U.S. patent application number 11/116664 was filed with the patent office on 2006-11-30 for methods and systems for enabling and stabilizing tooth movement.
This patent application is currently assigned to BAS Medical, Inc.. Invention is credited to Peter M. Breining, Dennis R. Stewart.
Application Number | 20060269892 11/116664 |
Document ID | / |
Family ID | 32312590 |
Filed Date | 2006-11-30 |
United States Patent
Application |
20060269892 |
Kind Code |
A1 |
Breining; Peter M. ; et
al. |
November 30, 2006 |
Methods and systems for enabling and stabilizing tooth movement
Abstract
Orthodontic methods comprise applying force to reposition teeth
and administering a tissue remodeling and/or an angiogenic
substance(s) to the periodontal tissue surrounding the teeth to be
moved. The substance(s) may be delivered before, during, or after
the teeth are moved, and the substance(s) may be selectively
applied only to those teeth undergoing movement at any particular
time. The substance(s) may be applied from the dental repositioning
appliance or may be applied separately, either topically or by
injection.
Inventors: |
Breining; Peter M.; (San
Mateo, CA) ; Stewart; Dennis R.; (Los Gatos,
CA) |
Correspondence
Address: |
ROBINS & PASTERNAK
1731 EMBARCADERO ROAD
SUITE 230
PALO ALTO
CA
94303
US
|
Assignee: |
BAS Medical, Inc.
San Mateo
CA
94402-2525
|
Family ID: |
32312590 |
Appl. No.: |
11/116664 |
Filed: |
April 27, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10695299 |
Oct 27, 2003 |
6984128 |
|
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11116664 |
Apr 27, 2005 |
|
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60423026 |
Nov 1, 2002 |
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Current U.S.
Class: |
433/24 ;
433/215 |
Current CPC
Class: |
A61K 38/2221 20130101;
A61K 38/4886 20130101; A61C 7/12 20130101; A61K 31/19 20130101;
A61K 31/485 20130101; A61K 45/06 20130101; A61K 38/1825 20130101;
A61K 38/1866 20130101; A61C 7/00 20130101; A61C 19/063 20130101;
A61K 31/485 20130101; A61K 31/56 20130101; A61K 31/56 20130101;
A61K 38/2221 20130101; A61K 38/4886 20130101; A61K 38/1825
20130101; A61K 31/19 20130101; A61K 2300/00 20130101; A61C 7/08
20130101; A61K 2300/00 20130101; A61K 2300/00 20130101; A61K
2300/00 20130101; A61K 2300/00 20130101; A61K 2300/00 20130101 |
Class at
Publication: |
433/024 ;
433/215 |
International
Class: |
A61C 3/00 20060101
A61C003/00; A61C 5/00 20060101 A61C005/00 |
Claims
1. A method for enhancing tooth mobility or stability, said method
comprising administering a tissue remodeling and/or angiogenic
substance(s) to a living host.
2. A method as in claim 1, wherein the host will be having, is
having, or has had orthodontic treatment.
3. A method as in claim 1, wherein the substance(s) comprises
relaxin or an analog or mimetic thereof.
4. A method as in claim 1, wherein the substance(s) comprises an
angiogenic substance(s) selected from the group consisting of VEGF,
bFGF, estrogen, nitrous oxide and naltrexone.
Description
[0001] This application is a continuation of application Ser. No.
10/695,299, filed on Oct. 27, 2003, which claims the benefit of
U.S. Provisional Application No. 60/423,026, filed on Nov. 1, 2002,
the full disclosures of which are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to medical apparatus
and methods. More particularly, the present invention relates to
methods and systems for facilitating, accelerating, and stabilizing
tooth movement before, during and after orthodontic procedures.
[0004] Orthodontic procedures suffer from four major problems.
