|Year : 2013 | Volume
| Issue : 1 | Page : 39-42
Silicone obturator: As an aid for retention of interim prosthesis in edentulous maxillary defect
Suresh Venugopalan1, KS Kiran Kumar2
1 Department of Prosthodontics, Saveetha Dental College, Chennai, India
2 Department of Prosthodontics, Malabar Dental College, Malappuram, Kerala, India
|Date of Web Publication||22-Aug-2013|
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A maxillofacial prosthesis intends to replace missing oral or facial structures and its associated functions, but the restoration gets complicated when patients are subjected to en bloc surgical removal of oral and facial structures due to metastasized neoplasm. The post-surgical radiation therapy may hold-up reconstructive procedures and implant therapy. Conventional hollow obturators constructed out of polymethyl methacralate can be reliable interim prostheses. However, whether an edentulous maxillary defect can retain a long serving interim prosthesis is questionable. In this case report, the advanced room temperature vulcanizing silicone material was used to construct the hollow obturator and the same was employed as a long serving retentive aid for the interim prosthesis in an edentulous maxillary defect.
Keywords: Hollow bulb obturator, maxillectomy, oro-antral communication
|How to cite this article:|
Venugopalan S, Kiran Kumar K S. Silicone obturator: As an aid for retention of interim prosthesis in edentulous maxillary defect. SRM J Res Dent Sci 2013;4:39-42
|How to cite this URL:|
Venugopalan S, Kiran Kumar K S. Silicone obturator: As an aid for retention of interim prosthesis in edentulous maxillary defect. SRM J Res Dent Sci [serial online] 2013 [cited 2021 May 8];4:39-42. Available from: https://www.srmjrds.in/text.asp?2013/4/1/39/116832
| Introduction|| |
In a society that values facial appearance, disfigurement of the same becomes socially unacceptable hence, the maxillofacial prosthesis, which restores or replaces the stomatognathic system and associated facial structures must be constructed with utmost care. The common etiologies for acquired defects of the oral cavity are cancer and traumatic injury.  Tumors occurring in the maxilla and associated structures can be benign or malignant, but the ablative surgery due to malignancy may remove varying portions of the maxilla. This loss of the maxilla results in a series of defects with differing complexity ranging from Classes 1 to 4: Class 1 - maxillectomy without an oro-antral fistula, Class 2 - low maxillectomy not including, orbital floor or contents, Class 3 - high maxillectomy involving orbital contents and Class 4 - radical maxillectomy including orbital exenteration.  The Class 3 and 4 maxillectomy defects crossing the facial midline and involving the orbital floor possess a greater challenge for both the reconstructive surgery using iliac or fibula grafts as well as the prognosis.  The resultant maxillary or soft palate defect and an oro-antral communication will impair speech, functions of mastication, and deglutition. 
The acquired defect in a partially edentulous patient can be obturated using a definitive prosthesis, which derives valuable retention and support from the remaining natural teeth and tissues, whereas, in completely edentulous arches with oro-antral communication retaining prosthesis is complicated. 
With the advent of implants and magnets, the construction of a definitive prosthesis can be made possible in edentulous arches. However, during the post-surgical period and radiotherapy, the healing of the surgical site and the mode of retention for the interim prosthesis requires priority. ,,
| Case Report|| |
A 62-year-old male patient was referred to the department of prosthodontics for a surgical stent. The medical records showed that the patient was diagnosed with metastasized sino-nasal malignant carcinoma involving the left maxilla, associated maxillary sinus structures, as well as the orbital floor. The surgeon's treatment plan was to do a complete resection of the left maxillary sinus, an exenteration of the left orbit (en bloc removal of the entire orbit involving partial or total removal of the eye) and a hemi-maxillectomy of the neoplastic maxilla [Figure 1].
Immediate surgical stent
On pre-surgical oral examination, the patient was completely edentulous in relation to both arches. Therefore, using irreversible hydrocolloid impression material, a diagnostic impression was recorded. The extent of maxillary surgical resection was marked on the cast and arbitrarily scored for 2 mm depth. A surgical stent was then fabricated using auto-polymerizing resin. At the flanges of the surgical stent, holes were drilled using a No. 6 round bur. It was then subjected to a chemical disinfection using 2% alkaline glutaraldehyde solution and stored in a diluted betadine mouthwash solution.
The en mass surgical resection on the left side of the face was performed on the surgical table beginning with the maxillary alveolar bone and up to the superior orbital rim. The surgical stent constructed from pre-surgical impressions was then stabilized and retained in its planned position using suture material, which secured the flanges with the mucosa. Post-surgically, the patient was subjected to 60 cGy of radiation therapy for a period of 4 weeks; and 6 such cycles were planned spanning 8 months due to the severe metastatic nature of the carcinoma.
