U.S. patent application number 11/716441 was filed with the patent office on 2007-11-01 for dental implant.
This patent application is currently assigned to Perioseal, Inc.. Invention is credited to Donald P. Callan.
Application Number | 20070254265 11/716441 |
Document ID | / |
Family ID | 38648721 |
Filed Date | 2007-11-01 |
United States Patent
Application |
20070254265 |
Kind Code |
A1 |
Callan; Donald P. |
November 1, 2007 |
Dental implant
Abstract
A dental prosthesis comprises an implant, an abutment and a
crown. The implant has distal and proximal portions with the
implant proximal portion including distal and proximal segments.
The implant proximal segment has an outer surface. The abutment has
distal and proximal segments and defines an abutment shoulder
therebetween. The abutment shoulder is configured to
circumferentially engage the outer surface of the implant proximal
segment such that an implant abutment joint is defined
therebetween. The crown is configured to be positioned over the
abutment and the implant such that the crown covers the implant
abutment joint. The implant proximal segment has an annular concave
cross-section such that the crown distal end has a rounded shape to
reduce the potential for stress cracking of the crown.
Inventors: |
Callan; Donald P.; (Little
Rock, AR) |
Correspondence
Address: |
STETINA BRUNDA GARRED & BRUCKER
75 ENTERPRISE, SUITE 250
ALISO VIEJO
CA
92656
US
|
Assignee: |
Perioseal, Inc.
|
Family ID: |
38648721 |
Appl. No.: |
11/716441 |
Filed: |
March 9, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60795876 |
Apr 28, 2006 |
|
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Current U.S.
Class: |
433/174 |
Current CPC
Class: |
A61C 8/0048 20130101;
A61C 8/005 20130101; A61C 8/0054 20130101; A61C 8/006 20130101 |
Class at
Publication: |
433/174 |
International
Class: |
A61C 8/00 20060101
A61C008/00 |
Claims
1. A dental prosthesis, comprising: an implant having distal and
proximal portions, the implant proximal portion including distal
and proximal segments, the implant proximal segment having an outer
surface; an abutment having distal and proximal ends defining an
abutment shoulder therebetween, the abutment shoulder being
configured to circumferentially engage the outer surface of the
implant proximal segment such that an implant abutment joint is
defined therebetween; and a crown configured to be positioned over
the abutment and the implant such that the crown covers the implant
abutment joint.
2. The dental prosthesis of claim 1 wherein: the outer surface of
the implant proximal segment is tapered; the abutment including an
abutment cavity formed complementary to the outer surface to
facilitate circumferential engagement of the abutment shoulder to
the outer surface.
3. The dental prosthesis of claim 2 wherein the tapered outer
surface is conically shaped and having a half angle of about 45
degrees.
4. The dental prosthesis of claim 1 wherein the implant distal
segment is cylindrically shaped.
5. The dental prosthesis of claim 1 wherein the implant distal
segment defines a circumferential undercut between the implant
distal portion and the implant proximal segment.
6. The dental prosthesis of claim 5 wherein the undercut has an
arcuately shaped cross section.
7. The dental prosthesis of claim 1 wherein the abutment has an
abutment neck disposed adjacent the abutment distal end, the
abutment neck having a reduced cross section in an axial
direction.
8. The dental prosthesis of claim 1 wherein: the crown includes a
crown distal portion defining a crown distal end having a crown
cavity formed therein; the crown cavity being configured
complementary to the abutment proximal segment such that the crown
distal end circumferentially engages the implant proximal
segment.
9. The dental prosthesis of claim 1 wherein: the receipt of the
abutment proximal portion and the abutment proximal segment into
the crown cavity resulting in the engagement of the crown distal
portion to the outer surface of the implant proximal segment such
that the crown implant joint is defined therebetween; the implant
abutment joint being covered by the crown distal portion; a layer
of adhesive being disposed between the implant proximal segment and
the crown cavity at the crown implant joint.
10. The dental prosthesis of claim 1 wherein: implant proximal
portion defines an implant proximal end having an implant aperture
disposed therein; the abutment includes abutment proximal and
distal portions, the abutment distal portion being configured to be
insertable into the implant aperture.
11. The dental prosthesis of claim 1 wherein the abutment proximal
portion has a frusto-conical outer surface.
12. The dental prosthesis of claim 1 wherein the implant proximal
segment has a concave cross section.
13. The dental prosthesis of claim 12 wherein: the implant proximal
segment is defined by upper and lower conical surfaces; the lower
conical surface extending upwardly from the prosthetic margin and
having a half angle of up to about 45 degrees; the upper conical
surface extending downwardly from the implant proximal end and
having a half angle of up to about 5 degrees; a radius being formed
between the upper and lower conical surfaces.
14. The dental prosthesis of claim 13 wherein: the implant proximal
segment has a height of about 1 millimeter (mm); the upper conical
surface intersecting the radius at a tangent thereof; the concave
cross section being configured such that the tangent is offset
radially inwardly from the prosthetic margin by about 0.2 mm to
about 1 mm.
15. A dental prosthesis, comprising: an implant having distal and
proximal portions, the implant proximal portion including distal
and proximal segments, the implant distal segment defining a
circumferential undercut between the implant distal portion and the
implant proximal segment, the implant proximal segment having an
implant proximal end; an abutment having abutment distal and
proximal ends and defining an abutment shoulder formed
therebetween, the abutment shoulder being configured to directly
engage the implant proximal end such that an implant abutment joint
is defined therebetween; and a crown configured to be positioned
over the abutment and the implant such that the crown covers the
implant abutment joint.
16. The dental prosthesis of claim 15 wherein the undercut has an
arcuately shaped cross section.
