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 Table of Contents  
CASE REPORT
Year : 2020  |  Volume : 14  |  Issue : 2  |  Page : 85-88

Prefabricated light-polymerizing plastic pattern for fabrication of cast partial framework of obturator prosthesis – A novel technique


1 Division of Prosthodontics and Crown and Bridge, Army Dental Centre R and R, New Delhi, India
2 Department of Dental Surgery and Oral Health Sciences, Division of Prosthodontics and Crown and Bridge, Armed Forces Medical College, Pune, Maharashtra, India

Date of Submission17-Mar-2020
Date of Acceptance19-May-2020
Date of Web Publication15-Jul-2020

Correspondence Address:
R Vijaya Kumar
Department of Dental Surgery and Oral Health Sciences, Division of Prosthodontics and Crown and Bridge, Armed Forces Medical College, Sholapur Road, Pune - 411 040, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JODD.JODD_14_20

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  Abstract 


This case report aims to report a novel application of a prefabricated light-polymerizing plastic resin for the construction of cast partial denture (CPD) framework for the fabrication of a definitive obturator. Prefabricated light polymerizing plastic patterns have been introduced in dental labs and are used in the fabrication of CPD framework. This novel technique shows how it minimizes laboratory time and cost by removing some of the steps involved during metal-based definitive obturator fabrication. A case of maxillectomy was rehabilitated using light polymerizing plastic pattern for the fabrication of metal-based definitive obturator.

Keywords: Definitive obturator, dental curing light, LIWA, prefabricated light polymerizing plastic patterns


How to cite this article:
Viswambaran M, Kumar R V, Bahri R. Prefabricated light-polymerizing plastic pattern for fabrication of cast partial framework of obturator prosthesis – A novel technique. J Dent Def Sect. 2020;14:85-8

How to cite this URL:
Viswambaran M, Kumar R V, Bahri R. Prefabricated light-polymerizing plastic pattern for fabrication of cast partial framework of obturator prosthesis – A novel technique. J Dent Def Sect. [serial online] 2020 [cited 2020 Oct 22];14:85-8. Available from: http://www.journaldds.org/text.asp?2020/14/2/85/289745




  Introduction Top


The modalities of management of maxillectomy defects with a metal-based definitive obturator have been clearly outlined with various available classifications and type of designs required in managing these defects.[1],[2],[3] Fabrication of cast partial denture (CPD) framework for obturator is a complex process because of various challenges involved including clinical challenges like limited mouth opening, rehabilitations of defect part in the design, also often we have limited teeth to provide as an abutment or for supporting the prosthesis, oral hygiene maintenance and more importantly various complex laboratory procedures involved,[4] which are time-consuming, expensive and technique sensitive.

Recently, prefabricated light polymerizing plastic patterns have been introduced, which are being used in the fabrication of CPD framework. Here, a novel technique is suggested for using the light polymerizing plastic resin pattern for fabrication of CPD framework for obturator prosthesis. “LiWa” (WP Dental, GmbH Bevern/Hamburg) light polymerizing plastic resin pattern was used in this case report for the rehabilitation of a maxillectomy defect with metal-based definitive obturator.[5],[6]


  Case Report Top


A 70-year-old female reported to the Department of Dental Surgery, Armed Forces Medical College, with the chief complaint of inability to eat or drink due to nasal reflux and difficulty in speech [Figure 1]. The patient's history revealed that she had been operated for carcinoma of the left maxillary sinus about 1 year back, following which she had undergone radiotherapy as well. Extraoral examination revealed a depressed left check area, the left side condyle of TMJ showed restricted movements and mouth opening of 30 mm.
Figure 1: Preoperative frontal view of patient

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Intraoral examination revealed a maxillectomy defect measuring 5 cm ×3 cm anteroposteriorly and mediolaterally, which was present on the left side. Only four maxillary teeth, i.e., 11, 12, 13, and 17 were present. Due to healing of the split-thickness skin graft on the left side, contracture of the left buccal mucosa along the cheek had taken place. The patient had a full complement of mandibular teeth, with only 38 missing.

The treatment plan was to rehabilitate the maxillectomy defect with a metal-based definitive obturator using “LiWa” light polymerizing resin pattern for the fabrication of the CPD framework.

Procedure

Treatment sequence involved making of diagnostic impression to evaluate the defect, including surveying and custom tray fabrication. Custom-made special tray was fabricated for a secondary impression making using tray material. Elastomeric tray adhesive was applied, and a small gauze piece tagged with silk thread was placed in the defect to prevent the ingress of impression material into the undercuts. Impression was made using elastomeric impression material using the putty wash technique [Figure 2]. The impression was disinfected as per laid out protocols, and cast poured using Type III dental stone [Figure 3].
Figure 2: Secondary impression with elastomeric impression material

