U.S. patent application number 14/225337 was filed with the patent office on 2014-10-30 for implant with internal multi-lobed interlock.
This patent application is currently assigned to Nobel Biocare Services AG. The applicant listed for this patent is Nobel Biocare Services AG. Invention is credited to Steven M. Hurson.
Application Number | 20140322670 14/225337 |
Document ID | / |
Family ID | 32232973 |
Filed Date | 2014-10-30 |
United States Patent
Application |
20140322670 |
Kind Code |
A1 |
Hurson; Steven M. |
October 30, 2014 |
IMPLANT WITH INTERNAL MULTI-LOBED INTERLOCK
Abstract
A dental implant for supporting a dental prosthesis comprises a
body portion and a top surface. The implant further comprises an
internal cavity with an opening located at the top surface. The
internal cavity comprises an interlock chamber having a depth
measured from the top surface equal to a first distance. The
interlock chamber comprising a cylindrical portion and plurality of
semi-circular channels arranged around a periphery of the
cylindrical portion. A threaded chamber that includes threads is
located below the post-receiving chamber. The cylindrical portion
has a first radius and the channels have a second radius, a ratio
of the first radius to the second radius being between
approximately 4:1. and 2:1.
Inventors: |
Hurson; Steven M.; (Yorba
Linda, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nobel Biocare Services AG |
Zurich-Flughafen |
|
CH |
|
|
Assignee: |
Nobel Biocare Services AG
Zurich-Flughafen
CH
|
Family ID: |
32232973 |
Appl. No.: |
14/225337 |
Filed: |
March 25, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12896715 |
Oct 1, 2010 |
8721335 |
|
|
14225337 |
|
|
|
|
11952349 |
Dec 7, 2007 |
|
|
|
12896715 |
|
|
|
|
11011513 |
Dec 14, 2004 |
|
|
|
11952349 |
|
|
|
|
10800818 |
Mar 15, 2004 |
|
|
|
11011513 |
|
|
|
|
09670708 |
Sep 27, 2000 |
6733291 |
|
|
10800818 |
|
|
|
|
60156198 |
Sep 27, 1999 |
|
|
|
Current U.S.
Class: |
433/173 |
Current CPC
Class: |
A61C 8/008 20130101;
A61C 8/0054 20130101; A61C 8/0066 20130101; A61C 8/006 20130101;
A61C 8/0062 20130101; A61C 8/0059 20130101; A61C 8/0069 20130101;
A61C 8/005 20130101; A61C 8/0068 20130101; A61C 8/0024 20130101;
A61C 8/0074 20130101; A61C 8/0015 20130101 |
Class at
Publication: |
433/173 |
International
Class: |
A61C 8/00 20060101
A61C008/00 |
Claims
1-36. (canceled)
37. A dental implant for supporting a dental prosthesis, the dental
implant comprising a body portion and a top surface, the implant
further comprising an internal cavity with an opening located at
the top surface, the internal cavity comprising an interlock
chamber having a depth measured from the top surface equal to a
first distance, and a threaded chamber that includes threads and is
located below the interlock chamber, the chamber channel being
formed as a single continuous curve having substantially no
internal corners.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority and benefit under 35
U.S.C. .sctn.119(e) of U.S. Provisional Patent Application Ser. No.
60/156,198, filed Sep. 27, 1999.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to dental implants
and, more particularly, to an improved implant with an improved
internal interlock for supporting other dental implant components
with corresponding interlock structures.
[0004] 2. Description of the Related Art
[0005] Implant dentistry involves the restoration of one or more
teeth in a patient's mouth using artificial components. Such
artificial components typically include a dental implant and a
prosthetic tooth and/or a final abutment that is secured to the
dental implant. Generally, the process for restoring a tooth is
carried out in three stages.
[0006] Stage I involves implanting the dental implant into the bone
of a patient's jaw. The oral surgeon first accesses the patient's
jawbone through the patient's gum tissue and removes any remains of
the tooth to be replaced. Next, the specific site in the patient's
jaw where the implant will be anchored is widened by drilling
and/or reaming to accommodate the width of the dental implant to be
implanted. Then, the dental implant is inserted into the hole in
the jawbone, typically by screwing, although other techniques are
known for introducing the implant in the jawbone.