17. A dental prosthesis, comprising: an implant having distal and
proximal portions, the implant proximal portion including distal
and proximal segments, the proximal segment having a concave cross
section, the implant proximal segment having an implant proximal
end; an abutment having abutment distal and proximal ends and
defining an abutment shoulder formed therebetween, the abutment
shoulder being configured to directly engage the implant proximal
end such that an implant abutment joint is defined therebetween;
and a crown configured to be positioned over the abutment and the
implant such that the crown covers the implant abutment joint.
18. The dental prosthesis of claim 17 wherein: the proximal segment
is defined by upper and lower conical surfaces; the lower conical
surface extending upwardly from the prosthetic margin and having a
half angle of up to about 45 degrees; the upper conical surface
extending downwardly from the implant proximal end and having a
half angle of up to about 5 degrees; a radius being formed between
the upper and lower conical surfaces.
19. The dental prosthesis of claim 18 wherein: the upper segment
has a height of about 1 mm; the upper conical surface intersecting
the radius at a tangent; the concave cross section being configured
such that the tangent is offset radially inwardly from the
prosthetic margin by about 0.2 mm to about 1 mm.
20. The dental prosthesis of claim 19 wherein: the crown includes a
crown distal portion defining a crown distal end having a crown
cavity formed therein the crown cavity being configured
complementary to the abutment proximal segment such that the crown
distal end circumferentially engages the implant proximal segment.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 60/795,876, filed on Apr. 28, 2006 and
entitled DENTAL IMPLANT, the entire contents of which is expressly
incorporated by reference herein.
STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT
[0002] (Not Applicable)
BACKGROUND
[0003] The present invention relates generally to dental prostheses
and, more particularly, to a dental prosthesis including an
implant, an abutment which is attachable to the implant, and a
crown which is attachable to the abutment and the implant such that
the joint defined between the abutment and the implant is covered
and effectively sealed.
[0004] As is well known in the art, dental prostheses are commonly
used in the dental field to address extensive damage to teeth
caused by injury or disease. A typical dental prosthesis comprises
an implant, an abutment and a crown. The implant itself generally
comprises a metallic component which is implanted or embedded into
the bony structure of a patient's mouth subsequent to the removal
of the damaged tooth alone or in combination with one or more
adjacent teeth. The installation of the implant is typically
initiated by forming a hole in the bony structure and then
embedding the implant into the bony structure by screwing the
implant into the hole via threads formed on an exterior of the
implant.
[0005] After the implant has been embedded into the bony structure,
the bone normally recovers and grows around the implant, thus
resulting in bone/implant integration. To enhance the integration
of the implant into the bone, the implant may be coated with a
surface finish such as etched titanium and/or a biocompatible
coating such as hydroxylapatite (HA). Subsequent to the embedding
of the implant into the bony structure, the abutment is attached to
the implant. Such attachment may be accomplished through the use of
a cement, by the engagement of complementary male and female
threads formed on or in the abutment and implant, or by the mating
of corresponding tapers or other geometries formed on or in the
abutment and implant.
[0006] When attached to the implant, a portion of the abutment
extends above the gum line of the patient for purposes of
facilitating attachment of the crown to the implant. If the implant
is embedded into the bony structure such that the implant is
completely disposed below or submerged within the gum line of the
patient, the attachment of the abutment to the implant requires a
second surgical procedure for purposes of accessing the implant.
However, if the implant is embedded into the bony structure in a
manner wherein a portion thereof protrudes above the patient's gum
line, then the attachment of the abutment may be accomplished
without the need for the second surgical procedure, thus requiring
only the initial surgical procedure to complete the implantation or
embedding process.
[0007] As was previously indicated, the crown of the dental
prosthesis is attached to that portion of the abutment which
extends above the patient's gum line. In the prior art, crowns are
fabricated and installed in accordance with well-established
procedures which include taking a transfer impression of the
exposed portion of the abutment to establish with precision its
configuration and orientation, thus insuring a complete attachment
of the crown thereto. The exposed portion of the abutment to which
the crown is attached may have the natural form of a prepared
tooth, or an artificial form of a particular geometry adapted to
achieve a secure attachment of the crown. The attachment of the
crown to the abutment is typically accomplished through the use of
an adhesive and/or cement, or through the engagement of
corresponding male and female threads on or in the crown and
abutment to each other. The attachment of the crown to the abutment
completes the assembly of the dental prosthesis.
[0008] As will be recognized from the aforementioned description of
the dental prosthesis, the assembly thereof results in the
formation of several joints. These joints include the joint formed
by the attachment of the crown to the abutment, and the joint
formed by the attachment of the abutment to the implant. Of these
joints, that joint considered most important in relation to the
long-term viability of the prosthesis is the joint between the
implant and the abutment which is commonly referred to as the
implant abutment joint or "IAJ".
[0009] Recent research in the dental field has suggested that the
IAJ plays a key role in bone loss around the implant. Though such
bone loss has not been well studied or well documented, it is
believed to be a common occurrence which is at least partially
attributable to the IAJ serving as a site for bacterial invasion
and colonization. Over time, such bone loss can compromise the
integrity of the implant or cause its failure by breaking loose
from the bony structure into which the implant is embedded.
[0010] Obviously, such failure, in addition to providing
inconvenience and discomfort for the patient, is of serious medical
concern due to the resulting bone loss or mutilation potentially
rendering the installation of a replacement implant difficult or
impossible. The joint formed by the attachment of the crown to the
abutment is also susceptible to bacterial invasion which
contributes to bone loss around the implant.