First, the braces or other appliances which effect the tooth
movement must be worn for long periods of time. Second, even after
a successful orthodontic treatment, the teeth often relapse towards
their original positions once the braces or other treatment
appliances are removed. Third, the mechanically induced movement of
teeth can cause significant discomfort to the patient. Fourth, the
wearing of braces is esthetically displeasing, uncomfortable, and
compromises oral hygiene. While recently introduced clear plastic
visible "aligners" largely overcome the latter problems, such
aligners are not suitable for all patients. Moreover, the aligners
do not reduce treatment time, do not reduce the risk of relapse,
and do not lessen the pain associated with tooth movement in the
jaw.
[0005] For these reasons, it would be desirable to provide improved
orthodontic technologies for moving teeth which overcome at least
some of the problems noted above. In particular, it would be
desirable to provide orthodontic methods and systems which can
reduce the time necessary to effect a desired tooth movement, which
can reduce the pain associated with tooth movement, which can
reduce the tendency of teeth to relapse to their original positions
after the orthodontic treatment is stopped, and/or which can reduce
the time in which unsightly braces need to be worn.
[0006] 2. Description of Background Art
[0007] Nicozisis et al. (2000) Clin. Orthod. Res. 3:192-201,
describes experiments which demonstrate the presence of endogenous
relaxin in cranial tissue of mice and speculates that relaxin may
be used as an adjunct to orthodontic or surgical therapy to promote
manipulation of sutural tissues or affect stability. The
application of electrical current to stimulate bone growth and
remodeling in orthodontic procedures is described in U.S. Pat. Nos.
4,854,865; 4,519,779; and 4,153,060. Appliances for local and
systematic drug delivery to the gingival tissues are described in
U.S. Pat. Nos. 6,159,498, 5,633,000; 5,616,315; 5,575,655;
5,447,725; 5,294,004; 4,959,220; 4,933,183; 4,892,736; 4,685,883;
and Re. 34,656. Polymeric shell appliances for repositioning teeth
are described in U.S. Pat. No. 5,975,893. The full disclosures of
each of the above U.S. patents are incorporated herein by
reference.
BRIEF SUMMARY OF THE INVENTION
[0008] The present invention provides improved methods and systems
for repositioning teeth in patients. In addition, the present
invention provides improved methods and systems for stabilizing
teeth which have already been repositioned in order to reduce or
eliminate the tendency of the repositioned teeth to relapse, i.e.,
move back toward their prior positions. The methods for
repositioning teeth comprise applying force to at least one tooth,
and typically to more than one tooth and/or to different teeth over
time, in the jaw of the patient. For both repositioning or
stabilizing, tissue remodeling and/or an angiogenic substance(s) is
administered to the patient to promote remodeling of periodontal
tissue surrounding the root(s) of the tooth or teeth to be moved.
Preferred substance(s) will bind to and activate the relaxin
receptor in the tissues which anchor the teeth or other
craniofacial structures. Most preferred is relaxin or an analog or
mimetic thereof which combines tissue remodeling activity with
angiogenic activity. Analogs include peptides, oligomers,
fragments, etc. which comprise the active region of native relaxin
and mimetics include small molecule drugs, typically below 2 kD,
designed to mimic the activity of native relaxin. Alternatively,
substance(s) with predominantly angiogenic activity could be
selected, such as VEGF, bFGF, estrogen, nitrous oxide, naltrexone,
or the like. Further alternatively, collagenases or other
tissue-softening enzymes could be utilized to promote periodontal
tissue remodeling according to the present invention. In some
instances, it may be desirable to combine two or more tissue
remodeling and/or angiogenic substance(s) having differing
activities. In other instances it may be desirable to deliver
different tissue remodeling and/or angiogenic substance(s) at
different times during the orthodontic treatment and/or to
different regions of the periodontal tissue.
[0009] The term "relaxin" means human relaxin, including intact
full length relaxin or a portion of the relaxin molecule that
retains biological activity [as described in U.S. Pat. No.
