39 Oral Rehabilitation
This chapter reviews the necessary steps and timeline for prosthetic reconstruction following surgical resection and/or reconstruction for head and neck cancer. Close communication between members of a patient’s oncologic team is necessary in order to deliver the best postsurgical results to the patient. The ultimate goal is to restore form and function as close as possible to presurgical conditions.
Maxillofacial prosthetics is a subspecialty of prosthodontics which focuses on rehabilitation of those patients with defects or dysfunction resulting from disease, such as cancer, trauma, or congenital malformations. In restoring the oral cancer patient, it is the goal of the maxillofacial prosthodontist to achieve form and function as close to the pre-disease state as possible. In these patients, problems with swallowing, chewing, speaking, and lip function are common, depending on the size and location of the tumor.
At present, there exist two options for restoring form and function to those patients having undergone a maxillectomy. Prosthetic treatment consists of construction of removable obturator prosthesis to fill the remaining void after total or partial resection of the osseous and soft tissues of the maxilla. Surgical reconstruction of the defect using a microvascular free flap, often containing bone, is another alternative. 1
Reconstruction with an obturator prosthesis reduces surgical time and offers the immediate restoration of form and function. Having a removable obturator allows for evaluation of the surgical site thereby allowing recurrence to be detected at an early stage and without relying solely on serial imaging. Conversely, a malfunctioning obturator may result in speech deficits, improper mastication, dysphagia, or facial disfigurement. 2 – 5
39.2 Surgical Obturator
39.2.1 Presurgical Visit
About 2 weeks prior to the planned surgical procedure, it is important to make preliminary impressions. The impressions are needed of both arches and can be made with irreversible hydrocolloid. Making two maxillary impressions allows for utilization of one cast for the surgical obturator and keeping an unmodified cast for fabrication of the interim obturator. This is important in the event that positive margins dictate the need for further resection than originally planned. It is necessary to extend the impression posteriorly in order to capture the area of the hard and/or soft palate which will be resected.
The stone model should then be marked by the surgeon to indicate the planned extent of the resection, including any teeth which will be removed along with the resection. A surgical obturator will then be designed and fabricated out of polymethyl methacrylate resin in the laboratory for insertion immediately following the resection. In these instances, it is always helpful to maintain remaining dentition in which to anchor the surgical obturator, whether by clasps or by wiring around the teeth. The number of wire clasps to retain the obturator should be increased in order to account for any additional teeth that may be needed to be removed with the resection that were not foreseen. Should no teeth be available for clasping, it is always possible to wire the surgical obturator in place through residual maxillary alveolus.
It is prudent to fabricate surgical obturators without any denture teeth replacing missing dentition due to the lack of ability for adjustments and try-ins prior to or during the surgical procedure. In order to not create any occlusal interferences, it is best to leave the surgical obturator out of the occlusal plane. If the patient is losing teeth in a highly esthetic area or the patient is not having any opposing dentition, it is possible to fabricate the surgical prosthesis with denture teeth. The surgical obturator should return from the laboratory finely polished and ready for insertion (▶ Fig. 38.2 and ▶ Fig. 39.1).
39.2.2 Time of Surgery
The surgical obturator can be inserted by the surgeon following the resection or by a dental team member, namely the maxillofacial prosthodontist. The surgical obturator is installed following placement of surgical dressing and will remain in place for 7 to 10 days following the surgery. The surgical obturator will allow the patient to speak and swallow normally immediately postoperatively. It also has many psychological benefits as well, as it allows the patient to wake up from surgery without feeling the extent of their surgical defect. Once the surgery is completed, the second stone cast can be modified to indicate the teeth removed during surgery. This cast is then sent to the laboratory for fabrication of an interim obturator which will also include denture teeth to replace the missing dentition.
39.2.3 Postsurgical Visit
After 7 to 10 days of healing, the surgical obturator and surgical dressing is removed by the dental team member. This is generally performed without any local anesthetic; although, when wiring through the residual alveolus is performed, some topical or local anesthetic may decrease patient discomfort. If the surgical obturator is fixated to the teeth or alveolus, the wires are cut and removed with a quick pulling motion, followed by the removal of the surgical obturator. If no fixation of the obturator was performed, the surgical obturator is removed, revealing the surgical dressing. The surgical dressing is then removed, and the defect is evaluated for any debris, signs of infection, or bleeding. Suction is used to remove any debris and the defect is now prepared for insertion of the interim obturator prosthesis.
39.3 Interim Obturator
An interim maxillary obturator, generally replacing most or all teeth within the defect, is made after surgical resection and inserted once initial healing is completed to restore functions such as speech, mastication, and deglutition. This prosthesis also plays an important role in preventing collapse of facial soft tissues in the area of the defect and irritation to the surgical site. 6 Once the surgical obturator is removed and the surgical defect is cleaned, the interim obturator is tried in. A resilient silicon liner is used to mold the obturator to the surgical defect. The material is allowed to set while the patient performs some head motions, such as chin-to-chest and chin-to-shoulder, as well as neck circles in order to capture movements of the surrounding tissue. When the material has fully set, the interim obturator is removed and excess material is trimmed, making certain not to remove too much material from the posterior and lateral aspects of the obturator which would compromise the seal of the prosthesis.
