REMOVABLE PROSTHODONTICS SECTION EDITORS

LOUIS BLATTERFEIN S. HOWARD PAYNE

Treatment of open occlusions with onlay and overlay removable partial dentures

John B. Farmer, D.M.D.,* and Mark E. Connelly, D.D.S.** U. S. Army DENTAC, Fort Carson, Cola., and U.S. Army Regional Dental Activity, Fort Sam Houston, Tex

T he construction of removable partial dentures as the primary treatment in patients with congenital or acquired oral defects is well documented.1*2 Recently, the use of removable partial overdentures has been described with endodontically trea&d teeth used for support. 3,4 The purpose of this article is to describe an onlay removable partial denture approach for treat- ment of open-bite occlusions (open occlusion of anterior teeth) with the use of vital teeth.

BACKGROUND

The open occlusion phenomenon may be manifested in all types of malocclusions. Vertical bony dysplasia or an interference that does not allow the opposing teeth to occlude may result in an open occlusion. Salzmann5 stated that tongue position over the incisal edge or occlusal surface is the primary cause. Abnormal swal- lowing and tongue thrusting are primary contributing factors. Individual habits such as thumb-sucking and lip-sucking also predispose to open occlusion. In some instances supraeruption of posterior segments may result in an anterior open occlusion.

Proffit and Vig6 state that two things produce lateral or posterior open occlusion. These are: “mechanical interference with eruption either before or after the tooth emerges from the alveolar bone, or (2) failure of the eruptive mechanism of the tooth so the expressed amount of eruption does not occur.” Therefore, lateral placement of the tongue in a posterior open bite (occlusion) may be a result of the malocclusion, not the cause. Even though the causative factors are an enigma, the malocclusions that result are readily apparent.

Orthodontic treatment is accomplished through ver-

The opinions and assertions expressed herein are those of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense.

*I,ieutenant Colonel, DC, U.S. Army DENTAC, Fort Carson, COIO.

**Formerly. Colonel, DC, U.S. Army; Commander, U.S. Army Re- gional Dental Activity, Fort Sam Houston, Tex.; Associate Profes- sor, University of Alabama, School of Dentistry, Birmingham, Ala.

tical movement of the maxillary teeth. Resistance to the extrusion of the natural teeth by the tongue, orbicularis muscle complex, and periodontal ligament offers a high potential to relapse.

Orthodontic treatment of posterior open occlusion that is the result of an interference by the tongue or cheek may be ,successful. However, the more posterior and the more teeth involved in the open occlusion, the poorer the prognosis for successful orthodontic therapy. Proffit and Vi& state that posterior open occlusion that is the result of failure of the eruption mechanism will not respond favorably to orthodontics. In these instances, possible ankylosis of the involved teeth could result, and orthodontic treatment may result in intru- sion of the normal teeth. Proffit and Vig6 recommend prosthodontic replacement of these teeth.

Often joint orthodontic-oral surgery procedures are used. This usually involves segmental osteotomy repo- sitioning procedures in combination with orthodontic retention. Patients for whom joint orthodontic-oral surgery procedures cannot offer predictably stable results should be considered for prosthodontic treat- ment.

Prosthodontic considerations

The choice of prosthodontic treatment. for the anteri- or open occlusion depends on several factors.

1. The labial position and inclination of the a&ted maxil- lary anterior teeth in the anterior open occlusion patient

2. The vertical distance between the incisal edges of the maxillary teeth and the occlusal plane

3. The anterior lip placement and the esthetics of the smile line

Patients with pronounced labial version of the affect- ed teeth may require extraction in some instances to obtain proper alignment of the denture teeth.

Many patients exhibit severe anterior open occlusion with little or no Ilabial flaring of the teeth. Such patients are ideally suited for a removable partial denture (Fig. 1). All teeth onlaid by the removable partial denture

MARCH 1984 VOLUME 51 NUMBER 3

MALOCCLUSION AND REMOVABLE PARTIAL DENTURES

Fig. 1. Severe anterior open occlusion where orth- Fig. 3. Removable partial denture framework derives odontic and surgical correction are contraindicated. support from all onlaid teeth.

