U.S. patent application number 10/587497 was filed with the patent office on 2007-12-20 for anchoring element for use in bone.
Invention is credited to Stanton R. Canter.
Application Number | 20070292820 10/587497 |
Document ID | / |
Family ID | 34798107 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070292820 |
Kind Code |
A1 |
Canter; Stanton R. |
December 20, 2007 |
Anchoring Element for Use in Bone
Abstract
An anchoring element for use in bone has a proximal end and a
distal end. The distal end may be embedded in bone with the
proximal end exposed. An abutment surface is disposed toward the
proximal end. The anchoring element includes four surfaces that
define the distal end. A generally cylindrical first surface
defines an exterior of the anchoring element and includes a first
external thread having a pitch. An annular second surface is
disposed toward the distal end and joined to the first surface
along an outer circumference of the second surface. A third surface
concentric with the first surface is joined to the second surface
along an inner circumference of the second surface. A fourth
surface disposed between the distal end and the proximal end of the
first surface is joined to the third surface along an outer
circumference of the fourth surface.
Inventors: |
Canter; Stanton R.;
(Tarzana, CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET
FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
34798107 |
Appl. No.: |
10/587497 |
Filed: |
January 28, 2005 |
PCT Filed: |
January 28, 2005 |
PCT NO: |
PCT/US05/02717 |
371 Date: |
July 20, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11035266 |
Jan 12, 2005 |
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10587497 |
Jul 20, 2007 |
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60539633 |
Jan 28, 2004 |
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60539633 |
Jan 28, 2004 |
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Current U.S.
Class: |
433/173 ;
606/304 |
Current CPC
Class: |
A61C 8/0039 20130101;
A61C 8/0018 20130101; A61C 8/0022 20130101 |
Class at
Publication: |
433/173 ;
606/073 |
International
Class: |
A61C 8/00 20060101
A61C008/00; A61B 17/58 20060101 A61B017/58 |
Claims
1. An anchoring element for use in bone, the anchoring element
comprising: a first surface having a distal end and a proximal end,
at least a portion of the first surface including a first external
thread having a pitch; an abutment surface disposed toward the
proximal end of the first surface; an annular second surface
disposed toward the distal end of the first surface and joined to
the first surface along an outer circumference of the second
surface; a third surface concentric with the first surface and
joined to the second surface along an inner circumference of the
second surface; and a fourth surface disposed between the distal
end and the proximal end of the first surface and joined to the
third surface along an outer circumference of the fourth
surface.
2. The anchoring element of claim 1 wherein the first surface
includes a frustrated first conical portion adjacent the distal end
such that a smaller circumference of the first conical portion is
adjacent the distal end.
3. The anchoring element of claim 1 wherein the third surface
includes a frustrated second conical portion adjacent the distal
end such that a larger circumference of the second conical portion
is adjacent the distal end.
4. The anchoring element of claim 1 wherein at least a portion of
the third surface includes an internal thread having the pitch of
the first external thread.
5. The anchoring element of claim 4 wherein the internal thread is
self-threading.
6. The anchoring element of claim 1 wherein the fourth surface is
annular, the anchoring element further comprising: a fifth surface
concentric with the first surface and joined to the fourth surface
along an inner circumference of the fourth surface; and a sixth
surface disposed toward the distal end of the first surface and
joined to the fifth surface along an outer circumference of the
sixth surface.
7. The anchoring element of claim 6 wherein the fifth surface
includes a frustrated third conical portion adjacent the distal end
such that a smaller circumference of the third conical portion is
adjacent the distal end.
8. The anchoring element of claim 6 wherein the first surface, the
second surface, the third surface, and the fourth surface are on a
first part, the fifth surface and the sixth surface are on a second
part, and the fifth surface is placed adjacent to the fourth
surface by passing the second part through the first part.
9. The anchoring element of claim 6 wherein the first surface, the
second surface, and the third surface are on a first part, the
fourth surface, the fifth surface, and the sixth surface are on a
second part, and the fourth surface is placed adjacent to the third
surface by passing the second part through the first part.
10. The anchoring element of claim 6 wherein at least a portion of
the third surface includes a first internal thread having the pitch
of the first external thread and at least a portion of the fifth
surface includes a second external thread having the pitch of the
first external thread.
11. The anchoring element of claim 1 wherein the abutment surface
is at an angle to an axis from the proximal end to the distal end
of the first surface.
12. An anchoring element suitable for placement in a prepared molar
socket that includes interradicular bone, the anchoring element
comprising: abutment means for receiving a dental prosthesis; first
means for threadedly engaging an outer wall of the molar socket;
second means for bearing against a bottom surface of the molar
socket; and third means for bearing against a first surface of the
interradicular bone that generally faces the outer wall of the
molar socket.
13. The anchoring element of claim 12 wherein the first means
includes a frustrated first conical portion adjacent the second
means such that a smaller circumference of the first conical
portion is adjacent the second means.