[0007] The implant itself is typically fabricated from pure
titanium or a titanium alloy. Such materials are known to produce
osseointegration of the fixture with the patient's jawbone. The
dental implant fixture also typically includes a hollow threaded
bore through at least a portion of its body and extending out
through its proximal end which is exposed through the crestal bone
for receiving and supporting the final tooth prosthesis and/or
various intermediate components or attachments.
[0008] After the implant is initially installed in the jawbone, a
temporary healing cap is secured over the exposed proximal end in
order to seal the internal bore. The patient's gums are then
sutured over the implant to allow the implant site to heal and to
allow desired osseointegration to occur. Complete osseointegration
typically takes anywhere from four to ten months.
[0009] During stage II, the surgeon reassesses the implant fixture
by making an incision through the patient's gum tissues. The
healing cap is then removed, exposing the proximal end of the
implant. Typically, an impression coping in attached to the implant
and a mold or impression is then taken of the patient's mouth to
accurately record the position and orientation of the implant
within the mouth. This is used to create a plaster model or
analogue of the mouth and/or the implant site and provides the
information needed to fabricate the prosthetic replacement tooth
and any required intermediate prosthetic components. Stage II is
typically completed by attaching to the implant a temporary healing
abutment or other transmucosal component to control the healing and
growth of the patient's gum tissue around the implant site.
[0010] Stage III involves fabricating and placement of a cosmetic
tooth prosthesis to the implant fixture. The plaster analogue
provides laboratory technicians with a model of the patient's
mouth, including the orientation of the implant fixture relative to
the surrounding teeth. Based on this model, the technician
constructs a final restoration. The final step in the restorative
process is replacing the temporary healing abutment with the final
restoration.
[0011] As mentioned above, the implant typically includes a hollow
threaded bore for receiving and supporting the final tooth
prosthesis and/or various intermediate components or attachments.
The implant also typically includes anti-rotational means, which
are typically located on the proximal end of the implant. These
anti-rotational means are designed to mate with corresponding
anti-rotational means formed on the various mating components
(e.g., a healing abutments and/or an impression coping). These
anti-rotational means primarily serve to prevent relative rotation
between the mating component and the implant.
[0012] Such anti-rotational/indexing means frequently take the form
of a hexagonal boss or recess ("hex") formed on the proximal
portion of the implant. For externally threaded implants, the hex
may also be used to engage a driving tool for driving the implant
into an internally threaded bore or osteotomy prepared in the
patient's jawbone (mandible or maxilla). When the implant is fully
installed in a patient's jawbone, the hex or other indexing means
is typically exposed through the crestal bone so that accurate
indexing may be provided between the implant and the final
prosthesis and/or various intermediate mating prosthetic
components.
SUMMARY OF TILE INVENTION
[0013] One aspect of the present invention includes the realization
that prior art anti-rotational means typically include sharp
corners. When the implant and mating component are subjected to a
rotational force, these sharp corners are subject to high
concentrations of stress. The high stress concentrations can cause
the sharp corners to chip or wear away. This can cause the
anti-rotational means to take on a circular shape, which reduces
the ability of the anti-rotational means to resist rotation. The
chipping or wearing away can also result in fitting errors between
the implant and the mating components. In some cases, the high
stress concentrations can also cause the implant to crack at or
near the corners of the anti-rotational means thereby shortening
the life of the implant.
[0014] Another aspect of the present invention includes the
realization that prior art anti-rotational means typically offer
little resistance to lateral forces. That is, prior art
anti-rotational means typically do not prevent the mating component
from "tipping" off the implant. Furthermore, prior art
anti-rotational means typically provide little or no tactile
feedback to the oral surgeon to indicate that the mating component
is properly seated in the implant.
[0015] Yet another aspect of the present invention is the
recognition that traditional anti-rotation means, such as a
hexagonal recess, are difficult to machine. Specifically, a special
reciprocating tool, such as a broach, typically must be used to
form a hexagonal recess.
[0016] Accordingly, it is a principle object and advantage of the
present invention to overcome some or all of the above-mentioned
limitations in the prior art. Thus, one aspect of the present
invention provides for a dental implant for supporting a dental
prosthesis comprises a body portion and a top surface. The implant
further comprises an internal cavity with an opening located at the
top surface. The internal cavity comprises an interlock chamber
having a depth measured from the top surface equal to a first
distance. The interlock chamber comprising a cylindrical portion
and plurality of semi-circular channels arranged around a periphery
of the cylindrical portion. A threaded chamber that includes
threads is located below the post-receiving chamber. The
cylindrical portion has a first radius and the channels have a
second radius, a ratio of the first radius to the second radius
being between approximately 4:1. and 2:1.
