7 Maxillofacial Prosthetics

7

Maxillofacial Prosthetics

A hospital dental service is quite often called upon by the otorhinolayrngology, radiation therapy, speech pathology, head and neck surgery, plastic surgery and reconstructive surgery, or oral and maxillofacial surgery service to serve a supporting role in the care of the patient who requires a maxillofacial prosthesis, or to help in determining the treatment options for patients with a variety of intraoral or extraoral defects. These defects may be either congenital or acquired in their etiology. Similarly, the general dental resident might be called to assist an attending maxillofacial prosthodontist on the staff. Because dentists with formal maxillofacial training are not available in most hospitals, the general dental attending and resident staff should be familiar with the more common maxillofacial prosthetic problems and prosthesis.

Obturator Prosthesis: Types

Surgical Orburator

  • Sometimes referred to as an immediate obturator
  • Serves as a temporary prosthesis that is usually inserted in the operating room (theater) immediately following the surgical removal of a portion or all of the maxilla or surrounding osseous structures, including the alveolar bone
  • Functions to separate the oral and nasal cavities that would otherwise communicate with each other following surgery
  • Allows a patient to speak and swallow without the leakage of food and fluids from the mouth into the nasal cavity
  • Usually fabricated from polymethyl methacrylate (PMMA) with wrought wire clasps engaging the remaining teeth for retention
  • In edentulous situations, retention is gained by extension into the tissue undercuts created by the surgical resection
  • Usually removed seven to 10 days post-resection and modified as needed as the patient continues to heal
  • Eventually replaced with an interim or definitive obturator to restore the maxillary defect

Interim Obturator

  • Replaces the surgical obturator after the completion of initial healing following a maxillary resection, or if no further surgery is required
  • Function is similar to that of the surgical obturator. Most commonly separates the nasal, antral, and oral cavities, thereby improving a patient’s ability to speak and swallow after surgery. Maxillofacial prostheses may separate the internal from external environment; for example, the nose and paranasal sinuses from the orbit
  • May have a cast metal framework or be fabricated from PMMA with wrought wire clasps for retention to teeth. With the advent of implants, these may be retained via precision attachments secured to intra- and extra-oral implants
  • As the margins of the surgical defect become more stable, teeth may be added, although an interim obturator may also require frequent modification
  • Usually used no longer than six to 12 months and is replaced by a definitive obturator once the resection site has fully healed or no further surgery is anticipated

Definitive Obturator

  • Often referred to simply as an “obturator.” Its function is to separate the oral and nasal cavities to allow the patient to eat and drink without nasal regurgitation. Also reduces the hypernasality of speech following maxillary resection. Yet, maxillofacial prostheses may also assist with closure and separation of a variety of cutaneous, mucosal, and skeletal craniomaxillofacial defects
  • Used to prosthetically rehabilitate all or part of a maxilla and the associated structures removed during surgical resection
  • Usually placed after nine to 12 months, once healing is complete
  • Fabricated from a cast metal base (chromium–cobalt or titanium alloy) with cast clasps for retention. PMMA is processed to obturate the defect and provide soft tissue support. With the development of newer material, soft lined obturator prostheses are available. Prosthetic teeth are added for esthetics and speech. Usually there are light or no occlusal contacts on the resected side of the prosthesis
  • In edentulous patients the undercuts within the defects are engaged for retention. Resilient polymer material may be processed into the undercut areas to improve retention
  • Osseointegrated implants also may be placed into the alveolar bone in the non-resected maxilla for additional retention and stability in the edentulous resection patient

The Maxillary Resection Patient

Etiology and Incidence

A maxillectomy is often necessary for benign and malignant tumors of the maxillary sinus, hard palate, and often the soft palate. The extent of the surgery depends upon the size and pathology of the tumor.

