Indian Journal of Dental Research

CASE REPORT
Year
: 2012  |  Volume : 23  |  Issue : 2  |  Page : 279--282

An alternative treatment of occlusal wear: Cast metal occlusal surface


Sandeep Kumar, Aman Arora, Reena Yadav 
 Department of Prosthodontics and Crown & Bridge, D.A.V. (C) Dental College & Hospital, Yamunanagar, Haryana, India

Correspondence Address:
Sandeep Kumar
Department of Prosthodontics and Crown & Bridge, D.A.V. (C) Dental College & Hospital, Yamunanagar, Haryana
India

Abstract

Acrylic resin denture teeth often exhibit rapid occlusal wear, which may lead to decrease in the chewing efficiency, loss of vertical dimension of occlusion, denture instability, temporomandibular joint disturbances, etc. There are various treatment options available like, use of highly cross linked acrylic teeth, amalgam or metal inserts on occlusal surface, use of composite, gold or metal occlusal surface, etc. Several articles have described methods to construct gold and metal occlusal surfaces, however, these methods are time-consuming, expensive and requires many cumbersome steps. These methods also requires the patient to be without the prosthesis for the time during which the laboratory procedures are performed. This article presents a quick, simple and relatively inexpensive procedure for construction of metal occlusal surfaces on complete dentures.



How to cite this article:
Kumar S, Arora A, Yadav R. An alternative treatment of occlusal wear: Cast metal occlusal surface.Indian J Dent Res 2012;23:279-282


How to cite this URL:
Kumar S, Arora A, Yadav R. An alternative treatment of occlusal wear: Cast metal occlusal surface. Indian J Dent Res [serial online] 2012 [cited 2021 Sep 26 ];23:279-282
Available from: https://www.ijdr.in/text.asp?2012/23/2/279/100441


Full Text

 Introduction



The use of acrylic resin denture teeth has been criticized because of the rapid occlusal wear that leads to changes in centric occlusion, temporomandibular joint disturbances, loss in chewing efficiency, [1] loss of vertical dimension of occlusion [2] and hence can result in denture instability. The extent of wear varies depending on the clinical situation and the amount of time the prosthesis has been in use. Various articles [1],[2] describes the construction of metal occlusal surfaces for the patients having the history of occlusal attrition, bruxism, orofacial tardive dyskinesia, self-induced excessive chewing, and idiopathic parafunctional mandibular movement.

Metal occlusal surface may be indicated, a) when constructing a denture, that is to be opposed by reconstructed dentition with gold occlusal surfaces, b) when constructing a complete denture, removable partial denture or overdenture with a functionally generated path concept in which considerable modification of the denture teeth is necessary to place the occlusal surface and core in harmony, c) to reinforce and strengthen the denture.

This article presents a quick, simple, and relatively inexpensive procedure for construction of metal occlusal surfaces on complete dentures.

 Case Report



A 64 year old male patient reported to the Department of Prosthodontics in D.A.V. (C) Dental College, Yamunanagar, Haryana, with the chief complaint of decreased chewing efficiency with the continuous use of denture, and he wanted a denture in which chewing efficiency is maintained as the time passes but at lowest cost possible. He was bothered only about the functional efficiency of the denture and not about the esthetics. On clinical examination, the patient was found to be complete edentulous with well formed ridges and a Class 1: orthognathic ridge relation was present with both the ridges parallel to the occlusal plane. History revealed that the patient was wearing the denture since 5 years, and in that duration he got his denture made two times due to frequent attrition of the teeth and an instability of the denture.

On the basis of clinical examination and history, it was concluded that the frequent attrition of the teeth could either be due to self induced excessive chewing or idiopathic parafunctional mandibular movement, but there was no tenderness or discomfort in areas of the muscles of mastication and temporomandibular joint. Various treatment options were described to the patient like, (a) denture or implant supported overdenture with highly cross-linked acrylic teeth, (b) denture or implant supported overdenture with metal occlusal surface, (c) implant supported fixed prosthesis.

Patient was ready to compromise the esthetics of the denture provided the denture is economical, with the best functional efficiency and had no time constraint. Therefore, the denture with the metal occlusal surface was planned as the patient's all concerns were addressed. In addition, it improves the degree of masticatory ability and prevents the attrition of the teeth.

 Procedure



Preliminary impressions were made with an impression compound (Y- Dents, MDM Corporation, Delhi) and poured with dental plaster to obtain primary cast. Custom acrylic resin trays (DPI RR cold cure, DPI, India) were fabricated and border molding was done with low fusing compound (DPI pinnacle tracing sticks, DPI, India). Final impressions were made using zinc oxide eugenol impression paste (DPI impression paste, DPI, India) for both arches and impressions were poured with Type III dental stone (Kalstone, Kalabhai, India) to obtain master cast. Temporary denture bases and wax rims (Y- Dents, MDM Corporation, Delhi) were made to record face bow transfer and maxillo-mandibular relationship and transfer this relationship to the semi-adjustable articulator (Hanau H2, Teledyne Waterpik Ft. Collins). Vertical Dimension of Occlusion (VDO) was established by using two methods. In first method, two points were marked - one on the tip of nose; and other on an immovable part of chin. To know the vertical dimension at rest (VDR) position, the patient was asked to repeat the letter 'M' several times and then the distance between the points was measured. VDO = VDR minus free way space (2- 3mm). Second method was to create at least 1mm of closest speaking space between occlusal rims.

