COMPLETE DENTURES

A METHOD OF ARRANGING ARTIFICIAL TEETH FOR CLASS II JAW

RELATIONS

IRVING R. HARDY, D.M.D.,’ AND GINO PASSAMONTI, M.D., D.M.D.**

Middleboro, Mass., and Tufts University, School of Dental Medicine, Boston, Mass.

T HE CASTS of patients’ jaws with Class II jaw relations always look odd when they are mounted on the articulator. The lower cast appears to be too far back

in its relationship to the upper cast. However, the artificial teeth must be arranged to harmonize with the centric relation, even though the problems of tooth arrange- ment are complicated by the disharmony in the sizes of the two jaws. The problems involve both mechanical and esthetic considerations.

This article describes a method of arranging artificial teeth for patients with an unfavorable Class II jaw relationship. The posterior teeth are positioned so that esthetics and proper lip and cheek support are not sacrificed in order to develop an occlusion free of lateral interference.

PRELIMINARY RECORDS

After the casts have been mounted in the articulator, the twelve anterior teeth are arranged for the best possible esthetic result,l and the occlusal vertical dimen- sion, which previously had been tentatively determined, is rechecked by the “closest speaking space technique.“2

The occlusal plane best suited to the patient is selected, and blocks of V-Of posterior teeth3 are tentatively placed on the upper trial base. Sometimes it will be observed in this experimental arrangement that the block of teeth might provide for better centralization of masticatory forces4 if it is placed considerably distal to the “normal” location.

SPACE FILLER

To achieve this more favorable arrangement, an additional cuspid may be set on either side of the upper dental arch and aligned in the arch like a first bicuspid.

*Emeritus Professor of Prosthodontics, Tufts University, School of Dental Medicine, and Fulbright Professor of Prosthodontics, University of Rome.

**Currently Associate Professor of Dentistry, Chairman, Department of Prosthetics, Uni- versity of Detroit, School of Dentistry, Detroit, Mich.

tdustenal Company, New York and Chicago.

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Volume 13 Number 4 CLASS II JAW RELATIONS 607

When such a space filler is used, a cuspid is better than a bicuspid because it is ~zot to be a part of the posterior occlusal scheme. The lack of a palatal cusp is an advantage, because it allows space for the lower cuspid to “wander” in and out of centric position without cuspal interference.

If the V-O block is set so that its buccal surface is in the position required for appearance, its occlusal surface will be so far to the buccal that it will make inadequate oc:clusal contact with normally placed lower posterior teeth. This, of course, is because of the fact that the upper dental arch is so much wider than the lower one in these patients.

This part of the problem can be solved by moving the upper V-O blocks toward the palate far enough to occlude with lower teeth properly positioned on the lower ridge. While this will bring the occlusal surfaces into a good occlusal relationship, the buccal surfaces of the upper teeth will be so far in (toward the palate) that the appearance of the arrangement will be totally unacceptable.

M:ODIFICATION OF THE UPPER TOOTH BLOCKS

This situation can be corrected by adding tooth-colored wax to the buccal sur- faces of the tooth blocks and carving the wax to the contour of the teeth. Then, the trial bases can be carried to the mouth and the tooth arrangement checked to make sure the carved contours are esthetically correct.

The waxed and recontoured tooth blocks are removed from the trial base, and Basked, and the waxed-in areas are duplicated in acrylic resin of the proper shade. (This procedure brings to the posterior teeth nuances of shading which give them complete harmony with hand-molded anterior teeth.)

When processing is completed and the flash is removed, the teeth are polished, returned to the trial base, and waxed into place (Fig. 1). It will be noted that the overjet (horizontal overlap) is extremely marked. This “looks funny” on the articulator (Fig. 2), but people with Class II malocclusions carry the mandible far anterior to the centric relation when they are relaxed. Also, they bring the mandible well forward while speaking SO the appearance in the mouth is entirely

acceptable.

Fig. l.-The dentures are waxed ready for processing. The buccal surfaces of the maxillary teeth have been moved buccally by a facade of wax added to the block of V-O teeth and carved to reproduce the shape of these surfaces. Note the horizontal and vertical overlap of the anterior teeth.

HARDY AND PASSAMONTI J. Pros. Den. July-August, 1963

Fig. 2. Fig. 3.

Fig. Z.-The buccal surfaces of these posterior teeth have been built out with acrylic resin to form an esthetic arch form and the metal cutting blades are in a favorable position for occluding with the cutting blades in the smaller dental arch of the mandibular denture shown in Fig. 3.

Fig. 3.-The teeth on the mandibular denture are correctly related to the mandibular ridge.

Fig. 4.-A stock block of V-O posterior teeth has been waxed in the center of the palate for comparison with the modified tooth blocks used in the denture. The buccal surfaces of the block on one side have been built out further than on the other side. There was a greater disharmony of the sizes of the two residual arches on one side than on the other.

Fig. B.-The necessary vertical and horizontal overlaps have been restored and the full width of the arch in the bicuspid region has been achieved by building a facade on the buccal surfaces of the V-O tooth blocks.