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Figure 3: Master cast

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After surveying of master cast, designing of the metal framework was done on the master cast itself. Here, the laboratory steps were different vis-à-vis conventional laboratory steps during the fabrication of the CPD framework. First, and significantly the laboratory step of processing refractory cast was not necessary for this technique, saving a lot of steps and minimizing the use of materials. After due blocking of undercuts and providing relief wax, light-curing polymerizing resin was adapted as per the decided design on the master cast. The requisite minor connectors, occlusal rests, major connectors were attached to the master cast itself. The preformed shapes and sizes available with the LiWa light-curing polymerizing resin [Figure 4] make adaptation of various parts of the framework easy. All the component parts were adapted as per the manufacturer's directions on the non-defect area of the palate [Figure 5]. For the defect area, the preformed wax patterns were slightly modified to adapt to the requirement of obturator bulb portion and attached to the wax pattern as four small “V” or “U” shaped extensions. This pattern on the master cast was placed in the light chamber supplied by the manufacturer and subjected to complete curing as per the standard protocol. This resin wax pattern of obturator prosthesis made from LiWa light-curing polymerizing system was carefully retrieved from the cast and tried in patient mouth for evaluating fit and extension, which is a major advantage in the framework fabricated with this technique. The framework was retrieved from the patient's mouth and sprue [Figure 6] with a reservoir of appropriate size attached to the framework pattern and again subject to light curing as per the manufacturer's direction. Once the curing cycle is completed, the framework is retrieved, and laboratory steps followed thereafter are similar to that of conventional CPD framework fabrication. On completion of framework casting, finishing and polishing, the framework was tried in the patient's mouth and was seen to have an accurate fit. The occlusal rims were made, and maxillomandibular relations recorded. Try in of the waxed up obturator was done, and final obturator prosthesis consisting of bulb portion and missing teeth was fabricated using heat cure resin [Figure 7]. The definitive obturator prosthesis was inserted in the patient's mouth [Figure 8]. The patient was given routine directions regarding the maintenance of the prosthesis and was advised for periodic evaluation.
Figure 4: Light-curing resin/waxes (LIWA system)

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Figure 5: Cast partial framework made with – light-curing resin/waxes

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Figure 6: Attachment of the sprue

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Figure 7: Metal based definitive obturator made with – light curing resin/waxes

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Figure 8: Metal based definitive obturator made with – light curing resin/waxes in situ

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  Discussion Top


Conventional wax-up techniques are well debated in the prosthodontic literature. Initial reports on light-curing/polymerizing waxes used in the fabrication of removable CPDs were published around 2003. There are various technique sensitive steps involved during the fabrication of conventional CPD which can potentially affect the fit and accuracy of the framework, and these include errors in wax blocking out, distortion of wax pattern, dimensional changes in the refractory material, procedures used for finishing and polishing of the metal framework. Also material used for the duplication and finesse of the technician working.

Some of these steps are minimized during the fabrication of the CPD framework with light polymerizing waxes, especially since there is no necessity for duplication of cast, a lot of steps can be spared, resulting in more accurate fitting CPD prosthesis.[7] Various authors have observed that the CPD framework made using light-curing/polymerizing waxes have had a better fit of the framework during try-in and the insertion of the prosthesis. Improvements and advances in materials over the years have reduced the number and size of various discrepancies in the fabrication of conventional CPD framework.[8],[9] Light polymerizing resin/waxes may be an advancement towards the same. The novel technique showed in this case report suggests that prefabricated light polymerizing plastic patterns like “LiWa” can be successfully used in the fabrication of the CPD framework for obturator prosthesis also. It significantly reduced the working time, saved materials, and some of the intermediary laboratory steps removed.


  Conclusion Top


Rehabilitation of post ablative maxillectomy defect was achieved by CPD-based definitive obturator fabricated using light polymerizing resin/waxes. A good fit of the CPD framework was confirmed by careful examination in the patient's mouth. The result indicates that the technique was effective in easing the fabrication process by performing the waxing step directly on the master cast instead of using a refractory cast. Along with saving time and cost, in this case, it was successfully used in customizing the design for fabrication of the CPD framework of a definitive obturator.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Desjardins R. Early rehabilitative management of the maxillectomy patients. J Prosthet Dent 1977;38:311.  Back to cited text no. 1
    
2.
Aramany MA. Basic principles of obturator design for partially edentulous patients. Part I: Classification. J Prosthet Dent 1978;40:554-7.  Back to cited text no. 2
    
3.
Beumer J 3rd, Curtis TA, Marunick MT. Maxillofacial Rehabilitation: Prosthodontic and Surgical Considerations. 1st ed. St Louis (MO): Ishiyaku EuroAmerica, Inc; 1996. p. 202-6.  Back to cited text no. 3
    
4.
Fenlon MR, Juszczyk AS, Hughes RJ, Walter JD, Sherriff M. Accuracy of fit of cobalt-chromium removable partial denture frameworks on master casts. Eur J Prosthodont Restor Dent 1993;1:127-30.  Back to cited text no. 4
    
5.
Augthun M, Zyfuss M, Spiekermann H. The influence of spruing technique on the development of tension in a cast partial denture framework. Int J Prosthodont 1994;7:72-6.  Back to cited text no. 5
    
6.
Cristina MB, Liliana S, Sorin P. Using of light curing “waxes” in the removable partial denture technology. Int Poster J Dent Oral Med 2007;9:371-8.  Back to cited text no. 6
    
7.
Kumar MV, Murugesan K, Bhagath SN. The accuracy of fit of cast clasps designed with conventional wax pattern and light cured patterns: A comparative in vitro study. SRM Univ J Dent Sci 2010;1:10-13.  Back to cited text no. 7
    
8.
Takaichi A, Wakabayashi N, Igarashi Y. Prefabricated light-polymerizing plastic pattern for partial denture framework. Contemp Clin Dent 2011;2:402-4.  Back to cited text no. 8
[PUBMED]  [Full text]  
9.
Swelem AA, Abdelnabi MH, Al-Dharrab AA, Abdel Maguid HF. Surface roughness and internal porosity of partial removable dental prosthesis frameworks fabricated from conventional wax and light-polymerized patterns: A comparative study. J Prosthet Dent 2014;111:335-41.  Back to cited text no. 9
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]



 

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