Alveolar bone loss in overdentures: A 5-year study

REMOVABLE PROSTHODONTICS

SECTKIN

EDITORS

LOUIS BLATTERFEIN 5. HOWARD

PAYNE

GEORGE A. ZARB

Alveolar bone loss in overdentures: A S-year study Robert J. Crum, D.D.S.,* and George E. Rooney, Jr., D.D.S.** VA Hospital, Hines, Ill., and VA Center, Wood, Wis.

S

everal studies have shown that removal of all natural teeth and the wearing of complete dentures for a long time generally results in alveolar bone 10~s.“~Tallgren 1 2 found that after removal of teeth and replacement with complete dentures, maxillary and mandibular alveolar resorption over a 7-year period was in the ratio of 1:4. In a longitudinal study, Tallgren3 observed that the average reduction of anterior mandibular ridge height was 9 to 10 mm over a 25-year denture-wearing period. Reduction of the maxillary ridge during this same period amounted to 2.5 to 3 mm. Carlsson and Persson4 studied morphologic changes of the mandible following removal of teeth and placement of dentures. They found that the mandible lost 4 mm in height during the first year and that the resorption increased to 5 mm after 2 years and 6.7 mm 5 years following tooth removal. Carlsson and associates” also studied alveolar bone loss in 40 patients with edentulous maxillae and bilateral edentulous posterior mandibles. one group of 12 patients used only a complete maxillary denture; the second group of 16 patients used maxillary dentures and bilateral mandibular removable partial dentures, while a third group of 12 patients used a complete maxillary denture opposed by a removable partial denture with a Dolder Bar attached to the canines. At the 2-year follow-up no change was observed in mandibular contour in group 1; there was some change in groups 2 and 3. Also, the maxillary anterior process decreased an average of 1 mm in groups 1 and 2, while no change was observed in the group 3 patients. Miller’ advocated overdentures as a means of preserving residual alveolar bone, and he reported lessened resorption of alveolar ridge tissue over a period of 6 years in 46 overdenture patients. *Staff Prosthodontist, VA Hospital, Denver, Colo. **Chief, Dental Service, VA Center, Wood, Wis.

610

This clinical study was conducted to determine the amount of vertical residual alveolar bone loss in the anterior part of the maxillae and mandible in two groups of patients: one group with complete maxillary dentures and mandibular overdentures, and the other group with complete maxillary and mandibular dentures.

MATERIALS AND METHODS Sixteen men aged 46 to 67 years of age who had all their natural anterior teeth prior to treatment were studied over a 5-year postextraction period. One group (group 1) of eight patients was treated with overdentures made over endodontically treated mandibular canines (Fig. 1). These canines were reduced to approximately 1.5 mm above the gingival margin, and the occlusal portion of the pulp chambers was sealed with silver amalgam. Group 2 was treated with complete maxillary and mandibular dentures. Radiographic analysis was performed on cephalometric films made of the patients at the following intervals: (1) pie-extraction, (2) 3 weeks postextraction, and (3) at l-year intervals. Each film was made with the patient’s mandible in the rest position. The postextraction radiographs were made without dentures in the mouth. Seven films were made for each patient, and the cephalometric analysis was made by the use of tracings and superimposition of films and tracings. The analysis of the amount of tissue change was confined to bone and not soft tissue. Serial diagnostic casts were also made at the same time intervals and were analyzed by gross comparison only. Carlsson” also used study casts to supplement the cephalometric radiographic analysis. The amount of vertical bone resorption of the anterior part of the maxillary process was determined by measuring a perpendicular from the NL (nasal line) to the lowest point on the alvedar

DECEMBER

1978

VOLUME

40

NUMBER

6

ALVEOLAR BONE LOSS IN OVERDENTURES

1. A patient from group 1 with two retained mandibular canines which have been reduced for use with an overdenture.

Fig. 2. Landmarks used for cephalometric determination of amount of alveolar bone loss in the maxillae and mandible. NL, Nasal line, the line through the spinal point and pterygomaxillare, ML, Mandibular line, a line tangent to the lower border of mandible through the gnathion.

process (Fig. 2). Bjork8 defines the reference

Table I. Vertical bone resorption

.Fig.

as the line through

line NL

the spinal point and the pterygo-

Vertical

maxillare. The

amount

of vertical

bone

anterior part of the mandibular determined

by the measurement

to the ML (mandibular the ML as a tangent of the mandible

made

of the

the gnathion.

alveolar

by comparative

analysis

The

total

part of the maxillary

processes

group

was determined

of the cephalometric

individual

patients

at the

were

impression procedures teeth

2 with the complete maxillary

lar dentures

films

different

arranged

insertion

fabricated

using

the

same

and with cuspless acrylic resin

on a flat occlusal

of the dentures

plane.