5,023,321, preferably recombinant human relaxin (H2)] and other
active agents with relaxin-like activity, such as Relaxin and
portions that retain biological activity Like Factor (as described
in U.S. Pat. No. 5,911,997 at SEQ ID NOS: 3 and 4, and column 5,
line 27-column 6, line 4), relaxin analogs and portions that retain
biological activity (as described in U.S. Pat. No. 5,811,395 at SEQ
ID NOS: 1 and 2, and column 3, lines 16-40), and agents that
competitively displace bound relaxin from a receptor. Relaxin can
be made by any method known to those skilled in the art, for
example, as described in any of U.S. Pat. Nos. 5,759,807; 4,835,251
and co-pending U.S. Ser. No. 07/908,766 (PCT US90/02085) and Ser.
No. 08/080,354 (PCT US94/0699).
[0010] The tissue remodeling and/or angiogenic substance(s) will be
delivered at a delivery rate and a total dosage which are selected
to facilitate tooth repositioning and tissue remodeling. Typically,
the dosage rates will be in the range from 1 ng to 500 .mu.g per
day, usually from 10 ng/day to 20 .mu.g/day, preferably from 20
ng/day to 10 .mu.g/day. The dosage and other aspects of the
delivery may be adjusted from time-to-time in response to the
effectiveness of treatment, such as the resistance of a particular
tooth or group of teeth, where the dosage might be increased if
resistance is not sufficiently reduced in response to an initial
dosage.
[0011] The substance(s) may be delivered at any point during the
orthodontic treatment where tooth repositioning and/or tissue
remodeling may be promoted. For example, the substance(s) may be
applied prior to any application of force intended to move the
teeth. Additionally or alternatively, the substance(s) may be
applied during all or any portion of the time during which force is
being applied to move the teeth. Further additionally or
alternatively, the substance(s) may be applied after the teeth have
been repositioned to a final desired configuration. In the latter
case, application of the substance(s) may be particularly effective
for promoting tissue remodeling in order to reduce the risk of
relapse. In such instances, the substance(s) may be delivered using
retainers or other appliances intended to help maintain the teeth
in their desired final configuration. When being delivered to
inhibit relapse, the remodeling and/or angiogenic substance(s) may
be delivered for a limited period of time in a limited period
before and/or immediately following the end of the orthodontic
procedure or may be delivered continuously or periodically for long
periods of time or indefinitely following the end of the
orthodontic procedure. For example, the substance(s) may be
delivered to some or preferably all of the regions of the gingiva
where teeth have been moved in order to promote stabilization and
remodeling of the tissue, usually over a period of one to eight
weeks, more usually two to six weeks prior to the end of
treatment.
[0012] The teeth may be repositioned by any conventional
orthodontic appliance intended for applying force to move teeth. In
particular, the present invention is compatible with both the use
of wire and bracket systems, commonly referred to as "braces," as
well as with newer systems employing removable appliances for
repositioning teeth, such as the Invisalign.RTM. System, available
from Align Technology, Inc., Santa Clara, Calif., and the "red,
white, and blue" system available from Sybron Dental Specialties,
Irvine, Calif. The present invention will also be useful with
dental "positioners" which are elastomeric appliances having
pre-formed tooth-receiving cavities where the patient bites into
the elastomeric appliance in order to force tooth movement.
Finally, the present invention may be used with dental retainers
which are polymeric shell appliances typically used to maintain a
final, desired tooth configuration and prevent relapse. When used
with dental repositioning appliances of any type, the application
of the tissue remodeling and/or angiogenic substance(s) according
to the present invention will usually both facilitate tooth
movement by modifying the tissue structures within the periodontal
tissue which anchor the teeth and also promoting tissue remodeling
which allows such tissue structures to accommodate the repositioned
teeth with less tendency toward relapse.