14. The anchoring element of claim 12 wherein the third means is
further for compressing the interradicular bone.
15. The anchoring element of claim 12 wherein the third means is
further for threadedly engaging the first surface of the
interradicular bone.
16. The anchoring element of claim 15 wherein the third means is
further for cutting a thread in the first surface of the
interradicular bone.
17. The anchoring element of claim 12 further comprising: fifth
means for bearing against a side wall of a hole prepared in the
interradicular bone.
18. The anchoring element of claim 17 wherein the fifth means is
further for compressing the interradicular bone.
19. The anchoring element of claim 17 wherein the fifth means is
further for threadedly engaging the side wall of the hole in the
interradicular bone.
20. A method for placing an anchoring element to receive a dental
prosthesis in a molar socket that includes interradicular bone, the
method comprising: cutting a generally cylindrical outer wall in
the molar socket to receive a first surface of the anchoring
element, the first surface having a distal end and a proximal end,
at least a portion of the first surface including a first external
thread having a pitch; cutting a generally annular flat surface in
the molar socket at a distal end of the cylindrical outer wall to
receive an annular second surface of the anchoring element, the
second surface being disposed toward the distal end of the first
surface and joined to the first surface along an outer
circumference of the second surface; cutting a generally
cylindrical surface on the interradicular bone that generally faces
the outer wall of the molar socket to receive a third surface of
the anchoring element, the third surface being concentric with the
first surface and joined to the second surface along an inner
circumference of the second surface; placing the anchoring element
into the molar socket by screwing the first surface into the outer
wall of the molar socket until the second surface of the anchoring
element bears against the annular flat surface in the molar socket
and the third surface of the anchoring element bears against the
cylindrical surface on the interradicular bone.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 60/539,633 filed on Jan. 28, 2004.
BACKGROUND OF THE INVENTION
[0002] Anchoring elements are used in a variety of dental, medical,
and surgical procedures where it is desired to embed a mechanical
attachment into living bone. One example of a procedure that uses
anchoring elements is dental prosthesis using embedded
implants.
[0003] Dental implants provide a desirable prosthesis for patients
who are missing one or more natural teeth. A dental implant
includes an anchoring element that is embedded into the jawbone and
a prosthetic tooth that is attached to and supported by the
anchoring element. The prosthetic tooth may be attached directly to
the anchoring element or an abutment fixture may be attached to the
anchoring element and support the prosthetic tooth in turn. An
appropriate anchoring element will support bone growth that invades
the anchoring element such that the anchoring element becomes
integrated with the surrounding bone in a process termed
osseointegration.
[0004] An anchoring element to support a prosthetic tooth may be
embedded in what is termed a two-stage procedure. In the first
stage, the anchoring element is embedded into the jawbone and the
surgical site is then closed. After a period of months the
anchoring element will achieve osseointegration. The site of the
anchoring element is then re-opened surgically to allow the
attachment of a prosthetic tooth.
[0005] More recently techniques have been developed that permit a
dental implant to be embedded in a one-stage procedure. In a
one-stage procedure, the anchoring element is embedded and a
prosthetic tooth is immediately fitted. The immediately fitted
prosthetic tooth may be an interim prosthesis that allows the soft
tissue to properly heal and maintains the spacing and alignment of
adjacent teeth during the period of osseointegration. A permanent
prosthetic tooth may be fitted at a later date after at least some
osseointegration has occurred without requiring an additional
surgical procedure.
[0006] To achieve successful osseointegration it is necessary that
the anchoring element fit closely into the surrounding bone,
generally having a gap of no more than 1.5 millimeters. It is also
important that the anchoring element not move relative to the
surrounding bone during the period of osseointegration. Where the
anchoring element cannot be closely fitted to the surrounding bone,
it may be necessary to use bone-grafting materials to fill the
space between the anchoring element and the surrounding bone.
[0007] Molars are commonly missing teeth. The use of an implant to
replace a molar presents some special difficulties. Molars
generally have multiple roots. The mandibular molars of the lower
jaw generally have two roots. The maxillary molars of the upper jaw
generally have three roots. In a fresh extraction site the void
left by the molar roots presents a site that can be difficult to
fit with an anchoring element. In addition, the bone in the molar
region of the jaw generally consists of a thin hard layer of
cortical bone surrounding a core of softer spongy cancellous bone.
The cancellous bone may provide poor support for the anchoring
element prior to osseointegration.
[0008] A molar is a relatively large tooth and it is desirable to
use an anchoring element having a relatively large diameter to fill
the void following an extraction. However, the use of a wide
anchoring element may require that a significant amount of bone be
removed from the extraction site to accommodate the anchoring
element. This may leave only a small amount of cortical bone
available to support the anchoring element which may be embedded in
predominantly cancellous bone. In particular, the use of a wide
anchoring element may require removal of the triangular
mound-shaped mass of bone that is found between the roots known as
the interradicular bone. Thus, it is difficult to place an
anchoring element in a fresh molar extraction site with sufficient
stability to allow embedding of a dental implant with a one-stage
procedure.