Prior

they were remounted,

showed vertical

to and

over the same patients

3 and 4. The tracings

that

study.

alveolar bone (approximately

Vertical

bone

resorption

is shown in Table

the mean

resorption

portions

overdentures

I. The

of the maxillae The

maxillary showed

1.8 mm for the anterior mm for the anterior of 5 years

for

both

height

patients

were taken the

greatest

at yearly portion

intervals of the

50%) occurred

and

loss of during

in group

vertical

reduction

of the mandible

postextraction.

THE JOURNAL OF PROSTHETIC DENTISTRY

The

lar overdenture mandible.

1 of

over a in

that the use of the mandibu-

helps preserve

The reduction

or part of the mandible complete

and 0.6

patients

DISCUSSION The findings indicate

of the

and mandibular

part of the maxillae part

of

and the mandible

dentures

a mean

groups

figures represent

of the vertical

at 5 years postextraction. with complete

period

and mandibles

the first year after extractions.

RESULTS

anterior

in

and 6. findings

patients

and mandibles

of the majiillae

The

None

The

in the denture patients (group 2) are shown in Figs. 5

showed

and mill-in were performed.

period.

(group 1) are shown in Figs.

of the dentures were relined during the period of the

selective grinding

showed 5.2 mm of 5-year

tracings of the maxillae

the overdenture

and mandibu-

bone loss on the maxil-

lae of 1.7 mm, while the mandible bone resorption individual

dentures

Mandible

Overdenture (group 1) Conventional dentures (group 2)

defines

intervals. The

Maxilla

Patient group

to the lower border of the body

of the anterior

and mandibular

of the

of a perpendicular

resorption

(mm)

process was

line) (Fig. 2). Bjork

through

linear resorption

resorption

alveolar

bone

alveolar

bone in the

in the height of the anteriin those patients

upper and lower dentures

amounted

wearing to 5.2

mm, as compared with 0.6 mm for the overdenture patients. This represents eight times more loss in the patients

with

anterior

mandibular

complete

dentures.

bone

The

amount

of

loss in the overdenture

611

CRUM AND ROONEY

OVERDENTURES

&=-

CONVENTIONAL

DENTURES

’

3

Fig. 3. Individual cephalometric tracings of the maxillae in patients in group 1 (reduced in size). The dotted lines show bone levels after 5 years.

OVERDENTURES

Fig. 4. Individual cephalometric tracings of the mandibles in patients in group 1 (reduced in size). ‘TXe dotted lines show bone levels after 5 years.

612

Fig. 5. Individual cephalometric tracings of the maxillae in group 2 patients (tracings reduced in size). Then dotted lines show bone levels after 5 years.

CONVENTIONAL DENTURES

Fig. 6. Individual cephalometric tracings of the mandibles in group 2 patients (tracings reduced in size). The dotted lines show bone levels after 5 years.

DECEMBER

1978

VOLUME

40

NUMBER

6

ALVEOLAR BONE LOSS IN OVERDENTURES

patients was similar to that observed patients

wearing

partial

dentures

Tallgren

found

by Tallgren*

and complete

maxillary

dentures.

absence

of

of the anterior

denture

patients

that

the reduction

in these patients

amounted

period.

studies clearly

the advantage

indicate

teeth in the anterior in the

results

of retaining

group

dentures,

of the mandible

maxillae. This loss represents These

Tallgren

findings.

The

loss of bone

similar

in both

resorption greater

than

dentures. vertical

reduction

part of the

maxillary

overdenture

complete

in the

denture

group.

also found that the mean reduction process in the partial in

denture

the

cal

articles

proprioception

have

1.

in the patient

i.