[0017] Another aspect of the present invention provides for a
prosthodontic assembly for installing a prosthetic tooth. The
prosthodontic assembly comprises a first prosthodontic component
and a second prosthodontic component. The first prosthodontic
component comprising a body portion and a top surface. The first
prosthodontic component further comprising an internal cavity with
an opening located at the top surface. The internal cavity
comprising an interlock chamber having a depth measured from the
top surface equal to a first distance. The interlock chamber
comprising a cylindrical portion with a plurality of semi-circular
channels arranged around a perimeter of the cylindrical portion. A
threaded chamber that includes threads is located below the
interlock chamber. The cylindrical portion has a first radius and
the channels have a second radius. A ratio of the first radius to
the second radius is between approximately 4:1. and 2:1. The second
prosthodontic component comprising an interlock area comprising a
plurality of semi-circular protrusions configured to mate with
channels of the first prosthodontic component.
[0018] Yet another aspect of the present invention provides for a
dental implant for supporting a dental prosthesis. The dental
implant comprising a body portion and a top surface. The implant
further comprising an internal cavity with an opening located at
the top surface. The internal cavity comprising an interlock
chamber having a depth measured from the top surface equal to a
first distance. A threaded chamber that includes threads and is
located below the post-receiving chamber. The interlock channel
being formed as a single continuos curve having substantially no
internal corners.
[0019] Still yet another aspect of the present invention provides
for a prosthodontic assembly for installing a prosthetic tooth. The
prosthodontic assembly comprises a first prosthodontic component
and a second prosthodontic component. The first prosthodontic
component comprising a body portion and a top surface. The first
prosthodontic component further comprising an internal cavity with
an opening located at the top surface. The internal cavity
comprising an interlock chamber having a depth measured from the
top surface equal to a first distance. The interlock chamber being
formed as a single continuos curve having substantially no internal
corners. A threaded chamber that includes threads is located below
the post-receiving chamber. The second prosthodontic component
comprising an interlock area having a shape that corresponds to the
shape of the interlock chamber.
[0020] For purposes of summarizing the invention and the advantages
achieved over the prior art, certain objects and advantages of the
invention have been described herein above. Of course, it is to be
understood that not necessarily all such objects or advantages may
be achieved in accordance with any particular embodiment of the
invention. Thus, for example, those skilled in the art will
recognize that the invention may be embodied or carried out in a
manner that achieves or optimizes one advantage or group of
advantages as taught herein without necessarily achieving other
objects or advantages as may be taught or suggested herein.
[0021] All of these embodiments are intended to be within the scope
of the invention herein disclosed. These and other embodiments of
the present invention will become readily apparent to those skilled
in the art from the following detailed description of the preferred
embodiments having reference to the attached figures, the invention
not being limited to any particular preferred embodiment(s)
disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] These and other features of this invention will now be
described with reference to the drawings of a preferred embodiment
which is intended to illustrate and not to limit the invention. The
drawings contain the following figures
[0023] FIG. 1A is a side view of a dental implant having certain
feature and advantages according to the present invention;
[0024] FIG. 1B is a top plan view of the dental implant of FIG.
1A;
[0025] FIG. 1C is a cross-sectional view of the dental implant of
FIG. 1A;
[0026] FIG. 1D-F are side views of the dental implant of FIG. 1A
inserted into a patient's jawbone at different depths;
[0027] FIG. 2A is a side view of an abutment having certain
features and advantages according to the present invention;
[0028] FIG. 2B is a detail view of the abutment of FIG. 2A;
[0029] FIG. 2C is a top plan view of the abutment of FIG. 2A;
[0030] FIG. 2D is a bottom plan view of the abutment of FIG.
2A;
[0031] FIG. 3A is a cross-sectional view of a coupling screw having
certain features and advantages according to the present
invention;
[0032] FIG. 3B is a top plan view of the coupling screw of FIG.
