combination syndrome.doc

Combination Syndrome

PURPOSE

Rapid bone resorption and subsequent soft tissue changes beneath removable prostheses

are often perplexing and disheartening to both patient and clinician. The purpose of this

Clinical Update is to define the term combination syndrome and present current

prevention, treatment, and maintenance strategies employed in preserving bone.

BACKGROUND

In 1972, Kelly1 coined the term combination syndrome, a descriptive term recognizing

five characteristic changes occurring with time and often combined in a combination

case-a mandibular distal extension removable partial denture opposing a maxillary

complete denture. The five characteristic features typically present in patients diagnosed

with combination syndrome are:

1) Bone loss in the anterior aspect of the maxillary ridge.

2) Tuberosity down growth or overgrowth (with or without sinus pneumatization).

3) Palatal papillary hyperplasia.

4) Hyper eruption of the mandibular anterior teeth.

5) Bone loss beneath the removable partial denture bases.

6) Other investigators have identified at least six associated changes that may also

occur. 2,3

a. Decrease in occlusal vertical dimension.

b. Occlusal plane discrepancies.

c.Anterior repositioning of the mandible.

d. Poor adaptation of one or both prostheses.

e.Epuli formation.

f. Periodontal changes.

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DISCUSSION

Although longitudinal studies indicate that generalized resorptive patterns occur with

time,4 bone resorption beneath removable prostheses is complex and poorly understood.

The rate of resorption is affected by many variables and predisposing factors, such as

extraction history, quality and use of the prosthesis, parafunctional forces, and systemic

diseases like diabetes and osteoporosis.5 Also, considerable variation in resorptive rates

exists among individuals. Most astonishing are the extreme cases-the person whose bone

resorbs rapidly and continuously despite extreme preventive measures and the person

whose edentulous ridges respond very favorably despite heavy functional and

parafunctional forces. The typical patient, however, falls between these extremes and is

able to tolerate moderate, intermittent, compressive forces. Patients with a high Frankfurt

mandibular plane angle and severe parafunctional forces, such as heavy clenching or

grinding, demonstrate the most trauma to the residual ridges.4 Normal, functional forces

load the denture-bearing areas for about 5 minutes a day as opposed to 17.5 minutes a day

for those demonstrating parafunction. 6 Tallgren's longitudinal study4 showed that, on

average in edentulous patients after the first 7 years, the mandible resorbed four times

faster than the maxilla, probably because the mandible has a smaller bearing area, a less

advantageous shape for broad stress distribution, and it lacks the secondary bearing area

afforded by the hard palate. Also, most of the bone resorption in both arches occurred

during the first year.4 Numerous studies of ridge preservation clearly demonstrate the

advantages of immediate dentures, retaining overdenture abutments, and utilizing such

concepts as broad stress distribution, peripheral seal, minimal anterior tooth contact, and

balanced occlusal schemes.7 To mitigate bone loss, the most critical time period is during

the first year after initial delivery.4 Sadly, during this time, recall and maintenance are

often overlooked or brushed aside by practitioner and/or patient because the patient has

just been recently restored. Initial changes to the bearing bone are greatest early,

especially in immediate and recent extraction cases, and occur to some degree in all

cases. Such changes usually are painless and do not initially degrade function, comfort,

or support, and they remain unobserved by the patient.

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A "TYPICAL" SCENARIO

A review of the hard and soft tissue changes occurring with time in a typical combination

case will elucidate how and why such untoward changes occur.

Loss of mandibular posterior support occurs first as the new mandibular RPD loads the

primary denture-bearing areas, and initial resorption begins. Buccal shelf areas and the

posterior crest of the ridge resorb faster if immature extraction sites are present, the

patient has never worn a distal extension RPD before, or a corrected cast technique or

suitable post-delivery reline was not done. Obviously, if the patient refuses to wear the

mandibular prosthesis or one was not fabricated, then the advantages of prosthodontically

augmented posterior support are gone. An exception to this may be found in a severe

Angle's Class /1, division 1, malocclusion case in which sufficient posterior support may

exist if enough premolars are present.8

As mandibular posterior support is lost the occlusal load shifts anteriorly. With artificial

tooth wear, forward-posturing of the mandible, and increased anterior protrusive contact,

the maxillary anterior ridge resorbs in response to untoward forces generated by the

remaining natural teeth through the displaced maxillary denture base. Varying degrees of

soft tissue change and support occur, especially in the maxillary anterior ridge area.

