Changes caused by a mandibular removable partial denture opposing a maxillary complete denture

Changes caused denture oppesing

by a mcmd a muxitkwy

Ellsworth Kelly, D.D.S.* School of Dentistry, Uniuersity

of California,

r remov p4BHkll compbe de&we

San Francisco,

A

Calif.

lthough many advances have been made in denture prosthetics, the great problem is still with us: coping with the resorption of the residual alveolar ridge and managing or preventing the secondary soft tissue changes brought on by bone loss. The resorption occurring beneath denture bases has been investigated*-” and we have some knowledge of the rate of resorption of the residual bony ridge. Investigators agree that individual differences in the rate of resorption of the ridges are very great. Underlying metabolic, hormonal, and nutritional causes account for this difference and we know very little about these factors. knowledge From clinical experience and clinical studies,l”j l1 we have considerable of the prosthetic factors which influence bony resorption. We know that moderate, intermittent forces exerted on the bony ridge by a prosthesis may be stimulating and help preserve rather than destroy the bony ridge. l2 We know that excessive force causes resorption of the residual ridge. De Van I3 stated that compressive forces are well tolerated by the edentulous ridges while shearing forces are not. This concept has been utilized by many techniques which minimize the lateral forces exerted by dentures. The principle of wide coverage with the complete or partial removable denture base to minimize the force per unit area is basic14 and has served us well. Yet we are not able to do anything for those people who are very susceptible to bone loss because of underlying systemic causes and who, in spite of our best efforts, often end up with very little bone remaining. On the other hand, we do have the knowledge to prevent excessive bone loss from traumatic forces exerted by or on the denture bases. Observation of a number of denture patients will show that we are failing to put this knowledge into practice. Destruction of the residual ridge from occlusal trauma is not uncommon. Very common is the almost total loss of bone in the anterior part of the maxillae brought about by only natural anterior teeth remaining in the mandible and occluding with a compelte upper denture. The anterior part of the maxillae is the weakest part of the upper arch to resist stress and when the Read

before

*Professor

140

the Academy of Removable

of Denture Prosthodontics.

Prosthetics

in Detroit,

Mich.

Volume Number

27 2

Partial

Fig. 1. A maxillary anterior teeth and tion often effects.

arch that has supported a Class I partial denture

denture

opposing

complete denture

141

a complete upper denture against six natural lower for 14 years shows the changes that this combina-

lower anterior teeth occlude anterior to the basal support, trauma is inevitable. Many of these patients have distal-extension partial lower dentures but this does not seem to prevent this type of destruction in the upper jaw. The degenerative changes, in these patients include more than the loss of bone. An overgrowth of the maxillary tuberosities often occurs. These enlargements are usually fibrous but they may be bony enlargements. Papillary hyperplasia of the palatal mucosa may occur concurrently. The remaining mandibular anterior teeth seem to extrude along with the bony process, and excessive bone loss occurs in the posterior part of the ridge under the partial denture bases. These five changes may constitute a syndrome, as they are quite characteristic. These changes are (1) loss of bone from the anterior part of the maxillary ridge, (2) overgrowth of the tuberosities, (3) papillary hyperplasia in the hard palate, (4) extrusion of the lower anterior teeth, and (5) the loss of bone under the partial denture bases. I call this the “combination syndrome.” COMPLETE

UPPER

DENTURES

OPPOSING

PARTIAL

LOWER

DENTURES

Completely edentulous maxillae and partially edentulous mandibles anterior teeth remaining are common situations. In the past two years, patients treated in the prosthodontic clinic at the School of Dentistry of the of California received complete maxillary dentures opposing mandibular dentures. This represents 26 per cent of the denture patients. Some of dentures had distal support but most of them did not. THE COMBINATION

with only 130 of 495 University partial the partial

SYNDROME

The early loss of bone from the anterior part of the maxillary jaw is the key to the other changes of the combination syndrome. With the anterior loss of bone, a flabby hyperplastic connective tissue makes up the anterior part of the ridge. This hyperplastic tissue does not support the denture base and usually it folds forward,