3A;
[0033] FIGS. 4A-C are schematic illustrations of preferred shapes
of the interlock regions of the dental implant of FIG. 1A and the
mating abutment of FIG. 2A;
[0034] FIG. 5A is a side view of a final abutment having certain
features, and advantages according to the present invention;
[0035] FIG. 5B is a front view of the final abutment of FIG.
4A;
[0036] FIG. 5C is a bottom plan view of the final abutment of FIG.
4A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0037] FIGS. 1A-1C illustrate a preferred embodiment of a dental
implant 10 having certain features and advantages in accordance
with the present invention. As will be explained below, the implant
10 is configured to receive and support one or more dental
attachments or components such as, for example, healing caps,
impression copings, temporary abutments, and permanent abutments.
The implant 10 is preferably made of a dental grade titanium alloy,
although other suitable materials can be used.
[0038] As best seen in FIG. 1A, the outer surface of the implant 10
preferably includes a body portion 12, a neck 14, and a collar 16.
The body portion 12 of the implant 10 is preferably tapered and
includes threads 18 that match preformed threads made along the
inner surface of the patient's jawbone (not shown). However, it
should be appreciated that the body portion 12 can be configured so
as to be self-tapping. It should also be appreciated that although
the illustrated body portion 12 is tapered or conical, the body
portion 12 could also be substantially cylindrical. Finally, the
body portion 12 could be unthreaded if the surgeon prefers to use
an unthreaded implant.
[0039] The body portion 12 of the implant 10 is also preferably
acid-etched. Acid-etching produces a rougher surface, which
increases the surface area of the body portion 12. The increased
surface area promotes osseointegration. Alternatively, the body
portion 12 of the implant can be coated with a substance that
increases the surface area of the body portion 12. Calcium
phosphate ceramics, such as tricalcium phosphate (TCP) and
hydroxyapatite (HA), are particularly suitable materials.
[0040] As best seen in FIG. 1C, the neck 14 lies between the body
portion 12 and the collar 16. The neck 14 preferably has a diameter
that is less than the diameter of the Collar 16. The collar 16 of
the implant is substantially cylindrical and has a top surface 24
that is substantially flat. The collar 16 is defined in part by a
vertical side wall 26 that is preferably greater than 1 millimeter
in length. In the preferred embodiment, the length of the collar is
approximately 2 millimeters.
[0041] The neck 14 and the collar 16 form a "variable placement
zone". The length and configuration the variable placement zone
allows for "variable positioning" of the dental implant 12. That
is, the surgeon can vary the height of the implant 10 with respect
to the crest of the jawbone. For example, as shown in FIG. 1F, the
implant 10 can be placed supra-crestally (i.e., the top surface 24
of the implant 10 is positioned above the crest 27 of the jawbone
29) without exposing the threads 18 of the body region 12. In this
arrangement the collar 16 extends through the gums and acts as the
temporary healing abutment thereby saving the surgeon and the
patient time and money by eliminating stage II surgery.
Alternatively, the surgeon can place the top surface 24 of the
implant 10 level with the alveolar crest (i.e., the tooth socket in
the jawbone) for esthetics (see FIG. 1E). In yet another
alternative arrangement, the surgeon can submerge the collar 16
into the jawbone such that the top surface 24 lies flush with the
crest of the jawbone (see FIG. 1D). In this arrangement, the
surgeon can utilize the standard three stage process described
above.
[0042] It should, however, be noted that several advantages of the
present invention can be achieved with an implant 10 that (i) does
not include a variable placement zone or (ii) includes variable
placement zone that is smaller or larger than the preferred
embodiment. For example, several advantages of the present
invention can be achieved with an implant without the neck 14
and/or the collar 16. Similarly, the neck 14 and/or collar 16 can
have dimensions that are smaller or larger than the illustrated
embodiment. However, the illustrated embodiment, with the neck
region 14 and collar 16, is preferred because it best allows for
the flexibility described above.
[0043] As best seen in FIG. 1C, the implant 10 includes an internal
socket 28. The socket 28 includes a threaded chamber 30 and an
interlock chamber 34. The threaded chamber 30 is threaded and
preferably has a diameter that is less than the interlock chamber
34.
