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The effect of estrogen on the bone and teeth of rabbits and in relation to orthodontic tooth movement

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The effect of estrogen on the bone and teeth of rabbits and in relation to orthodontic tooth movement

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Content THE EFFECT OF ESTROGEN ON THE BONE AND
TEETH OF RABBITS AND IN RELATION
TO ORTHODONTIC TOOTH MOVEMENT
A Thesis
Presented to
the Faculty of the Department of Orthodontics
School of Dentistry
University of Southern California
In Partial Fulfillment
of the Requirements for the Degree
I, Master of Science
John William Murphy D.D.S.
August 1953

'5f
This thesis, written by
under the guidance of hAA...Faculty Committee
and approved by all its members, has been
presented to and accepted by the Council on (J
Graduate Study and Research in partial fullfillment of the requirements for the degree of
o/^ ^ ceDe-
:
Se4
(
Faculty Committee
Chairman

TABLE OF CONTENTS
PAGE
Introduction 1
Revlevr of the literature 1
Materials and methods 5
Observations 6
Discussion 11
Summary . 13
LITERATURE CITED 20
REFERENCES 21

LIST OF FIGURES
FIGURE PAGE
1. Side of Pressure of Control Animal. Bone
Apposition 15
2. Side of Pressure of Control Animal. Osteoclastic Action of Bone 15
3. Side of Tension of Control Animal. Thin
Layers of Bundle Bone 15
Side of Pressure of Experimental Animal
Receiving Estrogen for Twenty-two Days.
Presence of Osteoclasts 15
Side of Pressure In Experimental Animal
Receiving Estrogen Twenty-two Days. Con
tinuing Osteoclastic Action and Narrow
Periodontal Membrane
5.
17
6. Side of Tension In Animal Receiving Estrogen
Twenty-two Days. Bone Apposition and newly
Formed Bone 17
7. Side of Pressure In Animal Receiving Estrogen
Twenty-nine Days. Severe Changes and Osteo
clastic action 17
8. Side of Pressure In Animal Receiving Estrogen
Twenty-nine Days. Periodontal Membrane Is
Practically Gone 17

iv
FIGURE PAGE
9. Side of Pressure in Animal Receiving Estrogen
Twenty-nine Days. Thin Periodontal Membrane . 19
10. Side of Pressure in Animal Receiving Estrogen
Thirty-nine Days. Osteoblastic Activity . . .
11. Side of Tension in Animal Receiving Estrogen
Thirty-nine Days. Spicules of Bundle Bone . .
12. Side of Tension in Animal Receiving Estrogen
Thirty-nine Days. Well Organized Periodontal
Membrane Characteristic of Retention . . . , .
19
19
19

INTRODUCTION
It has been demonstrated by a number of experimental
studies that estrogen exerts a definite Influence upon
bone resulting in the p3?oduction of osteosclerosis,
present investigation was undertaken to deterroine what
effect on tooth movement would result from such an estrogen
created condition.
The
REVIEW OF THE LITERATURE
It has been shown that administration of large doses
of estrogen produced osteosclerosis in the skeleton of the
rat and mouse (Gardner and Pfeiffer, *38 and Urlst,
Budy, and McLean, 'L8; Stahl, Weinmann, Schour, and Budy,
*50), demonstrated by injection of estrogen so that the
alveolar bone became sclerosed. It was confined to the
medullary bone cavities and consisted of apposition of a
specific type of bone tissue with increased mineral con
tent . It was found by these workers that repeated
injections of small doses of alpha-estradiol benzoate
resulted in a greater deposition of bone than in a single
large dose. It was thus possible to create in these
animals a degree of bone mineralization comparable to that
existing in older control animals.
It is well known (Oppenheim *30) that a mild

2
orthodontic force produces slight compression of the perio
dontal membrane with a concomitant ischemia on the pressure
Following bone resorption of the spicules on the
pressure side of the tooth, bone apposition will taJce place
on the tenion side; blood vessels become relaxed and
redeposition of bone becomes possible.
The orthodontic appliance consisted of a stainless
steel band using a universal bracket on each of the two
lower incisors (Plate I, Fig. a) of the rabbit,
dontic force was applied by a .015 bent wire expanding loop
between the teeth (Fig. b) and attached to each bracket so
The bands were
side.
The orthothat the two incisors were spread apart,
cemented and force was applied for seven days for each
rabbit before sacrificing the animal to make histologic
slides.
All animals were decapitated immediately after
sacrifice and the mandibles were removed for sectioning.
Specimens were cut into blocks containing the two incisors
and surrounding tissues, and fixed in formol-acetlc acid—
80 per cent alcohol (5cm formalin; 5cm acetic acid; and
90cm 80 per cent alcohol) for at least three to four days.
Ten per cent nitric acid in fomalln was used as a decalci
fying agent, because its penetration is rapid, thus
preventing excessive action of the acid on the soft tissue.