[0011] The present invention addresses the susceptibility of the
IAJ and the crown/abutment joint to bacterial infestation by
providing a dental prosthesis which is configured to effectively
cover and seal these joints. In addition, the dental prosthesis of
the present invention also prevents micro-movement between the
abutment and the implant at the IAJ which, under the forces of
mastication (i.e., chewing), can result in the development of
micro-gaps at the IAJ. Such micro-gaps can harbor bacteria which
can lead to inflammation and, ultimately, failure of the
implant.
BRIEF SUMMARY
[0012] Provided is a dental prosthesis which comprises an implant,
an abutment and a crown. The implant is adapted to be embedded into
the bony structure of a patient's mouth. The abutment is attached
to the implant in a manner wherein an implant abutment joint is
defined therebetween. The crown is attached to the abutment and the
implant in a manner wherein the implant abutment joint is covered
by the crown. The attachment of the crown to the abutment and
implant may be facilitated through the use of adhesive (e.g.,
dental cement) extending between the crown and the implant (i.e.,
crown implant joint).
[0013] The adhesive within the crown implant joint effectively
seals the implant abutment joint as well as protects the crown
implant joint. More particularly, the adhesive isolates such joints
from the gum line in the patient in order to prevent migration of
bacteria into the joints. The implant has distal and proximal
portions with the implant proximal portion including distal and
proximal segments. The implant proximal segment includes an outer
surface. The abutment also has distal and proximal portions with
distal and proximal ends being disposed respectively adjacent
thereto. The abutment distal and proximal portions define an
abutment shoulder therebetween.
[0014] Importantly, the abutment shoulder is configured to
circumferentially engage the outer surface of the implant proximal
segment with increased joint surface area which thereby improves
joint strength. In addition, the circumferential engagement between
the abutment shoulder and the implant provides improved resistance
to micro-movement of the abutment relative to the implant. The
elimination of such micro-movement reduces the risk of cracking of
the adhesive and also minimizes the development of micro-gapping at
the joint which, in turn, reduces the potential for periodontal
pathogens. The implant abutment joint and the crown implant joint
are sealed from bacterial invasion due to the positioning of the
crown over the abutment and implant.
[0015] The implant may be comprised of an elongate, externally
threaded implant distal portion which is insertable into the bony
structure of the patient's mouth. The implant proximal portion
itself includes distal and proximal segments. The implant distal
segment may have a generally cylindrical outer surface or it may be
circumferentially undercut. The circumferential undercut which
defines the implant distal segment interconnects the implant distal
portion to the implant proximal segment. The implant proximal
segment may have an outer surface which may be tapered or
concave.
[0016] If tapered, the implant proximal segment is preferably
conically shaped at an angle of about 45.degree. although other
angles are contemplated. More preferably, the implant proximal
segment is formed at an angle of less than about 45.degree. and
greater than about 3.degree. relative to an axis of the implant. If
concave, the implant proximal segment may itself include conical
portions which interface with the crown and are therefore
preferably formed at the above-mentioned half-angles of between
about 45.degree. and 3.degree. to avoid cracking of adhesive
between the crown and implant while eliminating the need for
overly-tight manufacturing tolerances which increase manufacturing
costs.
[0017] The abutment may include an abutment cavity formed in the
abutment proximal portion adjacent to the abutment shoulder.
Preferably, the abutment cavity is formed complementary to the
outer surface of the implant proximal segment in order to
facilitate the circumferential engagement of the abutment shoulder
to the outer surface. The abutment proximal portion engages the
outer surface of the implant proximal segment at a lower end of the
abutment proximal portion. Additionally, it is contemplated that
the abutment cavity may be configured to engage the outer surface
of the implant proximal segment in surface-to-surface or
edge-to-surface contact therebetween.
[0018] The abutment distal portion defines an abutment shaft.
Extending axially within the implant proximal end is an implant
bore which is sized and configured to receive the abutment shaft.
In one embodiment, the implant bore may have a generally circular
cross-sectional configuration with the abutment shaft being of
complementary cylindrical configuration although other
configurations are contemplated. The abutment distal portion or
abutment shaft may be advanced into the implant bore and may be
secured therewithin through the use of adhesive.
[0019] Alternatively, the implant bore may be internally threaded
with the abutment distal portion or abutment shaft being externally
threaded to facilitate threadable engagement therebetween. The
abutment proximal portion may have a frusto-conically shaped outer
surface such that the abutment forms a truncated cone. The abutment
may optionally include an abutment neck formed adjacent the
abutment shoulder and which has a generally reduced cross-sectional
area in an axial orientation as compared to the cross-sectional
configuration of the immediately adjacent portions of the abutment.
Advantageously, the abutment neck minimizes the overall size of the
abutment while still providing a configuration which may
effectively engage the outer surface of the implant proximal
segment.
[0020] The crown of the dental prosthesis includes a crown distal
portion which itself defines a crown distal end having a crown
cavity disposed therewithin. The crown cavity has a shape which is
complementary to the outer surface of the abutment proximal portion
as well as the outer surface of the implant proximal segment.
Receipt of the abutment proximal portion and implant proximal
segment into the crown cavity results in engagement of the crown
distal portion to the implant proximal segment via direct contact
therebetween. In this manner, the implant abutment joint defined
between the abutment proximal portion and the implant proximal end
is covered and may be thereafter sealed through the use of
adhesive.
[0021] In a further embodiment, the implant proximal segment may
have a generally circumferential or annular concave cross-section
such that the crown distal end can be provided with a complementary
rounded or blunt circumferential edge instead of a less desirable
circumferential knife edge configuration. The rounded shape of the
crown distal end provides increased surface to more uniformly
distribute occlusal forces applied to the joint.