[0009] Another circumstance that can present difficulties in
placing an anchoring element for a dental implant occurs in cases
where it is desired to place a dental prosthesis in a healed
extraction site. When a molar is lost, the alveolar ridge that
supports the teeth is fairly rapidly resorbed. This causes a loss
of height of the jawbone in the area of tooth loss. When an
anchoring element is to be embedded in a healed extraction site, it
may not be possible to place an anchoring element to a very great
depth.
[0010] In the lower jaw, the presence of the mandibular alveolar
nerve in the lower jaw limits the depth of the anchoring element.
In the upper jaw the maxillary sinus limits the depth. These
limiting anatomical features may require the use of a short
anchoring element, perhaps 5 to 8 millimeters in length. The use of
short anchoring elements for such cases has a lower rate of
long-term success because of the reduced surface area available for
osseointegration.
[0011] It would be desirable to have an anchoring element that can
be used to place a dental implant in the molar area both for fresh
extraction sites and for healed sites.
SUMMARY OF THE INVENTION
[0012] An anchoring element for use in bone has a proximal end and
a distal end. The distal end may be embedded in bone with the
proximal end exposed. An abutment surface is disposed toward the
proximal end. The anchoring element includes four surfaces that
define the distal end. A generally cylindrical first surface
defines an exterior of the anchoring element. At least a portion of
the first surface includes a first external thread having a pitch.
An annular second surface is disposed toward the distal end and the
first surface is joined to the second surface along an outer
circumference of the second surface. A third surface concentric
with the first surface is joined to the second surface along an
inner circumference of the second surface. At least a portion of
the third surface may include an internal thread having the pitch
of the first external thread. A fourth surface disposed between the
distal end and the proximal end of the first surface is joined to
the third surface along an outer circumference of the fourth
surface.
[0013] In another embodiment, an anchoring element includes six
surfaces that define the distal end. At least a portion of a first
surface includes a first external thread. An annular second surface
is disposed toward the distal end and joined to the first surface
along an outer circumference of the second surface. A third surface
concentric with the first surface is joined to the second surface
along an inner circumference of the second surface. An annular
fourth surface is disposed between the distal end and the proximal
end and joined to the third surface along an outer circumference of
the fourth surface. A fifth surface concentric with the first
surface is joined to the fourth surface along an inner
circumference of the fourth surface. A sixth surface is disposed
toward the distal end and joined to the fifth surface along an
outer circumference of the sixth surface.
[0014] In another embodiment, an anchoring element for use in bone
has a proximal end and a distal end. The distal end may be embedded
in bone with the proximal end exposed. The anchoring element
includes a generally cylindrical first surface, at least a portion
of the first surface including an external thread. An abutment
surface is disposed at the proximal end of the anchoring element.
The abutment surface is at an angle to an axis from the proximal
end to the distal end of the anchoring element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a pictorial view of an anchoring element for use
in bone that embodies the invention.
[0016] FIG. 2 is a plan view of the distal end of the anchoring
element shown in FIG. 1.
[0017] FIG. 3 is a cross section of the anchoring element taken
along the line 3-3 shown in FIG. 2.
[0018] FIG. 4 is a plan view of the distal end of the anchoring
element of FIGS. 1 through 3.
[0019] FIG. 5 is a side elevation of another anchoring element that
embodies the invention.
[0020] FIG. 6 is a plan view of the proximal end of the anchoring
element of FIG. 5.
[0021] FIG. 7 is a cross section taken along section line 7-7 shown
in FIG. 6.
[0022] FIG. 8 is a plan view of the proximal end of the anchoring
element of FIGS. 5 through 7.
[0023] FIG. 9 is a pictorial view of another anchoring element that
embodies the invention.
[0024] FIG. 10 is a plan view of the proximal end of the anchoring
element of FIG. 9.
[0025] FIG. 11 is a cross section of the anchoring element taken
along the line 11-11 shown in FIG. 10.
[0026] FIG. 12 is a plan view of the distal end of the anchoring
element of FIGS. 9 through 11.
[0027] FIG. 13 is a cross section of the anchoring element with the
distal portion taken along the section line 13-13 shown in FIG. 12
and the proximal portion taken along the section line 11-11 shown
in FIG. 10.
[0028] FIG. 14 is a cross section view of another anchoring element
that embodies the invention.
[0029] FIG. 15 is a cross section of the anchoring element shown in
FIG. 14 with the distal portion sectioned similarly to the view of
FIG. 13.
[0030] FIG. 16 is a cross section of a mandibular molar extraction
site.
[0031] FIG. 17 is a cross section of the extraction site shown in
FIG. 16.
[0032] FIG. 18 is a cross section similar to the view of FIG. 16
showing the preparation of the extraction site for embedding an
anchoring element.