3
PLATE I 'f T
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!

ABBREVIATIONS
a. - Universal "bracket on lower incisors
b. - .015 bent wire expanding loop
c. - Assembled appliance
Lower photograph
Animal wearing appliance

5
The blocks were prepared for sectioning by the celloidln
method, that is, dehydrated in various alcohols Infiltrated
with 10, 25, and 50 per cent nitrocellose. The specimens
were sectioned 20-20 u thick, and stained with hemotoxylin
and trlosln.
MATERIALS AND METHODS
Five young female rabbits were used for this experi
ment. Four of this group received 0.25 mg* injections of
alpha-estradiol benzoate intramuscularly dally for periods
varying from twenty-two to thirty-nine days (Table I). The
control had no estrogen injections. All animals were
subjected to orthodontic tooth movement for an identical
time of seven days.
TABLE I
No. of dally
injections
No. of days of
Rabbit No. Orthodontic Treatment
Control 0 7
#1 22 7
#2 29 7
#3 39 7
39 7

6
OBSERVATIONS
Plate II is a diagrammatic representation of the area
under investigation. The side of pressure is the eistal
surface of the incisors and is characterized by changes in
the periodontal membrane in which the attachment fibers are
wavy and the interstitial spaces are ovoid in nature. The
alveolar bone shows osteoclastic action. On the other
hand, the side of tension is the mesial surface, and bone
apposition will be noted. The attachment fibers of the
periodontal membrane are tense and the interstitial spaces
are elliptical in nature.
The control animal exhibited changes on the side of
pressure as evidenced by the formation of bone spicules in
the alveolar crest region. This is a characteristic of the
existence of the retention state (Plate III, Fig. 1). At
the apical portion of the tooth, osteoclastic action is
seen alongside the bone (Fig. 2). The periodontal membrane
on this surface shows varying degrees of degeneration such
as hemorrhage and hyallnlzation, a feature characteristic
of severe trauma in tooth movement. A thin layer of bundle
bone is noted on the side of tension and osteoblasts and
osteoid material are observed lining the margins of the
bone. The fibers of the periodontal membrane still appear
tense, and the interstitial spaces appear elliptical in

7
PLATE II
t

ABBREVIATIONS
P.S. - Pressure side
T.S. - Tension side
D. - Dentin
£n. - Enamel
O.S. - O.K. surface
R.S. - Repair surface
Su. Suture

9
nature (Fig. 3). In contrast the animal which received
estrogen injections for twenty-two days exhibited a
decrease in alveolar bone resorption (Fig. 4). The tipping
action of the tooth movement has resulted in a slight
degeneration of the periodontal membrane on the mesial
apical surface. This is demonstrated by the disorganiza
tion of the periodontal fibers in that region (Fig. 5)*
Here one can readily see evidence of osteoclastic
action on the alveolar bone and at the same time there is
produced a marked narrowing of the periodontal membrane.
However, on the side of tension there is an attempt at bone
apposition, a thin layer of newly formed bone is evident
(Fig. 6) consisting of thin, highly cellular lamellae lined
by osteoblasts. The periodontal membrane on this surface
is still in the state of tension as the interstitial spaces
are eliptlcal in nature.
The animal receiving estrogen for twenty-nine days
presented a picture of bone changes of increased severity.
These traumatic changes were reflected by the loss of bone
at the alveolar crest as well as along the cortical surface
(Fig. 7). As a result of these changes there was a marked
shortening of the height of the alveolar crest with a
concomitant narrowing of the alveolar bone. There are no
evidences of osteoclasts lining the periodontal membrane

10
margin of the alveolar bone. This is in part due to the
severe degeneration of the periodontal membrane which now
shows no evidence of cellularity, but consists of hemor
rhage and necrosis. Figure 8 is another view of the side
of pressure in which the cementum is now adjacent to
compact bone. Due to the limitation of tooth movement the
periodontal membrane has practically disappeared. Under
higher power there is a thin layer of periodontal membrane
between the dense alveolar bone and the tooth (Fig. 9).
On the side of tension, well developed bone spicules are
arranged in parallel layers in the same direction as the
line of force. These spicules are bundle bone in nature
and stain lighter than the older compact bone (Fig. 11).
The two animals receiving estrogen for thirty-nine
days present a picture not of tooth movement but one of
retention. The side of pressure in such an animal is shown
in Figure 10. Here osteogenesis is taking place character
ized by marked osteoblastic activity. There are no signs
of osteoclastic activity involving the bone. The perio
dontal membrane is in the process of reorganization. There
is no evidence of degeneration. On the side of tension
(Fig, 12) the newly formed bone that was deposited during
tooth movement has now become lamellated bone and the
periodontal membrane appears well organized to receive the