Fig. 2. Patient with posterior open occlusion with “submerged” ankylosed posterior teeth.

Fig. 4. Bead retention is provided for attachment of acrylic resin and facaded teeth.

framework will provide excellent support and stability. Teeth to be clasped are selected in the same manner as for a conventional removable partial denture.’ The lateral or posterior open occlusion may be treated in a similar manner (Fig. 2).

Technique

The occlusal surfaces of the teeth to be onlaid offer excellent support for the removable partial denture (Fig. 3). Conventional rests are placed on selected teeth when appropriate. To minimize interferences in seat- ing an extensive onlay casting, it is recommended that minute grooves and fissures be smoothed out and highly polished prior to making the final impression. Bead retention (retention beads for metal casting, No. 14, Kay-See Dental Mfg. Co., Kansas City, MO.) rather than raised conventional retentive mesh (Fig. 4) is provided for acrylic resin bases. This method elimi- nates thin regions of acrylic resin, is more hygienic, and

achieves additional space for placement of the denture teeth.8 Retentive clasp elements that are to be covered by acrylic resin should have sufficient relief contoured in the resin to allow for flexibility of the clasps. This will permit proper insertion and removal of the remov- able partial denture without stressing the abutments.

The master cast is blocked out in the usual manner to eliminate undesirable undercuts and is duplicated in reversible hydrocolloid. A refractory cast is poured with a gypsum-bound investment (Investic, Ticonium Co., Albany, N.Y.) and the framework is waxed up. The wax pattern is sprued, invested, and burned out at 1250” F for 3 hours. The framework is then cast in a nickel-chrome-beryllium alloy (Ticonium Premium 100, Ticonium Division, CMP Industries, Inc., Alba- ny, N.Y.) with an induction casting machine and finished and polished in the conventional manner.

The framework is tried-in to correct the fit and evaluate the stability of the casting (Figs. 5 and 6).

THE JOURNAL OF PROSTHETIC DENTISTRY 301

FARMER AND CONNELLY

Fig. 5. Framework try-in. Fig. 7. Completed removable partial denture restores esthetics and function. Patient quickly adapted to prosthesis.

Fig. 6. Intraoral view of onlay casting with bead retention and lingual finishing line.

Chloroform and rouge or disclosing wax is used for refinement of the internal surface of the casting. The framework then can provide stability for an accurate centric jaw relation record or for a functionally gener- ated path technique in posterior open occlusion situa- tions. The denture teeth are arranged for proper placement in relation to lip contour and occlusal plane. The completed prosthesis restores both esthetics and function (Figs. 7 and 8).

Postinsertion maintenance

Proper oral hygiene techniques are emphasized meticulously to the patient.9 The increased tooth cover- age necessary with an onlay removable partial denture potentiates the probability for plaque accumulation and caries and inhibits normal gingival stimulation.

The patient is instructed in the importance of proper cleansing techniques. The use of disclosing media in

Fig. 8. Completed onlay removabie partial denture for patient with posterior open occlusion.

conjunction with thorough brushing and use of floss is necessary on a daily basis.

Application of a topical fluoride gel (0.4% stannous fluoride) three times weekly for 2 to 3 minutes is essential to prevent the occurrence of caries beneath the prosthesis.

The patient is also instructed to remove the prosthe- sis at bed time to allow the supporting tissues to return to normal contour, to clean the prosthesis after each meal if possible, and to clean it thoroughly each night with a soft-bristled denture brush and soap and water. The patient must demonstrate the ability to clean the clasps, rests, and tissue-side parts of the prosthesis. The use of a commercial cleanser is an adjunctive aid to proper cleansing.

