Hollowing of Obturators for Post-Mucormycosis Maxillary Defects: Technique Based Case Series

Introduction

Maxillofacial defects may be congenital or acquired in nature. Acquired defects are mostly due to trauma, tumor or infection and the resulting surgical intervention often results in severe disfigurement and functional impairment.^1,2 Systemic conditions like high glucose levels, diabetic ketoacidosis, and increased steroid therapy are common aggravating factors for infections from bacteria, viruses, and fungi due to compromised cellular mechanisms.³ Post COVID-19, there have been a rise in number of defects in the maxillofacial region due to mucormycosis. Such patients suffer from difficulty in chewing, swallowing, have an impaired speech and facial disfigurement.⁴

Maxillary obturator prosthesis serves to close the large maxillectomy defects after surgical reconstruction, thus ensuring restoration of function, tissue continuity and natural facial appearance. Unsupported weight of the prosthesis on defect side compromises the retention of the prosthesis. Following case series presents various techniques adopted to reduce the weight and enhance the retention of maxillofacial prosthesis.

Case Presentation

Four patients, two partially and two completely edentulous patients with completely healed maxillectomy sites due to mucormycosis visited the department for treatment. These cases were treated for closure of the maxillary defects using various techniques for fabricating a hollow bulb obturator prostheses. All the patients gave informed consents for the purpose of the study.

Case Report 1

First patient was a 69 year old male with chief complaint of missing teeth and defect in the left side of upper arch (Figure 1a). The patient was a known diabetic since 7-8 years and had undergone left endoscopic debridement with sublingual inferior partial maxillectomy under general anaesthesia (GA) for sino-nasal mucormycosis with defect not crossing the midline and hence could be classified as Aramany’s Class I defect.⁵ The defect line was well healed and a cast partial denture (CPD) with two hollow shims was planned for the patient to reduce weight.

The primary impression was made with alginate (Zelgan 2002; Dentsply, Delhi) and a custom tray was fabricated to which a secondary impression was made with alginate (Figure 1b, 1c). A CPD framework was designed, fabricated and tried for fit before jaw relation and try-in.

Single hollow shim to reduce the weight in large defect could not be given due to intervening CPD framework. So two hollow shims were planned to be fabricated using Chalian’s technique i.e. one for the defect and other for the area beneath teeth, which were later joined using self-cure acrylic resin.⁶

The steps for the occlusal hollow shim fabrication were as follows.

A bite was recorded using bite registration material (Huge) so as to re-orient the trial denture after shim fabrication. 2-3 mm of wax was carved out of the waxed up trial in the buccal and lingual region to make space for the heat-cure acrylic resin in the final prosthesis. Also, four orientation stops were left for stabilization of the shim during packing. After this, a putty index was made which was poured in modelling wax (Figure 1d,e).

A dental stone cast was obtained from the wax replica and was blocked out 2-3 mm beyond gingival zenith. 1-2 mm modelling wax was adapted over the walls and a putty index was made, which was kept over the selfcure acrylic resin packed in this region (Figure 1f). The remaining portion gave the exact dimension of the shim where in the lid was made of aluminium foil reinforced with self-cure acrylic resin (Chalian’s technique) (Figure 1g).

The steps in hollow shim fabrication for defect area - After blocking out the undercuts, five orientation stops for the shim were cut in a single sheet of modelling wax (Figure 1h). A 2 mm thick layer of self-cure acrylic resin was adapted over it with three supporting pillars to prevent sagging of the lid that was made using aluminium foil reinforced with self-cure acrylic resin.

Now, CPD framework and shim made for defect area were placed on the cast and interference between the two was checked and cleared out (Figure 1k). The occlusal shim along with the teeth was re-oriented on this cast using the bite that had been recorded after trial. The assembly was united using self-cure acrylic resin, after confirming the orientation using previously recorded bite-registration record (Figure 1l).

Flasking and dewaxing was done in conventional manner. During packing, it was ensured that the heat-cure acrylic resin flowed between the retentive loops of the CPD and also between the shims (Figure 1m). A final finished and polished single piece hollow obturator weighing 42 grams was fabricated and delivered to the patient (Figure 1n, o). Figure 1p shows post-operative intra-oral photographs of the patient.

Limitation of the technique

Fabrication procedure and re-orientation of the two shims (occlusal part and obturator part) before packing was complicated.

Case Report 2

The second patient was a 54 year old male who underwent endoscopic debridement and right inferior partial maxillectomy due to post-COVID mucormycosis. The patient had a history of diabetes mellitus, hypertension and coronary artery disease since five years. The defect did not cross the midline and hence was classified as Aramany’s Class I defect.⁵ Figure 2a shows preoperative intra-oral photographs of the patient.

The primary impression was made using alginate impression material (DPI Algitex®). After border molding the custom tray, a final impression was made using addition silicone putty and light body material (President) (Figure 2b, c). Cast surveying was done and it was decided to cast only the clasps rather than the whole framework so as to further reduce the prosthesis bulk as compared to the previous case and to reduce the complexity of two separate shims fabrication.