[0033] FIG. 19 is a cross section of the upper portion of the
extraction site shown in FIG. 18.
[0034] FIG. 20 is a cross section of the lower portion of the
extraction site shown in FIG. 18.
[0035] FIG. 21 is a cross section of an anchoring element embedded
in the extraction site prepared as shown in FIG. 18.
[0036] FIG. 22 is a cross section of a first part of another
anchoring element that embodies the invention.
[0037] FIG. 23 is a side view of a second part of the anchoring
element.
[0038] FIG. 24 is a view of the second part shown in side view
installed into the first part shown in cross section to form the
anchoring element.
[0039] FIG. 25 is a view of an alternate position for the second
part relative to the first part of the anchoring element shown in
FIG. 24.
[0040] FIG. 26 is a cross section of a first part and side view of
a second part forming another anchoring element that embodies the
invention.
[0041] FIG. 27 is a cross section of a first part and side view of
a second part forming another anchoring element that embodies the
invention.
[0042] FIG. 28 is a cross section of a first part of another
anchoring element that embodies the invention.
[0043] FIG. 29 is a side view of a second part of the anchoring
element.
[0044] FIG. 30 is a view of the second part shown in side view
installed into the first part shown in cross section to make the
complete anchoring element.
[0045] FIG. 31 is a cross section of another anchoring element that
embodies the invention.
[0046] FIG. 32 is a cross section of another anchoring element that
embodies the invention.
[0047] FIG. 33 is a cross section of another anchoring element that
embodies the invention shown as it may be embedded in bone.
[0048] FIG. 34 is a side view of another anchoring element that
embodies the invention.
[0049] FIG. 35 is a side view of another anchoring element that
embodies the invention.
[0050] FIG. 36 is a cross section of another anchoring element that
embodies the invention.
[0051] FIG. 37 is a cross section of another anchoring element that
embodies the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0052] FIG. 1 shows an anchoring element 100 for use in bone that
embodies the invention. The anchoring element may be fabricated of
any biocompatible material known or discovered to promote
osseointegration such as titanium or a titanium alloy. The portions
of that are to be in intimate contact with bone can display various
surface characteristics. These portions can be titanium plasma
sprayed, coated with hydroxy-apatite (HA coated), surface machined,
sand blasted, or acid etched to promote osseointegration.
[0053] For convenience in description, the anchoring element 100
will be described with reference to a distal end and a proximal
end. The distal end is shown in FIG. 1 as the end to the lower
right and is the end that is embedded to the greatest depth in
bone. The proximal end is the end to the upper right and is the end
that may be exposed when the anchoring element 100 is embedded in
bone.
[0054] The anchoring element 100 includes a first surface that is a
generally cylindrical exterior surface of the anchoring element.
The term "generally cylindrical" is used to describe a surface that
is substantially rotationally symmetric about an axis that extends
from the distal end to the proximal end. The first surface may
include a screw thread 112. It will be appreciated that a screw
thread is not rotationally symmetric in the strictest sense. A
screw thread or similar feature is intended to be included by the
term "substantially rotationally symmetric." The exterior surface
of the anchoring element 100 may include features such as the
aforementioned screw thread and other features such as shoulders
102, tapered portions 110, and the like, all of which are intended
to be included by the term "generally cylindrical."
[0055] At least a portion of the first surface of the anchoring
element 100 may include a first external thread 112 having a pitch.
The thread 112 may be of any of a variety of forms known or
discovered to be effective for embedding the anchoring element in
bone. The thread 112 may include self-threading (thread cutting)
features or other features that aid in embedding the anchoring
element into bone or that promote osseointegration.
[0056] The first surface may include a frustrated first conical
portion 110 adjacent the distal end of the anchoring element 100
such that a smaller circumference of the first conical portion is
adjacent the distal end. The first conical portion 110 may
facilitate placing the anchoring element 100 into a hole that is
prepared in the bone to receive the anchoring element. The first
conical portion 110 may provide a somewhat smaller leading distal
end that allows the anchoring element 100 to initially engage the
bone with minimal force and align the anchoring element to the hole
that has been prepared in the bone.
[0057] The first conical portion 110 may be unthreaded or may
partially or fully intersect the first external thread 112. In one
embodiment the first conical portion 110 may have a smallest
diameter at the distal end of the anchoring element 100 that is
approximately a root diameter of the first external thread. The
first conical portion 110 may gradually increase in diameter toward
the proximal end thereby providing a gradually increasing thread
depth.
[0058] The anchoring element 100 may include an abutment surface
disposed toward the proximal end of the first surface. The abutment
surface may be of any of a variety of known or discovered forms
that permit attachment to the anchoring element.
[0059] FIGS. 1 through 3 illustrate an abutment surface that may be
provided to receive a dental prosthesis. The illustrated abutment
surface includes an external hex surface 104 that may provide a
wrenching surface for embedding the anchoring element 100. The
illustrated abutment surface further includes a locating recess 106
and an internal anchoring thread 108 to receive a devices that is
coupled to the anchoring element by a screw.