Finally, the patient is placed on a Smonth recall

302 MARCH 1984 VOLUME 51 NUMBER 3

MALOCCLUSION AND REMOVABLE PARTIAL DENTURES

schedule and scheduled for a routine prophylaxis every 6 months. The importance of meticulous oral hygiene practices and prosthesis maintenance cannot be over- emphasized, particularly in patients with onlay remov- able partial dentures.

DISCUSSION

After insertion of the onlay removable partial den- ture, the patient may experience some awkwardness in speech and complain of tongue crowding. These com- plaints are usually transient; however, a speech pathol- ogist may provide counseling and speech therapy exercises if needed. The patient’s aberrant tongue habits may cease with continued use of the removable partial denture.

Restoration of the occlusal plane results in a signifi- cant increase in function. However, sudden increase in the functional requirements of teeth not previously used may result in discomfort to the onlaid teeth. This discomfort is usually temporary.

The advantages of the onlay removable partial denture approach are as follows.

1. 2.

3.

4.

5.

The existing dentition is used with minimal alteration. Proper alignment of the denture teeth provides improved esthetics by means of a facade. The correction of the occlusal plane achieves increased functional occlusion. The procedure can be diagnostic, and it provides informa- tion useful to the orthodontic-oral surgery team for anticipated surgical procedures. The procedure is reversible and the removable partial denture in many instances can serve as an interim prosthesis.

The onlay removable partial denture also has appli- cation in restoring a malposed mandibular dentition to a proper occlusal plane when more extensive treatment modalities are contraindicated. This is appropriate when the maxillary complete denture opposes natural lower teeth and the mandibular dentition has an uneven occlusal plane. lo This approach should be

considered in instances when restoration of the plane of occlusion is a foremost objective.

SUMMARY

The onlay removable partial denture has the prima- ry purposes of restoration of esthetics and function through a conservative modification of the existing dentition. It is particularly applicable to open occlusion situations and in improving an uneven mandibular occlusal plane. Its use should be supplemented with specific instructions in proper cleansing and mainte- nance of the underlying dentition and the prosthesis and with scheduled recall appointments.

REFERENCES

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

Beumer, J., Curtis, T. A., and Firtell, D. M.: Maxillofacial Rehabilitation: Prosthodontic and Surgical Considerations. St. Louis, 1979, The C. V. Mosby Co., pp 160-169 and 229-

242. Birnbach, S.: Prosthetic management of the congenital cleft- palate patient. J PROSTHET DENT 35~654, 1976. Strohaver, R. A., and Travillion, H. M.: Removable partial overdentures. J PROSTHET DENT 35:624, 1976. Firtell, D. M., Herzberg, T. W., and Walsh, J. F.: Root retention and removable partial denture design. J PROSTHET DENT 42~131, 1979. Salzman, J. A.: Practice of Orthodontics. Philadelphia, 1966, J. B. Lippincott Co., vol 2, pp 590-591. Proffit, W. R., and Vig, W.: Primary failure of eruptions: A possible cause of posterior open-bite. Am J Ortho 80:173, 1981. Krol, A. J.: Removable Partial Denture Design: An Outline Syllabus, ed 3. San Francisco, 1981, University of the Pacific, School of Dentistry, pp 19-27. Morrow, R. M., Rudd, K. D., and Eissman, H. F.: Dental Laboratory Procedures: Complete Dentures. St. Louis, 1980, The C. V. Mosby Co., vol 1, p 449. Wagner, A. G.: Maintenance of the partially edentulous mouth and care of the denture. Dent Clin North Am 12755, 1973. Ellinger, C. E., Rayson, J. H., and Henderson, D.: Single complete dentures. J PROSTHET DENT 26:4, 1971.

Refrinl requests to: DR. JAMEZ B. FARMER 2539 SHALIMAR COLORADO SPRINGS, CO 80915

THE JOURNAL OF PROSTHETIC DENTISTRY 303