SECTIOK

RESEARCH AND EDUCATION

EDITOR

JOHN J. SHARRY

Residual alveolar ridge atrophy: Classifiication and influence of facial morphology Paul Mercier, D.D.S., F.R.C.D.(C),* and Roger Lafontant, M.D.** St. Mary’s Hospital Center, Montreal, Quebec, Canada

T

he loss of all natural teeth and their replacement with dentures is a universal disease particularly affecting some of the affluent nations. It is estimated that 24 million Americans are edentulous and must depend on dentures to eat their food.’ In Wales, 37% of the adult population have lost their teeth.’ In Canada, especially in Quebec, the proportion of denture wearers is estimated at 40% of the adult age group.d Anatomic changes will invariably take place within the alveolar processes of the jaws following dental extractions. When the teeth are present, the pressures exerted on these structures during contraction of the masticatory muscles are transmitted in the form of tension to the bone by the periodontal membrane. This type of stress is acceptable for the alveolar bone and may even serve as a stimulus for alveolar bone remodeling. Once the teeth are extracted, the whole distribution of forces is changed. The load is not directed to the entire bone, but is applied only on its surface. Alveolar bone can only tolerate this compression to a certain extent. The long-term effect of dentures over bone is the atrophy of the residual alveolar ridge or what Atwood4 calls reduction of residual ridges (RRR). Alveolar bone atrophy is cumulative and irreversible, since alveolar bone cannot regenerate. It differs from one individual to the other. It also varies at different times and different sites. Carlsson and Persson” has shown in a j-year longitudinal study that most of the bone loss takes place within the first few years after the extraction of teeth. Thereafter, the resorption proceeds at a slower pace. Nevertheless, it continues even 25 years following extractions, as demonstrated by Tallgren.” Its extent is four times greater in the mandible than in the maxillae. The *Director, Maxillary **Epidemiologist.

90

JANUARY

1979

Atrophy

41

OBJECT OF THE STUDY This study was undertaken with the purpose of measuring and classifying the different alveolar atrophies seen at the Maxillary Atrophy Clinic of St.

Clinic

VOLUME

large difference is mainly attributed to the absence of the palatal vault and a smaller denture-bearing surface for the mandibular ridge. Thus, the stress is much greater for the lower ridge than the upper ridge. It also affects the female much more than the male population in a proportion of 4 to 1, as shown in a previous article.’ Alveolar atrophy depends on many anatomic, biologic, and mechanical factors. Some studies have been directed toward the mechanical aspect of the problem.“, 9 Various occlusal forms for artificial teeth have been recommended. Flat cusp teeth would create less bone resorption. Others have reached totally different conciusions and favor anatomic teeth. Some have tried to relate the high incidence of alveolar atrophy among women to the hormonal imbalance that some women must go through after menopause. lo Osteoporosis-like symptoms with bone demineralization due to a surplus of anabolic hormones and an estrogen deficit appear. This factor surely does not affect the many women in their thirties afflicted with considerable residual alveolar ridge atrophy. Other causes must be studied. The anatomic factor has not been thoroughly investigated. Only brief mention of the influence of the facial morphology on residual alveolar ridge atrophy is found in the literature.” Many more women than men are affected by denture problems, and women tend to have, in general, smaller skeletons and shorter faces than men. This main feature is sufficient to suggest an investigation into the role played by the morphology of the face.

NUMBER

I

0022-3913/79/010090

+ 11$01.10/O Q 1979 The C. V. Mosby Co.

RESIDUAL

ALVEOLAR

RIDGE ATROPHY

. . . . . . . . ..*......m..w...................m

Fig.

1.

Angular, linear, and sagittal area measurements.

Mary’s Hospital Center. The measurements will permit us to follow the progression of bone loss under dentures. The classification will facilitate the selection of the treatment of choice for patients handicapped by dentures. The second object of this study was to evaluate the influence played by the facial morphology on the extent of alveolar bone resorption. DEFINITIONS Residual alveoiar ridge atrophy. Reduction of the residual ridge of alveolar bone of the edentulous maxillae and mandible, synonymous with alveolar bone resorption. Facial morphology. The morphology of the lower two thirds of the face. Reference is made in this study to the vertical plane. Total facial height at rest (TFH). The distance in millimeters measured on the radiograph between nasion and gnathion. Frankfort mandibular plane angle (FMA). The angle in degrees between the Frankfort horizontal plane and the mandibular plane. The normal is 24 +- 2 degrees. Low values are representative of patients with severe vertical overlap (closed bite). High values are found in patients with little vertical overlap (open bite). Sag&al upper area (SU). The sagittal area measured in square millimeters that serves to qualify the degree of atrophy of the residual upper alveolar ridge.

