Fabrication of Hollow Maxillary Denture Using Caramel Spacer - an Innovative Method

Introduction

Extreme resorption of the maxillary denture bearing area may lead to problems with prosthetic Rehabilitation. Fabrication of complete denture in such cases result in a heavy maxillary denture, which can lead to poor denture bearing capacity i.e. decreased retention and resistance.¹ This problem can be overcome by reducing the weight of maxillary denture, by making it hollow. Denture can be made hollow by using a solid three dimensional spacer, including dental stone², cellophane wrapped asbestos³, silicone putty⁴, modelling clay⁵ or salt⁶ during laboratory processes to exclude denture base material from the planned hollow cavity of the prosthesis.
Holt et al⁵ processed a shim of indexed acrylic resin over the residual ridge and used a spacer which was then removed and the two halves luted with auto polymerized acrylic resin.
O’Sullivan et al1 described double flask method for fabricating a hollow maxillary denture using silicone putty. Though this technique was useful in estimation of the spacer thickness, but removal of putty was found to be difficult especially from the anterior portion of the denture. Moreover, the openings made from the distal end had to be sufficiently large to retrieve the hard putty.
This article describes an innovative technique for the fabrication of a hollow maxillary denture using caramel spacer.⁷

CASE REPORT

A 68-year-old male patient reported to the Department of Prosthodontics and Crown-Bridge for prosthetic rehabilitation of maxillary and mandibular edentulous ridges. On examination, it was found that both the upper and lower arches were completely edentulous and severely resorbed. His upper lip was long, the inter-ridge distance was more than normal with increased interarch space. Hence it was decided to fabricate complete set of denture. The following treatment options for complete denture were available to the patient.

1. Implant supported complete denture.
2. Conventional Complete denture.
3. Hollow maxillary complete denture and conventional mandibular complete denture.

Pros and cons of all options were explained to the patient. The patient approved hollow maxillary complete denture and conventional mandibular denture as treatment modality because it was light in weight, inexpensive and non-surgical procedure.

Procedures for Fabrication of Hollow Maxillary Denture.

• Preliminary and final impressions were made in conventional manner using impression compound and zinc oxide eugenol (DPI Impression paste, Mumbai, India) respectively.
• At the time of jaw relation, due consideration was given to adjust maxillary occlusal rims properly as to provide proper aesthetics to the patient with long upper lip. Teeth (Acry Pan, Ruthinium, India) were selected and arranged in balanced occlusion and try-in was done. The trial denture was duplicated in irreversible hydrocolloid (Zelgan 2002, DENTSPLY) and poured with die stone (Kalstone, Kalabhai Karson) (figure 1). A template of the duplicated trial denture was made with 0.5-mm thermoplastic sheet (Erkodent) in vacuum heat-pressed thermoforming unit ((Erkopress 300Tp). The trial denture was then processed in the standard manner up to the wax elimination stage.



Fig 1: Trial denture and duplicated denture cast

• 2 mm modelling wax (Modelling wax, Dento kem, India) adapted over master cast to ensure adequate and uniform thickness of resin in the complete denture (figure 2).



Fig 2: Modelling wax adapted on master cast

• For the purpose of achieving the hollow cavity, first a temporary putty spacer (Zeta Plus, Zhermack) was made (figure 3).



Fig 3: Putty Spacer

• Template was placed over the putty spacer and an endodontic file with a rubber stop was used to measure the space between the template and the adapted modelling wax on master cast (figure 4).



Fig 4: Template adapted on master cast with putty index and checked space using endodontic file with rubber stoppe

• Putty spacer was lubricated with Vaseline and putty index was formed.
• Sugar was heated in a stainless steel bowl on an open flame till it became caramel and then poured into the putty index, and allow it to cool (figure 5).



Fig 5: Caramel spacer poured on putty index

• Caramel spacer was removed and its exact replication was verified by placing between the master cast with 2mm of modelling wax adapted over it and template (figure 6).



Fig 6: Caramel spacer and putty spacer

• After this, a trial closure was carried out using the temporary putty spacer (figure 7), the flask was opened and temporary putty spacer was retrieved (figure 8). The hollow space left by the temporary putty spacer was now filled with the caramel spacer and final closure of the flasks was achieved (figure 9). The denture was acrylized in conventional manner.
• The denture was retrieved. Two small openings were made distal to the most distal tooth (figure 10 &11). The denture was then immersed in a bowl of water overnight to allow dissolution of caramel spacer. The hollow cavity was air dried, and the openings were sealed using autopolymerizing acrylic resin.



Fig 6: Caramel spacer and putty spacer



Fig 10: Processed FInal denture



Fig 11: Hollow denture

• Dentures were then finished, polished, and delivered to the patient (figure12). The patient was reviewed after a week, and minor adjustments were made.

Discussion

The method described in this case has several advantages over previously described techniques for the hollow denture fabrication. Most of the methods described in the literature have either used two flasks which is time consuming and requires multiple measurements to achieve adequate thickness of acrylic resin.^2-6 The technique described above used only single flask. The thickness of the acrylic resin can be controlled and uniform thickness can be acheived using this technique. This technique eliminates the requirement of two identical flasks and the extra step of fabrication of a permanent record base.
Caramel is a brown product originating from various sugars when they are heated. Caramel is used as a spacer in this case because it can be shaped as needed, it becomes hard as soon as it cools down, it does not adhere to or interact with acrylic resin, and can be easily retrieved from the putty index.
The major drawback of this technique is that solid caramel is brittle and therefore should be handled with care.⁷

Conclusion:

Hollow maxillary complete denture is boon to patients with increased inter ridge distance and severely resorbed ridges. It besides enhancing the retention considerably reduces the weight of the prosthesis and prevents transmission of detrimental forces to the underlying tissues. This technique overcomes the disadvantages of the older techniques. Hence, it’s a simple, economical, time-saving and a predictable technique.

References