally, the sinus walls should be grafted, if possible. Again, split-thickness skin will limit polypoid tissue formation and keep mucus formation to a minimum.⁴¹ The roof of a sinus grafted with skin will allow its use as a supporting wall for the prosthesis.

Impressions can be made before surgery to provide diagnostic casts (Fig. 98-15). These casts will aid in fabrication of a prosthesis to be inserted at the time of surgery. These prostheses are usually made from polymethylmethacrylate resin and can be made with or without prosthetic teeth. The advantage of having no functioning dental components to these prostheses is that occlusal forces are left off the wound to allow for efficient healing. A surgical prosthesis offers advantages relating to speech, swallowing, and psychological well-being. Also, the prosthesis is helpful in securing a surgical bolster and aids the patient in acclimating to wearing a removable prosthesis. Because respiratory epithelium may remain within a sinus defect, prosthetic loading of this area can be problematic. The ability to clean the defect also becomes a concern, with hardened mucus being a particular obstacle for placement of a prosthesis. Grafting of the defect with split-thickness skin can create a more comfortable surface with fewer mucus secretions. As with any skin graft, positive pressure with a surgical bolster can aid with providing this type of surface. Perforating the graft with dispersed small incisions can minimize the likelihood of hematoma formation, thus improving take of the skin graft. In partially dentate patients, securing the prosthesis can be accomplished by incorporating stainless steel wrought wires in the prosthesis that encircle the most terminal teeth (also called abutments) (Fig. 98-16). In addition, the prosthesis can be wired to the abutment tooth closest to the defect using 25-gauge stainless steel wires. In edentulous patients, the prosthesis can be held in place using sutures, circum-zygomatic wiring, or several titanium screws (2.7, 10 mm) into the remaining hard palate. Care should be taken to ensure that the screws are placed in an angled fashion so as to allow screwdriver insertion at pack removal. In most cases the surgical prosthesis should be kept in place between 5 and 7 days.

Figure 98-15. Diagnostic cast made from a patient to undergo maxillectomy. Blue area to be included in resection and black wire diagrams denote abutment teeth to be used for surgical prosthesis.

Figure 98-16. A, Surgical prosthesis is tried for proper fit. B, A surgical bolster is added with xeroform gauze, denture-conditioning material, and stainless steel ligatures securing in place for 5 to 7 days. Note split-thickness skin graft sewn in lateral cheek flap.

(Surgery performed by Gary Clayman, DDS, MS.)

After this time, removal of the packing material and prosthesis should ideally be undertaken by the surgeon and prosthodontist. Removal of the packing material can precipitate a hemorrhage, and preparations with oxidized cellulose, gelatin foam, or microfibrillar collagen can be invaluable. At this time, transitioning the prosthesis by addition of tissue-conditioning material assists patients in becoming accustomed to placement and removal (Fig. 98-17). The patient is also instructed on how to cleanse the defect twice daily with a dilute solution of baking soda and salt. This can best be accomplished using an irrigation syringe and a dispersion attachment head. The patient returns weekly during the following month for changing of the material on the prosthesis as the defect continues to change shape.

Figure 98-17. A, At pack removal, interim obturators made from modification of surgical prosthesis. B, Photograph of an edentulous patient’s interim obturator. Patients are instructed on defect hygiene and placement/removal of prosthesis.

Definitive Obturation

After an extended period of healing (i.e., 6 weeks) following surgery and/or radiation therapy fabrication of a definitive prosthesis may take place. For dentate patients, this prosthesis can be made of either acrylic resin and stainless steel wrought wire clasps or a cast chromium framework that supports a bulb extension made of polymethylmethacrylate (Fig. 98-18). Specific recommendations for design have been well published.²⁶ Prostheses with masses of less than 45 g may remain solid, but prostheses of greater masses should be hollowed.^16,42 Edentulous patients are treated with prostheses made entirely of acrylic resin, the bulbs of which can be hollowed similarly. Teeth placed in the area of the defect serve as aesthetic replacements and prevent opposing tooth supraeruption but are of limited functional value.

Figure 98-18. Definitive obturator made with cast chrome base (A) for resection defect of pleomorphic adenoma (B).