[0060] The anchoring element 100 includes an annular second surface
120 disposed toward the distal end of the first surface and joined
to the first surface along an outer circumference 122 of the second
surface. The second surface 120 may engage the bottom of the hole
that has been prepared in the bone and thereby contribute
significantly to the stability of the embedded anchoring element
100. The second surface 120 may be substantially flat or may have a
rounded or other shape chosen to effectively cooperate with the
bottom of the hole that has been prepared in the bone to provide
initial stability.
[0061] As may be seen in the plan view of the distal end, the
anchoring element 100 includes a third surface 140 concentric with
the first surface and joined to the second surface 120 along an
inner circumference 124 of the second surface. At least a portion
of the third surface 140 may include an internal thread having the
pitch of the first external thread such that both threads will
advance the anchoring element 100 at the same rate as it is rotated
to embed the anchoring element into bone. The internal thread may
be of any of a variety of forms known or discovered to be effective
for embedding the anchoring element in bone. The internal thread
may include self-threading (thread cutting) features or other
features that aid in embedding the anchoring element into bone or
that promote osseointegration. It is contemplated that the hole in
the bone that is prepared to receive the anchoring element 100 may
leave residual bone in place such that the third surface 140 will
at least partially engage the bone to provide additional initial
stability and an additional surface for osseointegration.
[0062] The third surface 140 may include a frustrated second
conical portion adjacent the distal end such that a larger
circumference of the second conical portion is adjacent the distal
end. The second conical portion may facilitate placing the
anchoring element 100 into the portion of hole that includes
residual bone. The second conical portion may compress the residual
bone as the anchoring element 100 is embedded to further increase
initial stability.
[0063] The second conical portion may be unthreaded or may
partially or fully intersect the first internal thread. In one
embodiment the second conical portion may have a largest diameter
at the distal end of the anchoring element 100 that is
approximately a root diameter of the first internal thread. The
second conical portion may gradually increase in diameter toward
the proximal end thereby providing a gradually increasing thread
depth.
[0064] The anchoring element 100 includes a fourth surface 130
disposed between the distal end and the proximal end and joined to
the third surface 140 along an outer circumference of the fourth
surface 132. It is contemplated that the hole in the bone that is
prepared to receive the anchoring element 100 may leave an upper
surface on the residual bone such that the fourth surface 130 will
engage the upper surface to provide additional initial stability
and an additional surface for osseointegration.
[0065] FIG. 3 is a cross-section of the anchoring element 100 taken
along a diameter as shown by the section line 3--3 in FIG. 2. FIG.
3 may aid in visualizing the relationships between the various
surfaces of the anchoring element 100. FIG. 3 may also aid in
visualizing a possible interaction of the conical sections with the
threads at the distal end.
[0066] FIGS. 5 through 8 illustrate another anchoring element 200
that embodies the invention. This embodiment includes many features
that are similar to the anchoring element 100 illustrated by FIGS.
1 through 4. Similar features for anchoring element 200 have been
given reference numerals that are the reference numerals used for
anchoring element 100 increased by 100.
[0067] In this embodiment the anchoring element 200 includes an
abutment surface 204 in the form of a frustrated square pyramid.
The abutment surface 204 may provide a wrenching surface. If the
anchoring element is used to support a dental prosthesis, a
prosthetic tooth may be directly coupled to the abutment surface
204 such as by cement.
[0068] FIG. 7 shows a cross section of the anchoring element 200
taken along the section line 7--7 as shown in the plan view of the
proximal end of FIG. 6. The first surface may be a slightly larger
in diameter than the third surface. It may be seen in FIG. 7 that
there will be a comparatively thin cross-section where the roots of
the external thread 212 coincide with the internal thread. It may
be advantageous to arrange the internal threads so that the roots
coincide with the crest of the external thread to avoid a thin
cross section.
[0069] The anchoring element 200 may be relatively short such that
if the first and/or third generally cylindrical surfaces include a
conical section, the conical section may occupy all or
substantially all of the first and/or third surfaces.
[0070] FIGS. 9 through 13 illustrate another anchoring element 300
that embodies the invention. This embodiment includes many features
that are similar to the anchoring element 100 illustrated by FIGS.
1 through 4. Similar features for anchoring element 300 have been
given reference numerals that are the reference numerals used for
anchoring element 100 increased by 200.
[0071] FIGS. 10 and 11 illustrate an abutment surface that may be
provided to receive a dental prosthesis. The illustrated abutment
surface includes a lobed locating recess 306 and an internal
anchoring thread 308 to receive a devices that is coupled to the
anchoring element 300 by a screw. The lobes of the locating recess
306 may prevent rotation of a coupled device and may provide a
wrenching surface for embedding the anchoring element 300.