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DENTISTRY

Sagittal lower area (SL). The sagittal area measured in square millimeters that serves to qualify the degree of atrophy of the lower residual alveolar ridge. MATERIALS AND METHODS Sample studied The experimental group consisted of 200 consecutive patients, 160 women and 40 men, handicapped with dentures and seen at the Clinic. Many attempts have been made at providing these patients with satisfactory dentures through conventional methods. Efforts had mainly failed because of the state of supporting tissues and the presence of residual alveolar ridge atrophy. In their complaint of lack of denture retention, the lower denture was more frequently mentioned than the upper one in a 3 to 1 ratio. To allow for age and sex comparison under the same parameters, 40 women were picked out at random from the original sample of 160 women to match the group of 40 men. The mean age of the female group was 48 k 10 years. The mean age of the male group was 47 t 14 years. The majority (95%) of both groups had had all their teeth extracted at the same time, either both the upper and the lower teeth or the lower teeth a few years after extraction of the upper teeth. The mean age for full-mouth extractions was 26 years for women and 25 years for men. The women had been wearing dentures for 24 + 7 years and the men for 21 z?z10

91

MERCIER

Table I. Classification Women

Extremely severe Severe Moderate Minimal None

of alveolar atrophy-Men Sag&at measurements (mm-)

Sagittal measurements Atrophy class

Table II. Classification

of alveolar atrophy-

AND LAFONTANT

Maxitta

(S.U.)

(mm:)

Mandible

300 and less 301-400 401-500 501-600 601 and over

(S.L.)

420 and less 421-560 561-700 701-840 841 and over

S.U., Sagittal area of alveolar bone of maxillae. S.L.. Sagittal area of alveolar bone of mandible.

Atrophy

Maxtlta

class

(S.U.)

Mandible

360 and less 361-470 471-580 581-690 691 and over

Extremely severe Severe Moderate Minimal None

(S.L.)

480 and less 481-030 631-780 781-930 931and over

S.U.. Sagittal area of alveolar bone of maxillae. S.L.. Sagittal area of alveolar bone of mandible.

Points. years. Fifty-eight percent of the entire experimental group, women and men, had worn their first dentures unmodified for more than 8 years, and 20% for more than 4 years. Only 22% had had regular prosthetic care with either rebasing or remaking the first dentures within the first 4 years. A majority (78%) of the women wore their dentures at night, at least the upper one. The percentage of men sharing this habit was 72%. The control group was made up of 40 women and 40 men seen in private practice for consultation or for removal of their impacted wisdom teeth. Requirements were the presence of most of the natural teeth and the absence of gross periodontal disease to obtain control specimens free of alveolar bone atrophy. The mean age was 21 + 7 years for women and 26 k 7 years for men. Thus the study was carried out with 160 individuals forming four groups equally divided into two independent samples, one experimental and one control.

Point 0. The projection

of the pogonion on the

mandibular

plane. The most prominent point of the alveolar process of the anterior aspect of the maxillae. Infradenlale (Id). The most prominent point of the alveolar process of the anterior aspect of the mandible. Zd-40. A point of the mandibular plane 40 mm from the point 0. Sag&l area measurements. S.C: An area (transverse lines) that follows the lower palatal plane from point A to PAS, down along the crest of the alveolar process to PY, and returns to point A. S.L. An area (transverse lines) that follows the uppermost contour of the inferior border of the mandible from gnathion to fd-$0, perpendicular to the crest, then forward to the symphysis and returns to gnathion. Proslhion (Pr).