[0013] The substance(s) of the present invention may be applied and
administered in a wide variety of ways. Most simply, and as
presently preferred, the substance(s) could be "painted" or
otherwise topically applied to the patient's gingiva using a
conventional single-use applicator such as a swab, brush, syringe,
or the like. The substance(s) may be prepared in a conventional
form of topical composition, such as a gel, cream, ointment, or
other fluid or liquid substance. Alternatively, the substance(s)
could be administered by injecting into the periodontal tissue.
Additionally, the substance(s) could be delivered using a patch or
other appliance which is worn on the teeth or gingiva, optionally
being formed as part of the same appliance which is used to move
the teeth, e.g., a bracket or removable shell appliance or
retainer. In such instances, the substance(s) may be incorporated
into conventional drug reservoirs which both maintain a supply of
the substance(s) and which release the substance(s) at a controlled
rate, over time, to target sites on the gingiva. Suitable drug
delivery structures for delivering the substance(s) to the patient
gingiva are described in the patent and medical literature, see,
e.g., U.S. Pat. Nos. 6,159,498, 5,575,655; 5,194,003; 4,933,182;
and 4,685,883, the full disclosures of which are incorporated
herein by reference.
[0014] In some instances, it may be desirable to provide for
enhanced penetration of the substance(s) into the gingival. For
example, the substance(s) could be formulated with tissue
penetration or permeation enhancers, such as dimethylsulfoxide
(DMSO). Alternatively or additionally, the substance(s) can be
delivered while applying energy in a manner to promote tissue
penetration, including the application of an electric current in
order to achieve electroporation or iontophoresis, and/or the
application of ultrasound energy. The currents needed to provide
for electroporation are relatively low, typically around 0.1 mA can
be provided by batteries contained within the delivery structure or
alternatively by external structures which are periodically applied
to the gingiva or appliances present over the gingiva. Similarly,
ultrasound-enhanced substance delivery can be effected by
transducers incorporated into the delivery appliances and/or
provided by external appliances. Suitable ultrasound conditions are
from 20 kHz to 100 kHz at energy levels of one to ten
J/cm.sup.2.
[0015] A particular advantage of the present invention is that
particular teeth can be treated with the substance(s) while other
teeth in the same jaw remain untreated. In this way, those teeth
which are to be moved at any point during the course of orthodontic
treatment may be "relaxed" and prepared for movement while other
teeth which are needed as "anchor teeth" remain untreated. In this
way, the wire and bracket system, removable aligner, or the like,
may be anchored on those teeth which have not been treated with the
substance(s), while those teeth which are intended to be moved may
be treated and more readily moved. Of course, during a normal
orthodontic treatment, different teeth will be targeted for
movement at different times. The present invention allows only
those teeth which are intended to be moved at any particular time
to be treated at that time while other teeth in the dentition
remain untreated during that time and available as anchor teeth for
performing the orthodontic treatment.
[0016] The present invention may also advantageously be combined
with other orthodontic treatment protocols, such as
electroosteogenesis where a small electrical current is applied to
the gingiva or jaw to stimulate the tissues. It is believed that
the combination of the substance(s) with such electroosteogenesis
could provide tooth movement which is improved over that achieved
with either approach alone. Moreover, the application of the
electric current might act to provide "electroporation" and enhance
the uptake of the substance(s) into the periodontal tissues, as
described above.
[0017] In a further aspect of the present invention, improved
orthodontic treatment methods are provided. The orthodontic
treatment methods are of the type where at least one tooth in a
patient jaw is repositioned. The improvement comprises
administering at least one tissue remodeling and/or an angiogenic
substance to the patient before, during, or after the force has
been applied. The preferred aspects of this method are generally
the same as described above.