[0044] With reference to FIGS. 1B and 1C, the interlock chamber 34
includes a substantially cylindrical portion 35. The interlock
chamber 34 also includes a plurality of channels 36, which prevent
the rotation of a dental component. Preferably, the interlock
chamber 34 includes three semi-circular channels 36, which are
arranged along the periphery of the cylindrical portion 35. Mote
preferably, each channel 36 is located approximately 120 degrees
apart from each other. The channels 36 preferably extend from the
top surface 24 to the bottom 37 of the cylindrical portion 35. That
is, the channels 36 have the same depth as the cylindrical portion
35.
[0045] The cylindrical portion 35 has a first radius R1 and the
semi-circular channels 36 have a second radius R2. The ratio
.alpha..sub.1 of the first radius R1 to the second radius R2
preferably is between 2:1 and 4:1. In the preferred embodiment the
ratio .alpha..sub.1 is about 3:1. This arrangement is preferred to
minimize the stress concentrations in the dental implant 10, as
will be explained below. To reduce stress concentrations further,
the interfaces 39 between the channels 36 and the cylindrical
portion 35 are preferably rounded.
[0046] The interlock chamber 34 is preferably dimensioned to be as
large as possible without significantly compromising the structural
integrity of the vertical side wall 26. This arrangement is
preferred because it increases the surface area of the interlock
chamber 34. The larger surface area results in a more stable
connection between the implant 10 and the mating dental component.
Accordingly, the interlock chamber 34 has a third radius R3, which
is approximately equal to the first radius R1 plus the second
radius R2. The third radius R3 is sized such that the thickness T1
(i.e., the radius R4 of the implant minus R3) of the vertical wall
26 is greater than a minimum value, which provides sufficient
structural integrity for the implant 10. For an implant made of
dental grade titanium alloy, the preferably minimum value is
approximately 0.4-0.8 millimeters. Another preferred aspect of the
shape of the interlock chamber 34 is the ratio between the radius
R4 of the implant 10 and the radius R2 of the channels 36. More
specifically, the ratio between the radius R4 of the implant and
the radius R2 of the channels 36 is preferably between 4:1 to 5:1.
In the preferred embodiment, the ratio is about 4.5:1.
[0047] The internal socket 28 also preferably includes a
post-receiving chamber 32, which lies between the interlock chamber
34 and the threaded chamber 30. The post-receiving chamber 32 is
preferably substantially cylindrical. The diameter of the
post-receiving chamber 32 is preferably less than the diameter of
the interlock chamber 34. The post-receiving chamber also
preferably includes a chamfered region 37, which is adjacent the
threaded chamber 30.
[0048] One aspect of the present invention is that the implant 10
provides significant resistance to lateral (i.e., "tipping")
forces. Accordingly, the interlock chamber 34 preferably has a
depth D1 as measured from the top surface 24 that is greater than
about 1 millimeter (see FIG. 1C). In the preferred embodiment, the
interlock chamber has a depth of approximately 1.5 millimeters.
Moreover, the post-receiving chamber 32 preferably has a depth D2
of greater than about 3 millimeters. In the preferred embodiment,
the post-receiving chamber has a depth of approximately 4.0
millimeters.
[0049] FIGS. 2A-2D illustrates a dental component configured to
mate with the implant 10 described above. The illustrated dental
component is an abutment 38. As will be explained below, the
abutment 38 can be formed into a variety of dental components, such
as, for example, a healing cap, impression coping, a temporary
healing abutment, and a final abutment. Preferably, the abutment 38
is made of dental grade titanium; however, other suitable materials
such as plastic can be used.
[0050] As best seen in FIG. 2A, the outer surface of the abutment
38 includes an upper region 40, a curved region 42, an interlock
region 44, and a post 46. In the illustrated embodiment, the upper
region 40 is substantially smooth, cylindrical and has a top
surface 48 that is substantially flat. The curved region 42
connects the upper region 40 to a bottom surface 50, which is
substantially flat.
[0051] The illustrated shape of the abutment 32 can be used as an
healing abutment, which is typically used during the second healing
period to shape the patient's gums. However, as mentioned above,
the abutment 38 can be modified or otherwise formed into many
different types of dental components. Therefore, it should be
appreciated that the upper and curved regions 40, 42 of the
abutment can be formed into any desirable shape.
