Composite occlusal surfaces for acrylic resin denture teeth

Carlos Eduardo Vergani, DDS, PhD, a Eunice Teresinha Giampaolo, DDS, PhD, a and Aria Lucia Machado Cucci, DDS, PhD a S~o Paulo State University, Araraquara Dental School, Araraquara, Brazil

Acrylic resin denture teeth often exhibit rapid occlusal wear, which may lead to a loss of chewing efficiency and a loss of vertical dimension of occlusion. The use of metal occlusal surfaces on the acrylic resin denture teeth will minimize occlusal wear. Several articles have described methods to construct metal occlusal surfaces; however, these methods are time-consuming, costly, and some- times considered to be unesthetic. These methods also require that the patient be without the prosthesis for the time necessary to perform the laboratory procedures. This art ide presents a quick, simple, and relatively inexpensive procedure for construction of composite occlusal surfaces on complete and partial dentures. (J Prosthet Dent 1997;77:328-31.)

M a t e r i a l s o f which the occlusal surfaces o f arti- ficial teeth arc made deserve serious consideration by the dentist. These considerations should be based on minimizing attrition o f occlusal surfaces, maintaining the established vertical dimension o f occlusion, and maintaining positive planned contact of posterior teeth. Acrylic resin teeth are more easily adjusted and may pro- duce less trauma in slight malocclusion. Mso, there is a chemical bond between the denture base resin and acrylic resin teeth. However, the use of acrylic resin denture teeth has been criticized because o f the rapid occlusal wear that leads to changes in centric occlusion, tem- poromandibular joint disturbances, loss in chewing effi- ciency, and extrusion of opposing teeth.

Some brands o f resin teeth are similar to composites in their ability to resist wear, but these are relatively new and many brands are still being sold that exhibit fairly rapid occlusal wear. When posterior acrylic resin teeth wear in function at a faster rate than anterior teeth, they may cause occlusal prcmaturities and a loss of vertical di- mension of occlusion. As a result, more stress is placed on the anterior ridges, which may cause a loss of alveolar ridge height in the anterior segments. 2 Porcelain teeth are more stable against wear than acrylic resin teeth are. However, porcelain teeth will often chip and fracture and cause wear on the opposing natural dentition and resto- rations. The hardness of porcelain makes adjustment dif- ficult, and when it is worn in the patient's mouth, porce- lain may cause a clicking sound that is uncomfortable)

Several methods have been advanced in the dental lit- erature to construct metal occlusal surfaces on the acrylic resin teeth to prevent wear and increase chewing effi- ciency for complete and partial dentures, a-9 The meth- ods for constructing gold or base metal occlusal sur- faces are t ime-consuming, costly, and often unesthetic. They also require that the patient be without the pros-

aAssJstant Professor, Removable Partial Dentures, Department of Dental Materials and Prosthodontics.

thesis for the time necessary to perform the laboratory procedures.

The placement of large silver amalgam restorations in resin posterior teeth seems to be a simple method to im- prove efficiency of the teeth. Wear of the resin teeth is also reduced. However, the resin parts of the occlusal surfaces wear more quicldy than the amalgam inserts, leaving the amalgam raised above the occlusal surfaces.I°

Visible light-cured composites have become popular for many prosthodontic applications because their wear properties have been improved, n These applications in- clude replacement of lost or broken denture teeth, ~2,13 construction of composite denture teeth on removable partial metal framework, 1~ characterization o f acrylic resin denture teeth, ~sa6 and correction o f acrylic resin denture teeth wear.17

Compared with metal occlusal surfaces, the advan- tages o f composite occlusal surfaces are (1) the proce- dure can be accomplished in the dental office and thus eliminate the time required to send it to a laboratory, (2) the cost to the patient is much lower than that of metal occlusal surfaces, (3) the material is esthetically pleasing, and (4) it is not required that the patient be without the prosthesis.

The purpose o f this article was to describe a quick, simple, and relatively inexpensive procedure for construc- tion o f composite occlusal surfaces on complete and partial dentures.

P R O C E D U R E

The procedure will be illustrated with a removable partial denture (RPD); however, it can be used with slight changes for complete dentures as well.

1. Make a removable prosthesis, complete or partial, with acrylic resin posterior teeth. Adjust and cor- rect the occlusion in the usual manner. Allow the patient to wear the denture(s) after the occlusion is correct and the adjustment period is completed. (At the end of this period the dentures are ready for the

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Fig. 1. Quick-set plaster cast with removable partial denture in place.

fabrication o f the composi te occlusal surfaces.) 2. For the RPDs, make an irreversible hydrocolloid

impress ion with the prosthesis in the pa t ien t ' s month. Block out undercuts in the denture base with wax and pour a cast with quick-set plaster a s stone (Fig. 1). Adapt and contour utility wax so that all undercuts around the teeth are eliminated and a 2 to 3 m m shelf is created. The wax should cover the buccal and lingual surfaces o f the denture teeth and at least one adjacent stone tooth up to a line approximately 2 m m from the occlusal surfaces o f the teeth.