Interim room temperature vulcanizing silicone obturator prosthesis
Two weeks from the day of surgery, an impression of the maxillary arch with defect was recorded using irreversible hydrocolloid impression material and a cast was constructed. The defect area was completely waxed up (up to 3 mm) on the definitive cast. A mechanical groove extension encircling the orifice of the defect was crafted on the wax. On the land of the cast boxing wax was adapted circumferentially and dental plaster mix was incrementally poured to obtain the plaster index [Figure 2]. The cast and index was placed inside hot water bath for 5 min to eliminate the wax and was then separated with ease. Mould-releasing aerosol (Factor II Inc. A-503) was sprayed on to the master cast and the index. Then, the RTV silicone material (Factor II Inc. A-2000 platinum) was packed into the defect area and the plaster index was repositioned back into the master cast. The re-orientation of plaster index to master cast was also verified using keys scored on its land area. After an overnight curing at room temperature and a short curing cycle at an elevated temperature of 74°C inside the hot air oven for 3 hours, the mold was allowed to return to room temperature [Figure 3]. The RTV silicone obturator was then retrieved from the mould. Silicone trimming wheels with varying coarseness were used sequentially to obtain the final finished and polished silicone obturator (3 M Trimming wheel no. 5115, 5114, 5113, 5112 - Factor II Inc., USA).
A mixture of dental plaster and pumice of 1:1 ratio was placed inside the silicone obturator to prevent any ingress of unwanted acrylic resin, which will also aid in easy retrievability of the denture base [Figure 4]. The denture base was constructed using auto polymerizing resin (Clear resin, Dental Products of India, Mumbai), which mechanically engaged the grooves that were present on the orifice of the silicone obturator. Upon flushing the plaster pumice mix, we obtained a hollow bulb silicone obturator mechanically separable from the denture base.
Thus, a completely edentulous denture base with a hollow RTV silicone bulb was fabricated. In this, the mechanical groove at the orifice will aid in retaining the maxillary denture base towards the tissue surface [Figure 5]. The patient was given post-insertion instructions and advised a compulsory maintenance phase involving regular cleaning of the intra-oral wound and the interim silicone prosthesis using 1% povidone-iodine solution. Patient was also recalled and reviewed at regular intervals.
| Discussion|| |
Retention of maxillary obturator in a completely edentulous patient with maxillary defect is usually compromised. This is because there is lack of both hard-and soft-tissue supports unlike the partially edentulous arches, wherein the prosthesis derives a part of retention, support and stability from the remaining natural teeth. An ideal way to obtain support/stability/retention for the obturator in the completely edentulous ridges is by placing implants in pre-maxilla, tuberosity or the vomer bone. The decision of placing implants in irradiated patients and their success rate depends on many factors such as radiation dose, number of radiation cycles, the area of radiation, and the systemic condition of the patient. A systematic review conducted by Ihde et al. concluded that implants placed in irradiated bone exhibited 2-3 times greater failure rates compared to non-irradiated bone and also with doses of 50 Gy or more having a higher failure rate.  Furthermore, implants placed in the maxilla had a higher failure rate compared to mandibular irradiated bone.  The implant retained obturator prosthesis therapy has a better success rate for patients with congenital defects, minimum acquired defects, or/non-metastasized malignant carcinomas, which are not subjected to radiation therapy after the surgery. ,,
Although, certain studies indicate implant osseo-integration and prosthetic loading in maxillectomy patients. The time span reported for such complete process is long (12-18 months post-surgically). Hence, a well-retained/stable/supported interim obturator plays a more vital role during the transition from the interim prosthesis to the definitive prosthesis. 
In this case report, the interim obturator constructed using RTV silicones was engaged into the undercuts along the lines of palatal resection, the nasal and paranasal cavity, the medial wall of the defect and also to the band of buccal scar tissues. Since, the RTV silicone obturator material is very resilient, the depths of the undercuts of the defect are firmly engaged. This results in the increased surface area, which can be used for better retention of the interim obturator fabricated for a completely edentulous patient with maxillary defect [Figure 6]. ,
The hollow silicone obturator is light weight. Therefore, the heaviness of the prosthesis in the patient's mouth is greatly reduced, and also, the patient's speech, deglutition, and comfort level is commendable [Figure 7]. ,
|Figure 7: Intraoral view of silicone obuturator and also aiding in retention of interim prostesis|
Click here to view
The silicone obturator is flexible and can be slowly teased out from the defect socket. It is also mechanically detachable from the denture base thereby making the prosthesis easier to remove and insert while maintaining the hygienic property of the prosthesis [Figure 8]. 
|Figure 8: Mechanically separable silicone obturator from interim prostheis|
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| Conclusion|| |
Thus, in cases of completely edentulous arches with acquired maxillary defect when the chances of reconstructive surgery, implant placement or osseo-integration are less, owing to the post-surgical radiation therapy, the denture base with hollow RTV silicone obturator can be a simple and/clinically approachable solution to interim prosthesis construction.
In Class 3 or Class 4 edentulous maxillary defects crossing facial mid-line, where interim prosthetic retention is questionable, the resilient RTV silicone material as an obturator and a mechanical retainer for both the defect and the denture base, respectively, can be practical.
Once the patient is medically fit, the facial aesthetics, orbital function, and oral rehabilitation can be achieved using reconstruction procedures and implant definitive prosthesis.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]