Many edentulous or partially edentulous patients have difficulty with retention and, in some cases, difficulty with support as well. In these cases, osseointegrated implants can anchor and support the obturator prosthesis. Although long-term follow-up studies of patients possessing implants in irradiated bone warrants their cautious use, implants remain potentially advantageous.⁴³ Because maxillary sinuses may be extensively pneumatized following tooth extractions, installation of implants into this area can be problematic unless bone is grafted into the sinuses. This use of sinus augmentation has been well documented and deemed to be successful with the use of implants.⁴⁴ This technique can be used on a nondefect side where a unilateral or posterolateral defect of the opposite side is present. Splinting of approximately four to five implants with a stress-breaking bar is generally suggested and provides the patient with a retentive, stable prosthesis that may offer improved support as well (Fig. 98-19). Recently, the use of zygomatic implants (extended length) has been suggested as an alternative to sinus augmentation.^20,45 The implant protocol for zygomatic implants mandates bilateral placement, and preservation of the infraorbital rim on the defect side may improve surgical stability. Both techniques require a screw-retained bar attachment to be made with the obturator (Fig. 98-20).⁴⁶ Remote anchorage sites have been suggested as a means of stabilizing prostheses rehabilitating maxillary defects.^46,47

Figure 98-19. A, Implant-retained obturator with sinus augmentation and, B, stress-breaking bar attachment of nondefect side.

Figure 98-20. Use of extended-length implants (A) that traverse lateral aspect of maxillary sinus and engage dense zygoma (B). Such implants obviate the necessity for sinus augmentation for installation of conventional endosseous implants.

(Courtesy of Samuel Zwectchenbaum, DDS.)

Mandibular Resection Prostheses

Resection of a portion of the mandible may be necessary to control disease and may or may not create a discontinuity defect. Because the mandible is so integral to oral and respiratory physiology, it is desirable to preserve function as much as possible.

If a marginal mandibulectomy is performed, a general guideline is to surgically preserve about 1 cm of vertical mandibular height for integrity. Subsequently, the remaining mandible can be rehabilitated with a split-thickness skin graft and removable tissue-borne prostheses, or alternatively it can be reconstructed with osseointegrated dental implants. In the dentate patient, preservation of the inferior alveolar nerve in the posterior mandible may preclude placement of implants if there is minimal bone available above the canal position to stabilize implants. In these cases, either nerve transposition⁴⁸ (Fig. 98-21) or onlay bone grafting can serve to provide an osseointegrated rehabilitation (Fig. 98-22).

Figure 98-21. Implant placement performed with mandibular inferior alveolar nerve repositioning.

Figure 98-22. A, Patient with squamous cell carcinoma resected at left alveolar ridge. B, Onlay bone grafting with iliac crest and endosseous implants.

(Courtesy of Michael Miloro, DMD, MD.)

In edentulous patients, placement of either conventional prosthetics or implant supported/retained prosthetics may be desirable. Often, prosthetics can rely on select placement of implants in the anterior mandible with specified posterior occlusal cantilevering (Fig. 98-23). This procedure is well documented, with recent evidence indicating immediate functionality when implants are placed in the native mandible.^49,50

Figure 98-23. A, Patient with squamous cell carcinoma resected by marginal mandibulectomy. Remaining decimated dentition insufficient to support prosthesis. B, Placement of implant supported by prosthesis 2 months after resection. Note remodeling of alveolus in comparison with postoperative Panorex.

(Courtesy of William Lydiatt, MD, and Michael Miloro, DMD, MD.)

Discontinuity Defects

If a discontinuity defect is created by composite resection, it may be feasible to collapse the defect and not reconstruct mandibular continuity. This becomes more feasible if the patient is edentulous because dentate patients will have significant occlusal discrepancies that make postoperative rehabilitation difficult to impossible. In these cases a significant cosmetic deformity may result because the lower third of the face is asymmetric (Fig. 98-24). Also, disability of the tongue usually results because portions of the tongue may be used to close the wound, making swallowing problems inevitable. Additional consideration is given to the fate of the proximal resection segment of the mandible after the resection. Reconstruction bars may create additional backscatter radiation if adjunctive radiation is used for tumor control (Fig. 98-25).

Figure 98-24. A, Mandibular composite resection without reconstruction resulting in, B, significant mandibular deviation.

Figure 98-25. Proximal segment without reconstruction results in deviation and displacement against maxillary posterior ridge.