Readings Radiographic

procedure

Lateral head films were made for each patient with the head positioned in a Whemer counterbalanced cephalostat. The film-anode distance was 152 cm. The distance between the median plane of the head and the film was 12.5 cm. Patients were requested to pronounce the letter M before closing their lips. In this fashion an attempt was made at recording the true facial height at rest. Points of reference, lines, and areas In addition to the points of reference-nasion, gonion, gnathion, porion, orbitale, anterior nasal spine, and posterior nasal spine-and the planes of reference-Frankfort horizontal, selia-nasion, palatal, and mandibular-which are commonly used in the field of cephalometrics, the following points and lines were determined (Fig. 1): 92

The points, lines, and areas were drawn directly on the film with a fine pencil. Angles were measured in degrees with a Geotec Protractor. Linear measurements were made in millimeters, and areas were measured in square millimeters with a planimeter (OTT, type 30, 113). RESULTS Classification

of atrophies

Patients were divided into five groups for both women and men in reference to an equal distribution of the readings, with control groups serving as baselines in the proportional determination of the groups (Tables I and II). It was felt that this classification into five groups, (1) no atrophy, (2) minimal atrophy, (3) moderate atrophy, (4) severe atrophy, and (5) extremely severe atrophy, was sufficiently descriptive of patients encountered. JANUARY

1979

VOLUME

41

NUMBER

1

RESIDUAL

ALVEOLAR

RIDGE

ATROPHY

WOMEN Experimental

group

27%

0A

Ex. Severe

Moderate

None

MEN Experimental

group

35% 32%

-

r

28% -

SL

su su

0E

E.. Severe

1-

SetWe

78

su cl Modem

te

Minimal

NWlC?

Fig. 2. A, Distribution according to the severity of atrophy according to the severity of atrophy for men.

DMriWion of the samples according to the severity of atrqhy The distribution of the experimental sample both for women and for men was spread widely and unevenly (Fig. 2). For women, most of the atrophies of the maxillae were in the moderate-to-minimal and no atrophy group, while for the mandible the moderate-to-severe and extremely severe groups were favored. For men, the distribution was more even, THE JOURNAL

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Minimal

Nt”e

for women. B, Distribution

but again with the same preference of severe atrophies for the mandibular ridge. This findiig conesponded with the main complaint of patients of having more problems with the lower denture than the upper denture.

Distribution

according to age groups

The distribution of subjects according groups is seen in Tables III and IV. Tables

to age III and 93

MERCIERANDLAFONTANT

Table III. Distribution

Table IV. Distribution

according to age groups-

Men

Women

A&F

(years)

TFH No.

Experimental group 15-24 1 25-34 4 35-44 8 45-54 16 55-64 10 65+ 1 Mean 40 48 k lO* (Total) Control group 1.5-24 28 25-34 10 35-44 2 55-64 65+ Mean 40 21 k 8 (Total)

FMA

(mm) (degrees)

S.U.

S.L.

(mm2)

(mm2)

108 112k6 11527 116f7 115+-S 113 115-c7

20 27f4 3Ok6 24k5 21f7 27 24~6

296 445flJl 565t148 534i120 414-cl67 496 494f139

608 564f179 616&l89 586f 87 507+112 460 5.53r1.52

119-1-6 119k5 129f5

28C.5 29&S 30f3

66klOl 735+91 932+28

loll? 74 1032+101 117Ort 18

X9+-7

28+5

685+117

1015f

88

*Mean -+ Standard deviation TFH, Total facial height. FMA, Vertical facial type. S.U., Sagittal area of alveolar bone of maxillae. S.L., Sagittal arca of alveolar bone of mandible

IV do not show any significant changes in the values of TFH, FMA, S.U., or S.L. in regard to the different age groups in the experimental and control groups for both women and men, except for a mild trend toward a reduction of these values past the age of 55. The values are in general higher for men than for women.

Facial morphology (vertical plane) and alveolar atrophy The relationship between the facial morphology in the vertical plane and the suggested classification was studied in regard to the facial height and the vertical facial type. Results indicate: A relationship between the totalfacial height (TFH) and the verticalfacial ype (FMA). In general, patients with

severe vertical overlap have a short face, while patients with open bites exhibit longer faces. This basic observation is supported in Fig. 3. A direct relationship seems to be present for the experimental and for the control groups for both women and men. A relationship between the totalfacial height (TFH) and the sagittai area of alveolar bone of the maxilla (S. U.) and of the mandible (S.L.). Figs. 4 and 5 seem to point out

that there is every reason to believe that some kind of

94

according to age groups-

Age (Y-J

No.