The obturator seal is then tested by having the patient insert the prosthesis and drink water without having any nasal leakage of the water. Speech is also tested and hyponasality or hypernasality, if present, are identified. The goal is to have the speech just slightly hyponasal in order to minimize the chance of air escape and nasal leakage quickly once the patient starts healing. If the patient’s voice is too hyponasal, breathing through his/her nose will be difficult and modifications must be made to the bulb portion of the obturator which is likely occluding the nasal passages. If the patient’s voice is hypernasal, more resilient liner may need to be added to the area of suspected air escape, typically at the posterior aspect of the obturator prosthesis.
For the first 1 to 2 months of healing post surgery, the patient should be evaluated every 2 to 4 weeks for nasal leakage of fluids, hypernasality, or sore areas caused by the obturator prosthesis. At these visits, silicon liner may need to be added to certain areas of the obturator in order to recreate the seal of the prosthesis. If sore areas develop, the obturator can be adjusted to provide relief there. Postsurgical chemotherapy or radiation therapy will lengthen healing time following surgery and predispose the patient to developing more irritation from the obturator. With these patients, frequent follow-up of 1 to 2 weeks is sometimes necessary in order to provide relief of the prosthesis.
Typically, about 3 months, following surgical resection in an otherwise healthy patient without chemotherapy or radiation therapy, is adequate time for complete healing. In patients with delayed healing, such as diabetics, waiting 4 to 6 months for complete healing is recommended. For a patient who has received chemotherapy or radiation therapy following surgical resection, it is recommended to wait at least 3 months following completion of chemotherapy or radiation therapy to start planning for a definitive restoration.
39.4 Definitive Obturator
39.4.1 Partially Edentulous
Restoring a patient who has had a maxillectomy and still has intact supporting dentition is one of the more favorable circumstances in maxillofacial prosthetics. It is of utmost importance to determine the survivability of the remaining dentition prior to designing an obturator framework (▶ Fig. 39.2, ▶ Fig. 39.3, and ▶ Fig. 39.4).
Following are some key points to consider:
What is the patient’s dental history? For example, do they seek routine dental care? Do they practice good oral hygiene? This is very important in determining which teeth, if any, should be utilized for supporting a prosthesis.
Does the patient have a history of head and neck radiation? If so, what was the dose to the area of the dentition? Postradiation patients are highly susceptible to developing dental caries at a much faster rate than nonirradiated patients; however, the dentition must be carefully examined and restored prior to fabricating any definitive prosthesis.
Are any teeth actively diseased? If so, these teeth need to be treated appropriately prior to fabricating any definitive restoration.
The prosthesis framework should be designed so as to distribute forces among the strongest remaining teeth while spreading out the forces as much as possible throughout the arch. It is important not to place too much pressure on any one tooth which could cause it to loosen prematurely, resulting in loss of a strategic tooth in the obturator design. Upon presentation following healing from surgery and radiation, preliminary impressions are made in order to evaluate the remaining dentition and design an appropriate obturator framework.
At a subsequent visit, selected teeth are prepared slightly in order to accept a metal framework. The framework itself is mostly tooth supported, which allows for less pressure to the underlying mucosa. The framework resting on the dentition allows for less movement of the obturator prosthesis during function. Once the teeth are modified accordingly, a final impression is made and a stone cast is poured. A metal framework, typically made of Cr-Co or Ni-Cr, is fabricated and subsequently tried in the patient’s mouth. The framework should have a passive fit and not put excessive pressure on any particular area. Slight adjustments can be made in order to achieve a passive fit of the metal framework.
Once the metal framework is completed, wax is placed in the edentulous areas in order to capture an occlusal relationship between the maxillary and mandibular dentition. This allows for prosthetic tooth placement corresponding to the patient’s existing dentition. Measurements are also made to determine the correct size and shape of the prosthetic teeth as well as the midline, if necessary, and occlusal plane. A shade is also selected in order to match the remaining dentition.
The next step is try-in of the metal framework with denture teeth set in wax to restore the edentulous areas. This is an important step for testing speech, esthetics, and occlusion prior to finalization of the prosthesis. Any changes to the teeth position, shape, size, or shade should be made while the teeth are still placed in wax. Once the wax set-up is acceptable to both the patient and the clinician, the prosthesis should be processed into acrylic resin at the laboratory. This process is done under heat and pressure to ensure a dense material which is more resistant to forces placed on the prosthesis by the opposing dentition.
The final processed prosthesis is then tried in and adjusted for areas of excess pressure on the tissue surface of the obturator. Pressure indicating paste is used to establish these areas and a bur is used to reduce the acrylic in the corresponding areas. The occlusion is also checked and adjusted as well as the tightness of any of the clasps incorporated in the prosthesis. The patient is then evaluated for speech and nasal leakage of fluids, just as in prior steps. It is important for the patient to be able to insert and remove the prosthesis without difficulty but also to have enough retention so that the obturator does not move while speaking and eating. The patient should also be given proper home care instructions for the prosthesis. It is important to keep the prosthesis clean and to not sleep with the prosthesis, as fungal infections can develop if the obturator is not removed for enough time during a 24-hour period. Follow-up adjustments are necessary, as with any new prosthesis, it can take some time to adapt to the new contours of the obturator. Generally, the first visit about 2 weeks following insertion of the definitive obturator is indicated, then every 2 to 4 weeks until the patient is comfortable (▶ Fig. 39.5, ▶ Fig. 39.6, and ▶ Fig. 39.7).