The key to functioning in these cases lies with preservation of the ramus, for which attachment of the muscles of mastication is preserved. Through removal of the ramus, less function is evident without balance of contralateral pull of pterygoid, temporal, and masseter muscles. If more of the ramus is retained and not maintained in its preoperative position, it may collapse on the maxillary buccal vestibule and obstruct maxillary dental hygiene procedures or the fabrication of a maxillary prosthesis. Furthermore, the ramal segment could be sequestered into the oral cavity. Reconstruction in these cases is the wiser choice and does not advocate joining the plate to small condylar remnants.⁵¹ If mandibular continuity is not preserved after resection, it may be desirable to reconstruct the area with an autogenous or alloplastic graft. Location of the resection may be indicative of the relative success of the reconstruction. Anterior reconstructions that cross the midline with a plate system alone may be less successful than those with an osseous reconstruction as well.⁵² Cosmetic and functional deformities are also more of a consideration in the anterior mandibular areas. This is perhaps due to the influence of the suprahyoid musculature on swallowing and respiration. Concurrently, it is considerably difficult to conform an osseous graft to an arch form in this area. Posterior or lateral resections appear to be less debilitating and problematic because a linear replacement of bone is frequently sufficient to reconstruct this area. A reconstruction with pedicled soft tissue may serve to deviate the remaining mandibular segments to the affected side. Osteomyocutaneous flaps are superior in reconstructing mandibular discontinuity to avoid this deviation and preserve maxillomandibular relationships vital to rehabilitation.

In some cases, autologous grafts offer a greater volume of viable bone with progenitor cells capable of creating a more favorable environment for osseointegration.³⁶ Nonvascularized or vascularized osteomyocutaneous flaps can also be used for reconstruction. It may be preferable to use vascularized flaps in previous operative beds or in areas that have been or will be irradiated, because the provision of a blood supply may offer a more predictable opportunity for the graft to remain viable. Vascularized iliac crest has been used with some degree of success for mandibular defects and some maxillary defects. Introduced by Hidalgo,^53,54 the use of vascularized fibular grafts has also shown a promising degree of success in the reconstruction of these complex mandibular defects.⁵⁵ Being a non-weight-bearing bone, the fibula is of reasonable dimension to functionally and cosmetically reconstruct the mandible. Additional phases of rehabilitation with titanium implants have been demonstrated to be uniquely applicable to these cases. Bicortical stability is typically well obtained at surgical installation, and long-term success has been favorable (Fig. 98-26). The choice of using either a sectional overdenture design or a screw-retained fixed prosthesis may be predicated on the amount of tissue missing, the function of the tongue, perioral scarring, and adjacent/opposing occlusion (Fig. 98-27). Frequently, the restoration to implant height ratio is seen to be greater than 1 : 1. Passive splinting of these implants is crucial to their long-term success, and close attention should be paid to the development of the occlusal scheme. Occasionally, it may be necessary to perform soft tissue revision procedures if the skin pedicle is thick or if a greater vestibular depth is necessary. This ensures soft tissue health and visibility for hygiene procedures.

Figure 98-26. Osteosarcoma of mandible resected and reconstructed with vascularized fibula and end endosseous implants.

(Courtesy of William Lydiatt, MD, and Perry Johnson, MD.)

Figure 98-27. Screw-retained ceramometal prosthesis used for patient in Figure 98-26.

Tongue Resection

Resection of the oral or pharyngeal tongue is occasionally necessary to control disease. Integral to swallowing, speech, and mastication, the tongue is often treated aggressively for tumor control. Centrally located malignant lesions have a propensity to metastasize bilaterally to the neck and may require extensive resection for tumor control. As a result of large resections of tongue muscle, wound closure becomes a concern for postoperative healing. Vascularized myocutaneous or fasciocutaneous flaps may be a valuable adjunct for reconstruction of these resections. However, these flaps are generally insensate and do not provide tissue conducive for normal swallowing and speech production. Physiology of swallowing has been described and is divided into three main phases: oral, pharyngeal, and esophageal. The voluntary oral phase can be further subdivided into two phases of oral preparatory and mastication.

