Definitive Maxillary Obturator Prostheses
Naveen YG, Rajesh Sethuraman, Paranjay Prajapati
Goal of prosthodontics is rehabilitation of missing oral and extra oral structures with restoration of normal function of mastication, speech, swallowing, appearance etc. Malignancies are common in oral region, which are treated through surgical intervention. Surgical intervention creates anatomic defect which forms communication among the oral cavity, nasal cavity and maxillary sinus. In such cases it is very difficult for the patient to perform various normal functions like mastication, swallowing, and speaking etc. Prosthodontic rehabilitation with obturator prosthesis restores the missing structures and act as a barrier between the communications among the various cavities.
Keywords: Obturator, Oro antral communication
Ablative surgical therapy is frequently adopted for the control of malignancies and other abnormal growths within the maxillary sinuses. This creates an anatomic defect that allows the oral cavity, maxillary sinus and nasal cavity to become one compartment(1). Prosthetic rehabilitation with obturator prosthesis is a predictable intervention to recreate an anatomic barrier between the cavities and to restore functional capabilities of speech, oral food intake and deglutition(2).
Rehabilitation of the maxillectomy defect has been well defined for prosthodontists and surgeons (3-7). All prosthodontists are aware of the basic objectives of prosthodontic therapy. The degree of extension into the defect varies depending upon the configuration of the defect, character of its lining tissue, and functional requirements for retention, support, and stabilization of the prosthesis(3). In large defects lacking palatal support, the obturator is aggressively extended vertically to engage the surgical defect and horizontally to the lateral aspect of the orbital floor, at the expense of its size and weight. Remaining structures are subjected to continuous stresses from such large, heavy obturator, jeopardizing the health of the tissues, and compromising patient function and comfort(4,5). To reduce the weight of the prosthesis, the bulb portion of the obturator is generally hollowed after it has been processed into acrylic resin. Weight reduction is especially important when the obturator prosthesis is suspended without bony or posterior tooth support on the defect side, as is the case with most maxillary resection prostheses(6). A hollow maxillary obturator may reduce the weight of the prosthesis by up to 33%, depending upon the size of the maxillary defect(7).
A 52-year-old male patient reported to the prosthodontic department of K.M.Shah Dental College and Hospital, Vadodara, Gujarat, for replacement of his existing obturator. The patient’s medical history revealed that he had under gone a surgical intervention with left sided modified neck dissection sparing IJV and spinal accessory nerve with left sided hemi mandibulectomy sparing the condyle and left sided maxillectomy due to squamous cell carcinoma affecting that particular region. Later, the defect was obturated with the help of an interim obturator. The intra-oral examination revealed a total maxillectomy of the left side. The presented defect situation corresponded to a Class I situation (resection performed along the palatal
midline) according to the Aramany classification of defects(3). All walls of the defect were lined with healthy mucosal graft. Tongue function was normal, and speech was altered without the obturator and considered fair with the prosthesis in place. The patient indicated that the prosthesis was not retentive and stable.
He was also not satisfied with esthetics. Only right quadrant teeth were present in both maxilla and mandible. On examination, it was found that the prosthesis was an interim obturator, not a definitive obturator
For this patient there was no alternative left other than prosthetic obturation with a definitive obturator. Considering stability, retention, load distribution and supra structure longevity, the decision was made to rehabilitate the patient with a hollow bulb obturator with the cast metal framework. As per design principles given by Aramany in 1978 for Class-I maxillectomy defect, a linear design for class-I defect was selected for this case(4). Where support was obtained from remaining palatal tissue and retention was achieved from the embrasure clasps made on the remaining premolars and molars. Bracing was achieved by extending the major connector till the palatal surfaces of the remaining natural teeth.
After the required intra-oral examination, preparation of rest seats on 16 and 17 and 14 and 15 was done to receive embrasure clasp of cast metal framework .