[0018] The present invention still further provides oral delivery
appliances comprising a structure and a tissue remodeling and/or an
angiogenic substance(s). The structure is mountable on or over at
least a portion of a patient gingiva, and the substance(s) is
carried by the structure so that said substance(s) is release into
at least a region of the gingiva while the structure is mounted on
or over the gingiva. Typically, the delivery appliance mounts over
the gingiva of an entire jaw, but in some instances it may mount
over the gingiva of less than the entire jaw. Typically, the
structure will include at least a portion which engages or mounts
over the gingiva adjacent the roots of the target teeth, typically
from one to twelve teeth, usually from one to six teeth, often from
one to five teeth, and sometimes only a single tooth. The appliance
may be in the form of a patch which adheres to the gingiva, a shell
which is removably placeable over the teeth in the gingiva, or the
like. The use of patches for delivery of the substance(s) may be
particularly advantages since the patches can be cut to size in
order to control dosage and/or delivery area to the gingiva. Such
modified patches may be applied or adhered directly to the gingiva
or alternatively may be positioned beneath a retainer which is worn
to maintain the positions of the teeth. When wire and bracket
orthodontic appliances are used, the delivery appliance may be
formed to mount on the wire or onto the bracket, may be
incorporated as part of the bracket or wire, or may be some
combination thereof. The relaxin or other tissue remodeling and/or
angiogenic substance may be incorporated into the oral delivery
appliance in a variety of ways. Most commonly, the relaxin will be
in a liquid, gel, or other releasable form which is incorporated
into a time-release structure to apply the substance to the gingiva
at a desired dosage rate. For example, the substance(s) may be
incorporated into a porous structure and/or in a reservoir which is
covered by a porous structure. In either case, the porous structure
acts as a rate-controlling membrane or barrier to achieve the
desired delivery rate. Alternatively, the substance(s) may be
present in a biodegradable matrix which degrades in the oral
environment over time to achieve a desired release rate of the
substance. Suitable degradable substances include polymers, such as
glycolic acid polymers and related materials.
[0019] In a still further aspect of the present invention, topical
oral compositions comprise a carrier and a tissue remodeling and/or
an angiogenic substance(s). The carrier is of the type which may be
topically applied to a patient's gingiva, typically being in the
form of a gel, cream, ointment, microemulsion or other liquid. The
tissue remodeling and/or an angiogenic substance(s) may be any of
the substance(s) listed above. The composition may be provided in
any conventional applicator, such as a tube, syringe, bottle, or
the like, and will be maintained in a sterile condition within the
applicator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 illustrates an oral tissue remodeling and/or an
angiogenic substance(s) delivery appliance constructed in
accordance with the principles of the present invention, in the
form of a patch.
[0021] FIG. 2 is a cross-sectional view taken along line 2-2 of
FIG. 1.
[0022] FIG. 3 illustrates the use of the patch of FIG. 1 in a first
exemplary protocol according to the present invention.
[0023] FIG. 4 illustrates the use of the patch of FIG. 1 in a
second exemplary protocol according to the present invention.
[0024] FIG. 5 illustrates the use of a polymeric shell appliance
for repositioning teeth and delivering a tissue remodeling and/or
an angiogenic substance(s) according to the principles of the
present invention.
[0025] FIG. 6 is a photograph illustrating the section of the
incisor which was excised for use in the push out testing described
in the Experimental Section.
[0026] FIG. 7 is a photograph illustrating the test equipment used
for the push out testing.
[0027] FIG. 8 is a graph showing the results of the push out
testing.
[0028] FIG. 9 is a photograph showing how the tooth wiggle testing
was performed.
[0029] FIGS. 10-13 are graphs showing the results of the pull out
testing.
[0030] FIG. 14 is a graph showing the results of the tooth wiggle
testing.
[0031] FIG. 15 illustrates the results of the dose response
testing.
DETAILED DESCRIPTION OF THE INVENTION
[0032] The present invention provides improved and facilitated
orthodontic treatment by delivering tissue remodeling and/or an
angiogenic substance(s) to periodontal tissue in which the teeth to
be moved are rooted or anchored. As used hereinafter, "periodontal
tissue" will refer to the connective tissue within the periodontal
tissues, specifically including the tissue and ligaments which
anchor the teeth in the bone. The application of the tissue
remodeling and/or an angiogenic substance(s) to the periodontal
tissue will both loosen the tissue and ligaments as well as promote
remodeling of the tissue during and after orthodontic
treatment.