Teeth arrangement was done with cross-linked acrylic teeth (Acryrock, S.p.a., Italy) and try-in was carried out. Then occlusal surfaces of the maxillary and mandibular posterior teeth were reduced by 2mm with the carbide trimming bur so as to create a 4mm interocclusal clearance [Figure 1]. The articulator was moved into lateral and protrusive positions to verify the space adequacy. The central portion of the teeth was reduced slightly more than the cusps to gain mechanical retention of the casting.{Figure 1}

Then the inlay wax (Blue Wax, MDM Corp., India) was added on the prepared denture teeth and the occlusal surface of the individual teeth was contoured [Figure 2]. Secondary anatomic details were carved and the waxed occlusion was checked in centric, lateral and protrusive positions.{Figure 2}

Wax pattern was carefully removed from the teeth and Sprue formers were attached with the wax pattern and these were carefully removed from the acrylic teeth to the undersurfaces of the acrylic resin patterns to reduce the need for extensive finishing and polishing of the occlusal surfaces after casting. Patterns were invested with phosphate bonded investment (Bellavest, Bego, Germany); and the metal casting process was completed using a Ni-Cr alloy (Wiron 99, Bego, Germany). After divesting the castings, the metal occlusal surfaces were recovered and polished [Figure 3]. Polished castings were positioned at their respective sites on the denture teeth ensuring that each casting was completely seated. The occlusion was checked in centric, lateral and protrusive positions. Wax was used to seal the casting and to modify the buccal and lingual resin contours. Addition of wax facilitates removal of the resin teeth after the boilout.{Figure 3}

The denture teeth were carefully removed along with the metal occlusal from the articulator for flasking. During flasking, the buccal surfaces of teeth in the mold were slightly depressed towards the occlusal surfaces. This facilitates the positive retention of the metal occlusal in the mold and permits easier removal of the resin teeth after the boilout. After dewaxing, the mold was flushed with clean boiling water to thoroughly remove the wax residues. Tin foil substitute was painted on the stone mold. A heat cure resin (DPI-heat cure, DPI, India) was selected that matched the shade of an anterior teeth, mixed according to the manufacturer's directions, and packed into the flask. After curing, the flask was opened; the occlusal units were removed and polished.

The occlusal units were repositioned in the wax trial denture and the occlusion was checked in centric, lateral and protrusive positions [Figure 4]. The dentures were cured using heat cure acrylic resin (DPI-heat cure, DPI, India) in the usual conventional manner and after curing, the dentures were finished, polished and were ready to be delivered to the patient [Figure 5]. During insertion of the complete denture, it was checked for border extension, proper adaptation and occlusion in centric, lateral and protrusive positions [Figure 6]. Patient was satisfied with the chewing efficiency and esthetics of the denture. Patient was re-evaluated after every 3 months for 2 years to solve any problem associated with the denture and to know about the functional efficiency of the denture. {Figure 4}{Figure 5}{Figure 6}

 Discussion



Metal or gold occlusal surfaces have been reported to cause minimal wear to opposing occlusal materials. [3] This technique should be considered in cases where the prosthetic occlusion is in contact with an enamel, composite resin, porcelain, or a combination of such materials. [4]

There is no cement or bonding agent used to secure the castings to the denture teeth. As a result, discoloration will not occur at the interface, and the castings will not become loose. Instead of individual units, single joint unit is fabricated to improve the retention and provide an ease in finishing and polishing of the casting.

Display of metal is considered to be the main disadvantage of using metal occlusal surface, but the patient was not concerned about the display of the metal because he was more than satisfied with the chewing efficiency of the denture - his main concern. Some author advocates the use of light cure composite resin to duplicate the occlusal surface. Although the composite resin on occlusal surfaces will wear, but the rate of wear is less than that of the most acrylic resin denture teeth. [5]

In alternate treatment options, (a) implants could not be placed because of high cost, needed surgical intervention and also increased chair side time; (b) cross linked acrylic teeth could be used in relation to the patients comfort, chair side time and is economical, however, but when compared, the wear resistance of metal is negligible and also requires same chair side time, therefore metal occlusal was planned.

 Summary and Conclusion



This article has described a technique that uses the custom made occlusal portions as the patterns for casting base metal occlusal surfaces. Acrylic resin is attached to the metal occlusal surfaces via direct resin processing. During recall evaluation, the patient was satisfied with the functional efficiency of the denture and did not report any problem associated with the metal occlusal denture.

References

1Wallace DH. The use of gold occlusal surfaces in complete and partial dentures. J Prosthet Dent 1964;14:326-33.
2Koehne CL, Morrow RM. Construction of denture teeth with gold occlusal surfaces. J Prosthet Dent 1970;23:449-55.
3Barco MT, Synnott SA. Precision metal occlusal surfaces for removable partial dentures. Int J Prosthodont 1989;2:365-7.
4Elkins WE. Gold occlusal surfaces and organic occlusion in denture construction. J Prosthet Dent 1973;30:94-8.
5Vergani CE, Giampaolo ET, Cucci AL. Composite occlusal surfaces for acrylic resin denture teeth. J Prosthet Dent 1997;77:328-31.