Osteoradionecrosis of the Mandible Treatment & Management

Two specific intervals exist in which prudent clinical practice can diminish the incidence of osteoradionecrosis (ORN). These are in the pretreatment phase and in the rehabilitation phase.

All patients diagnosed with head and neck cancer (HNC) who may need radiotherapy to the oral cavity in the course of their cancer treatment should undergo a thorough pretreatment dental evaluation. The dentist who completes the evaluation must have experience with the management of patients with HNC. Such an individual is usually a part of the multidisciplinary cancer therapy team at large institutions but must be sought when treatment occurs elsewhere.

Prior to beginning radiation therapy, all patients should undergo a thorough dental evaluation, including full mouth radiographs, dental and periodontal diagnosis, and prognosis for each tooth. Outline a complete treatment plan, taking into account the patient's motivation and compliance based upon discussions with the patient and his or her family. Patient education regarding the need for meticulous oral hygiene and frequent follow-up must be stressed.

The dentist should perform prophylaxis, periodontal scaling, caries control, and fabrication of fluoride trays.

Teeth that cannot be salvaged with conservative endodontic therapy should be extracted. Ideally, extractions should be performed 3 weeks prior to beginning radiation therapy. Extraction of teeth during radiation therapy should be discouraged and delayed until the completion of treatment with resolution of the oral mucositis.

To prevent radiation caries, patients should begin daily fluoride treatment with 1% neutral sodium fluoride gel in prefabricated trays for 5 minutes each day. This practice should continue for life.

Medical therapy in treatment of ORN is primarily supportive, involving nutritional support along with superficial debridement and oral saline irrigation for local wounds. Antibiotics are indicated only for definite secondary infection. Pentoxifylline has been used for the treatment of radiation-related soft tissue injury with some success. Its use in the treatment of mandibular ORN is unknown, however.

Hyperbaric oxygen (HBO) therapy is outlined below.

Treatment of mandibular ORN is controversial. In 1983, Marx demonstrated successful resolution of mandibular ORN in 58 patients using a staged protocol with HBO and surgery.^[3] HBO transiently elevates tissue oxygen tension and stimulates fibroblastic proliferation and oxygen-dependent collagen synthesis. This allows for angiogenesis in the radiated bed. This does not totally resolve the radiation injury, however, and some degree of tissue hypoxia persists.

Current protocol for treatment of mandibular ORN, according to Marx

Stage I: Perform 30 HBO dives (1 dive per day, Monday-Friday) to 2.4 atmospheres for 90 minutes. Reassess the patient to evaluate decreased bone exposure, granulation tissue that covers exposed bone, resorption of nonviable bone, and absence of inflammation. For patients who respond favorably, continue treatment to a total of 40 dives. For patients who are not responsive, advance to stage II.

Stage II: Perform transoral sequestrectomy with primary wound closure followed by continued HBO to a total of 40 dives. If wound dehiscence occurs, advance patients to stage III. Patients who present with orocutaneous fistula, pathologic fracture, or resorption to the inferior border of the mandible advance to stage III immediately after the initial 30 dives.

Stage III: Perform transcutaneous mandibular resection, wound closure, and mandibular fixation with an external fixator or maxillomandibular fixation, followed by an additional 10 postoperative HBO dives.

Stage IIIR: Perform mandibular reconstruction 10 weeks after successful resolution of mandibular ORN. Marx advocates the use of autogenous cancellous bone within a freeze-dried allogeneic bone carrier. Complete 10 additional postoperative HBO dives.

The use and efficacy of HBO prior to tooth extraction has been debated in the literature. Those who argue against the use of HBO prior to tooth extraction state that the overall risk of developing ORN with preradiation or postradiation extractions is quite low, that HBO therapy is expensive, and that it is time consuming.^{[5, 6]} HBO has not definitely been shown to prevent the development of ORN, and it does not reverse established ORN. However, several studies have shown some benefit in using HBO in the management of Stage I and II ORN.^{[7, 8]} Most reconstructive surgeons currently use vascularized free tissue transfers instead of HBO therapy in the management of stage III ORN.