With continuing wear and displacement of the maxillary complete denture superiorly and

anteriorly, the occlusal plane drops posteriorly, and the occlusal vertical dimension

decreases. Often, epuli form at the maxillary labial flange and fibrous connective tissue

overgrowth occurs, overlaying the tuberosities. Because of poor adaptation to the

underlying mucosa and probable poor oral hygiene, inflammatory papillary and palatal

hyperplasia occur, and the patient may notice decreased retention of the complete denture

and seek a reline. If a reline is done without correcting the etiologic conditions and/or

without proper tissue conditioning, the pathologic processes are perpetuated, often at an

accelerated rate.

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Depending on the periodontal support, the remaining natural teeth may flare, extrude,

and/or become more mobile. "Pneumatization" of the tuberosities (the mechanism of this

is not clearly understood) may occur, and the shifted plane of occlusion and lack of

posterior support may result in mucosal stripping at the major connector and further

stress placed on the natural teeth. These events, usually occurring together, are the

hallmark of combination syndrome, which will occur unless proper diagnosis, treatment

planning, execution of treatment, and proactive recall and maintenance are done.

PLANNED PROSTHODONTICS AND PREVENTION

The concept of "planned prosthodontics” encourages astute clinical evaluation that

discerns not only the early signs and symptoms of combination syndrome, but also

recognizes the possibility of the syndrome's occurring and the treatment potential of the

patient.

To satisfy the fundamental criteria of support, function, and esthetics in rehabilitating

these patients and preventing or limiting further degradation with time, the following

concepts should be considered.,

1. Preserve overdenture abutments in the mandibular posterior

and/or maxillary anterior. If these abutments and overlaying prosthesis are

physiologically adjusted to be loaded only under forceful biting pressure, they

will serve a very useful proprioceptive, bone-sparing function. 9

2. Consider restoring the mandibular posterior occlusion utilizing

current implantology techniques. Then, restore the maxillary arch with a single-

unit denture.

3. Stay abreast of research involving implant fixtures, such as

overdenture abutments, and consider using this treatment modality when

indicated. 10-13

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4. Correct plane of occlusion discrepancies and vertical

dimension problems prior to definitive treatment.

5. Tissue-condition prior to impression making.

6. Utilize acceptable impression techniques, and apply the

principle of broad stress distribution. 7

7. If possible, "harden" surfaces of artificial teeth to prevent

premature wear. Consider amalgam inserts or metallic occlusal surfaces. 14

8. Maintain careful records of plaque control, mobility patterns,

and pocket depths.

9. Educate your patient! Demand meticulous oral hygiene and

care of the prostheses, and be sure the patient leaves the prostheses out of the

mouth daily for at least 8 hours. Emphasize the vital importance of recall,

maintenance, and awareness of parafunctional habits.

RECALL AND MAINTENANCE

Bone resorption beneath complete dentures, distal extension removable partial dentures,

and extensive Kennedy Class IV removable partial dentures occurs painlessly and most

extensively during the first year of functional use. Recall and maintenance visits during

this period are critical to limiting initial bone loss and preserving remaining bone.

Educating the patient in oral hygiene and prosthesis home care techniques and in the

importance of maintenance visits is vital to success.

After post-delivery visits at 24-hours, 1-week, and 1-month, maintenance appointments

should be scheduled at 3 months, 6 months, and 1 year during the first year.

Each maintenance appointment should include, but not be limited to, the following:

1. Extraoral observations with the prostheses worn. Swallowing should be easy,

unstrained, and with light posterior bracing. Look carefully for forward thrusting of

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the mandible. If deemed necessary by observation, query the patient about tongue

position and possible tongue thrusting.

2. Verify that the VDO, VDR, and closest-speaking space are within normal limits.

3. Intraorally, evaluate the prostheses for stability and retention. Ask the patient about

comfort and function.

4. Ask the patient to remove the prostheses, watching for removal problems, and

assess cleanliness. Check the finished and intaglio surfaces for possible tampering

by the patient. Look for wear in areas you would hope to see it--the more posterior

the better.

5. Visually observe and palpate intraoral structures as you conduct an oral cancer

screening examination. Check and record mobility patterns, pocket depths, and

plaque control efforts.

6. Ask the patient to insert the prostheses, and watch for insertion problems. Place

cotton rolls bilaterally in the premolar areas and have the patient close gently for

about 10 minutes. Verify that centric relation position and maximum intercuspal

position (centric occlusal position, if cuspless teeth are used) are coincident and that

eccentric movements are easy and maintain balance. Protrusive contacts should

still be very light, if at all.

7. Remove the prostheses and check primary and secondary denture-bearing areas.

Apply disclosing wax to the peripheries, crest of the ridge areas, and buccal shelf

areas of the RPD and reinsert it. Apply the wax to the premaxillary area and

hamular notches of the CD and to any periphery areas that appear to be insulting the

vestibular mucosa, and reinsert the denture. Rearticulate the patient in centric

relation position, and have him/her bite firmly on the posterior teeth for a few

minutes.