[0072] In this embodiment the anchoring element the fourth surface
330 is annular. The anchoring element further includes a fifth
surface 350 concentric with the first surface and joined to the
fourth surface 330 along an inner circumference 334 of the fourth
surface. A sixth surface 360 is disposed toward the distal end of
the first surface and joined to the fifth surface 350 along an
outer circumference 362 of the sixth surface.
[0073] The fifth surface 350 may include a second external thread
on all or part of the fifth surface. The second external thread has
the pitch of the first external thread such that all threads will
advance the anchoring element 300 at the same rate as it is rotated
to embed the anchoring element into bone. The second external
thread may be of any of a variety of forms known or discovered to
be effective for embedding the anchoring element in bone. The
second external thread may include self-threading (thread cutting)
features or other features that aid in embedding the anchoring
element into bone or that promote osseointegration. It is
contemplated that the hole in the bone that is prepared to receive
the anchoring element 300 may provide a secondary hole in the
residual bone such that the fifth surface 350 will at least
partially engage the bone to provide additional initial stability
and an additional surface for osseointegration.
[0074] The fifth surface 350 may include a frustrated third conical
portion adjacent the distal end such that a smaller circumference
of the third conical portion is adjacent the distal end. The third
conical portion may be unthreaded or may partially or fully
intersect the second external thread on the fifth surface 350. In
one embodiment the third conical portion may have a smallest
diameter at the distal end of the anchoring element 300 that is
approximately a root diameter of the second external thread. The
third conical portion may gradually increase in diameter toward the
proximal end thereby providing a gradually increasing thread depth.
The second and third conical sections may act to compress the
residual bone between the third and fifth generally cylindrical
surfaces.
[0075] FIG. 13 is a cross-section view of anchoring element 300
shown in FIGS. 9-12 where the lower part of the cross-section is
taken along section line 13--13 shown in FIG. 12 so that the fifth
surface is not cut by the cross-section and the fifth surface may
be seen. The portion of the cross-section between the fourth
surface 330 and the proximal end is taken along section line 11--l1
shown in FIG. 10.
[0076] FIGS. 14 and 15 illustrate another anchoring element 400
that embodies the invention. This embodiment includes many features
that are similar to the anchoring element 300 illustrated by FIGS.
9 through 13. Similar features for anchoring element 400 have been
given reference numerals that are the reference numerals used for
anchoring element 300 increased by 100.
[0077] In this embodiment the anchoring element 400 the first
surface includes a shoulder surface 402 in the form of a frustrated
conical section. Such a conical shoulder is intended to be included
by the term "generally cylindrical." The anchoring element 400 may
be relatively short such that an internal anchoring thread 408
extends into the portion of the anchoring element 400 defined by
the fifth surface 450.
[0078] FIGS. 16 through 20 illustrate an exemplary use of an
anchoring element 500 that embodies the invention to provide a
dental prosthesis for an extracted molar tooth.
[0079] FIG. 16 shows a cross-section of a socket following the
extraction of a mandibular molar having two roots. The
cross-section is taken along a section line that is mesiodistal
(running from the front to the back of the head). The socket
includes the interradicular bone 510 which separated the roots of
the extracted molar.
[0080] FIG. 17 shows a cross-section of the socket viewed from the
top and looking down into the socket. An outline of the cervical
collar 512 taken along section line 17A--17A in FIG. 16 is shown.
An outline of each of the two roots 514, 516 taken along section
line 17B--17B in FIG. 16 is shown.
[0081] FIG. 18 shows a cross-section of a prepared molar socket
which is the socket of FIG. 16 after a hole has been prepared to
receive the anchoring element. FIG. 19 is a top down cross-section
of the prepared molar socket at the cervical collar 512 taken along
section line 19--19 in FIG. 18. It may be seen the prepared hole
520 may not remove all of the cervical collar 512. Generally it is
desirable to provide a large periphery of contact between the
anchoring element 500 and the cervical collar 512 to provide good
initial stability. However, it is also desirable to preserve as
much bone as possible consistent with preparing a hole that will
provide good initial stability and good osseointegration. In
particular, the bone may have a relatively thin and hard cortical
layer surrounding a softer inner core of cancellous bone. It is
desirable preserve the cortical bone which will provide much more
initial stability than the spongy cancellous bone.
[0082] The anchoring element 500 may be sized to come within at
least 1.5 millimeters of all parts of the socket so that
osseointegration will occur. The anchoring element 500 may be sized
so that about 75% or more of the periphery at the cervical collar
is in direct contact with the anchoring element to provide good
initial stability.
[0083] FIG. 20 shows a cross-section of the socket of FIG. 16 after
a hole has been prepared to receive the anchoring element. FIG. 20
is a top down cross-section of the prepared hole at the roots 514,
516 taken along section line 20--20 in FIG. 18. It may be seen the
prepared hole 522 may not remove all of the socket that surrounded
the roots. It may also be seen that a substantial portion of the
interradicular bone 510 is preserved as residual bone in the
prepared molar socket. The distal portion of the prepared hole 522
includes an annular region 524 to receive the portion of the
anchoring implant between the first surface 501 and third surface
503. The second surface 502 of the anchoring element 500 may bear
against the bottom surface 524 of the molar socket 522 to increase
initial stability of the anchoring element.