After the mouth preparation, light cure resin wax patterns for clasps were made (Figure 2d), invested and casted (Figure 2e). A temporary denture base was fabricated incorporating the cast-clasps after adaptation to their respective positions to record the jaw relation. Try-in was done, the cast-clasp assembly was separated from the denture base and was replaced with baseplate wax, leaving the defect area hollow for the adaptation of putty index. While making the index, a putty stalk was attached to help in stabilizing the index during packing (Figure 2f, g).

After dewaxing as shown in Figure 8a, a trial closure was done with silicone index and later the index was removed completely to fill the hollow space using common salt. After acrylization, the salt was removed by creating holes in the final denture base and were later sealed using self-cure acrylic resin (Figure 2h, i). The final prosthesis weighed 39 grams (Figure 2j).

Case Report 3

A 47 year old female patient reported to the department with chief complaint of missing teeth and inability to eat food. She had a history of diabetes mellitus and hypertension since five years. Oral examination revealed that the patient had completely edentulous maxillary and mandibular arches with Aramany’s Class I defect on the right side of the maxilla, not crossing the midline.⁵ (Figure 3a) The patient had undergone endoscopic debridement with maxillectomy under GA due to sino-nasal mucormycosis. A complete denture hollow obturator prosthesis was planned for the patient.

The final impression was made using President putty and light body impression material in a border molded custom tray fabricated on a primary cast obtained from alginate primary impression (Zelgan 2002; Dentsply, Delhi) (Figure 3b, c).

After jaw relation and try-in, the acrylic denture base was cut from the defect (Figure 3d) and wax was scooped out from the occlusal portion in residual ridge region. On the defect in the cast, single sheet of baseplate wax was adapted with four orientation stops carved out for shim stabilization (Figure 3e). Layer of self-cure acrylic resin was adapted over the wax spacer in the trial denture. These two self-cure resin halves were then joined together with self-cure acrylic resin to obtain the hollowed shim (Figure 3f).

After conventional wax-up, flasking and dewaxing was done. Hollow shim prepared for the defect was stabilized in the defect over a layer of packed heat-cure acrylic resin and further packing was done in conventional manner. The finished and polished complete denture obturator prosthesis weighed 33 grams (Figure 3g, h).

A 61 year old diabetic female reported to the department with a post COVID-vaccination mucormycosis history. The oral examination revealed completely edentulous maxillary arch with defect on the right side not crossing the midline i.e. Aramany’s Class I defect and completely dentulous mandibular arch (Figure 4a). The patient had undergone endoscopic debridement with right total maxillectomy under GA due to rhino-orbital mucormycosis. It was planned to rehabilitate the patient with a complete denture hollow obturator prosthesis.

The steps followed for the fabrication were as follows.

After primary and secondary impressions as in previous case, jaw relation and try-in were carried out (Figure 4b, c). The denture base in the defect region was completely cut out and was replaced with wax for making a putty index (President). Putty stalk was also made for stabilization (Figure 4d). Flasking and dewaxing was carried out in the conventional manner.

Discussion

Mucormycosis is an opportunistic fungal infection which is caused by fungi Mucormycetes, which is fulminant and has a high mortality risk. One of its most commonly found type is Rhino-cerebral (sinus and brain) mucormycosis which can even spread up to the brain via paranasal sinuses. This type is most common in India and diabetes mellitus remains the leading predisposing factor accounting up to 88% of rhino-cerebral mucormycosis cases.^7-9 The risk further increases with corticosteroids used for managing cytokine storm associated with COVID-19.^9-11

This case series presents four cases with a common history of uncontrolled diabetes mellitus and mucormycosis that warranted surgical resection of maxilla including alveolar bone, teeth and soft tissues. The problems encountered post resection are altered facial appearance, difficulty in mastication, swallowing, speech. This causes psycho-social insecurity in such patients and lowers their self-confidence.⁷ Such defects require rehabilitation using obturator prosthesis that separate the communication established between the oral cavity and nasal cavity after the surgical resection to improve mastication, swallowing and speech. Large defects and absence of multiple teeth compromise the retention and prognosis of such cases. In such cases, undercuts in defects need to be engaged for augmenting retention. Reducing the weight of the appliance by making hollow obturators can significantly improve retention, comfort and prognosis of such prostheses.⁷ In past, obturators have been made hollow by using salt, jaggery, soap, plaster, sugar, and pumice, etc. as spacers which are removed after acrylization or alternatively a separate heat-cure or self-cure acrylic lid is fabricated, which is later sealed onto the defect in the prosthesis.^12-16 

These techniques involve sealing of two piece or spacer removal holes which might lead to leakage at some point promoting moisture and microbial growth in hollow part.¹⁷ One piece prosthesis with hollow shim packed during acrylization (Chalian’s technique) takes care of this limitation.⁶ This case series has presented various procedural modifications required for the hollow shim fabrication necessitated by varying clinical defects size and location, mode of prosthesis retention and fabrication. Fabrication of hollow bulb obturators in such patients helped in reduction of prostheses weight, hygiene maintenance facilitation and improved speech intelligibility. This helped in improving the patients’ mastication, deglutition and improved the social interaction while boosting their confidence.

Conflict of Interest

Nil

Acknowledgement

Nil