A note on Obturator prostheses for hemimaxillectomy patients

              
Introduction
Probably the most common of all intraoral defects are in the maxilla, in the form of an opening into the antrum and nasopharynx. Defects in the maxilla may be divided into these defects resulting from congenital malformations and the acquired defects resulting from surgery for oral neoplasms. This note considers the rehabilitation of acquired defects of the palate which are the result of trauma, disease, pathological changes, radiation burns, or surgical intervention. The opening produced may be quite small or it may include any portion of the hard and soft palate, the alveolar ridges, and the floor of the nasal cavity.Post-surgical maxillary defects predispose the patient to hypernasal speech, fluid leakage into the nasal cavity, and impaired masticator function.
In the total rehabilitation of the maxillectomy patient, the maxillofacial-prosthodontist has two primary objectives:
• To restore the functions of mastication, deglutition,and speech.
• To achieve normal oro-facial appearance.


The prostheses needed to repair the defect is termed as a maxillary obturator. An obturator (Latin: obturare, to stop up) is a disc or plate, natural or artificial, which closes an opening or defect of the maxilla as a result of a cleft palate or partial or total removal of the maxilla for a tumour mass. The goals of prosthetic rehabilitation for total and partial maxillectomy patients include,

• separation of oral and nasal cavities to allow adequate deglutition and articulation
• possible support of the orbital contents to prevent enophthalmos and   diplopia
• support of the soft tissue to restore the midfacial contour
• and an acceptable aesthetic results.


The indications for the use of an obturator:
An obturator may be used
    • To act as a framework over which tissues may be shaped by the surgeon.
    • To serve as a temporary prosthesis during the period of surgical correction.
    • To restore a patient's cosmetic appearance rapidly for social contacts.
    • When surgical primary closure is contra-indicated.
    • When the patient's age contraindicates surgery.
    • When the size and extent of the deformity contra-indicates surgery.
    • When the local avascular condition of the tissues contraindicates surgery.
       When the patient is susceptible to recurrence of the original lesion which produced the deformity .



The obturator fulfils many functions:

    • For feeding purposes, it may be used to keep the wound or defective area clean, and may enhance the healing of traumatic or post-surgical defects

    • It may help to reshape and reconstruct the palatal contour and/or soft palate
    • It improves speech or, in some instances makes speech possible
    • In the important area of esthetics, the obturator can be used to correct lip and cheek contour
    • It can benefit the morale of patients with maxillary defects
    • When deglutition and mastication are impaired, it can be used to improve function
    • It reduces the flow of exudates into the mouth
    • The obturator may be used as a stent to hold dressings or packs post-surgically in maxillary resections. It reduces the possibility of post-operative haemorrhage, and maintains pressure either directly or indirectly on split-thickness skin grafts, thus causing close adaptation of the graft to the wound which prevents the formation of a haematoma and ultimate failure of the graft.


Obturators for acquired defects of palate
Almost all acquired palatal defects are precipitated by resection of neoplasms of the palate and paranasal sinuses. The extent of the resection is dependent on the size, location, and potential behaviour of the tumour.
Prosthodontic therapy for patients with acquired surgical defects of maxilla can be divided into three phases of treatment with each phase having different objectives.


The surgical obturator
It is a base plate type appliance which is constructed from the pre-operative impression cast and inserted at the time of resection of the maxilla in the operating room.


The advantages of surgical obturation are as follows:

• The surgical obturator provides a matrix on which the surgical packing can be placed. The obturator maintains the packing in the proper relationship thus ensuring close adaptation of the skin graft to the raw surface of the cheek flap when grafting is used.
• The obturator reduces oral contamination of the wound during the immediate post-surgical period and may thus reduce the incidence of local infection.
• The obturator enables the patient to speak more effectively by reproducing normal palatal contours and by covering the defect.
• The obturator permits deglutition, thus the nasogastric tube may be removed at an earlier date.
• The obturator lessens the psychological impact of surgery by making the post-operative course easier to tolerate.
• The patient is reassured that rehabilitation has begun.
• The obturator may reduce the period of hospitalization.
• If desired, artificial anterior teeth may be added for aesthetics, so that when the patient recovers from the operation, the teeth and facial appearance are psychologically comfortable. The mental well-being of the patient is boosted considerably.