[0084] The bottom surfaces 530, 532, 534 of the prepared hole are
also significant. It is desirable that the bottom surfaces support
a significant portion of one or more of the second surface 502,
fourth surface 504, and sixth surface 506 (if present) of the
anchoring element 500. For this reason, the hole may be prepared
with bottom surfaces 530, 534 that are below the lowest point of
the roots if permitted by other anatomical structures such as the
mandibular nerve 518 or maxillary sinus. A flat surface 532 may be
prepared on the proximal portion of the residual interradicular
bone 510 to support the fourth surface 504. The flat surface 532 on
the proximal portion of the residual interradicular bone 510 may be
generally parallel to the bottom surface 530 of the prepared molar
socket 500.
[0085] The first surface 501 of the anchoring element 500 is
adapted to threadedly engage the outer wall 522 of the molar
socket. The first surface 501 may include a frustrated first
conical portion adjacent the second surface 502 such that a smaller
circumference of the first conical portion is adjacent the second
surface. The conical surface may aid in placing the anchoring
element into the prepared molar socket. The conical surface may
compress the bone surrounding the outer wall of the prepared molar
socket, particularly in the upper portion adjacent the cervical
collar, which may increase bone density and support for the
anchoring element.
[0086] The third surface 503 of the anchoring element 500 is
adapted to bear against a first surface 511 of the interradicular
bone 510 that generally faces the outer wall 522 of the molar
socket. The third surface 503 may have a frustrated conical form
such that it may compress the interradicular bone, particularly in
the upper portion, which may increase bone density and support for
the anchoring element 500. The third surface 503 may include screw
threads, which may be self-cutting threads, for threadedly engaging
the first surface 511 of the interradicular bone 510.
[0087] The anchoring element 500 may include a fifth surface 505.
The prepared molar socket may therefore include a secondary hole
526 in the residual interradicular bone 510 to receive the fifth
surface 505. The fifth surface may bear against a side wall of the
secondary hole. The fifth surface 505 may have a frustrated conical
form such that it may compress the interradicular bone,
particularly in the upper portion, which may increase bone density
and support for the anchoring element 500. The fifth surface 505
may include screw threads, which may be self-cutting threads, for
threadedly engaging the side wall of the secondary hole 526.
[0088] FIGS. 22 through 25 show another anchoring element 600 that
embodies the invention. A first part 610 includes a first surface
601, a second surface 602, a third surface 603, and a fourth
surface 604. A second part 620 includes a fifth surface 605 and a
sixth surface 606. The fifth surface 605 is joined to the fourth
surface 604 by screwing the second part 620 into the first part
610. The resulting assembly provides an anchoring element 600 that
has similar features to the anchoring element 300 shown in FIG. 9.
It may be possible to adjust the position of the sixth surface 606
relative to the second surface 602 as shown by FIGS. 24 and 25.
[0089] FIG. 26 shows another anchoring element 700 that embodies
the invention. A second part 720 is screwed into a first part 710
to provide an anchoring element 700 that has similar features to
the anchoring element 400 shown in FIG. 14. The second part 720 may
be shaped so that it can screwed into an interference fit with the
first part 710 such that the anchoring element 700 functions as a
single piece after assembly.
[0090] FIG. 27 shows another anchoring element 800 that embodies
the invention. A second part 820 passes through an unthreaded
opening 814 in a first part 810 to provide an anchoring element 800
that has similar features to the anchoring element 400 shown in
FIG. 14. The second part 820 may include a head surface 822 that
bears against a shoulder surface 812 on the first part when both
parts are embedded in bone. When both parts are assembled into an
anchoring element 800 by being embedded in bone, the second part
820 may be adjusted to change the distally directed pressure of the
first part 810 against the bone.
[0091] FIGS. 28 through 30 show another anchoring element 900 that
embodies the invention. A first part 910 includes a first surface
901, a second surface 902, and a third surface 903. The third
surface 903 extends from the distal end to the proximal end
providing a through passage that includes an internal thread for a
least a portion of the third surface. A second part 920 includes a
fourth surface 904, a fifth surface 905, and a sixth surface 906.
The second part 920 further includes a joining surface 922 that is
generally cylindrical and concentric with the fifth surface 905. At
least a portion of the joining surface may include an external
thread that mates with at least a potion of the threaded third
surface 903 of the first part 910. The third surface 903 is joined
to the fourth surface 904 by screwing the second part 920 into the
first part 910. The resulting assembly provides an anchoring
element 900 that has similar features to the anchoring element 300
shown in FIG. 9.