8. Verify that intimate contact occurs in all primary denture-bearing areas.

9. Disclosing wax gives a satisfying three-dimensional representation that can be

measured with a periodontal probe or explorer. Pressure-indicator paste is not as

useful for this purpose.

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10. Assess the need for relining, if alveolar resorption has occurred

enough to warrant it. Record your assessment in the patient record and follow up

with treatment, if indicated.

11. If CR and CO are not coincident, the patient has inadequate

posterior contact, the patient postures forward to function, and/or the articulation in

excursions is not balanced, do a patient remount using a periphery or putty cast for

the CD, a cast made with a pickup impression of the RPD (poured in stone and/or

low-fusing metal), a facebow transfer, and repeatable records. Assess the need for

equilibration, relining, rebasing, and/or remaking.

12. Expect to see early resorption in all immediate cases and those

in which extractions were made within 6 months of delivery.

13. Retention, although not as important as support and stability, is

significant and of concern to the patient. Overdenture abutments may need to be

reduced in height, repolished, and corresponding areas in the prosthesis

physiologically relined and adjusted.

14. Both prostheses should be thoroughly cleaned and lightly

repolished. Areas that retain calculus despite the patient's heroic efforts at cleaning

should be recontoured and repolished to be less plaque-retentive.

15. Review and reinforce plaque control and the care and cleaning

of the prostheses. Do a prophylaxis of the remaining natural teeth or appoint the

patient.

16. Encourage the patient to ask questions and become involved in

treatment and maintenance!

Recall and maintenance for combination case patients cannot be overemphasized. The

goal of getting through the first year with minimal bone resorption and other changes to

hard and soft tissues is achievable only through careful recall, maintenance, and follow-

up treatment. Semiannual maintenance appointments should be conducted after the

critical first year.

CONCLUSIONS

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Support and function suffer if supporting bone is lost. When a patient's tooth loss pattern

approaches that encountered in a combination case-a few remaining natural teeth, usually

in the mandibular anterior, opposing an edentulous maxilla-warning buzzers should go

off in the mind of the educated clinician, because the challenge to successfully restore the

patient while preserving supporting bone and protecting the mucosa requires astute

diagnosis, sensible treatment planning, careful treatment, and proactive maintenance.

REFERENCES

1. Kelly E Changes caused by a mandibular removable partial denture opposing a

maxillary complete denture. J Prosthet Dent 1972,,27.,140-50.

2. Bruce RW Complete dentures opposing natural teeth. J Prosthet Dent 1971,26.448-

55.

3. Saunders TR, Gillis RE, Desjardins RP. The maxillary complete denture opposing the

mandibular bilateral distal-extension partial denture: Treatment considerations. J

Prosthet Dent 1979,,41:124-8.

4. Tallgren A. The continuing reduction of the residual alveolar ridges in complete

denture wearers: A mixed-longitudinal study covering 25 years. J Prosthet Dent

1,972,,27.,120-32.

5. Stahl SS, Wisan JM, Miller SC. The influence of systemic diseases on alveolar bone. J

Am Dent Assoc 1952,45.277.

6. Heartwell CM, Rahn AO. Syllabus of complete dentures. 4th ed. Lea & Febiger

1985,,44

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7. Boucher CO. A critical analysis of mid-century impression techniques for full

dentures. J Prosthet Dent 1951(l):472-91.

8. Ellinger CW, Rayson JH, Henderson D. Single complete dentures. J Prosthet Dent

1971,,26:4-10.

9. Carlsson GE, Thilander H, Hedegard B. Histologic changes in the upper alveolar

process after extractions with or without insertion of an immediate full denture. Acta

Odont Scand 1967,,25:123-46.

10. Lingquist L W, Rockler B, Carlsson GE. Bone resorption around fixtures in

edentulous patients treated with mandibular fixed tissue-integrated prostheses. J

Prosthet Dent 1988;59:59-63.

11. Engquist B, Bergendal T, Kallus T, Linden U. A retrospective multicenter evaluation

of osseointegrated implants supporting overdentures. Int J Oral Max Fac Impl

1988;3:129-34.

12. von Wowern N, Harder F, Hjorting-Hansen E, Gotfredsen K. IT/ implants with

overdentures: A prevention of bone loss in edentulous mandibles? Int J Oral Max Fac

lmpl 1990,,5:135-9.

13. Sennerby L, Carlsson GE, Bergman B, Warfvinge J. Mandibular bone resorption in

patients treated with tissue-integrated prostheses and in complete denture wearers. Acta

Odont Scand 1988; 46:135-40.

14. Wallace D. The use of gold occlusal surfaces in complete and partial dentures. J

Prosthet Dent 1964; 14:326-33.

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combination syndrome.doc

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