[0033] The tissue remodeling and/or angiogenic substance(s) may be
delivered to the periodontal tissue in a variety of ways, including
systemic delivery, local injection, local topical application,
continuously, periodically, and combinations thereof. Topical
delivery is presently preferred and may be achieved using a
conventional surface applicator, such as a brush, swab, syringe,
squeeze tube, sponge, or other similar device. Alternatively,
topical delivery may be effected using various controlled release
devices, such as retainers, patches, orthodontic brackets and
wires, and other appliances which may be positioned on or over the
teeth and which have been modified in order to release the
substance(s) to the gingiva. In some cases, it will be desired to
deliver the drug into the gingival margin which is the line or
groove along the gingiva-tooth interface. Substances may be applied
as part of formulations which are delivered over the gingiva and/or
into the sulcus. In some instances, it may be desirable to plant
small substance delivery structures directly into the sulcus in a
manner analogous to the delivery of antibiotics using systems, such
as the PerioChip.RTM. available from Dexcel Pharma. The following
specific examples of patches and structures for delivering the
tissue remodeling and/or angiogenic substance(s) of the present
invention are meant to be exemplary and not limiting.
[0034] Referring to FIGS. 1 and 2, the substance(s) may be applied
in a variety of ways, including using a patch 10 which typically
comprises a reservoir layer 12, a rate controlling membrane 14, and
an adhesive layer 16. A patch 10 may be cut into strips, smaller
patches, or the like, and may be applied to the gingiva in order to
effect topical delivery of the substance(s) from the reservoir into
the tissue.
[0035] As shown in FIG. 3, the patch 10 of FIG. 1 may be cut into
smaller strips or pieces 20 which may be placed over the gingiva
overlying individual teeth. In this way, the teeth T1 and T2, for
example, may be treated to facilitate movement and promote
periodontal tissue remodeling, according to the present invention,
while adjacent teeth T3 and T4, as well as other non-treated teeth,
remain available as anchor teeth for effecting orthodontic
treatment, typically using conventional wire and bracket systems
(not shown). In FIG. 3B, the positioning of the patches 20 over the
roots of the teeth is shown.
[0036] In FIG. 4, a continuous strip 30 of the patch material 10 is
shown placed over the gingiva of eight adjacent teeth. The strip
30, of course, could extend around the entire gingiva of one jaw.
In this way, the substance(s) can be delivered to all teeth at
once. Such treatment might be preferred, for example, for treating
teeth after the teeth have reached their final position in order to
promote tissue remodeling. Alternatively, the strip 30 could be
configured so that the tissue remodeling and/or an angiogenic
substance(s) are released only from particular locations on the
strip to treat individual target teeth, achieving the same type of
treatment as shown in FIG. 3. Although patch and strip placement in
FIGS. 3 and 4 is shown only on the labial side of the gingiva, the
strips could be placed additionally or alternatively on the lingual
side of the gingiva.
[0037] Referring now to FIG. 5, a dental retainer or aligner 40 is
shown for placement over the dentition of a single jaw 42. A crown
portion 44 of a retainer/aligner 40 is configured to be removably
positionable over the teeth, while a skirt portion 46 is configured
to lie over the gingiva, usually both the labial and lingual sides
of the gingiva. The skirt is configured to retain and release the
tissue remodeling and/or an angiogenic substance(s), either over
its entire surface or over selected regions 48 as shown. In this
way, the substance(s) may be selectively delivered to individual
teeth or to the entire dentition in a single jaw, depending on the
particular treatment protocol.
[0038] The following examples are offered by way of illustration,
not by way of limitation.
Experimental
[0039] Two studies are presented, one examining properties of the
periodontal and gingival tissues to relaxin and the second on dose
finding.