The competency of the lips is mandatory for the oral phase to function effectively because a lip seal will create a boundary for bolus transportation. Mastication is an independent function of the tongue for tougher-consistency foods, and efficiency is also dependent on dental status of the patient. The time taken for the bolus to be transported to the posterior oral cavity past the anterior faucial arch demarcates the oral transit time. In healthy adults, the oral transit time can be about 1 to 2 seconds. After tumor-ablative surgery of the tongue or mandible, the range of motion needed for swallowing and speech production may not be sufficient. In these cases the height of the palatal vault may not allow appositional contact of the remaining tongue tissue to propel the bolus of food or liquid into the pharyngeal area where the involuntary phase of the swallowing reflex is initiated. Consequently, lowering of the palatal surface prosthetically can aid in providing a surface that approximates the extent of the tongue’s range of motion postsurgically. This prosthesis, known as a palatal augmentation prosthesis, can be used in dentate or edentulous patients (Fig. 98-28).^56,57 In patients with dysphagia, palatal augmentation prostheses have been shown to decrease oral transit times, thereby increasing swallowing efficiency.⁵⁸

Figure 98-28. Palatal augmentation prosthesis (A) used for improved patterns of swallowing and speech in this patient (B), who undertook the resection of a base of tongue squamous cell carcinoma.

Articulatory speech debility is dependent on the area(s) of the tongue that are resected. For instance, resection of the anterior or tip of the tongue may not allow articulation of linguoalveolar sounds such as /t/, /d/, /n/, or /s/. In other cases the base or sides of the tongue may be resected to create deficiencies in /g/, /ng/, /k/, or /c/. In these cases a prosthesis may serve to better aid production of these sounds. Because the shape needed for swallowing may be markedly different from that which is necessary for speech production, a prosthesis with interchangeable surfaces being incorporated into a palatal augmentation or a mandibular “tongue” prosthesis has been advocated. Each respective surface is used specifically for speech or swallowing.^51,59 Regardless of the type of prosthesis being constructed, involvement of a speech pathologist can be quite instructive to patients and the maxillofacial prosthodontist.

Soft Palate Resection

As a component of Waldeyer’s ring, the soft palate is occasionally included in resection of tumors of squamous cell origin. Because of its dynamic nature, the soft palate, like the tongue, is integral to swallowing and speech. The anterior faucial arch serves as a landmark for the involuntary phase of swallowing and, if included in resection, can predispose the patient to aspiration. An anatomic deficit of the soft palate can also create velopharyngeal insufficiency, which may result in nasal regurgitation of swallowed matter and nasal speech production. Replacement of velar function with pharyngeal flaps is reserved for conservative soft palatal defects that may be acquired or congenital. A prosthesis (known as a speech aid) replacing soft palate function should obturate the pharyngeal recess at the level of the first cervical vertebra or Passavant’s pad, frequently seen as a conglomeration of muscular tissue in the superior pharyngeal constrictor (Fig. 98-29). At this level, the extension of the prosthesis should serve to partially fill the pharyngeal recess while providing room for the dynamic nature of the pharyngeal and tongue musculature. A stable reference for the prosthesis starts with assessment of the oral cavity. Anchorage for the prosthesis can be tooth borne or partially or completely tissue borne. For tooth-borne prostheses, anchorage with molar teeth becomes advantageous because anchorage closer to the vectors of dislodging forces discourages premature loosening with function.

Figure 98-29. Patient with soft palate resection restored with speech aid (A) or pharyngeal obturator prosthesis (B).

Soft palate function can also be affected by cerebrovascular accidents, demyelination diseases, or surgical procedures. The anatomic structures, in these cases, may be incompetent in performing velopharyngeal closure. A palatal lift prosthesis may serve to provide the patient also with better speech production and improved swallowing patterns and it may stimulate the musculature to perform at increased functional levels.^60–62 For the palatal lift prosthesis to be effective, some pharyngeal muscular movement must be present. To effectively evaluate the closure of the soft palate, a nasal endoscope can aid in directly identifying deficiencies.

Intraoral rehabilitation of congenital and acquired defects has historical roots in traditional restorative dentistry. It is within this literature that restoring a patient’s preoperative level of function has proved essential. Quality-of-life and clinical outcome studies have been shown to validate these goals and objectives. These achievements have been taken to a higher level with our knowledge of osseointegration, tissue physiology, and technology. Continued developments in tissue engineering and other related technology will continually explore and improve outcomes in this complex area of clinical treatment.

Prosthetic Management of Acquired Facial Defects

Facial defects acquired from trauma or surgery can be devastating and among the most socially crippling for the patient. There is a tremendous emphasis on perfection and beauty in today’s society. The prosthetic restoration of patients who are not surgical reconstruction candidates can lead to their return to active, productive lives and complete social acceptance.