[0052] As best seen in FIG. 2A, an inner bore 52 extends through
the center of the abutment 38. The inner bore 52 is preferably
divided into a first and second region 54, 56. The first region 54
has a diameter that is slightly larger than the diameter of the
second region 56. Accordingly, a seat 59 is formed between the
first and second regions 54, 56. The seat 59 supports a bolt 60
(see FIG. 3A), which will be described below. The second region 56
preferably includes internal capture threads 62 that are preferably
double threaded.
[0053] With continued reference to FIG. 2A, the bottom surface 50
is substantially flat and has a diameter approximately equal to the
diameter of the top surface 24 of the implant 10. Extending from
the bottom surface 50 is the interlock region 44, which is
configured to fit within the interlock chamber 34 of the implant
10. Accordingly, as best seen in FIGS. 2B and 2D, the interlock
area 38 includes a substantially cylindrical portion 63. The
interlock area 38 also includes protrusions 64, which are
configured to fit within the channels 36 of the implant.
Accordingly, in the preferred embodiment, the protrusions 64 are
arranged around the perimeter of the interlock area at
approximately 120 degrees.
[0054] Below the interlock area 44 is the post 46. The post 46 is
preferably substantially cylindrical and is configured to fit
within the post-receiving chamber 32 of the implant.
[0055] Turning now to FIGS. 3A and 3B, the coupling screw 60
mechanically couples the abutment 38 to the implant 10. The
coupling screw 60 is also preferably made of a dental grade
titanium alloy; although other suitable materials can be used. The
coupling screw 60 is sized and dimensioned to extend through the
inner bore 52 of the blank abutment 38 and into the socket 28 of
the implant 10. The coupling screw 60 has an externally, threaded
lower region 68 that passes through the internal capture threads 62
of the abutment 38 and engages the threaded chamber 30 of the
implant 10. The threads 68 of coupling screw 60 engage the capture
threads 62 so that the coupling screw 60 does not become
disassociated as the abutment 38 is transferred and fitted to the
patient's mouth.
[0056] The coupling screw also preferably includes a hexagonal
recess 70 located on a top surface 72 of the screw 60. The
hexagonal recess 70 allows for the insertion of a hexagonally
shaped tool such as a conventional Allen.RTM. wrench to remove the
coupling screw 60 from the implant body 10.
[0057] As mentioned above, during stage I surgery, the dental
implant 10 is typically inserted into a pre-made hole formed in the
patient's jawbone. A driving tool (not shown) is typically used to
screw the implant into the pre-Made hole. Accordingly, a distal end
of the driving tool is preferably configured to mate with the
interlock chamber 34 of the implant 10. That is, the distal end of
the driver is preferably configured substantially the same as the
interlock region 44 of the abutment 38 described above. When the
driving tool is mated to the implant, the distal end of driver can
be used to transmit torque to the implant through the interlock
chamber 34 so as to drive the implant 10 into the pre-made hole. If
the implant 10 is self-tapping, a particularly large amount of
torque is required to drive the implant 10 into the bone. For,
conventional implants with hexagonal recesses, this large amount of
torque can cause the implant to crack at the apexes of the
hexagonal recesses. This reduces the strength of the implant and
can cause fluids and bacteria to enter the implant.
[0058] An advantage of the illustrated implant 10 and mating
abutment 38 is that when subjected to rotational forces the stress
concentrations in the implant 10 and the abutment 38 are minimized.
Stress concentrations refer to areas of large stress caused by
geometric discontinuities (i.e., stress risers) and/or the
application of large loads over a small area or at a point (e.g.,
at a corner or apex). Areas of large stress concentrations are
often the starting point of material damage, which can ultimately
lead to material failure by fracture (i.e., cracking). Thus, by
minimizing stress concentrations, the durability of the implant 10
and the abutment 38 can be increase. The reduction in stress
concentration derives from the particular preferred shape of the
interlock chamber 34 of the implant 10 and the mating interlock
region 44 of the abutment 38.
[0059] FIGS. 4A-C are schematic representations of the shape 78 of
the interlock chamber 34 and the interlock region 44. FIG. 4A
compares the shape 78 to a triangle 79. As seen in FIG. 4A, the
shape 78 of the interlock region is in, the form of an elliptically
modified triangle 79. That is, the apexes and sides of the triangle
are substantially rounded. As shown in FIGS. 4B and 4C, the shape
78 provides a smooth transition from the apex 82 to the sides 80.