142

.I. Prosthet. February,

Kelly

Fig. 2. Mounted diagnostic casts show bony loss and upper anterior region, enlarged tuberosities, and extruded

rolled lower

(hyperplastic) anterior teeth.

soft

tissue

Dent. 1972

in

the

Fig. 3. With the loss of anterior maxillary bone, overgrowth of the tuberosities, and upward migration of the lower anterior teeth, the patient shows no upper anterior teeth but does show upper posterior teeth because of the dropping of the distal end of the occlusal plane of his dentures. a characteristic deep fold or crease (Fig. 1). As bone and ridge height arc lost anteriorly, the posterior residual ridge becomes larger with the development of enlarged tuberosities. These enlarged tuberosities are usually made up of fibrous tissue, but in some patients the bone height seems to have increased also. With these changes, the occlusal plane migrates up in the anterior region and down in the back. After a time, the natural lower anterior teeth migrate upward, the anterior teeth on the complete denture disappear under the patient’s lip, and both dentures migrate downward in the posterior region. The esthetics are poor with the patient showing none of the upper anterior teeth and too much of the lower anterior teeth, and the occlusal plane drops down to expose the upper posterior teeth (Figs. 2 and 3 i . Excessive bony resorption under the lower removable partial denture bases occurs to permit these changes, and often inflammatory papillary hyperplasia develops in the palate (Fig. 4). The histopathology of the hyperplastic anterior ridge tissue, and the fibrous tissur which develops over the tuberosities is revealing. Microscopic examination of these tissues shows that the flabby tissue and the hard tissue over the tuberosities are indistinguishable. They are made up of mature, dense, fibrous connective tissue. This tissue in both locations has dense bundles of collagen fibers, with relatively few ceilular elements, with very few inflammatory cells. It is rather avascular with an overlying epithelium that is almost normal, but shows some evidence of hyperplasia (Fig. 5). This is also the histopathology of a mature epulis fissuratum if we discount the area of ulceration caused by the denture border. This similarity is surprising because the hyperplastic anterior tissue is freely movable while the fibrous tissue over the tuberosity is hard. However, all three of these conditions (the flabby anterior forming

Volume Number

Partial

27 2

Fig. 4. Papillary bination syndrome.

hyperplasia

ridge, the fibrous trauma from the same is logical. The difference must be explained appeared and the ally unsupported over the tuberosity MECHANICS

in

the

palate

denture

often

opposing

accompanies

the

complete

other

denture

changes

143

of the com-

tuberosity, and the epulis fissuratum) are the result of prolonged denture base. Therefore, the fact that the tissue response is the in consistency of fibrous tuberosities and flabby anterior ridges on a mechanical basis. The anterior bony ridge has virtually disconnective tissue replacement is a narrow projection of tissue virtuon the labial or lingual surface. On the other hand the fibrous tissue is supported by a broad base of bone below.

WHICH

PRODUCE

THE COMBINATION

SYNDROME

The resorption of the bone in the anterior region initiates the changes which we call the combination syndrome. Natural anterior maxillary teeth have increased bony resorption under maxillary dentures. + 5 While bone is being lost in the anterior region in the upper jaw, bony resorption also occurs under the mandibular partial denture bases. The maxillary denture then moves up in the anterior region and down in the posterior region in function. This tipping action is illustrated in the diagram (Fig. 6) which was traced from cephalometric radiographs of a patient who had been wearing a complete upper denture opposing a lower partial denture for 16 years. The fulcrum of movement in this patient is in the cuspid-first bicuspid region, Our patients show that at first the fulcrum is well to the posterior, just anterior to the tuberosity. With the posterior palatal seal, a negative pressure is produced posterior to the fulcrum line. This negative pressure may account for the enlarged tuberosities and the papillary hyperplasia. Carlssonl observed one patient who had an increase in the maxillary ridge height in the molar region after wearing dentures for two years. He postulated : “It may have been due to the development of a fibrous part possiblyl owing to the suction effect when the denture moved.” A number of authors15-1r have associated a void, a “suction chamber,” or other form of negative pressure with