[0022] As was mentioned above, such occlusal forces are typically
the result of mastication (i.e., chewing) and are transmitted in an
axial direction from the crown to the implant. The uniform
distribution of the occlusal forces at the crown distal end reduces
the susceptibility of a failure of the crown distal end due to
overstressing and cracking. In addition, formation of the concave
cross-section on the implant proximal segment may further reduce
the loads placed on the adhesive which may lead to the failure of
the adhesive joint between the crown distal end and the implant
proximal segment.
[0023] Further, in accordance with the dental prosthesis, there is
provided a method of installing the dental prosthesis into a
patient comprising the initial step of drilling a hole into the
bony structure of the patient's mouth or oral cavity. Thereafter,
the implant of the dental prosthesis may be threaded into the hole
in the bony structure. The abutment may then be attached to the
implant in a manner wherein the implant abutment joint is defined
between the abutment and the implant.
[0024] The layer of adhesive may be applied to exposed portions of
the abutment and the implant which interface with the crown cavity.
The crown may then be attached to the abutment and the implant in a
manner wherein the implant abutment joint is covered by the crown.
The flow of adhesive between the crown and the implant seals the
implant abutment joint as well as the joint between the crown and
the implant. The abutment may be joined to the implant through the
use of the adhesive and/or via threadable engagement.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] These and other features and advantages of the various
embodiments disclosed herein will be better understood with respect
to the following description and drawings in which like numbers
refer to like parts throughout and in which:
[0026] FIG. 1 is an exploded perspective view of a dental
prosthesis constructed in accordance with an embodiment and
illustrating an implant, an abutment and a crown of the dental
prosthesis;
[0027] FIG. 2 is a perspective view of the dental prosthesis of
FIG. 1 in an assembled state;
[0028] FIG. 3 is a cross-sectional partial view of the dental
prosthesis and illustrating an implant proximal segment and
circumferentially engaging with an abutment shoulder and further
illustrating the crown being positioned over the abutment and
implant and covering an implant abutment joint;
[0029] FIG. 4 is a cross-sectional view of the dental prosthesis
which is substantially similar to that shown in FIG. 3 but
illustrating an implant distal segment having an undercut
configuration generally configured as a continuous radius;
[0030] FIG. 5 is a cross-sectional view of the dental prosthesis in
a configuration similar to FIG. 4 but illustrating the undercut
configured as a short conical portion transitioning into an implant
body via a circumferential radius;
[0031] FIG. 6 is a cross-sectional view of the dental prosthesis
substantially similar to that which is shown in FIGS. 3 and 4 but
omitting an abutment neck of the abutment;
[0032] FIG. 7 is a cross-sectional view of the dental prosthesis
substantially similar to that shown in FIG. 6 but including the
configuration of the implant having the undercut as shown in FIG.
4;
[0033] FIG. 8 is a cross-sectional view of the dental prosthesis
and illustrating the implant proximal segment having a concave
cross-section;
[0034] FIG. 8a is an enlarged cross-sectional view of the dental
prosthesis illustrating the implant abutment joint;
[0035] FIG. 9 is a cross-sectional view of the dental prosthesis
substantially similar to that which is shown in FIG. 8 but
including the configuration of the implant having the undercut as
shown in FIG. 4;
[0036] FIG. 9a is an enlarged cross-sectional view of the abutment
of FIG. 9;
[0037] FIG. 10 is a cross-sectional view of the dental prosthesis
and which is configured substantially similar to that shown in FIG.
4 but wherein the abutment shoulder is configured to directly
engage a top portion of the implant;
[0038] FIG. 10a is an enlarged cross-sectional view of the dental
prosthesis of FIG. 10 and illustrating the configuration of the
abutment; and
[0039] FIG. 11 is a cross-sectional view substantially similar to
that shown in FIG. 10 but which includes the configuration of the
implant as shown in FIG. 8.
DETAILED DESCRIPTION
[0040] Referring now to the drawings wherein the showings are for
purposes of illustrating various embodiments of the present
invention only and not for purposes of limiting the same, FIGS.
1-11 depict a dental prosthesis 10 which, in its broadest sense,
comprises an implant 20, an abutment 50 and a crown 80. The implant
20 is adapted to be embedded into the bony structure of a patient's
mouth or oral cavity. The implant 20 itself includes an elongate
implant distal portion 26 which defines an implant distal end 22.
The implant distal portion 26 may be further divided into an
implant body 32 and an implant trunk 31. The implant distal portion
26 may further include external threads 33 formed on the implant
body 32 which are preferably configured to be threadably engaged to
the bony structure.
[0041] The implant 20 may further include an implant neck or
implant proximal portion 28. As can be seen in the figures, the
implant proximal portion 28 is separated from the implant trunk 31
by an annular implant shoulder 30. Depending on the specific
configuration of the implant proximal portion 28, the
cross-sectional area of the implant proximal portion 28 may
slightly exceed the cross-sectional area of the implant trunk 31
resulting in the formation of the annular implant shoulder 30
therebetween. As was earlier mentioned, the implant trunk 31 is
disposed above the implant body 32 and serves as the portion of the
implant 20 that connects the implant body 32 to the implant
proximal portion 28.
[0042] The implant proximal portion 28 itself may be comprised of
an implant distal segment 37 and an implant proximal segment 34.
The implant distal and proximal segments 37, 34 converge at a
prosthetic margin 40. The implant proximal portion 28 further
defines an implant proximal end 24 which may include an implant
bore 42 formed therewithin. The implant bore 42 may have a variety
of axial cross-sectional configurations such as hexagonal and/or
cylindrical cross-sections and is generally configured to extend
axially at least partially through the implant proximal portion 28
and into the implant distal portion 26. As can be seen in the
figures, the implant bore 42 may extend to approximately the
mid-point of the implant distal portion 26.
