Key Messages: The light weight of the hollow bulb obturator does not add to the self-consciousness of physiologic changes in muscle balance and it also does not cause excessive atrophy in muscle balance[N1] . Decreased weight of prosthesis positively affects one of the fundamental problems in retention leading to improved physiologic function.
Fabrication of prosthesis for an edentulous patient with a large maxillary defect will challenge the skill of even the most experienced clinicians. With any size palatal perforation, retention in the classical sense of complete denture prosthesis is impossible. Several methods have been described for open and closed hollow bulb obturator fabrication. Both of these types of obturators are lightweight prostheses that can be easily tolerated by the patient (1-3). The bulb portion, which accommodates the defect area must add to the retention and stability by extending adequately into the defect to achieve a seal (4,5). However, greater extension means additional weight to the prosthesis and with the gravitational force; these forces may exert a dislodging force on the obturator (4). This article describes a double investment and double curing technique of fabricating a single piece hollow bulb denture obturator in a completely edentulous patient with partial maxillary resection.
A 62 year old male patient was referred to the Prosthodontic Department of Government Dental College and Hospital, Ahmedabad, Gujarat, for restoration of a left side maxillary defect created after surgical intervention. The patient’s medical history revealed that the patient had undergone surgery for a squamous cell carcinoma on the left side of the maxilla 14 months ago. The patient had used an interim obturator without teeth incorporation for the past 8 months. On intra oral examination, the defect was extending medially from the buccal mucosa to the midpalatine region and anteriorly from the canine region to the posterior extend of the hard palate, involving some part of the soft palate (Fig. 1). The patient presented with an obvious and typical nasal twang and he was experiencing difficulty in speech and deglutition. Extra oral examination exhibited sunken appearance on left side of face due to hemi-maxillectomy.
Figure 1. Intraoral view of the defect
A preliminary impression was made using putty body of rubber base impression material (Speedex, Coltene, Whaledent product, Switzerland) in a non-perforated stock metal tray(Jabbar &company, Worli, Mumbai, Maharashtra) to record the extension of the defect (Fig. 2). Then primary cast was poured.
Figure 2. Primary impression of the defect
Figure 3. Final impression of the defect
Figure 4. Final cast of the defect
Figure 5. Subsequent to first dewaxing 2 mm thick wax up on master cast
Figure 6. Second dewaxing for denture base fabrication of the defect
Figure 7. Heat cure denture base for hollow bulb fabrication
Figure 8. Salt crystals in base of the defect for hollow bulb fabrication
Figure 9. Cellophane sheet over salt crystals for
Figure 10. Single piece hollow bulb denture obturator
Figure 11. Denture obturator in patient’s mouth
The present double investment technique for hollow bulb obturator has several advantages over the other techniques described so far. Because of prior curing of 2 mm thick denture base, the salt crystals do not glue to the unpolymerized acrylic resin in dough stage, resulting in complete removal of salt crystals during trial closure. This technique maintains the integrity of the obturator during final closure. It also avoids the tedious work of removing salt crystals from partially polymerized acrylic resin. As the chemically cured acrylic resin is proven to be carcinogenic and causes primary intraosseous carcinoma (PIOC) or squamous cell carcinoma in patients (6) , in this double investment technique, chemically cured acrylic resin was not used for closing the holes created while removing salt crystals after curing the prosthesis as in other techniques.
Design & type of the obturator prostheses vary according to the location and extent of the defect (7-10). Owing to the simplicity of fabrication and maintenance, maxillary obturator prosthesis is a more frequent treatment option than surgical reconstruction (11-14).
For favorable retention, stability, support, patient comfort and cleanliness, the obturator prosthesis should be light in weight. Increased weight of the obturator prosthesis is usually a foremost concern to the prosthodontists. When we review the previous literature, there are various techniques of hollow bulb fabrication in which it is proved that, by reducing the weight of the obturator through making it hollow, preservation of the existing residual alveolar ridge & defective margins is possible.
Hollow bulb obturators assign fabrication of the lightweight prosthesis that is readily tolerated by the patient, while effectively extending into the defect (1-3).
The material used for fabrication of hollow bulb obturator should be biocompatible with the oral structures. Hollow bulb obturator reduces the weight of the acrylic resin. In that way, patient becomes comfortable with the prosthesis.
At a distance, from thorough knowledge and skills of the prosthodontist, use of biocompatible materials & modifying the type of obturator also may be accepted by patients. By understanding the needs of the patient, clinicians can modify the technique of prosthesis fabrication for successful rehabilitation.
Authors are thankful to the Department of Prosthodontics, Government Dental College and Hospital, Ahmedabad -380016, Gujarat, India.
Conflict of interest: Nil
Funding information: Nil
Prostheses. J Prosthet Dent 1993; 70: 546-7