The decision of whether to manage a facial defect surgically or prosthetically is often a difficult one. Most patients would rather have surgical reconstruction. However, the advantages and disadvantages of each method must be considered as the decision is made. The patient’s functional status and overall health are concerns. Radiation treatment to the defect area results in a reduced blood supply and can prevent some surgical procedures. The texture, contour, and color of the surrounding tissue must also be considered, as well as the need to examine the surgical area for an extended period after the original intervention. Achieving the correct shape to restore contour can be difficult with living tissue, and large defects may require staged procedures. If all of these factors can be managed positively and there are no other contraindications, the patient and surgeon may opt for surgical reconstruction. If the defect can be successfully managed with the patient’s own tissues in an aesthetically acceptable fashion, this may be the first choice. Otherwise, a prosthesis is required.

Prosthetic management of facial defects has its disadvantages as well. Although excellent contour and color are attainable, the prosthetic materials used have fairly limited life spans—usually 18 to 24 months. The prosthesis may have to be retinted during that time, depending on its environment. Craniofacial implants or adhesives must be used to retain the prosthesis, and it should be removed for a few hours regularly each day to maintain the underlying tissues in a healthy state. Various masking techniques such as large-framed glasses or cosmetics are often used to hide margins. Some patients develop chronic mechanical tissue irritation from wearing prostheses, and allergic responses, though not common, may affect prosthesis use. Despite this, excellent cosmetic results and patient acceptance are obtainable in the vast majority of cases (Table 98-1).

Prosthesis retention can be managed in several ways. Where possible, tissue undercuts should be used. Tissue “pockets,” particularly those that have been lined with split-thickness skin grafts, can be effective as retentive aids. The most common of the retentive aids used are the skin adhesives. These have been effective, and there are several kinds in use. Mechanical aids such as glasses frames, double-faced tape, or straps are also used where appropriate. Craniofacial implants can be used and have several distinct advantages over the other types of retention. With several strategically placed implants, connecting bars can be used, with corresponding clips or other types of attachments that are bonded to the tissue side of the prosthesis. These hold the prosthesis securely, adding a measure of confidence for the patient and allowing him or her to accurately place it without the sometimes irritating effects of an adhesive. Where possible, this is the retention of choice, particularly for large facial prostheses.

Previously irradiated patients may not be good candidates for craniofacial implants due to compromised blood supply to the supporting bone. However, implant placement within the first 3 months after radiation is possible due to the delayed tissue response. Use of hyperbaric oxygen treatments in irradiated patients also improves the bone and soft tissue response to implant placement. Patients with facial prostheses must have good manual dexterity and the ability to keep the prosthesis and defect clean.

A psychosocial support system of family or friends helps to ensure success in dealing with a facial prosthesis, especially for older patients. Those without this support and the dexterity required may have difficulty and cease wearing the prosthesis. The patient’s willingness to accept the defect and cope with it, as well as having reasonable expectations, are of paramount importance. The most cosmetic and retentive prosthesis is still a failure if the patient cannot deal with it. Interdisciplinary discussions between the surgeon and the maxillofacial prosthodontist before or during surgery will be helpful in the management of the primary disease and the postoperative rehabilitation of the patient. Although the eradication of disease and the preservation of the patient’s life are the first priority, there are intraoperative procedures the surgeon can complete that will greatly enhance the tissues surrounding the defect for support and retention of a prosthesis. These procedures are best discussed according to the type of facial defect involved. The most common types of facial surgical defects are the nasal, auricular, and orbital.

Nasal Defects

Many variations of acquired defects are caused by ablative surgery involving the nose. Where there is a relatively small, isolated defect, a split- or full-thickness skin graft can be used if primary closure is not feasible. In these cases, prosthetic management need not be considered unless the surgeon wishes to observe the defect for an extended period of time. Defects involving greater areas including not only skin but bone, subcutaneous tissues, and mucosal lining can be reconstructed using various flap procedures with or without autogenous support. If more than half the nose is resected, a complete rhinectomy should be considered. Alar tabs or unsupported tissue surrounding the defect do nothing for prosthetic support and, in fact, hinder the fabrication of a cosmetic prosthesis. Although it may be possible for the patient to wear a prosthesis, more margins will be visible, thus compromising the aesthetic value. Centrally located defects, leaving the nasolabial folds intact with surrounding supported tissue, provide the best base for restoration (Fig. 98-30). Those defects that extend beyond the nose laterally or toward the upper lip are more difficult to restore due to greater tissue mobility in these areas; they therefore require greater exposure of margins. Placement of split-thickness skin grafts, particularly at those margins extending toward the lip, will be beneficial in preventing scar contraction of the lip and will provide a firm, immobile base for the inferior margin of the prosthesis. Craniofacial implants are useful in the retention of a nasal prosthesis and should be placed in the anterior floor of the nose where there is sufficient bony support. They are best used in conjunction with split-thickness skin grafts, and their position should be such that the abutments will extend into the greatest thickness of the subsequent nasal prosthesis (Fig. 98-31).