Microvascular reconstruction

Microvascular free tissue transfer offers the clinician and patient a 1-stage procedure to correct mandibular ORN. Significant experience and documentation of the use of immediate reconstruction of the mandible using free bone flaps has been reported in the literature. Microvascular free tissue transfer is considered the standard of care for stage III ORN management. Particular care must be exercised in delineating the margins of resection when a primary bone flap is planned. Preoperative planning must also address the availability of suitable recipient vessels within the neck for microvascular anastomosis.

After resection of nonviable bone, vascular free tissue transfer offers immediate reconstruction and restoration of mandibular continuity. Free tissue transfers offer patients a shorter treatment course, often without the need for HBO.

Early criticism of microvascular reconstruction of the mandible included inadequate bone stock for prosthetic dental reconstruction, prolonged ICU stay and hospitalization, and increased donor site morbidity. Experience with microvascular reconstruction has lessened these concerns.

The literature in fact shows that dental rehabilitation can reliably be successfully completed on patients who receive fibula or iliac free bone flaps. Documented cases also exist of implant-supported dental rehabilitation in patients who underwent scapula and radial bone flaps, although these certainly are exceptions to the norm.^{[9, 10, 11, 12, 13]} The total treatment cost is decreased when primary mandibular reconstruction is completed with free tissue transfer.

Prudent clinical practice can diminish the incidence of ORN at 2 specific intervals. These are in the pretreatment phase and in the rehabilitation phase.

The risk of developing ORN is clearly cumulative in relation to radiation dose, and risk continues throughout the patient's life. In fact, the risk of ORN in patients who must undergo procedures that involve the mandible following radiation treatment increases with time from radiation therapy. Before dental rehabilitation, perform a careful assessment of risk of ORN. Prior to dental extraction or dental implant placement, radiation fields and doses must be ascertained. The clinician must then determine the patient’s potential benefit from HBO therapy on a case-by-case basis.

The use of HBO therapy prior to implant placement has also been debated. The use of HBO may decrease morbidity and increase the success of dental implant therapy. Recent studies have shown an increase in long-term dental implant failure in patients who did not receive HBO with implant placement.^[14] The placement of dental implants in irradiated jaws carry the same risk for developing ORN as those seen with tooth extractions in a similar clinical setting.

Prior to dental extraction/implant placement, consider HBO if surgery will occur in a field of radiation that is known to have received 60 Gy. Follow the standard HBO regimen of 20 preoperative treatments and 10 postoperative treatments. Perform surgery in as atraumatic a fashion as possible. When placing dental implants, allow for a marked decrease in integration rates (65-80% vs 95%).

Data available are insufficient to assist clinicians faced with the management of osteoradionecrosis (ORN) in counseling patients as to the anticipated outcome of therapy. Additional documentation regarding the costs and successful outcomes for primary versus secondary reconstruction are needed. Patient satisfaction for each available therapy must be further investigated. A significant problem exists when consulting with patients who received previous radiation therapy prior to dental extraction. The costs of prophylactic hyperbaric oxygen (HBO) are a major consideration because inadequate outcome data often result in failure to receive insurance authorization for prophylactic HBO.

The increased use of radiation therapy concurrently with chemotherapy warrants attention to incidence rates for development of osteoradionecrosis (ORN). The potential for increased tissue sensitivity in the setting of such therapy has not been well studied. Development of late complications of therapy is seldom considered in short-term studies of multimodality therapy. Efforts should be made to monitor patients who have been enrolled in such treatment protocols for long periods of time to evaluate the quality of life and late complications of therapy.

Modalities and treatments for mandibular ORN are numerous and controversial. Although some authors recommend a combination of hyperbaric oxygen (HBO), sequestrectomy, resection, and free bone grafts, others recommend vascularized free tissue transfer without HBO. Definite advantages and disadvantages of each method exist. Several important facts are known, including the following:

• HBO reduces radiation-induced hypoxia, hypovascularity, and hypocellularity and improves wound healing.
• Dead necrotic bone requires resection.
• Vascularized free tissue transfer provides an immediate reconstruction option with a shortened treatment course.