Experimental group 2 15-24 7 25-34 9 35-44 45-54 10 9 55-64 3 65-k Mean 40 48 k 14* (Total) Control group 15 - 24 15 25-34 20 5 35-44 45-54 55-64 6.5 + 40 Mean 26 f 7 (Total)

TFH (-9

FMA (dew-e4

S.U.

S.L.

(mm:)

(mm:)

122&l 125k7 127t.6 129i5 120f9 124+-S 125k7

20+3 23f7 2424 28f5 23k6 32-7 25k6

520+ 80 538+ 70 576+ 96 592t116 491k132 46Oi-152 543f120

774k166 769-+ 75 656-+148 737,191 622k15.5 626+- 96 692i162

133 -c 8 28 i 6 131 + 6 25 t 6 13424 25-c4

821 i 129 1142 t 95 847 C 123 1178 f 101 901~1061211+-122

132 f 7 26 t 6

841 k 126 1168 It 104

*Mean k Standard deviation. TFH, Total facial height. WA, Vertical facial type. S.U., Sagittal arca of alveolar bone of maxillae. S.L.. Sagittal area of alveolar bone of mandible.

direct relationship exists between the total facial height and the area of alveolar bone measured. This relationship also applies to the control group. A relationship between the vertical facial #e (FMA) and the sagittal area of alveolar bone of the maxiiia (S. U.) and of the mandible (S.L.). Figs. 6 and 7 seem to point

out again that there is a strong correlation between the severity of atrophy as determined by the area measurements and the degree of opening of the bite determined by the FMA angle. This relationship affects the mandibular ridge (S.L.) more strongly than the maxillary ridge (S.U.) and seems more evident with the female group.

DISCUSSION Despite numerous small errors in the projection of the skull on the film or in the location of landmarks on the radiograph, cephalometric radiography remains a reasonably precise and easy system for performing numerous craniofacial measurements.12 The landmarks utilized in this study provide a sound basis for a proposed classification. The inclusion of the basal bone of the mandible and the use of a sagittal projection for area measurements remain more precise than a panoramic view, with its inherent image distortion, or an occlusal view of the

JANUARY lW9

VOLUMEu

NUMBERI

RESIDUAL

ALVEOLAR

RIDGE

ATROPHY

WOMEN

WOMEN

Experimental

group

Control

group

. 130

. 126

.

110

.

.

A

TFH mm

.

.

102

0

.

.

.. . . . . ... . : .. : .. . . . . . .. . .

.

106

.

.

es ‘EL

14

18

22

26

30

34

38

42

‘,O

,4

18

22

26

FMAO

30

34

3X

62

FMA’

MEN

MEN

Experimental

group

Control

group

.

138

134

. .

. . :

I30 126

. . 1.

.

142

126

. .

..

l

.. . .

. l .

.

.

.

.

.

122

. 118

12

16

20

24

28

32

36

40

FM A’

Fig. 3. A, Relationship

between the total facial height (TFH) and the vertical facial type (FMA) for women. B, Relationship between the total facial height (TFH) and the vertical facial type (FMA) for men.

mandible, which only assesses the width of the mandible.‘:’ The measurements used give relative values of a sagittal area, since they do not represent the true area of the alveolar bone. It is felt that a classification based on a linear measurement of the

Age differences. Because of the relatively young age of the controls and the limited spread of the groups, no definite conclusions can be drawn from Tables III and IV which show, with age, a mild trend toward a reduction of TFH, FMA, KU., and

anterior

S.L. values. However, this reduction would be in harmony with the potential senile atrophy of the old

mandible

was not quantitatively

sufficient

to present a true assessment of each atrophy. The percentage of error between three readings taken on the planimeter for each case is 4%, as found previous study. ’ ’

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DENTISTRY

in a

age. Sex differences. All values are higher for the male groups, with the exception

of the FMA

mean value

95

MERCIER

LAFONTAN-f’

WOMEN

WOMEN

. Control

.

grovp

.

130

.

118

. . . .

.

‘.. .

. 122

. . .

.

.

:

126

. TFH mm

AND

.

TFH mm

.

.

118 ,111 .

.

.. .

.

.

. .

:

‘I0

I

.

.

.

.

KM

.

.

. . .

.

l .