Figure 98-30. Small, centrally located nasal defect with nasolabial folds intact and no involvement of the upper lip.

Figure 98-31. Nasal defect restored with a prosthetic nose.

Auricular Defects

As with nasal defects, flexible remnants of the ear such as the lobe and helix should be removed unless surgical reconstruction of the ear is anticipated. The tragus, however, should be retained because part of the anterior margin of the prosthesis can be hidden behind it. A defect that results from a partial resection is much more difficult to restore prosthetically than that of a total auriculectomy. If an attempt at surgical reconstruction has been made and has failed, the tissue should be completely removed (Fig. 98-32). A split-thickness skin graft will provide a firm, immobile tissue bed for the prosthesis. Full-thickness or hair-bearing skin grafts should not be used. It should be remembered that prosthesis margins that must overlay the condylar area can loosen during function if they rely on adhesive for retention. If implants can be placed in a position such that they will be in the thickest part of the auricular prosthesis, usually close to the helix, they will provide maximum retention and patient confidence.

Figure 98-32. Auriculectomy defect with split-thickness skin graft in place and a bar splint supported by craniofacial implants. Notice the presence of the tragus.

The auricular prosthesis has two major advantages over the nasal or midface prosthesis; the viewer cannot focus on both ears at the same time because they are located laterally, and the patient’s hair can be used to hide a portion of the margin (Fig. 98-33).

Figure 98-33. Prosthetic ear in place with the tragus masking the anterior margin.

Ocular Defects

Evisceration, enucleation, or exenteration of the eye requires, more than any other, the combined efforts of the surgeon and maxillofacial prosthodontist for a successful restoration. After evisceration, or removal of the global contents, a spherical implant is placed within the scleral space. A thin, custom ocular prosthesis or scleral shell is fabricated to fit over the implanted sclera and reproduce the contour and aesthetics of the original eye. Because the muscles controlling globe movement are left intact, movement of the prosthesis should be relatively good. This prosthesis must be thin to keep the eye from appearing exophthalmic and to accommodate the potential movement.

Enucleation is the total removal of the eye after severing the optic nerve and detaching the ocular muscles. The space provided by the procedure, along with placement of an implant in the posterior wall associated with the muscles, makes it possible to provide an aesthetic, mobile, custom ocular prosthesis.

The aesthetic and functional restoration of the orbital exenteration defect, where all the contents of the orbit are removed, is a difficult one. Its success usually depends on the amount of tissue that must be removed beyond the orbit. It is unique among the types of facial prostheses in that the eye within the prosthesis has no movement and the normal eye presents itself for easy comparison, unlike the ears (which are located laterally) or the nose (which has no basis for comparison on the face). During socialization, the eyes are usually focal points. In defects that extend beyond the orbit into the more mobile tissues of the face, the margin of the prosthesis can loosen during facial expressions if it relies solely on adhesive to retain it.

An ideal defect is one that is within the orbital boundaries with no marginal irregularities, lined with a split-thickness skin graft, and having sufficient depth to recreate normal anatomy with the oculo-facial prosthesis (Fig. 98-34). Without the skin graft, the tissues are much more sensitive and difficult to manage hygienically. If the eyebrow cannot be kept in normal position, it is best to remove it and include it in the area of the skin graft. Where possible, placement of implants in the lateral or superior orbital rims is a great advantage for retention of the prosthesis. As with placement for other types of facial prostheses, location of the implants and their angulation should be such that they will be in the thickest portion of the prosthesis. If these requirements can be met without compromising the patient’s cure, it will be possible to provide a defect that the patient can manage hygienically and one for which the most aesthetically pleasing and retentive prosthesis can be made (Fig. 98-35).

Figure 98-34. Orbital exenteration defect lined with a split-thickness skin graft that does not extend beyond the orbital rim.

Figure 98-35. Oculofacial prosthesis in place with margins masked by glasses.