5. Adapt and seal one thickness of baseplate wax or boxing wax to the outline of utility wax to confine acrylic resin when it is applied for maldng the acrylic resin indexes (Fig. 2).

6. With a fine camel hair brush, lubricate the teeth and wax with a separating medium such as water-soluble irreversible hydrocolloid. I t must be applied thinly with no excess. (An excessively thick layer of the sepa- rator coveting the occlusal surfaces will constitute dis- crepancies that prevent the reproduction of detail in the index.)

7. M a k e the acry l ic res in index . Pa in t c lear autopolymerizing acrylic resin thoroughly over the occlusal surfaces of the denture teeth. Care should be taken to avoid trapping air and to ensure faithful reproduction of the contoured surfaces. The index should be extended at least one tooth anteriorly and onto the acrylic resin base posteriorly. This must be done to provide adequate stops on the denture. Al- low the resin to polymerize. Make one index for each quadrant.

8. Remove the index and trim it so that it covers only the occlusal surfaces approximately 2 m m down the sides o f the teeth.

9. Remove the wax and clean the denture with green soap and warm water.

10. Prepare the resin denture teeth. For maxillary teeth,

.

4.

Fig. 2. Removable partial denture with utility wax and one thickness of baseplate wax adapted around teeth.

Fig. 3. Occlusal view shows completed undercut hoies [n acrylic resin denture teeth made with inverted cone bur.

11.

12.

13.

remove 1 m m of acrylic resin from the occlusal sur- face on the buccal side of the tooth and 2 m m of resin f rom the lingual side. Similar preparat ion is made on mandibular teeth, except remove 2 m m of resin f rom occlusal surfaces on both the buccal and lingual sides. Cut holes to a depth of 2 m m in each tooth. These mechanical undercut holes are placed with an in- verted cone carbide bur (Fig. 3). Treat the occlusal surface of the denture teeth with chloroform for 5 seconds; then rinse with water for 20 seconds, ls,17 This t reatment is repor ted to make the surface of the acrylic resin more porous and pro- vide bet ter interlocldng of the composi te with the acrylic resin.18 Avoid contaminat ion of the acrylic resin surface. Dispense equal amounts o f Bondli te resin and Bondlite activator (Kerr Co., Romulus, Mich.). Mix thoroughly and brush a thin layer into the mechani- cal undercut holes and over the occlusal surfaces. Cure this layer for 20 seconds by using light f rom a visible light source.

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Fig. 4. Clear acrylic resin index with V-shaped grooves made from lingual surfaces of teeth to edge of index.

Fig. 6. Occlusal view of completed removable partial den- ture.

Fig. 5. Index filled with light-curing composite is held firmly on denture while it is being cured.

14. Coat the labial and buccal surfaces of the denture base and denture teeth with the separating medium (Step 6). A note of caution: do not allow the sepa- rating medium to contact the Bondlite resin.

15. Choose the correct color of composite to match the artificial denture teeth.

16. Apply light-curing composite (Herculite XRV, Kerr Mfg. Co.) into the mechanical undercut holes of the artificial acrylic resin teeth and light cure the resin at a rate of 20 seconds for each denture tooth. Care should be taken to avoid overfilling the un- dercut holes with composite to avoid exceeding the depth of cure and preventing the index from seat- ing properly.

17. Try the indexes on the dentures and adjust them to fit properly.

18. Carve V-shaped grooves into the lingual surface of the acrylic resin index to allow excess composite ma- terial to escape from the index when it is applied (Fig. 4).

19. Apply a thin layer of the separating medium (Step 6) to the undersurface of the acrylic resin index.

20. Apply a thin layer of the light-curing composite over

Fig. 7. Side view of complete and partial dentures with com- posite occlusal surfaces made after this procedure.

the buccal, occlusal, and lingual surfaces of the acrylic resin index. Then position the index and press it firmly to place with finger pressure. Make sure that the an- terior and posterior stops are seated properly.

21. Excess material will escape through the V-shaped grooves. Remove the excess material before curing.

22. Light cure the composite at a rate of 20 seconds for each denture tooth (Fig. 5).

23. After the composite has cured, remove the index, trim away any excess material, create individual tooth sepa- ration with composite finishing diamonds, and polish with Soflex disks (3M Dental Products Div., St. Paul, Minn.) and composite polishing paste (3M Co.) (Fig. 6).

24. Examine the occlusion to determine that no changes have occurred and adjust if necessary. (Assuming that all the preceding steps were properly done, no occlusal corrections should be necessary [Fig. 7].)