144

Kelly

Fig. 5, A & B. Histologic sections of the (x100) ; (B) fibrous tuberosity (x100).

lesions:

(A)

A flabby

(hyperplastic)

anterior

ridge

inflammatory papillary hyperplasia of the palate. Wictorin” states that to prevent bony resorption, mechanical forces must be distributed over as large an area of the basal seat as possible, and the denture must make as little movement as possible against its basal seat, and that these factors are strongly interconnected. With the lower anterior teeth causing trauma and bone loss from the anterior part of the maxillae, and with the denture base moving more and more on its foundation, a very destructive situation exists. All kinds of questions come to mind. How fast do the degenerative changes develop? Is excessive bone loss in the anterior part of the maxillae with the other changes that follow inevitable or does it occur only in neglected patients, those without proper follow-up treatment in refitting the denture bases and readjustment of

z%zr ‘2’

Partial

denture

opposing

Fig. 5, C & D. (C) Inflammatory papillary hyperplasia similarity of A (hyperplastic ridge tissue) and B (fibrous The papillary hyperplasia shows (n) the fibrous core, (b) inflammatory cells.

complete

denture

145

(x40) ; (D) the same (x100). The tuberosity) is discussed in the text. the hyperplastic epithelium, and (c)

occlusion? If it is from neglect, what kind, and what amount of care is necessary to prevent it? Will the changes occur in all patients or only in susceptible patients with underlying metabolic, hormonal, or nutritional deficiency? PATIENT

HISTORIES

WITH

CEPHALOMETRIC

RADIOGRAPHS

In an effort to find answers to some of these questions, we started a study of 20 patients who were receiving complete maxillary dentures opposing distal-extension removable partial dentures. Only six of these patients have returned faithfully over

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J. Prosthet. Frbruary,

Kelly

Dent. 1972

Fig. 6. A diagram made from tracings from two cephalometric radiographs, one at physiologic rest position and the other with the teeth in centric occlusion. In this patient, with an advanced combination syndrome, the movement of the denture base is very great, causing positive pressure anterior to the fulcrum (F) and negative pressure posterior to this position.

Fig. 7. A lateral cephalometric the soft tissues of the ridge. Fig. 8. The lead and is very slightly

wire is in embedded

radiograph

of one of the subjects

place after the radiograph into the soft tissue.

shows

was made.

The

the lead wire lead

wire

outlining adheres

to

a three-year period so no conclusions can be drawn from this preliminary report. We made serial cephalometric radiographs with a 0.25 mm. diameter lead wire outlining the soft tissue on the right side of the ridge (Figs. 7 and 8). All of the patients received maxillary complete immediate dentures opposing Class I lower partial dentures. All were first-time denture wearers. The immediate dentures were constructed after the posterior teeth had been extracted and a healing period allowed. The first radiograph was made after the initial healing of the anterior part of the maxillary ridge had taken place, and after the anterior section of the immediate denture had been refitted with cold-curing acrylic resin. This was usually about four weeks after insertion of the dentures.

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complete

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Fig. 9. Cephalometric and show the and soft tissue,

tracings of each of the six subjects. They were made three years apart, changes that have occurred. The solid lines show the initial outline the bone the dotted lines indicate these outlines three years later (Table I).

A second radiograph was made after six to eight months. The patients were seen regularly over the first few months, and the dentures refitted and serviced as needed. After the first year, the third radiograph was made. At this time, the maxillary denture was relined or a new denture was constructed. After this, the patients were called annually for examination and radiographs. Measurements were made directly on the radiographs, using the sella-nasion line as a base. The results are expressed as millimeters of increase (plus) or millimeters of decrease (minus) in the residual ridge height. Table I shows these data for the maxillary bone and soft tissue. Tracings were made from the cephalometric radiographs. These show the changes graphically but not as accurately as the measurements directly on the radiographs (Fig. 9). All of the patients showed a loss of 1 to 3 mm. of ridge height in the anterior region. All of the subjects showed a loss of the underlying bone as well. All of the subjects showed an increase of 1 to 2.5 mm. height of the tuberosity with all but one having a corresponding increase in the height of the underlying bone. One subject had an increase in the height of the tuberosity but a slight loss of underlying bone. All of the subjects show a 1 .O to 1.5 mm. extrusion of the lower anterior teeth.