1: .

102

s-u. rml~

S.U. mm’

MEN

MEN

Exper~mentol

Control

group

i.6

116

142

Y2

$pup .

. .

.

. .

138

138 TFH

. .

.

.

.

1x1

.

.

TFH

. .

mm .

l .

130

l

l

!a

::

.

l .

.

1. .

. l



.

.

.

130 .

. .

.

mm

.

.

.

: .

:

II.5

.

:.



126. .

.

.

122

.

.

l

:

.

112

.

l

. .

.

. .

!I8

l

. .

118

l

. . .

200

2.0

280

320

360

400

440

480

S.U.

520

m

MO

LM)

I,. bl0

680

no

mo

.500

MO

610

no

160

MO

840

em

920

VW

100

to40

1080

S.U.m m’

Id

Fig. 4. A, Relationship between the total faciaI height (TFH) and the severity of the maxitlary atrophy (S.iY.) for women. B, Relationship between the total facial height (TFH) and the severity of the maxillary atrophy (S. C! ) for men. for the female control group. This FMA of 28 degrees is above the accepted norm of the general population, which is 24 t 4 degrees. It does not bear any great significance in the evaluation of the results. The general trend of higher values for men, especially for the total facial height and the areas S.U. and S.L., is normal and related to the overall growth differences between men and women. One of the objects of this study was to initiate a classification by the establishment of statistical norms. For this purpose we are fortunate to have access to a large pool of patients of all types of atrophy, especially in women. We are aware of the dangers inherent in a project which attempts to set norms of an abnormal state. It has taken many thousands of radiographs of the head to present the data commonly used in the field of dentofacial anomalies. Likewise, this is a first attempt at providing a classification. Revisions will be needed as more

96

data are collected, handled, and analyzed. Some minor adjustments of the S.U. values in the minimal to no atrophy range may be needed, since a few of the control groups are classified as cases of minimal atrophy. The classification suggested in this article allows us to make comparisons between the degree of atrophy and some of the facial characteristics of the patients. On the basis of the data presented, both the total facial height (TFH) and the vertical facial type (FMA) seem to play an important role in residual alveolar ridge atrophy. This relationship is more evident for the total facial height than for the vertical facial type, especially with the sample of men. It has been shown in numerous stud&j. I8 that the reduction of the alvedar ridge is accompanied by a decrease in the rest vertical dimension (RVD) and indirectly in the total facial height. Consequently,

JANUARY

1979

VOLUME

41

NUMBER

l

RESIDUAL

ALVEOLAR

RIDGE ATROPHY

WOMEN

WOMEN

Experimental

group

Control

.

‘30

.

group

* .

130

.

.

t20 .

I

.

‘22 :... T,F,H

.

126

.

.

.

:

118

.

. *

. .

. : .

*.

l .

lid

1

: .

122

. .

ii8

l

. .

. .*

. .

T,FmH

.

. .

l

.

I

.

.

114

.

MEN

a

: .

.

MEN Control

group

116

. .

.

142

.

. .

.

138

l .

.

. l

.

*

TFH mm

l

.

.

. .

. .

13. .

.

.

. .

.

IJO

.

.

. . . 126

.

:

.

:

. .

.

122

.

. .

Fig. 5. A, Relationship

between the total facial height (TFH) and the severity of the mandibular atrophy (XL.) for women. B, Relationship between the total facial height (TFI-I) and the severity of the mandibular atrophy (S.L.) for men.

the mandible rotates in a forward direction and the vertical dimension closes a few degrees. This decrease could be responsible for the loss of a few millimeters of TFH and the loss of a few degrees of FMA. We can assume that patients with a low FMA were born with a severe vertical overlap facial type that was not acquired by the closure of the vertical dimension following the extraction of the teeth. The same point can be expressed for the facial height. Some patients are born with short faces, others with long faces. The loss of all natural teeth will not transform a long face into a short one. The variations would remain small

there is and the less chance there is for an individual to reach a stage of severe atrophy in wearing dentures. This statement does not take into account the rate of resorption of each individual, since a long face may resorb faster than a shorter face due to factors other than the morphology of the face. 2. The further closed the vertical dimension of occlusion, the more compressive are the forces applied on the residual ridges and the greater are the chances for an individual with a closed vertical dimension of occlusion to reach the stage of extremely severe atrophy with dentures, especially for the

and would

mandible. As pointed out in the introduction, alveolar bone will accept compressive forces only ta the detriment

not affect greatly

the results.