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CLASS II JAW RELATIONS 600

A considerable vertical overlap of the anterior teeth on dentures is necessary for both the phonetics and the appearance of patients who have had a Class II mal- occlusion (Fig. 3). Most of these people have had a deep vertical overlap in their natural teeth. While it is unwise to build a malocclusion into dentures, some ver- tical overlap of the anterior teeth is desirable. However, the vertical overlap used on the dentures need not be as deep on the dentures as in the dentition they replace.

Hughes’j pertinent query, “\Vhat is Centric Relation” is perhaps more ap- plicable to Class II malocclusions than the more “normal” jaw relationship. An

anteroposterior rubbing action of the mandibular teeth against the maxillary teeth

is often incorporated in the masticatory stroke. The type of occlusion being suggested allows the patient to choose a maxillomandibular relationship which may tlot be in the centric relation but in one that is “comfortable.”

Fig. 4 shows a denture with a stock block of V-O posterior teeth waxed in the lbalate for comparison with the modified V-O blocks in the denture. This amount of facade is often necessary for proper appearance. In this denture, the V-O blocks

fell into a lrore favorable anteroposterior position than in the denture shown in Fig. 2, so the use of additional cuspids was not indicated.

A B

Fig. 6.-A second method for establishing occlusion between upper and lower teeth. A, The teeth do not rnake adequate contact because the upper arch is w-ider than the lower one. 5, Acrylic resin is added on the palatal surfaces of the upper teeth to establish the necessary occlusion.

The base material of the dentures is tinted” and sculptured to conform to care- fully contoured and shaded teeth which are arranged asymmetrically. These pro- cedures result in an excellent imitation of the dentition even though there is a dis- harmony in the size of the two arches in Fig. 5.

ANOTHER METHOD

Another method of meeting this problem is to proceed as outlined as far as the anterior teeth are concerned, and to arrange nonanatomic (0 degree) acrylic resin teeth in a position esthetically acceptable on the upper base. This will result in an unfavorable upper to lower tooth relationship (Fig. 6,,‘2 ) . Such an arrangr- merit is contraindicated because of the small area of occlusal contact. However, wax can be added to the @zfnZ surface of the upper teeth, and a platform built out at the occlusal level to afford adequate occlusal contact with the lower teeth (Fig. 6,B). This addition can be duplicated in resin at the time the denture is processed,

610 HARDY AND PASSAMONTI J. Pros. Den. July-August, 1963

and, after this surface is cured, it can be carved with a bur to provide grooves and spillways7 Nonanatomic procelain teeth might be the teeth of preference to occlude with this acrylic resin platform. Porcelain teeth with the original glaze intact will tend to induce little or no wear of the opposing resin8

The disadvantage of this method as compared to the building up of a facade over the buccal surfaces of the tooth block is that a very considerable amount of cutting efficiency which patients enjoy is lost. Patients like the “feel” of the teeth piercing the fo0d.O So, while the second method is a well tested and practical pro- cedure, it is now strictly a second choice.

A theoretical criticism of both methods is that they reduce the tongue space. However, clinical use of the methods has shown that patients adapt themselves to this unorthodox arrangement with little or no difficulty. WrightlO .has pointed out that crowding the tongue with a lower denture can be fraught with danger, but, clinically, some liberties can be taken in the maxillary denture without harm.

The situation is one of maxillomandibular abnormality, and abnormal condi- tions warrant and even demand treatment outside the “normal” concept.

SUMMARY

Two methods for establishing effective occlusal contacts on dentures for pa- tients who have had Class II malocclusions of their natural teeth have been described.

REFERENCES

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2. i

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Hardy, I. R.: Problem-Solving in Denture Esthetics, D. Clin. North America, pp. 305320, 1960.

Silverman, M. M.: The Speaking Method in Measuring Vertical Dimension, J. PROS. DEN. 3:193-199, 1953.

Hardy, I. R.: Developments in the Occlusal Patterns of Artificial Teeth, J. PROS. DEN. 1:14-28, 1951.

DeVan, M. M.: The Concept of Neutrocentric Occlusion as Related to Denture Stability, J.A.D.A. &:165-169, 1954.

Hughes, G. H., and Regli, C. P.: What is Centric Relation? J. PROS. DEN. 11:16-Z, 1961. Pound, E.: Esthetic Dentures and Their Phonetic Values! J. PROS. DEN. 1:98-111, 1951. Sauser, C. W., and Yurkstas, A. A.: The Effect of Various Geometric Occlusal Patterns

on Chewing Efficiency, J. PROS. DEN. 7:634-645, 1957. Sears, V. H. : Occluding Porcelain to Resin Teeth, D. Survey, 36:1144-1146, 1960. Payne, S. H. : Comparative Study of Posterior Occlusion, J. PROS. DEN. 2:661-666, 1952. Wright, C. R., Swartz, W. H., and Godwin, W. C.: Mandibular Denture Stability, Ann

Arbor, 1961, Overbeck Company, Publishers.

Box 431 MIDDLEBORO, MASS,

UNIVERSITY OF DETROIT SCHOOL OF DENTISTRY DETROIT, MICH.