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Fig. 10. One of the subjects, although given follow-up treatment, shows the beginning of degenerative changes. The soft tissue in the anterior part of the maxillary ridge is thickened and soft. Note the characteristic horizontal fold on the labial surface of the maxillary ridge.

Table I. Each figure represents over a period of three years Posterior Patient A, age B, age C, age D, age E, age F, age

an increase

tuberosity

Soft tissue +2.5 +1.0 +1.3 12.0 cl.0 +1.3

63 51 46 43 35 34

or decrease

ridge j

Bony

height ridge

+1.7 +1.0 +0.5 +1.7 --0.2 +o..i

(

in millimeters

Anterior Soft tissue -2.2 -3.0 -2.2 -1.5 -2.9 -1 .o

of ridge height

ridge 1

height Bony

ridge

-1.7 ..~3.0 -1.2 -1.0 -0.7 --0.5

This is significant since the measurements are very accurate because of the stability of the bony landmarks at the midline. One patient is beginning to show signs of the deterioration of the anterior part of the upper ridge which we attribute to trauma from the lower anterior teeth. This patient has a flabby thickening of the tissue, inflammation of the incisive papilla, and the beginning of a fold forming the labial surface of the ridge (Fig. 10) . All of the subjects have been successful denture wearers, well satisfied with their prosthesis. They have received better than average follow-up treatment in refitting the bases and equilibrating the occlusion. With the loss of tissue demonstrated in the anterior part of the upper jaw, and with a positive change developing in the posterior part of the ridge, and with the lower anterior tooth migration, it appears that any or all of these patients could develop the typical signs of the combination syndrome. PREVENTION

OF THE

COMBiNATION

SYNDROME

Preventing the degenerative changes that complete maxillary the Class I partial dentures bring about may only be possible

dentures opposing through treatment

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planning to avoid this combination of prostheses. Complete lower dentures opposing natural maxillary teeth are impossible prosthodontic combinations. Treatment planning should avoid the necessity for such a combination. The same could be done to eliminate the combination of complete upper dentures opposing Class I lower partial dentures. I do not advocate extracting lower anterior teeth to accomplish this but rather to retain weak posterior teeth as abutments by means of endodontic and periodontic techniques. Endosseous endodontic implants and the amputation of one lower molar root to preserve the other as an abutment are examples of some of the methods that could be applied. An overlay denture on the lower may avoid the combination syndrome from developing. Overlay dentures utilizing the lower tooth roots for stabilization provide a complete denture occlusion. SURGICAL

CORRECTION

OF CHANGES

IN THE BASAL

SEAT

Even after much damage has been done and gross changes have taken place, many dentists and patients prefer to remake the combination rather than sacrifice the remaining lower anterior teeth to make complete dentures. Surgery can do much to rehabilitate these patients. The flabby (hyperplastic) tissue can be removed, the papillary hyperplasia can be eliminated, and the enlarged tuberosities can be reduced. This allows the distal end of the occlusal plane to be raised to the proper level, and allows the lower partial denture bases to be fully extended. This is extremely important, and covering the maximum area possible for support of partial denture bases would help prevent the combination syndrome. Covering the retromolar pad where muscle and raphe attachments prevent or reduce resorption, and covering the buccal shelfI is necessary to retard bone loss. Often this is not done with removable partial dentures. SUMMARY Almost inevitable degenerative changes develop in the edentulous regions of wearers of complete upper and partial lower dentures. We have followed six patients over a three-year period with cephalometric radiographs to determine if these changes could be detected. In all six subjects, early changes that could become gross changes were apparent. In one of them degenerative clinical change is beginning to appear. This problem might be solved with treatment planning to avoid the combination of complete upper dentures against distal-extension partial lower dentures. The alternative of complete maxillary and mandibular dentures is not attractive to patients. Preserving posterior teeth to serve as abutments to support lower partial dentures and to provide a more stable occlusion is a better alternative. Ill-fitting dentures have been blamed for all of the lesions of the edentulous tissues, yet the most perfect denture will be ill-fitting after bone is lost from the anterior part of the ridge. Removable dentures need periodic attention at least as often as the natural teeth.