[0040] I. In Vivo Studies of the Periodontal Ligament
[0041] A rat model was utilized because the rat has been
historically used for many orthodontic studies. There were five
animals per treatment group. Rats were treated for 1 or 3 days with
human relaxin (H2 gene product) or vehicle control (Table 1 below).
Relaxin or control vehicle was administered via Alzet implanted
minipumps. In addition, relaxin treated rats received a 0.5 mg
bolus injection (1.43 mg/kg) of relaxin at the time pumps were
placed. TABLE-US-00001 TABLE 1 Days of Treatment Control Relaxin 1
Day C1 (n = 5) R1 (n = 5) 3 Days C3 (n = 5) R3 (n = 5)
[0042] The jaws were collected for transport to the University of
Washington for analysis. The day 1 jaws were delivered fresh, and
the day 3 jaws were delivered frozen. Teeth from each treatment
group were tested for "looseness" using a material testing device
(MTD), and the periodontal ligament (PDL) was tested in a
"push-out" test. The rest of the jaw was saved for histological
analysis.
[0043] II. Objectives
[0044] These tests evaluated the ability of human relaxin (H2) to
accelerate tooth movement during orthodontic procedures in a rat
model. These studies examined the short term effects of relaxin on
tooth looseness using circulating relaxin and a material testing
device (MTD).
[0045] A. Tooth Looseness Tooth displacement measured in response
to a known force was measured.
[0046] B. Push-Out Test The material properties of the PDL were
measured in a material testing device to obtain force/displacement
curves.
[0047] C. Histological Analysis The contralateral jaw was used for
histological analysis. Staining techniques were used to visualize
collagen and elastin.
[0048] III. Protocol
[0049] A. Treatment Groups Adult male Sprague-Dawley rate (89-94
days old) were purchased from Animal Technologies, Ltd, Livermore,
Calif. There were five animals per treatment group having body
weights of 300-350 grams. Rats were treated for 1 or 3 days with
human relaxin (H2 gene product) or vehicle control (Table 1).
Relaxin or control vehicle is administered via Alzet implanted
minipumps. In addition, relaxin treated rats received a 0.5 mg
bolus injection (1.43 mg/kg) at the time pumps were placed.
[0050] B. Relaxin Administration Human relaxin (H2) produced by
Connetics, Corp was administered using Alzet osmotic pumps as
previously described in the rat (Garber et al. (2001) Kidney Int.
59: 1184-85). Relaxin was administered at a rate of approximately 8
.mu.g/kg/hr. This delivery rate has been shown to result in a blood
concentration of approximately 150 ng/ml (Garber, Microchnik et al.
2001). To ensure relaxin levels rapidly achieved effective
concentrations, rats were given a bolus subcutaneous injection of
0.5 mg relaxin at the time of pump implant. Control animals
received the same volume of vehicle.
[0051] C. Animal Manipulations Animals were euthanized with
anesthesia overdose at each of the specified time intervals.
Maxillae were dissected into halves. One hemimaxilla was fixed in
10% formalin for 24 hours followed by decalcification in 10% EDTA
for two weeks with daily changes of the solution, dehydration in
increasing concentrations of ethanol, and embedding in paraffin for
immunohistochemical and histomorphometric analyses. The other
hemimaxilla was fixed, decalcified and frozen for the
immunohistochemical analyses. Calvarias were saved for examination
of sutures by similar procedures.
[0052] D. Measuring Tooth Movement
[0053] 1. Push Out Test Gingival tissues were dissected away, and a
2 mm disk was cut through the alveolar bone and incisor (FIG. 6).