[0043] The implant 20 may be fabricated from a metallic material
which is preferably a biocompatible material such as titanium or
other suitable materials. Additionally, certain areas of the
implant 20 such as the implant distal portion 26 may be coated with
hydroxylapitite (HA) or other suitable biocompatible materials in
order to assist in the integration of the implant 20 to the bony
structure of the patient's mouth. Additionally, the implant distal
portion 26 may be etched with a suitable acid or other solution.
The implant 20 may be provided in a wide variety of sizes to
accommodate dental structures of the patient. In this regard, the
implant 20 may be provided in a diameter of between about 3.5
millimeter (mm) to about 6.0 mm although other sizes are
contemplated to fit different patients. Likewise, the implant 20
may be provided in a variety of lengths such as from about 10 mm to
about 16 mm although longer and shorter lengths are
contemplated.
[0044] The dental prosthesis 10 further includes the abutment 50
which may be attached to the implant 20 in a manner to be described
in greater detail below. The abutment 50 itself may comprise an
elongate, cylindrically configured, shaft-like abutment distal
portion 56 and an abutment proximal portion 58. The abutment
proximal portion 58 may have a frusto-conical outer surface. As
such, the abutment proximal portion 58 may take the form of a
truncated cone although other shapes are contemplated. In the
dental prosthesis 10, the abutment distal portion 56 is preferably
sized and configured as an abutment shaft 66 such that an outer
surface thereof is configured complementary to the implant bore 42.
More specifically, the abutment shaft 66 may be provided with a
cylindrical shape having an outer diameter that is slightly less
than that of the implant bore 42.
[0045] Adhesive 100 may be applied to the abutment distal portion
56 prior to its advancement into the implant bore 42. Alternatively
or in combination therewith, adhesive 100 may be injected into the
implant bore 42 prior to the insertion of the abutment distal
portion 56 thereinto. The implant bore 42 may be sized and
configured to provide a gap between an abutment distal end 52 and a
bottom of the implant bore 42 such that adhesive 100 may accumulate
and harden, thereby strengthening the bond between the abutment 50
and the implant 20. As can be seen, the advancement of the abutment
distal portion 56 into the implant bore 42 is terminated by the
engagement of the abutment proximal portion 58 to the implant
proximal end 24 (i.e., by direct contact therebetween) and forming
the implant abutment joint 44.
[0046] As will be described in greater detail below, the unique
geometries of the implant proximal portion 28 in combination with
the geometry of the abutment distal end 52 results in an improved
interface at the implant abutment joint 44. As was earlier
mentioned, the implant abutment joint 44 is specifically configured
to prevent or reduce micro-movement between the abutment 50 and
implant 20 which, in turn, prevents micro-movement between the
crown 80 and the implant 20. Such micro-movement is typically the
result of forces of mastication in an occlusal or axial direction
(i.e. parallel to the implant longitudinal axis). Over time, such
micro-movement may result in micro-gapping between the crown 80 and
tooth which may cause the adhesive 100 to crack under the load and
which may then allow the harboring of bacteria in the joints of the
dental prosthesis 10 and the premature failure thereof in addition
to formation of periodontal pathogens.
[0047] Advantageously, the dental prosthesis 10, in at least one
embodiment, is uniquely configured to provide circumferential
engagement of the abutment distal end 52 to the implant proximal
segment 34 to prevent micro-movement therebetween. As was earlier
mentioned, such circumferential engagement of the abutment distal
end 52 to the implant proximal segment 34 provides for a more
uniform and even distribution of occlusal forces that are exerted
by the crown 80 upon the implant 20. Such forces on the crown 80
are transmitted to the abutment 50 and to the implant 20 at
respective ones of the implant abutment joint 44 and the crown
implant joint.
[0048] More particularly, the circumferential engagement of the
abutment 50 to the implant 20 provides greater surface area of
engagement between the implant 20 and the abutment 50 which
increases its resistance to micro-movement therebetween. In
addition, the configuration of the crown implant joint allows for a
reduction in the force per unit area. The reduced force per unit
area reduces susceptibility of adhesive 100 failure (i.e., cracking
of the adhesive 100) between the crown 80 and the implant 20 such
as may occur due to overloading of the adhesive 100 bond over time.
Furthermore, the circumferential engagement of the abutment distal
end 52 to the implant proximal segment 34 reduces stress cracking
of the crown 80 at its crown distal end 82 in direct contact with
the implant 20.
[0049] As can be seen in the figures, due to the configuration of
an outer surface of the implant proximal segment 34 and the
complementary mating surfaces of the abutment proximal portion 58,
when the abutment 50 is attached to the implant 20 in the
above-described manner, the abutment 50 is generally in continuous
circumferential engagement such that outer surfaces thereof are in
flush relationship to one another.
[0050] The dental prosthesis 10 further comprises the crown 80
which is preferably fabricated from an inert biocompatible material
such as ceramic and/or metal and is preferably configured in a
desired exterior surface configuration in a manner known in the
art. The crown 80 includes a crown distal portion 86 which defines
the crown distal end 82. Disposed within the crown distal end 82 is
a crown cavity 90 which is configured complementary to the abutment
proximal portion 58 and the implant proximal segment 34.
[0051] Depending on the configuration of the implant 20 and the
abutment 50, the crown cavity 90 may include an annular crown
chamfer 92 which is specifically configured to circumferentially
engage the implant proximal segment 34 and/or an abutment shoulder
60 disposed between the abutment distal and proximal portions 56,
58. As will be described in greater detail below, the crown cavity
90 is adapted to engage the abutment proximal portion 58 and
therefore has a shape which is complementary thereto. Additionally,
the crown chamfer 92 is adapted to receive the implant proximal
segment 34 and therefore has a shape which is complementary
thereto.