[0092] FIG. 31 shows another anchoring element 1000 that embodies
the invention. This embodiment includes a first surface 1001, a
second surface 1002, a third surface 1003, a fourth surface 1004, a
fifth surface 1005, and a sixth surface 1006 similarly arranged to
previously described embodiments. In this embodiment the second
surface 1002, fourth surface 1004, and sixth surface 1006 may be
curved. In this embodiment, only the first surface 1001 may include
a threaded portion. The fifth surface 1005 may be a right cylinder
such that this portion of the anchoring element 1000 may fit into a
pilot hole that may have been used to guide the preparation of the
bone to receive the anchoring element. The second surface 1002 may
include a conical portion to provide a close fit to residual
bone.
[0093] FIG. 32 shows another anchoring element 1100 that embodies
the invention. This embodiment includes a first surface 1101, a
second surface 1102, a third surface 1103, a fourth surface 1104, a
fifth surface 1105, and a sixth surface 1106 similarly arranged to
previously described embodiments. The anchoring element 1100 of
this embodiment is generally similar to the anchoring element 1000
of FIG. 31. The fifth surface 1105 and the second surface 1102 may
include conical portions to provide a close fit to residual
bone.
[0094] FIG. 33 shows another anchoring element 1200 that embodies
the invention. FIG. 33 is a cross-section of the anchoring element
1200 embedded in the posterior portion of a mandible along section
line in a bucco-lingual (cheek to tongue) direction. This
embodiment includes an abutment surface 1210 that is at an angle to
an axis from the proximal end to the distal end of the first
surface. The abutment surface 1210 may be substantially flat in the
area adjacent the proximal end of the first surface 1201. As shown
in FIG. 33, when an anchoring element is embedded in a healed molar
extraction site, resorption of the bone may cause the site to be
shallow with a surface that may be higher on one side 1220 than the
other 1222, generally being lower to the buccal (cheek) side 1222.
It may be seen that the angled abutment surface 1210 allows the
first surface 1201 to have greater contact with the bone without
leaving a portion of the anchoring element 1201 exposed above the
bone.
[0095] FIG. 34 shows another anchoring element 1300 that includes
an abutment surface 1310 that is at an angle to an axis from the
proximal end to the distal end of the first surface.
[0096] FIG. 35 shows another anchoring element 1400 that includes
an abutment surface 1410 that is at an angle to an axis from the
proximal end to the distal end of the first surface. In this
embodiment the threaded portion of the first surface may extend to
the abutment surface which may increase the threaded engagement of
the anchoring element 1400 to bone.
[0097] FIG. 36 shows another anchoring element 1500 that embodies
the invention. This embodiment includes many features that are
similar to the anchoring element 200 illustrated by FIGS. 5 through
8. Similar features for anchoring element 1500 have been given
reference numerals that are the reference numerals used for
anchoring element 200 increased by 1300. The anchoring element 1500
includes a fourth surface 1530 disposed between the distal end and
the proximal end and joined to the third surface 1540. The fourth
surface 1530 is in the form of a frustrated cone. It is
contemplated that the hole in the bone that is prepared to receive
the anchoring element 1500 may leave an upper surface on the
residual interradicular bone such that the fourth surface 1530 will
engage the upper surface to provide additional initial stability
and an additional surface for osseointegration. The conical shape
of the fourth surface may allow the residual interradicular bone to
be selectively compressed as determined by how far into the molar
socket the anchoring element 1500 is advanced. This may allow a
greater degree of compression to be applied when the residual
interradicular bone is soft and spongy.
[0098] FIG. 37 shows another anchoring element 1600 that embodies
the invention. This embodiment includes many features that are
similar to the anchoring element 200 illustrated by FIGS. 5 through
8. Similar features for anchoring element 1600 have been given
reference numerals that are the reference numerals used for
anchoring element 200 increased by 1400. The anchoring element 1600
includes a fourth surface 1630 disposed between the distal end and
the proximal end and joined to the third surface 1640. The fourth
surface 1630 is in the form of a convex curved surface. It is
contemplated that the hole in the bone that is prepared to receive
the anchoring element 1600 may leave an upper surface on the
residual interradicular bone such that the fourth surface 1630 will
engage the upper surface to provide additional initial stability
and an additional surface for osseointegration. The convex shape of
the fourth surface may allow the residual interradicular bone to be
selectively compressed as determined by how far into the molar
socket the anchoring element 1600 is advanced. This may allow a
greater degree of compression to be applied when the residual
interradicular bone is soft and spongy.
[0099] While certain exemplary embodiments have been described and
shown in the accompanying drawings, it is to be understood that
such embodiments are merely illustrative of and not restrictive on
the broad invention, and that this invention not be limited to the
specific constructions and arrangements shown and described, since
various other modifications may occur to those ordinarily skilled
in the art. It is to be understood that individual features shown
or described for one embodiment may be combined with individual
features shown or described for another embodiment. It is to be
understood some features are shown or described to illustrate the
use of the invention in the context of functional anchoring
elements and such features may be omitted within the scope of the
invention.
* * * * *