There are several principles relative to the design of surgical obturators

• The obturator should terminate short of the skin graft-mucosal junction.
• The obturator should be kept simple, lightweight and inexpensive.
• The obturator for dentate patients may be perforated at the interproximal extensions with a small dental bur to allow the obturator to be wired to the teeth at the time of surgery.
• Normal palatal contours should be reproduced to facilitate post-operative speech and deglutition.
• Posterior occlusion should not be established on the defect side until the surgical wound is well organized.
• In some patients, the existing complete or partial prosthesis may be adapted for use as an immediate surgical obturator. In edentulous patients, the existing prosthesis should be inspected carefully to ensure that it will adequately obturate the surgical defect. Often it is necessary to extend the prosthesis with autopolymerizing acrylic resin to cover the margin of resection on the soft palate. After the prosthesis is adjusted, it is relined with an intermediate reline material. It is wired or pinned to the alveolar ridge or zygomatic arches and/or anterior nasal spine and sometimes circumzygomatic and frontal wiring is employed to support the affected side. Clear resin is suggested so that the extensions and possible pressure areas can be more easily visualized at surgery.
• In dentate patients, retention may be obtained by wiring the prostheses to existing teeth. Retention from conventional clasp retainers may not be sufficient.
• The surgical obturator must not be removed for 7-10 days post-surgically.

The temporary obturator
The temporary obturator is constructed from the post-surgical impression cast which has a false palate and false ridge and generally has no teeth. The closed bulb extending into the defect area is hollow. The patient is usually seen every 2 weeks because of the rapid soft tissue changes that occur within the defect during organization and healing of the wound. The new lining material is placed or changed. It is best to remove all of the old interim lining material because of porosity, leading to bacterial contamination and precipitation of undesirable odours and mucosal irritations.
A definitive obturator is not indicated until the surgical site is healed and dimensionally stable and the patient is prepared physically and emotionally for the restorative care that may be necessary.
There are several reasons for constructing a new obturator. First, the periodic addition of interim lining material increases the bulk and weight of the obturator and this temporary material may become rough and unhygienic. Secondly, if teeth are included in the resection, the addition of anterior denture teeth to the obturator can be of great psychological benefit to the patient. Thirdly, if retention and stability are inadequate, occlusal contact on the defect side may result in improvement of these aspects.


The definitive obturator

 Approximately 6 months after surgery consideration may be given to the construction of a definitive obturator prostheses. It is constructed from the post-surgical maxillary cast. This obturator has a false palate, false ridge, teeth and closed bulb which is hollow. Often the temporary obturator will need to function comfortably for as long as 6 months. The timing will vary depending on the size of the defect, the progress of healing the prognosis for tumor control, the effectiveness of the present obturator, and the presence or absence of teeth. Changes associated with healing and remodeling will continue to occur in the border areas of the defect for at least 1 year. Dimensional changes are primarily related to the peripheral soft tissues rather than to bony support areas.
To reduce and improve adhesion and retention, a hollow obturator bulb is required for cleft palate prostheses and for dentures following maxillectomies.










General considerations concerning bulb design

•  A bulb is not necessary with a central palatal defect of small to average size where healthy ridges exist.
•  It is not necessary in the surgical or immediate temporary obturator.
•  It should be hollow to aid speech resonance, to reduce the weight on the unsupported side, possibly to provide facial aesthetics and to act as a foundation for a combination of extraoral prostheses in communication with the intraoral extension.
•  It should not cause the eye to move during mastication.
•  It should be one piece, if possible, to provide better colour matching and maximal patient acceptance.
•  It should always be closed superiorly. There are advantages and disadvantages to both forms (open and closed) of obturators. If the obturator is left open, nasal secretions accumulate leading to odour and added weight. If secretions do tend to accumulate, a small diagonal opening may be made between the inferior-lateral floor of the obturator through to the cheek surface for drainage. The other disadvantages of an open type hollow obturator include difficulty in polishing and cleaning the internal surface, from saliva, mucous crusts, food accumulation (unhygienic, foul smelling), and the inability to obtain support from the superior aspect in the defect area.
•  It should not be so large as to interfere with insertion if the mouth opening is restricted.

The advantages of a hollow bulb obturator

• The weight of the obturator is reduced, making it more comfortable and efficient.
• The lightness of the obturator improves one of the fundamental problems of retention and increases physiological function so that teeth and supporting tissues are not stressed unnecessarily.
• The decrease, in pressure to the surrounding tissues aids in deglutition and encourages the regeneration of tissue.
• The light weight of the hollow bulb obturator reduces the self-consciousness of wearing a denture.
• The lightness of the obturator does not cause excessive atrophy and physiological changes in muscle balance.

Numerous articles appear in the literature describing techniques for the fabrication of hollow obturators to decrease the weight of the prostheses and to make comfortable and well-tolareted prostheses . The construction of the definitive obturator will vary with the type of resection and the presence or absence of teeth. If the obturator is not properly designed and constructed, the stress on the remaining hard and soft tissues may be pathological and may lead to premature loss of abutment teeth and chronic irritation of soft tissues.
Movement of the obturator prostheses
The obturator may be displaced superiorly with the stress of mastication and will tend to drop without occlusal contact. The degree of movement will vary with the number and position of teeth that are available for retention, the size and configuration of the defect, the amount and contour of the remaining palatal shelf, height of the residual alveolar ridge, the size, contour, and lining mucosa of the defect and the availability of undercuts. Lack of retention, stability and support are common prosthodontic treatment problems for patients who have had a maxillectomy.
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