Accordingly, some of the anti-rotational stress is distributed away
from the apexes 82 towards the relatively flatter side walls 80.
These features help to reduce stress concentrations. Therefore, the
interlock regions 34, 44 of the implant 10 and the blank abutment
38 (particularly the channels 36 and the protrusions 64 are less
likely to chip and wear away as compared to prior art
anti-rotational means. Moreover, the implant 10 is less likely to
crack as compare to implants with hexagonal recesses, which tend to
crank at the apexes of the hexagonal recess when subjected to large
rotational loads (e.g., when a self-tapping implant is being
threaded into the patient's jawbone).
[0060] Another advantage of the illustrated arrangement is that the
abutment 38 and the implant 10 offer improved resistance to lateral
or "tipping" forces. This improved resistance to lateral forces is
due primarily to the depth of the interlock chamber 34 and the
post-receiving chamber 32. The improved resistance to lateral
forces also prevents the Coupling screw 60 from loosening, thereby
virtually eliminating movement between the implant 10 and the
abutment 38.
[0061] Yet another advantage of the illustrated arrangement is that
the interlock chamber of the implant 10 can be machined using a
conventional end mill. That is, because of circular shape of the
cylindrical portion 35, it can be machined with a conventional end
mill. Moreover, the semi-circular channels can also be machined
with a conventional end mill. This reduces the complexity of
manufacturing especially as compared to the machining of a
conventional hexagonal recess, which typically requires a
reciprocating tool, such as, for example, a broach.
[0062] The illustrated arrangement of the implant 10 and abutment
38 also provides improved tactile confirmation that the blank
abutment 38 is properly seated on the implant 10. That is because
of the depth of the post-receiving chamber 32, the oral surgeon can
feel the abutment 38 engaging the implant 10. This tactile
confirmation is especially important for posterior prosthetics
where visibility and working space are often compromised.
[0063] FIGS. 5A-5C illustrate a final abutment 86 having certain
features and advantages according to the present invention. The
final abutment 86 is preferably made from a dental grade titanium
allow, although other suitable materials can be use. The final
abutment 86 can alai be machined from the abutment 38 of FIGS.
2A-2D.
[0064] The lower region 87 of the final abutment 86 is
substantially identical to the lower region of the blank abutment
38 described above. Accordingly, the lower region 87 comprises a
lower surface 50, an interlock region 44 with protrusions 64, and a
post 46. As with the blank abutment 38, the interlock region 44
with protrusions 64, and the post 46 that are sized and dimensioned
to fit within the interlock chamber 34 and post-receiving chamber
32 of the implant 10.
[0065] Down the center of the final abutment 54 is an bore 48. The
inner bore 48 is preferably divided into two regions: a first
chamber 50 and a second region 52. Preferably, the diameter of the
first chamber 50 is slightly larger than the second chamber 52. A
screw passes through the screw receiving chamber 50 and engages the
threads of the threaded region 52 and the first chamber 22 of the
implant 10. Accordingly, the final abutment 54 can be permanently
attached to the implant. Alternatively, the final abutment 54 could
be cemented to the implant 10 using methods well known in art.
[0066] The upper surface 88 of the final abutment 86 is formed to
receive a prosthetic tooth. Accordingly, the prosthetic tooth (not
shown) has an inner surface configured such that the prosthetic
tooth can fit over the final abutment 86. The prosthetic tooth is
typically cemented to the final abutment 86.
[0067] Although this invention has been disclosed in the context of
certain preferred embodiments and examples, it will be understood
by those skilled in the art that the present invention extends
beyond the specifically disclosed embodiments to other alternative
embodiments and/or uses of the invention and obvious modifications
and equivalents thereof. In addition, while a number of variations
of the invention have been shown and described in detail, other
modifications, which are within the scope of this invention, will
be readily apparent to those of skill in the art based upon this
disclosure. It is also contemplated that various combination or
subcombinations of the specific features and aspects of the
embodiments may be made and still fall within the scope of the
invention. Accordingly, it should be understood that various
features and aspects of the disclosed embodiments can be combine
with or substituted for one another in order to form varying modes
of the disclosed invention. Thus, it is intended that the scope of
the present invention herein disclosed should not be limited by the
particular disclosed embodiments described above, but should be
determined only by a fair reading of the claims that follow.
* * * * *