It is rare to have a primary tumor of the gingiva covering the hard palate. Palatal tumors most often arise in the sinus and spread inferiorly through the sinus floor. They include:

  • Squamous cell carcinoma (the most prevalent type, at approximately 80%)
  • Adenocarcinoma
  • Minor salivary gland tumors

Suspected etiologic agents/predisposing factors:

  • Exposure to certain metal powders (chromium) or sawdust (furniture workers), chronic snuff use
  • Chronic sinusitis, nasal polyps
  • Ethanol
  • Tobacco products

Diagnosis/Clinical Presentation

  • Medial extension (into nasal cavity): Nasal discharge, congestion, epistaxis
  • Inferior extension (into oral cavity): Palatal swelling, loosening of maxillary teeth, ulceration of mucosa, ill-fitting dentures
  • Superior extension (into orbit): Orbital swelling, diplopia, epiphora, proptosis, unilateral fixed glaze
  • Anterior extension: Facial swelling, lack of sensation in skin, unilateral pain
  • Posterior extension: Otoalgia, trismus

Rationale for Immediate Obturation

Function

  • Maintain palatal contours after surgery
  • Provide a matrix to hold surgical packing against defect
  • Immediate speech improvement
  • Improve deglutition
  • Improve oral nutritional intake (nasogastric tube may be removed earlier)
  • Protect nasal tissues from contents of oral cavity

Psychology

  • Esthetics improved as teeth may be replaced
  • Phonetics are improved to permit intelligible communication
  • Defect is not as readily sensed by patient
  • Provides support and normal contours to soft tissues of face

Hygiene

Oral and nasal cavities are separated, thus preventing nasal regurgitation of food and liquids. This also maintains these two ecological units with their different bacterial flora.

Presurgical Treatment Planning

There is often very little time between the request for a dental consultation and the actual surgical procedure. It is imperative that a proactive working relationship exist between the dental service and the requesting surgical service. This allows for a thorough discussion of the proposed surgical resection, with consideration given to improving the postsurgical prosthetic rehabilitation.

Initial Dental Evaluation

  • Review the history of the present illness, past medical and surgical history, social history, and alcohol and tobacco use for information relevant to the condition and prognosis
  • Review the prior dental history:
    • Hygiene regimen
    • Frequency and nature of past dental care
    • Prior experience with removable dental prostheses
  • Obtain orthopantomographic and periapical radiographs to evaluate the teeth to be used for abutments, and plan appropriate treatment of carious and/or periodontally involved teeth. The potential for implant support can be considered at this time
  • Obtain intraoral and extraoral presurgical photographs as part of the patient’s medical record
  • Fixed dental bridgework may need to be sectioned if it spans a region where a surgical resection will be made
  • Obtain two sets of impressions (both maxilla and mandible) and pour both in dental stone. Obtain an interocclusal record:
    • Impression trays may require modification with wax or compound to accommodate all landmarks if tumor is extensive
    • One set of casts serves as diagnostic casts
    • One set serves as working laboratory casts
  • Abutment teeth should be identified to retain the surgical prosthesis. Modifications should be made to improve retention if indicated:
    • Survey appropriate undercut regions
    • Recontour teeth to improve undercuts
    • Restorations may be placed to alter undercuts
    • Consider dimples, grooves, and rests for additional retention
  • Consider implants
  • Select and record the appropriate mold and shade of teeth if they are to be included on the prosthesis
  • If a resection of extraoral facial tissues is anticipated, a facial moulage (mold) also may be obtained; this is supported with a plaster or acrylic backing to prevent distortion. It will serve as a presurgical record for postsurgical prosthetic rehabilitation

Dental–Surgical Treatment Planning Analysis

The member of the dental service responsible for the patient’s care should meet with a member of the surgical service performing the maxillary resection to discuss the planned procedure and any possible deviations from the plan that may be anticipated. The articulated diagnostic casts and radiographs should be available for the team to thoroughly discuss the patient’s condition and surgical/rehabilitative plan. The definitive rehabilitative plan should be developed before surgery.

The surgeon should outline on the cast the proposed incisions. The dentist should advocate the following points:

  • Consideration should be given to retaining as many sound teeth as possible without compromising disease-free surgical margins
  • Osseous structures should be preserved (i.e., anterior hard palate) if possible, again without compromising disease-free surgical margins
        If implants are considered, they should be placed at the time of surgery, before permanent bone damage from therapeutic radiation.
  • The incisions should be made through a socket where a tooth has been extracted to increase the support around the terminal abutment tooth.

The need for supplemental retention by transosseous or interdental wire, or preferably titanium screw fixation, should be discussed for edentulous patients. These include transalveolar vs. circumzygomatic vs. piriform aperture vs. interdental vs. palatal screw placement.

If postsurgical radiation therapy is anticipated by the surgeon or oncologist, teeth with a questionable prognosis should be removed in time to allow for healin/>

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Jan 12, 2015 | Posted by in Oral and Maxillofacial Pathology | Comments Off on 7 Maxillofacial Prosthetics
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