1. A cast metal framework was fabricated [Fig. 1] and checked intra-orally for retention and fit.
Figure 1 - Cast metal framework
2. The framework was used to make special tray, border molding was done and final pick-up impression was made.
3. Master cast was made with die stone. Master cast was duplicated after blocking out undesirable undercuts. Using this duplicate cast heat cured acrylic shim was constructed
4. The shim was attached to metal frame work, wax up and teeth setting was done and trial obturator was tried in the patient’s mouth [Fig. 2].
Figure 2- Waxed up trial obturator
5. Waxed up obturator was flasked, dewaxed and packed using heat cure acrylic. Table salt was incorporated in between shim and newly packed acrylic. After processing, salt was removed by creating two holes on the polished surface and injecting water till all salt was removed creating a hallow bulb. The obturator was finished and polished, [Fig. 3] inserted in the patient’s mouth to check adaptability.
Figure 3 – Final prosthesis
6. The post insertion follow-up and patient care were carried out at the prescribed intervals of time, which revealed that the patient was thoroughly satisfied and extremely comfortable with the functioning and esthetics of the prosthesis. There were no complications.
In dentate patients, primary retention, support, and stability of an obturator depend on the number and distribution of remaining teeth . Engagement of soft tissue undercuts including the scar band at the skin graft-mucosal junction, may also play a significant role particularly in edentulous patients(8). Wide surgical resections for the control of malignancies frequently result in a small number of remaining unilaterally clustered teeth(1). These remaining teeth serve as abutments for the obturator and are subjected to constant, nonaxial, cantilever forces(9,10). The skin graft-mucosal junction scar band will also stretch out over time and become ineffective in helping to retain the obturator.
The weight of an obturator can be significantly reduced by hollowing out the bulb(11).The importance of this procedure can be neglected and compromised due to restricted access and the difficulty of hollowing out the bulb(12,13). Using this technique, the thickness of obturator walls and palate are reduced to less than 1 mm, resulting in a significant decrease in weight. Vertical and horizontal extension of the lateral walls of the obturator can be maximized without additional increase in weight. The degree of obturator movement is minimized by improving obturator–tissue contact superior laterally(8). Abutment teeth and soft tissue undercuts will be subjected to less stress to meet the primary goal of prosthodontic rehabilitation, “preservation of the remaining structure” (14).
Structural durability is mandatory for longevity of the prosthesis. In these patients, chewing function is confined to the nonsurgical side due to the lack of support on the surgical defect side. The bulb portion of the obturator is designed so that the 3D configuration of congruous vertical and horizontal walls offset crack development and fracture propagation. Tensile stress accumulation developing along the midline of conventional complete dentures(15) resulting in fatigue fracture is not a problem in the case of maxillary obturators.
A stable record base is critical for recording an accurate maxillomandibular relationship and in evaluation of the esthetics and phonetics of the wax trial prosthesis (16, 17). The fit and stability of the record base for an obturator, however, is often compromised because of the size of the surgical defect and is further compounded by the need to block out undercuts and by under-extended borders. Conventional record bases can rotate into the defects when attempting the centric relation record, resulting in an inaccurate record. A processed record base provides maximum support, retention, and stability for a maxillofacial prosthetic patient(17) and additional steps of relining the record base with silicone resilient materials can be avoided(18).
Depending upon the nature of the defect, movement of the obturator varies and creates soreness and discomfort for the patient. These pressure sores are adjusted at the post insertion and subsequent follow-up appointments. To avoid the risk of perforation of the bulb, final contouring is accomplished after the patient is completely comfortable with the new obturator prosthesis. Patient benefits from the reduced weight of the obturator offset the costs and additionally incurred laboratory procedures for two-stage processing. Employing a lower temperature and a longer processing cycle than that used to process the record base minimizes dimensional change of the record base(19,20).
1. Naveen.Y.G, Senior Lecturer
2. Rajesh Sethuraman, Assistant Professor
3. Paranjay Prajapati, Post graduate Student, Department Of Prosthodontics, K.M. Shah Dental College, Vadodara, Gujarat, India.
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Address for correspondence Dr. Naveen.Y.G Flat no-9, Gokulash apartment, Near deluxe char rastha, Nizampura, Vadodara Gujarat PIN-390002 Mob No- 09725036672
Source of Funding: Nil Conflict of interest: None Declared
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