The resulting disk had alveolar bone, periodontal ligament (PDL),
tooth, and pulp and was embedded in paraffin. The embedded tissue
block was loaded onto a material testing device (FIG. 7) to produce
the stress-strain curve shown in FIG. 8. Stress = load cross
.times. - .times. sectional .times. .times. .times. area = kg
.times. / .times. mm 2 ##EQU1## Strain = elongation original
.times. .times. .times. length = % .times. .times. elongation
##EQU1.2##
[0054] 2. Wiggle Test The second premolar tooth was embedded in
paraffin and wiggled in place (FIG. 9). The amount of movement was
recorded.
[0055] The resulting amount of displacement was measured repeatedly
and averaged for each specimen.
[0056] IV. Results and Analysis
[0057] A. Material Testing The material testing of the rat jaws
included two different tests. These were the "push-out" test, and
the "wiggle" test. Separate teeth were used for each of these
tests, as explained below. The Day I specimens were delivered fresh
while the Day 3 were frozen so are only directly comparable with
the controls for that day.
[0058] 1. Push-Out Test The push-out test resulted in many
different parameters of a stress strain curve. Several of the more
relevant parameters were selected for the following graphs.
[0059] Referring to FIG. 10, peak load is a measure of the maximum
load (kilograms) that the PDL can withstand before breaking. The
PDL appears to be "weaker" with relaxin treatment, either at day 1
or day 3 of treatment.
[0060] Referring to FIG. 11, break load is the force in kilograms
needed to break the PDL. It was observed that the force was less
with relaxin treatment, indicating a softening of the ligament.
[0061] Referring to FIG. 12, energy is the area under the curve of
the force needed to break the PDL. Again, relaxin resulted in less
energy needed to break the PDL indicating its lessened resistance
to force.
[0062] Referring to FIG. 13, yield stress is the amount of stress
(kilograms/square mm) needed to cause the PDL to yield. The effect
of relaxin was to lower this parameter, indicating the ligament was
softer.
[0063] 2. Tooth Wiggle Referring to FIG. 14, the tooth wiggle test
demonstrated that the tooth was looser in the relaxin treated
animals. This was especially prominent in the day 1 treated
animals. The smaller difference seen on day 3 may be due to
freezing the tissue.
[0064] B. Histological Analysis The specimens were decalcified,
embedded, sectioned and strained with a variety of histological
stains. The PDL and gingival connective tissue were examined for a
reduction and/or reorganization in the collagen. Collagen normally
has a highly regular structure, which can be observed under a
microscope using polarized light. Intact collagen demonstrates a
birefringence or glow which is lost upon breakdown of the
collagen.
[0065] Comparison of the treated collagen with the untreated
control, under polarized label, demonstrated that the relaxin had
broken down the collagen. In the relaxin treated animals, the
collagen fibers have been shortened and no longer have the parallel
arrangement.
[0066] V. Dose Finding Experiment
[0067] The following test helps determine an effective dose of
relaxin for modification of collagen in the PDL and gingival
tissues. Relaxin was administered in different doses to the rat for
5 days via Alzet subcutaneous pumps. Again the material testing
device was used for measurement of the effects of relaxin. The
results are shown in FIG. 15.
[0068] The modulus is the slope of the stress strain graph. This
figure suggests a dose relationship of relaxin with the softening
of the PDL. It appears that even the lowest dose had modest effects
on the PDL, indicating that a small amount of relaxin would be
effective.
[0069] VI. Summary of Data
[0070] These data demonstrate for the first time that relaxin is
effective in vivo in modifying the mechanical characteristics the
ligaments that hold the tooth in the jaw. Major effects appear to
be on the collagen which comprises a large portion of the PDL and
gingival fibers. Relaxin affects these fibers as demonstrated by
histological and physical measurements. The result of this
modification of PDL and gingival fibers is to accelerate tooth
movement and prevent relapse. Our data on dose indicate that even
small amounts of relaxin may be effective in achieving these
effects.
[0071] While the above is a complete description of the preferred
embodiments of the invention, various alternatives, modifications,
and equivalents may be used. Therefore, the above description
should not be taken as limiting the scope of the invention which is
defined by the appended claims.
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