The author would like to express his appreciation to Dr. advice on oral pathology and to Dr. Leonard Chong for radiographs and tracings.

Louis S. Hansen for his help and his help with the cephalometric

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J. Prosthet. February,

Dent. 197’2

References 1. 2. 3. 4. 5. 6. 7.

8. 9. 10. 11. 12.

13. 14. 15. 16. 17.

Carlsson, G. E.: Measurements on Casts of the Edentulous Maxilla, Odont. Revy. 17: 386-402, 1966. Carlsson, G. E.: Changes in the Jaws and Facial Profile after Extractions and Prosthetic Treatment, Trans. R. Schools Dent., Stockholm and Umea, No. 12: 16, 1967. Carlsson, G. E., and Persson, G.: Morphologic Changes of the Mandible after Extraction and Wearing of Dentures, Odont. Revy. 18: 27-54, 1967. Carlsson, G. E., Bergman, B., and Hedegard, B.: Changes in Contour of the Maxillary Alveolar Process Under Immediate Dentures, Acta Odont. Stand. 25: 1-31, 1967. Wictorin, L.: Bone Resorption in Cases With Complete Upper Denture, Acta Radiol. Sppl. 228, 1964. Hedegard, B.: Some Observations on Tissue Changes With Immediate Maxillary Dentures, Dent. Pratt. 13: 70-78, 1962. Atwood, D. A.: A Cephalometric Study of the Clinical Rest Position of the Mandible. II. The Variability in the Rate of Bone Loss Following the Removal of Occlusal Contacts, J. PROSTHET. DENT. 7: 544-552, 1957. Atwood, D. A.: Some Clinical Factors Related to Rate of Resorption of Residual Ridges, J. PROSTHET. DENT. 12: 441-450, 1962. Atwood, D. A.: Reduction of Residual Ridges as a Disease Entity, Essay presented at meeting of the American Prosthodontic Society, Las Vegas, 1970. Neufeld, J. 0.: Changes in the Trabecular Pattern of the Mandible Following the Loss of Teeth, J. PROSTHET. DENT. 8: 685-697, 1958. Applegate, 0. C.: Conditions Which May Influence the Choice of Partial or Complete Denture Service, J. PROSTHET. DENT. 7: 182-196, 1957. Carlsson, G. E., Thilander, H., and Hedegard, B.: Histologic Changes in the Upper Alveolar Process After Extractions With or Without Insertion of an Immediate Full Denture, Acta Odont. Stand. 25: 123-146, 1967. De Van, M. M.: An Analysis of Stress Counteraction on the Part of Alveolar Bone With a View to Its Preservation, Dent. Cosmos 77: 109-123, 1935. Boucher, C. 0.: A Critical Analysis of Mid-Century Impression Techniques for Full Dentures, J. PROSTHET. DENT. 1: 472-491, 1951. Fairchild, J. M.: Inflammatory Hyperplasia of the Palate, J. PROSTHET. DENT. 17: 232237, 1967. Hickey, J. C., and Stromberg, W. R.: Preparation of the Mouth for Complete Dentures. J. PROSTHET. DENT. 14: 61 l-622, 1964. Campbell, R. L.: Relief Chambers in Complete Dentures, J. PROSTHET. DENT. 11: 230236, 1961. UNIVERSITY OF CALIFORNIA SCHOOL OF DENTISTRY SAN FRANCISCO, CALIF. 94422