11
brunt of mastication.
DISCUSSION
It has been found by several investigators that the
injection of estrogen results in an osteosclerosis of
alveolar bone (Stahl, ¥einmann, Schour, and Budy, '50).
However, these Investigators found that the osteosclerosis
of the alveolar bone was confined to the al-medullary
cavity, the newly deposited bone was not Just confined to
the sponglosa but Includes the alveolar bone surrounding
the incisor teeth. On the mesial surface, the alveolar
bone was unaffected, but the internal bony trabeculae at
the suture area between the two incisors became transformed
into compact bone. This Increased mineralization of the
supporting bone resulted in alterations in its response to
the stress of tooth movement. In the control animal, after
seven days of wearing the orthodontic appliance there was
still evidence of tooth movement and attempted repair.
On the other hand, the anim£G.s that received
estrogen Injection for twenty-two and twenty-nine days
showed signs of severe trauma due to the applied stress.
The periodontal membrane on the side of pressure showed
varying degrees of degeneration such as neci*osis and
hemorrhage. The bone deposition on the side of tension

12
appeared thicker than in the control animals,
probably due to the effect of estrogen.
A difference was found in the reaction of the tooth
to movement in regard to the duration of estrogen injecThere were marked differences in the animal
receiving twenty-two days of estrogen injection and those
receiving twenty-nine days of injection,
the periodontal membrane was more severe in the former
animal.
This was
tions.
The reaction-of
Not only did we see necrosis and hyalinization of
the periodontal membrane, but complete compression of the
structure with its resultant obliteration. In this animal
the bone architecture of affected are8.8 is more compact,
resulting in a more severe reaction as the tooth moved.
The animals that received thirty-nine days of injection
revealed a striking picture of contrast to the previous
described animals. There was an absence of microscopic
features usually indicative of active tooth movement.
Instead of histologic appearance was one of retention with
the density of bone increased. It is apparent that with
orthodontic forces similar to those used on the control
animal, the reaction of the supporting apparatus to tooth
movement under conditions of prolonged estrogenic Influence
is insufficient to show activity.
From this investigation it is felt that cyclical

13
changes in the hormonal concentration in hiimans may play a
role in orthodontic treatment in certain orthodontic cases
—especially in females at the time of puberty—where the
response of the tissues to tooth movement was found to be
inadequate for the previously used forces, the influence of
estrogen on bone deposition should be considered,
increase in orthodontic force may be indicated to create
the proper osteoclastic-osteoblastic reaction.
An
SUMMARY
It was found in these experiments that the response
of the periodontal structures to stresses as applied in
orthodontic tooth movement was influenced by hozmonal fac
tors as represented by the estrogen injections,
injections led to production of osteosclerosis in the
supporting bone and would thereby Influence the latter's
It was found that the perio
dontal 8tz*ucturee offered Increasing resistance to pressure
stress in accordance with the length of time of estrogenic
injection.
These
response to pressure stress.
Thus, with orthodontic forces similar to those used
on control animals, the reaction of the periodontal struc
tures to tooth movement under conditions prolonged
estrogenic Influence is insufficient to show activity.

14
I
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PLATE III
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ABBREVIATIONS
A.B. - Alveolar Bone
A.C. - Alveolar Crest
B.A. - Bone Apposition
B.S. - Bone Spicules
C. Cementum
D. Dentin
P.M. - Peridental Membrane
P.A. - Osteoclastic Action
Figure 1. Side of pressure of control animal.
Note bone apposition. X ll^-0
Figure 2. Side of pressure of control animal.
Note osteoclastic action of bone. X 14-0
Figure 3» Side of tension of control animal.
Note thin layers of bundle bone.
Side of pressure of experimental animal receiv
ing estrogen for twenty-two days.
Note the presence of osteoclasts.
X 240
X 240
Figure k.

16
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PLATE IV
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Figure 5. Side of pressure In experimental animal receiv
ing estrogen twenty-two days.
Note continuing osteoclastic action and narrow
periodontal membrane.
Side of tension In animal receiving estrogen
twenty-two days.
Note bone apposition and newly formed bone.
X 240
X 240
Figure 6.
Figure 7. Side of pressure in animal receiving estrogen
twenty-nine days.
Note severe changes and osteoclastic action.
X 240
Figure 8. Side of pressure in animal receiving estrogen
twenty-nine days.
Note the periodontal membrane is practically
gone. X 240

18
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Asset Metadata

Creator Murphy, John William (author)

Core Title The effect of estrogen on the bone and teeth of rabbits and in relation to orthodontic tooth movement

School School of Dentistry

Degree Master of Science

Degree Program Orthodontics

Degree Conferral Date 1953-08

Publication Date 06/01/1953

Defense Date 06/01/1953

Publisher Los Angeles, California (original), University of Southern California (original), University of Southern California. Libraries (digital)

Format theses (aat)

Language English

Contributor Digitized in 2024 by USC Digital Imaging Lab (provenance)

Advisor Baretto, Lucian A. (committee chair), Nagamoto, Geo (committee member), Soule, John D. (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-oUC113997ALG

Unique identifier UC113997ALG

Identifier etd-MurphyJohn-1953.pdf (filename)

Legacy Identifier etd-MurphyJohn-1953

Document Type Thesis

Format theses (aat)

Rights Murphy, John William

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