On the basis of the present discussion, we may infer the following: 1. The longer the face, the more alveolar bone

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DENTISTRY

of the bone substance. It has been shown on a

97

MERCIER

AND

LAFON TANT

WOMEN

WOMEN

38

.

. FMAO l

. .

. .

.

.

34

. . . . . . .

FMA’

.

.

l .

. . . . . .

.

10

l

.

. . .

26

.

.

.

.

l

l

.

*

.

.:

.

l .

.

l .

.

l

.

22

. .

. . .

m

. i.

.

.

. 32

l .

FMA’

~8

t.

:

l

l

l

.

.:.

. .

.

.

l .

l

.

.

24

.

.

.

.

2 I6

. .

. t’

’ .

t SUlTlKi:

sumrn

Fig, 6. A, Relationship between the vertical facial type (FMA) and the severity of the maxillary atrophy (S.U.) for women. B, Relationship between the vertical facial type (FMA) and the severity of the maxillary atrophy (S. C! ) for men.

gnathodynamometer by Sassouni” that the biting forces for patients with a closed vertical dimension are 3 to 4 times those generated by patients with an increased vertical dimension. This fact has been restated recently by Di Pietro and Moergeli.‘” The distribution of forces (Fig. 8) for the patient with a decreased vertical dimension with a square genial angle and primary elevator muscles attached more anteriorly than the patient with an increased vertical dimension and in a vertical direction does not favor the alveolar bone. The load on the denture-bearing tissues, in particular those of the mandibular ridge not protected by a palatal vault, is greater for these individuals. This load would become even more detrimental for those who wear their dentures day and night. In contrast, the masticatory forces for the patient with an increased vertical dimension are less compressive, since they are distributed to the entire bone. Finally, it must be reiterated that alveolar atrophy is a multicausal disease. Surely, total dental extractions at an early age and the abuses inflicted upon the alveolar bone by wearing ill-fitting dentures day 98

and night must have contributed to a large extent to the bone resorption witnessed in the experimental group.

PRACTICAL APPLICATIONS It is hoped that the classification will provide the clinician with the additional piece of information required for the selection of an adequate plan of treatment. For certain types of atrophy, a combination of surgery and prosthetics is required to provide a rapid solution for patients severely handicapped by dentures. It will permit the selection of a technique of choice for the treatment, based on exact figures and not only on a clinical impression. For our part, we are confronted with a situation where, in performing a total lowering of the floor of the mouth and the extension of the vestibule with skin grafting to increase denture stability and retention, we gain in certain patients more ridge width and depth and in other patients less than expected preoperatively when only guided by a subjective appraisal. It would be preferable to select procedures other than ridge extensions or surgical procedures, such as bone JANUARY

1979

VOLUME

41

NUMBER

1

RESIDUAL

ALVEOLAR

RIDGE ATROPHY

WOMEN

WOMEN

. . :. FMAO

30

. .

21

.

.

.

.

.

.

. .

.

.

181 .

.

.

.

.

.

.

. . . .. . . . .. . . .. . .

FMA”

. . .

.

:

.

.

.

22

.

. .

.

.

.

.

l

. l

: t

*

.

. .

.

.

.

.

.

.

SL mm’ MEN

MEN

Experimental

group

Control

4

FM A0

23 . 1

24

.

.

. . . .. 1

B

FMA’

. .

.

.

. . .

.

. .

. .

.

lb

0

.

.

.

2

.

.

l

group

1

.

:

.

. .

.

. .

i2 *cm

Fig. 7. A, Relationship between the vertical facial type (FMA) and the severity of the mandibular atrophy (XL.) for women. B, Relationship between the vertical facial type ~KMA ) and the severity of the mandibular atrophy (XL.) for men.

