MODIFIED APPROACH TO ENSURE A UNIFORM LAYER OF … · 2019. 12. 9. · J of IMAB. 2019 Oct-Dec;25(4) 2781 Original article MODIFIED APPROACH TO ENSURE A UNIFORM LAYER OF ELASTIC MATERIAL

J of IMAB. 2019 Oct-Dec;25(4) https://www.journal-imab-bg.org 2781

Original article

MODIFIED APPROACH TO ENSURE A UNIFORMLAYER OF ELASTIC MATERIAL FOR RELININGCOMPLETE DENTURES WITH SELF CURINGSILICONES

Mariana Yankova1, Bozhidar Yordanov1, Mariana Dimova-Gabrovska1, TodorPeev2,1) Department of Prosthetic Dental Medicine, Faculty of Dental Medicine,Medical University, Sofia, Bulgaria.2) Ex Deputy Rector of Medical University Sofia, Bulgaria, Private Practice,Sofia, Bulgaria.

Journal of IMAB - Annual Proceeding (Scientific Papers). 2019 Oct-Dec;25(4)Journal of IMABISSN: 1312-773Xhttps://www.journal-imab-bg.org

ABSTRACTSetting the Problem: In the available literature, the

preparation of the removable denture for the relining pro-cedure is subjective. It is not possible to ensure a uniformthickness of the relining material in all zones, with the riskof unwanted alteration of the previously determined regis-trations – occlusal plane, occlusal vertical dimension andinterocclusal relationship.

Purpose: The basic purpose of this article is to pro-pose a clinically and laboratory tested method for reliningcomplete dentures with a uniform layer of elastic materialand preserving of all clinicàlly determined registrations.

Materials and Method: To create a space and en-sure a uniform layer of elastic relining material, a vacuumshaped polypropylene space maintainer is fabricated. Thisclinical approach is illustrated by presenting a selectedclinical case with retentive maxillary tuberosities and se-vere mandibular bone atrophy.

Results and Discussion: The fabrication of a spacemaintainer for indirect relining of complete dentures withcold-curing silicones ensures a uniform layer of elastic re-lining material. The space maintainer is positioned in placeduring all clinical and laboratory steps, preserving in thisway the clinically determined registrations – occlusalplane level, occlusal vertical dimension and intermaxillaryrelations.

Conclusions: The proposed clinical and laboratorymethod for relining complete dentures with cold-curingsilicones is rational and effective. The space-maintainer se-cures a uniform layer of relining material, even distribu-tion of masticatory pressure to the mucosal-bone biologicbase and protects the denture against fracturing.

Keywords: elastic dental materials, silicone reliningmaterials, space maintainers, direct and indirect reliningtechniques;

INTRODUCTIONResilient or soft dental resins [1] have been known

for more than a century in dentistry [2, 3]. Today, resilient

dental materials have a variety of applications: reliningpartial and complete dentures in highly atrophied or reten-tive alveolar ridges, removing painful points of compres-sion (e.g. foramen mentale) due to exostosis, closing thevalve zone in the area of A-line and as a marginal elasticedge for improving the retention and stabilization of re-movable dentures [3, 4, 5, 6, 7, 8]. They are also used inoverdentures on dental implants [3, 8, 9, 10], in patientswith xerostomia, post-surgical passage defects (obturators),in temporary dentures during the healing period after den-tal implant placement to achieving osteogenesis [9, 10].

There are known several classifications of resilientdental materials. According to their chemical composition,they can be divided into two main types: acrylic-based andsilicone-based materials [3, 11, 12, 13]. According to someauthors, the production of new resilient materials requiresits classification into three groups: acrylic-based, silicon-based and vinyl-based [1]. Other authors have reported onthe application of fluorinated and olefin resilient materi-als [8]. Today, the most commonly used resilient materialsare silicone-based [3].

According to the technology, resilient resins are:heat-curing (for laboratory technique only) [8, 12, 14] -Molloplast B (Detax), cold-curing two-component (for bothclinical and laboratory technique) [7, 8, 10, 12, 13, 15] -Elite soft relining (Zhermack), Megabase Soft (Dreve), andlight-curing (for both clinical and laboratory technique)[16, 17] - (Trial).