[0052] In the dental prosthesis 10, attachment of the crown 80 to
the abutment 50 and/or implant 20 is facilitated through the use of
an adhesive 100 which may be applied to the outer surface of the
abutment proximal portion 58 and may include the application of
adhesive 100 to the abutment proximal end 54. Furthermore, adhesive
100 may be applied to the implant proximal segment 34. The crown 80
is then advanced over the abutment 50 and implant 20 such that the
abutment proximal portion 58 is snugly received into the crown
cavity 90 and the crown distal end 82 is circumferentially engaged
to the abutment proximal segment. Ideally, the crown 80 is sized
and configured such that when the abutment proximal portion 58 is
fully received into the crown cavity 90 and the crown distal end 82
is engaged to the implant proximal segment 34, the crown distal end
82 extends to and terminates at the prosthetic margin 40 defined
between the implant distal segment 37 and implant proximal segment
34.
[0053] When the crown 80 is attached to the abutment 50 and implant
20 in the above-described manner, the crown distal end 82, by
virtue of its extension to the prosthetic margin 40, is distal to
(i.e., extended below) the implant abutment joint 44 resulting in
the crown distal portion 86 completely covering the implant
abutment joint 44. Additionally, the adhesive 100 for securing the
crown 80 to the abutment proximal portion 58 and implant proximal
segment 34 preferably extends between the outer surface of the
implant proximal segment 34 and the crown cavity 90 adjacent the
crown distal end 82. Importantly, upon curing and/or hardening of
the adhesive 100, the implant abutment joint 44 is effectively
sealed and thereby isolated from the deleterious effects of
bacterial invasion, plaque and disease.
[0054] The cured and/or hardened adhesive 100 also prevents
bacterial migration between the crown 80 and implant 20 by sealing
the joint between the crown distal portion 86 and implant proximal
segment 34. Also, sealed by the curative adhesive 100 is the joint
between the crown 80 and the abutment proximal portion 58. Thus,
the adhesive 100 serves several essential purposes which includes
attachment of the crown 80 to the abutment 50 and implant 20,
sealing of the implant abutment joint 44, and sealing of the crown
implant joint for purposes of preventing bacterial invasion.
[0055] Referring more particularly now to FIG. 3, shown is the
dental prosthesis 10 wherein the abutment distal end 52 is
specifically configured to circumferentially engage the implant
proximal segment 34. More particularly, FIG. 3 illustrates an
embodiment of the dental prosthesis 10 wherein the implant proximal
segment 34 includes an outer surface which is tapered. More
specifically, the tapered outer surface of the implant proximal
segment 34 may be conically shaped in order to facilitate
circumferential engagement of the abutment distal end 52 thereto.
In one embodiment, the implant proximal segment 34 may be provided
at an angle indicated by the reference character .alpha..sub.1 as
shown in FIGS. 3 and 10a. Although the implant proximal segment 34
may be provided in any configuration, the angular range for
.alpha..sub.1 is preferably no greater than about 45.degree. and
preferably less than about 3.degree. relative to the implant
longitudinal axis.
[0056] As can be seen in the figures, the implant distal segment 37
of the dental prosthesis 10 may be generally cylindrically shaped
although other configurations for the implant distal segment 37 are
contemplated. The implant distal segment 37 is configured to
interface with soft tissue surrounding the bony structure into
which the implant 20 is embedded. The implant distal segment 37 may
have a height of about 1 mm although the implant distal segment 37
may be provided in any height.
[0057] Alternatively, as shown in FIGS. 4-5, the implant distal
segment 37 may define a circumferential or annular undercut 38
between the implant distal portion 26 and the implant proximal
segment 34. In this configuration of the dental prosthesis 10, the
implant distal segment 37 is interposed between the implant trunk
31 and the implant proximal segment 34 and interconnects the two.
The circumferential undercut 38 as shown in FIGS. 4-5 may have an
arcuately shaped cross-section.
[0058] Such arcuate cross-section may be defined by a continuous
radius extending from the prosthetic margin 40 (i.e., at the
convergence of the implant distal and proximal segments 37, 34) and
blending into the implant trunk 31. Alternatively, the
circumferential undercut 38 of the implant distal segment 37 may be
defined by a short conical or tapered surface which extends from
the prosthetic margin 40 toward the implant trunk 31 and which
blends into the implant trunk 31 by an annular radius.
[0059] As shown in FIGS. 1-9a, the abutment shoulder 60 is
specifically configured to circumferentially engage the outer
surface of the implant proximal segment 34. The abutment 50 may
include an abutment cavity 62 for at least partially receiving the
outer surface of the implant proximal segment 34. As shown in FIGS.
3-7, the outer surface of the implant proximal segment 34 may be
tapered and the abutment cavity 62 may have a conical shape in
order to interface with the outer surface of the implant proximal
segment 34. Optionally, the abutment cavity 62 may have a conical
shape with a half angle that is slightly smaller than the half
angle of the outer surface of the implant proximal segment 34.
[0060] In this manner, only a lower edge of the abutment proximal
portion 58 may engage the implant proximal segment 34 outer surface
in edge-to-surface contact. Optionally, the abutment 50 and outer
surface of the implant proximal segment 34 may be configured with
substantially equal half angles to provide surface-to-surface
contact between the abutment 50 and the implant 20. However, it is
contemplated that the abutment cavity 62 may be provided in a
variety of alternative shapes and sizes to provide the feature of
circumferential engagement therebetween. As was earlier mentioned,
such configuration is believed to uniformly distribute occlusal
forces imposed on the crown 80 and also provide a greater area
through which forces may be transferred between the abutment 50 and
the implant 20.