Fig. 8. Distribution

of masticatory forces in a patient with an open vertical dimension (open bite) /left], and in a patient with a closed vertical dimension (closed bite) (right].

grafts, for patients with measures below certain values. Also, the sagittal area measurement will permit us to follow in an accurate way the progress of bone resorption under dentures. Finally, it is hoped that this material will draw the attention of the THE JOURNAL

OF FROSTHETIC

DENTISTRY

clinician tions in overlap. risk of denture

who is confronted with total dental extraca short-face patient with a severe vertical The patient should be informed of a greater alveolar bone resorption and incipient problems. 99

MERCIER

SUMMARY A method for grading residual alveolar ridge atrophies of edentulous maxillae and mandible has been devised for men and women. Comparisons were made in women and in men between the degree of atrophy and the vertical facial morphology. The study suggests some relationship between the total facial height (TFH), the vertical facial type determined by the Frankfort horizontal mandibular plane (FMA), and the atrophy of the alveolar ridges, especially for the mandible. Certain practical applications of these findings were suggested. We acknowledge the financial support of the St. Mary’s Hospital Foundation. We are grateful for the technical assistance provided by Ms. Air&e Gervais.

REFERENCES Bureau of Economic Research and Statistics: A.D.A. Survey of Denture Wearers, 1976. 2. Todd, J. E., and Whitworth, A.: Adult Dental Health in Scotland 1972. London, 1974, H.M.S.O. 3. Nutrition Canada Survey 1972: Ottawa, 1972, Dept. National Health and Welfare. 4. Atwood, D. A.: Some clinical factors related to the rate of resorption of residual ridges. J PR~STHET DENT 13:441, 1.

1962.

5.

6.

Carlsson, G. E., and Persson, G.: Morphologic changes of the mandible after extraction and wearing of dentures. Odontol Revy l&27, 1967. Tallgren, A.: The continuing reduction of the residual alveolar ridges in complete denture wearers: A mixed longitudinal study covering 25 years. J PROSTHET DENT 31:120,

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1972

Mercier, P.: Atrophies des maxillaires et hypertrophies des muqueuses chez les tdentes: Epidtmiologie. J Can Dent Assoc 41:463, 1975.

AND LAFUNTAN?

Jones, P. M.: The monoplane occlusion for complete dentures. J Am Dent Assoc 85:94, 1972. 9. Woelfel, J. B., Winter, C. M., and Igarashi, T.: Five-year cephalometric study of mandibular ridge resorption with different posterior occlusal forms. J PROWI-IET DEN.I. 36:602. 1976. 10. Baylink, J.: Systemic factors in alveolar bone loss. ,J PROS8.

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11. Tallgren, A.: Alveolar bone loss in denture wearers as related to facial morphology. Acta Odontol Stand 28:251, 1970. 12. Carlsson, G. E.: Errors in X-ray cephalometry. Odontol Tidskr 75:99, 1967. 13. Wical, K. E., and Swoope, C. C.: Studies of residual ridge resorption Part I: Use of panoramic radiographs for evaluation and classification of mandibular resorption. J PROS-WET DENT 32:7, 1973. 14. Mercier, P.: The inner osseous architecture and the sagittal splitting of the ascending ramus of the mandibte. J Maxillofat Surg 1:171, 1973. 15. Tallgren, A.: The reduction of face height of edentulous and partially edentulous subjects during long term denture wear. Acta Odontol Stand 24:195, 1966. 16. Ismail, Y. H., George, W. A., Sassouni, V., and Scott, R. H.: Cephalometric study of the changes occurring in the face height following prosthetic treatment. Part I. Gradual reduction of both occlusal and rest face heights. .J PROSTHET DEU 19~321, 1968. 17. Sassouni, V.: A classification of skeletal facial types. Am J Orthodont 55:109, 1969. 18. Di Pietro, G. J., and Moergeli, J. R.: Significance of the Frankfort mandibular plane angle to prosthodontics. J PR~STHET DENT 36:624,

1976.

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ARTICLES TO APPEAR IN FUTURE ISSUES The effica* of rawmt A. 3. Sidhaye, hl.D.S., and S.

D. E. Smith, D.D.S., MAD., L. Brian Toolsor~, D.D.S., M.S.D., Charles L. Bolender, D.D.S., M.S., and James L. Lord, D.D.S., M.S.D.

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Residual alveolar ridge atrophy: classification and influence of facial morphology.

SECTIOK RESEARCH AND EDUCATION EDITOR JOHN J. SHARRY Residual alveolar ridge atrophy: Classifiication and influence of facial morphology Paul Merc...
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