S U M M A R Y

This article describes a procedure for duplicating pre- cisely the occlusal surfaces of functionally acceptable acrylic resin denture teeth in light-cured composite resin.

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Although the composite resin on occlusal surfaces will wear, the rate of wear is less than that of most acrylic resin denture teeth.

R E F E R E N C E S

1. McGivney GP, Castleberry DJ. McCracken's removable partial prosthodon- tics. 9th ed. St. Louis: Mosby-Year Book, 1995.

2. Whitman DJ, McKinney JE, Hinman RW, Hesby RA, Pelleu GB Jr. in vitro wear rates of three types of commercial denture tooth materials. J Prosthet Dent 1987;57:243-6.

3. Shultz AW. Comfort and chewing efficiency in dentures. J Prosthet Dent 1951 ;1:38-48.

4. Wallace DH. The use of gold occlusal surfaces in complete and partial dentures. J Prosthet Dent 1964;14:326-33.

5. Davies HG, Pound E. Metal cutting surfaces aid denture function. Dental Surv 1966;42:47-53.

6. Koehne CL, Morrow RM. Construction of denture teeth with gold occlusal surfaces. J Prosthet Dent 1970;25:449-55.

7. Woodward/D, Gattozi JG. Simplified gold occlusa[ technique for remov- able restorations. J Prosthet Dent 1972;27:447-50.

8. McCartney JW. Gold occlusal surfaces for acrylic resin denture teeth. J Prosthet Dent 1979;41:582-5.

9. Hansen CA, Clear K, Wright P. Simplified procedure for making gold oc- dusal surfaces on denture teeth. J Prosthet Dent 1994;71:413-6.

10. Sowter JB, Bass RE. Increasing the efficiency of resin posterior teeth. J Prosthet Dent 1968;19:465-8.

11. Wil[ems G, Lambrechts P, Braem M, Vanherle G. Composite resins in the 21 st century. Quintessence Int 1993;24:641-58.

12. Stameisen AE, Ruffino A. Replacement of lost or broken denture teeth with composites. J Prosthet Dent 1987;58:11%20.

13. Lipkin LS, Wescott T. Replacement of a fractured tooth on a removable partial denture by using two visible light-cured resin systems. J Prosthet Dent 1992;67:283-5.

14. Chang JC, Katz ST. Composite denture teeth made on a removable partial metal framework. J Prosthet Dent 1994;71:409-12.

15. Weiner S, Krause AS, Nicholas W. Esthetic modification of removable par- tial denture teeth with light-cured composites. J Prosthet Dent 1987;57:381- 4.

16. jooste C. Characterization of acrylic resin denture teeth, j Prosthet Dent 1992;67:279-80.

17. Nicholas WT. Correction of acrylic denture tooth wear with light-cured composite resin. J New Jersey Dent Assoe 1987;1:41-4.

18. Shen C, Colaizzi FA, girns B. Strength of denture repairs as influenced by surface treatment. J Prosthet Dent 1984;52:844-8.

Reprint requests to: DR. CARLOS E. VERGANI FACULDADE DE ODONTOLOGiA DE ARARAQUARA, UNESP RUA HUMAITA NO. ] 680 ARARAQUARA, SAO PAULO C.E.P., 14801-903 BRAZIL

Copyright © 1997 by The Editorial Council of The Journal of Prosthetic Den- tistry.

0022-3913/97/$5.00 + O. 10/1/78442

Short - term contaminat ion o f lu t ing cements by water and saliva. Mojon P, Kaltio R, Feduik D, Hawbolt EB, McEntee MI. Dent Mater 1996;12:83-7.

Purpose . Thc purpose of the study was to use surface hardness measurements to determine the short-term effect o f water, artificial saliva, and natural saliva on the hardening process of three luting cements. Material and Methods . Three luting cements (zinc phosphate, glass ionomer, and composite resin) were mixed, placed in a 1 x 5 mm mold and, after the appropriate setting time, subjected to various storage conditions before hardness testing. Uncontaminated samples were tested for microhardness as were samples contaminated at times 5 to 20 minutes after the initial mix with either water, artificial saliva, or natural saliva. The hardness of each sample was always measured at 30 minutes. Results . Glass ionomer samples were significantly harder then the zinc phosphate or composite cements after i week in 100% humidity storage condition. All forms of contamination decreased the hardness o f zinc phosphate and glass ionomer but had minimal effect on the resin cement. Contamination with water had the biggest effect on microhardness of all cements over that o f artificial or natural saliva. Effects o f contamination were time dependent with 10 to 15 minutes after the initial mix the critical period. Conc lus ions . The significance of this research is to direct clinicians to protect glass ionomer cements from water and saliva for the first 15 minutes after mixing. 3.5 References. ME RAZZOOG

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