When fabricating complete dentures with resilientmaterial lining, the clinical stages are not different fromthose for the classical complete dentures. Laboratory tech-nology, however, requires a space to be provided for theresilient material. This is necessary for the resilient mate-rial to have a uniform thickness, to preserve the occlusalplane level and the clinically pre-determined intermaxil-lary relation. When using heat-curing resilient materials, aspacer that can be made of different materials is used dur-ing the compression of the hard resin. In the literature [8,14, 18], there are detailed descriptions of this technology,using a wax plate as a spacer. Later, other authors have sug-

https://doi.org/10.5272/jimab.2019254.2781

2782 https://www.journal-imab-bg.org J of IMAB. 2019 Oct-Dec;25(4)

gested that the spacer can be made of self-curing or light-curing resin [16], silicone [19, 20], or vacuum-pressedthermofoil [21].

When using cold-curing resilient materials, two tech-nologies have been described - direct (clinical) and indi-rect (laboratory). The use of a spacer has not been discussed.Providing a space for the resilient material is accomplishedby removing 1-2 mm from the mucosal surface of the al-ready finished denture [3, 12, 13] and shortening the edgein the valve zone. In the direct technique, the next stepsinclude the application of an adhesive and placement ofthe resilient material, which is functionally formed in thearea of the valve zone by various functional tests. In theindirect technique with the finished denture, a functionalimpression with silicone materials is taken and transferredto the laboratory. There, a gypsum working model is cast.The impression material is then removed, and by abrading,as described above, space is provided for the resilient sili-cone material.

Setting the Problem: In the available literature, thepreparation of the removable denture for the relining pro-cedure is subjective. It is not possible to ensure a uniformthickness of the relining material in all zones, with the riskof unwanted alteration of the previously determined regis-trations – occlusal plane, occlusal vertical dimension andinterocclusal relationship.

Purpose: The basic purpose of this article is to pro-pose a clinically and laboratory tested method for reliningcomplete dentures with a uniform layer of elastic materialand preserving of all clinically determined registrations.

MATERIAL AND METHODTo illustrate the methodology, we present a selected

clinical case of a patient with retentive maxillary tuberosi-ties and severe mandibular atrophy (Fig. 1).

Fig. 1 a, b - Patient with retentive maxillary tuberosi-ties and severe mandibular atrophy; a) Intraoral view of theupper jaw; b) Intraoral view of the lower jaw

Fig. 2. Impression of the lower jaw; Fig. 3. Impres-sion of the upper jaw

For fabricating the dentures, we used the hard heat-curing resin Meliodent (Heraeus Kulzer), and for lining thedentures–the resilient cold-curing silicone materialElitesoftrelining (Zhermack).The method for providing auniform layer of the resilient material comprises the fol-lowing steps:

1. On the working models, cast by using preliminaryimpressions taken with a customized tray, a spacer was madeof 2 mm, thick soft vacuum shaped polypropylenethermofoil. (Fig. 2-6).

Fig. 4. Model of the upper jaw; Fig. 5. Model of thelower jaw

Fig. 6. The spacer of 2 mm, thick and soft vacuumshaped polypropylene thermofoil

Fig. 7-10. The spacers for the upper and lower jawand occlusion moulds with shafts


2. The spacer was used in all subsequent clinical stages: determination of the intermaxillary relation and testingwith the arranged teeth (Fig. 11).

Fig. 11 a, b. Clinical stage – sample with ordered teeth

3. After then, holes in the spacers were made in the area of canine teeth and the first molars (Fig. 12-15).

Fig. 12-15. Holes in the spacers

4. The prototypes of the dentures were placed in a cuvette, together with the spacers. (Fig. 16-18).

Fig. 16-18. Prototypes of the dentures before casing-in


5. After completion of the polymerization, the finished dentures were cleaned, and the spacers were removed.(Fig. 19-24)

Fig. 19-20. The finished dentures; Fig. 20. after polymerization, the spacers still not being removed

Fig. 23-24. The finished dentures after removing the spacers – view of the resin stoppers

Fig. 21-22. Finished dentures – removing the spacers

6. Due to the holes in the spacers on the mucosal surfaces of the dentures, stoppers were formed that assisted thelast clinical-stage – the taking of functional impressions (Fig. 23-24).