[0061] The abutment 50 may further include an abutment neck 64
disposed adjacent the abutment distal end 52 and the abutment
shoulder 60. The abutment neck 64 preferably has a reduced
cross-section in an axial direction relative to the cross-section
of an immediately adjacent portion of the abutment 50. More
particularly, the abutment neck 64 provides a locally thinned area
of the abutment 50 which allows for a reduction in the overall
volume occupied by the abutment 50 within the crown cavity 90 but
while still providing for circumferential engagement of the
abutment shoulder 60 to the outer surface of the implant proximal
segment 34. In the figures, the abutment 50 can be seen as having a
generally frusto-conical configuration while allowing the abutment
proximal portion 58 outer surface to blend in with the implant
proximal segment 34.
[0062] The crown 80 includes a crown distal portion 86 which
defines the crown distal end 82 having the crown cavity 90 formed
therein. The crown cavity 90 is configured to be complementary to
the abutment proximal segment such that the crown distal end 82 may
also circumferentially engage the implant proximal segment 34 as
shown in FIGS. 1-9a. As was earlier mentioned, receipt of the
abutment proximal portion 58 and abutment proximal segment into the
crown cavity 90 results in engagement of the crown distal portion
86 to the implant proximal segment 34 outer surface such that the
crown implant joint is defined therebetween. The implant abutment
joint 44 is covered by the crown distal portion 86 and a layer of
adhesive 100 may be disposed between the implant proximal segment
34 and the crown cavity 90 at the crown implant joint in order to
provide sealing engagement therebetween.
[0063] Regarding joining of the abutment 50 to the implant 20, the
abutment distal portion 56 may be externally threaded with the
abutment proximal portion 58 including a recess disposed within the
abutment proximal end 54 for receiving an implement such as a
screwdriver to threadably rotate the abutment 50. Additionally, the
implant bore 42 may be internally threaded. As such, attachment of
the abutment 50 to the implant 20 may be facilitated by threadable
receipt of the abutment distal portion 56 into the implant bore 42.
Optionally, adhesive 100 may be provided between the implant bore
42 and the abutment distal portion 56 or abutment shaft 66 in order
to secure the two components.
[0064] As can be seen in FIGS. 1-2 and 8-9a, in a further
embodiment, the implant proximal segment 34 may have an annular
concave cross-sectional shape. The implant proximal segment 34 is
configured to provide an arcuate interface between the implant
proximal segment 34 and the implant distal segment 37 (i.e., at the
prosthetic margin 40). As shown in FIG. 9a, the concave
cross-section of the implant proximal segment 34 may be defined by
a radius extending directly upwardly from a tangent of the radius.
Preferably, the radius intersects the prosthetic margin 40 at an
angle indicated by reference character .alpha..sub.1 and which is
preferably no greater than about 45.degree. relative to the implant
longitudinal axis and no less than about 3.degree. relative to the
implant longitudinal axis.
[0065] By limiting the angular orientation of the implant proximal
segment 34 to no greater than about 45.degree., the magnitude of
vertical forces transmitted from the crown 80 into the implant 20
across the adhesive 100 may be minimized. By minimizing the
magnitude of these vertical forces on the adhesive 100, the risk of
cracking the adhesive is avoided. In addition, limiting the angular
orientation of the implant proximal segment 34 to no greater than
about 45.degree. reduces the risk of stress-cracking and resultant
fracturing of the crown 80 at the crown distal end 82 where the
crown 80 engages the implant proximal segment 34. On the other
hand, by limiting the angular orientation of the implant proximal
segment 34 to no less that about 3.degree. reduces or eliminates
the need for overly-tight manufacturing tolerances of the crown 80
and/or implant 20.
[0066] More specifically, maintaining the angular orientation of
the implant proximal segment 34 to no less that about 3.degree.
allows for installation of the dental prosthesis 10 in keeping with
material and methods of dentistry known in the art. Finally,
limiting the angular orientation to no less than about 3.degree.
reduces the risk of adhesive 100 cracking and failure thereof
between the crown 80 and implant 20 and/or abutment 50 which would
otherwise compromise the structural integrity of the crown implant
joint and/or crown abutment joint. It should be noted that the
range of angular orientation described above for the implant
proximal segment 34 are applicable to all configurations of the
dental prosthesis 10 shown and described herein.
[0067] As can be seen in FIG. 9a, the radius may transition into an
upper conical surface 35 of the implant proximal segment 34.
Preferably, the upper conical surface 35 is formed at an angle
indicated in FIG. 9a by the reference character .alpha..sub.2 of at
least about 3.degree., as discussed above, although it is
contemplated that the upper conical surface 35 may be formed at the
angular orientation of no greater than about 45.degree. relative to
the implant longitudinal axis. The concave cross-section of the
implant proximal segment 34 provides a relatively large area upon
which forces from the crown 80 may be distributed into the implant
20. The concave cross-section provides a relatively large surface
area and, therefore, results in reduced force per unit area that
must be carried by the adhesive 100 which bonds the crown 80 to the
implant 20. In this manner, the concave cross-section of the
implant proximal segment 34 eliminates or prevents failure or
fracturing of the adhesive 100.
[0068] The implant proximal segment 34 may be defined by the
previously-mentioned upper conical surface 35 and a lower conical
surface 36 disposed adjacent the prosthetic margin 40. The lower
conical surface 36 may preferably extend upwardly from the
prosthetic margin 40 at an angle .alpha..sub.1 of no greater than
about 45.degree. although other angles are contemplated. As was
earlier mentioned, the upper conical surface 35 extends downwardly
from the implant proximal end 24 and intersects the annular radius
which also transitions into the lower conical surface 36.
[0069] As can be seen in FIG. 9a, the upper and lower conical
surfaces 35, 36 may be joined via a circumferential radius.