3.

4.

5.

denture

and Bowman”

tion of occlusal

loads in overdenture

than

patients patients

could with

the overdenture ability

patients

due to the

supporting

2,000

discriminate

had

discrete

gm the overloads

better They

dentures.

due to the fact that more

sensory

discriminatory ability

of the

teeth.

It may be hypothesized

that the discrete

to signal against a physiologic

proprio-

bone resorption.

denture

patients,

the proprioceptive

mucosa

is poor, and the constant

result in alveolar

bone

loss. The

OF PROSTHETIC

acts

overload of the system

and thus prevents

In the complete ability overloading sensory

DENTISTRY

6.

7

They

ceptive ability of the teeth under an overdenture

THE JOURNAL

of

the percep-

patients.

complete

reasoned that this was probably

role

with overden-

studied

found that at load levels above denture

on the

treated

tures.“, I” Pacer

treated

alveolar

while the complete

to alveolar

clinical

with complete overdentures

bone

maxillary

of the may

Tallgren, 7-year 1969.

of the

group was

complete

speculated

in

bone

study show that

maxillary

dentures

demonstrate

less verti-

reduction

than

and mandibular

patients

with

dentures.

REFERENCES

group. Several

results of a 5-year

complete

overdenture

maxillary

than

may contribute

and mandibular

to a mean

Tallgren’

greater

was

was slightly

wearing

group and 1.7 mm in the complete

slightly

The

maxillary

loss amounted

of 1.8 mm

to the

process The

group

patients

feedback

and a mean

of patients.

maxillary

bone

a ratio of 1:3 (maxillae

in the

in those

The

exhib-

results are also similar

groups

in the

with

loss of 5.2 mm of alveolar

loss of 1.7 mm in the anterior

to mandible).

2),

sensory

SUMMARY

for the

(group

tooth

destruction.

patients

and mandibular

part

to

of the

process.

control

ited a mean vertical in the anterior

The

part of the mandible

of the alveolar

complete maxillary

vertical

to the preservation patients,

bone in overdenture

free-end

part of the mandible

Patients

input of the tooth may contribute of alveolar

bilateral

0.8 mm over a 7-year

preservation

in

mandibular

8.

A.: Positional longitudinal

Tallgren, A.: rnorpholop-A

changes

study.

Acta

of complete Odontol

dentures-A

Srand

27:539,

The effect of denture wearirlg on facial 7-year longitudinal study. Arta Odontol

Stand 25:563, 1967. Tallgren, A.: The continuing reduction of the residual alveolar ridges in complete denture wearers: ‘4 mixedlongitudinal study covering 25 years. J PRWWIX DEWI 27:120, 1972. Carlsson, G. E., and Persson. G.: Morphologic changes of the mandible after extraction and wearing of dentures. Odontnl Revy 18~27, 1967. Carlsson, G. E.. Ragnarson, N., and Astrand, P.: Changes in height of the alveolar process in edentulous segments. Odontol Revy 75:193, 1967. Carlsson, mandible

G. E.. and Persson, G.: Morphologic changes of after extraction and wearing of dentures. Sven

Tandlak Tidskr 63:219, 1970. Miller, P. A.: Complete dentures J PROSTHE.~DENT 8:924, 1958.

supported

b) natural

teeth.

Bjork, ‘4.: The relationship of the jaws to the cranium. In Lundstrom, A.: Introduction to Orthodontics. New York, 1960, McGraw-Hill Book Co., Inc. Crum, R. J., and Loiselle, R. J.: Oral perception and proprioception: A review of the literature and its significance to prosthodontics. j PROSTHET DEN? 283215. 1972. Crum. R. J.? Loiselle, R. J., and Hayes, C. I(.: The stud attachment overlay denture and proprioception ,J Am Dent Assoc 82:583. 197 1. Pacer. F. J., and Bowman, D. C.: Occlusal force discrimination by denture patients. J PROSTHET Dew 33:602, 1975.

Repmt requests to: DR. ROBERT J. CRCM VETERANSADMINISTRATIONHOSPITAL DENVER. Co~o.

80220

feedback

613