7. After adjusting of the finished dentures by the anatomical-semi-functional method [22], these were used ascustomized trays, and functional impressions with the silicone material Elite regular (Zhermack) were taken with themouth closed and by applying the relevant functional tests [22].

8. When examining the finished impressions, the piercing stoppers could be seen. (Fig. 25-28)

Fig. 25-28. The functional impressions


9. The next steps includedcasting of functional impressions, preparing of hard gypsum models and mounting themodels and dentures on a specifically openedbinding clip for relining. (Fig. 29-30)

Fig. 29-30. Casting of hard gypsum models and mounting on an opened binding clip for relining

10. The impression material was removed. (Fig. 31-33)

Fig. 31-33. The models mounted on a binding clip for relining; the even thickness of the removed impressionmaterial is a guarantee for the even thickness of the resilient material

11. The dentures were treated as the edge in the valve zone was shortened by about 1-2 mm and a 2 mm wide and1 mm deep groove was formed on it (Fig.34-35) the stoppers were abraded, and the resilient silicone material was placedin the released space. Prior to placing the material on the dentures, an adhesive was applied according to the manufac-turer’s instructions.

Fig. 34-35. Treatment of the edge in the valve zone

12. The resilient silicone material was polymerized for 10 minutes at 40-45°C in a pressurized polymerizationapparatus and then processed according to the manufacturer’s instructions.

Fig. 36-38. The finished dentures


RESULTS AND DISCUSSIONThe use of a spacer in this indirect method for lining with cold-curing silicone material provides a uniform layer

of the resilient material. Its use in all clinical and laboratory stages makes it possible to preserve the clinically pre-determined parameters - the occlusal plane level and the intermaxillary relation.

Fig. 39-41. Use of the spacer at the clinical stage – sample with ordered teeth

Fig. 42. The finished dentures

The technique for lining with a cold-curing siliconematerial described so far in the scientific literature does notallow for the accurate preservation of these parameters. Theremoval of 1-2 mm from the inner denture surface prior toapplying the resilient material, as described in the litera-ture [3, 12, 13], is done in a rather subjective manner, with-out providing a uniform level in all areas.

This creates a real risk for creating an uneven sili-cone layer and a change in the occlusal plane level, usu-ally in the caudal direction. This also leads to a change inthe intermaxillary relation and reduction in the distancebetween the tooth rows at physiological rest.

CONCLUSIONS1. The use of a spacer in all clinical and laboratory

stages provides a predictable outcome.

2. The use of a spacer provides a uniform layer ofresilient material, thus enabling the even distribution ofmasticatory pressure and preventing from denture fracture.

3. The use of a spacer in all clinical stages makes itpossible to preserve the clinically pre-determined param-eters – the occlusal plane level and the intermaxillary re-lation.

Acknowledgements:We would like to express our gratitude to Mr Bozhidar

Tenev, dental technician at the Dental Laboratory of the Fac-ulty of Dental Medicine, Medical University – Sofia, for hisassistance in clarifying the technology and its implementa-tion and to Mr Tsvetan Borikin also dental technician at theDental Laboratory of the Faculty of Dental Medicine, Medi-cal University – Sofia, for making the dentures.

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Address for correspondenceDr Mariana Yankova, PhDDepartment of Prosthetic Dental Medicine, Faculty of Dental Medicine, MedicalUniversity, Sofia,1, St. G. Sofiiski blvd., Sofia, BulgariaE-mail: [email protected]; [email protected]

Please cite this article as: Yankova M, Yordanov B, Dimova-Gabrovska M, Peev T. Modified Approach to Ensure aUniform Layer of Elastic Material for Relining Complete Dentures With Self Curing Silicones. J of IMAB. 2019 Oct-Dec;25(4):2781-2787. DOI: https://doi.org/10.5272/jimab.2019254.2781

Received: 17/05/2019; Published online: 15/11/2019

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MODIFIED APPROACH TO ENSURE A UNIFORM LAYER OF … · 2019. 12. 9. · J of IMAB. 2019 Oct-Dec;25(4) 2781 Original article MODIFIED APPROACH TO ENSURE A UNIFORM LAYER OF ELASTIC MATERIAL