Preferably, the concave cross-section is configured such that the
tangent is offset radially inwardly from the prosthetic margin 40
by about 0.2 mm to about 1.0 mm. Such offset is believed to provide
an optimal joint configuration and may reduce or eliminate adhesive
100 failure such as by cracking between the crown 80 and the
implant proximal segment 34. The crown distal end 82 may have a
radiused configuration formed complementary to the implant proximal
segment 34 in order to eliminate stress over time.
[0070] As was earlier mentioned, the dental prosthesis 10 as shown
in FIGS. 1-9a, may be configured such that the abutment shoulder 60
is configured to circumferentially engage the outer surface of the
implant proximal segment 34. In this regard, the abutment 50
includes the abutment cavity 62 which is likewise formed to be
complementary to the outer surface of the implant proximal segment
34 to enable circumferential engagement therebetween. As was
earlier mentioned, such engagement may be a surface-to-surface or
surface-to-line circumferential engagement. If an abutment neck 64
is provided in the abutment 50, the abutment neck 64 is preferably
configured to blend into the upper and lower conical surfaces 35,
36 and radius of the implant proximal segment 34. The abutment
recess 68 may be further provided in the abutment 50 in order to
facilitate insertion of the abutment shaft 66 into the implant bore
42.
[0071] Referring to FIGS. 10-11, the implant proximal segment 34
may be configured such that the abutment shoulder 60 engages an end
face of the implant proximal end 24 as opposed to circumferential
engagement illustrated in FIGS. 1-9a. As can be seen in FIG. 10,
the implant distal segment 37 may include the annular undercut 38
configuration shown in FIGS. 4 and 5 and as described above. The
implant proximal segment 34 may have the conical shape described
above. As was also described above, the crown 80 covers the implant
abutment joint 44 when the crown 80 is mounted on the abutment 50.
More specifically, for the configurations shown in FIGS. 10 and 11,
the crown 80 is configured to extend over and cover the implant
abutment joint 44.
[0072] As shown in FIG. 11, the implant distal segment 37 may be
configured substantially similar to that shown in FIG. 10 but
includes the configuration of the implant proximal segment 34 shown
in FIG. 8a. For the configuration shown in FIG. 11 where the
implant proximal segment 34 has a concave cross-section, the
abutment 50 is preferably configured such that the implant proximal
segment 34 is substantially continuous with the outer surface of
the abutment proximal portion 58 when the abutment 50 is attached
to the implant 20.
[0073] Having thus described various embodiments of the dental
prosthesis 10 constructed in accordance with the present invention,
a method of installing such prosthesis into a patient's mouth will
now be described. Installation of the dental prosthesis 10 is
initiated by first drilling a hole into the bony structure of the
patient's mouth. Thereafter, the externally-threaded implant distal
portion 26 may be embedded into the bony structure of the patient's
mouth by threadable engagement. The implant 20 is preferably
embedded to a level such that the implant proximal segment 34
protrudes above the bony structure. However, the implant proximal
segment 34 may be disposed below, at, or above the patient's gum
line.
[0074] Subsequent to embedding the implant 20 into the bony
structure, the abutment 50 is rigidly attached to the implant 20 in
the above-described manner and may be accomplished through the use
of an adhesive 100 and/or via threadable engagement of the abutment
50 and implant 20 to one another. After attachment of the abutment
50 to the implant 20, a transfer cast is made of exposed portions
of the abutment 50 and implant 20. Such exposed portions include
the outer surface of the implant proximal segment 34 and the
frusto-conical outer surface of the abutment proximal portion 58.
The transfer cast is used to fabricate the crown 80 in order to
ensure complete coverage of exposed portions of the abutment 50 and
implant 20.
[0075] Subsequent to fabrication of the crown 80, a layer of the
adhesive 100 may be applied to exposed portions of the abutment 50
and implant 20 (i.e., outer surface of the abutment proximal
portion 58 and outer surface of the implant proximal segment 34).
The crown 80 may be then be attached to those portions of the
abutment 50 and implant 20 which are covered by adhesive 100. Such
attachment results in the implant abutment joint 44 being
completely covered by the crown distal portion 86. Furthermore,
such attachment results in the flow of adhesive 100 between the
crown cavity 90 and the outer surface of the implant proximal
segment 34.
[0076] The adhesive 100 preferably extends between the crown cavity
90 and the outer surface of the abutment proximal portion 58. For
configurations of the implant 20 wherein the implant proximal
segment is formed at an angle .alpha..sub.2 as steep as 30 as shown
in FIGS. 8a and 9a, the abutment neck 64 results in the creation of
an annular void between the crown cavity 90 and the implant
20/abutment 50. Advantageously, such annular void provides an area
within which excess adhesive 100 may collect to avoid the
undesirable effects of hydraulic pressure build-up of adhesive 100
that may otherwise occur between the crown 80 and implant
20/abutment 50.
[0077] The curing of the adhesive 100 results in sealing of the
implant abutment joint 44, the crown implant joint, and the
abutment crown joint 70. Such sealing eliminates the susceptibility
of such joints to bacterial invasion or other deteriorations.
Furthermore, the unique interface between the implant proximal
segment 34 and the abutment 50 prevents micro-movement of the
abutment 50 and the crown 80 relative to the implant 20.
Furthermore, the integrity of the adhesive 100 is also improved
such that the susceptibility to fractures and resultant bacterial
invasion is lessened.
[0078] The above description is given by way of example, and not
limitation. Given the above disclosure, one skilled in the art
could devise variations that are within the scope and spirit of the
invention disclosed herein. Furthermore, the various features of
the embodiments disclosed herein can be used alone or in varying
combinations with each other and are not intended to be limited to
the specific combination described herein. Thus, the scope of the
claims is not to be limited by the illustrated embodiments.
* * * * *