U.S. patent application number 13/030283 was filed with the patent office on 2012-08-23 for porous implant device for supporting a denture.
This patent application is currently assigned to Zimmer Dental. Invention is credited to Jeffrey Bassett, Michael Collins, Chris Gervais.
Application Number | 20120214128 13/030283 |
Document ID | / |
Family ID | 44993958 |
Filed Date | 2012-08-23 |
United States Patent
Application |
20120214128 |
Kind Code |
A1 |
Collins; Michael ; et
al. |
August 23, 2012 |
Porous Implant Device for Supporting a Denture
Abstract
A dental implant device has an implant portion for being placed
in a bore in bone. The implant portion has a coronal end portion
and a porous metal portion. A metal coupling has a coronal end
configured for connection to a denture support piece. The coupling
also has an apical end integrally formed with the coronal end and
engaging the porous metal portion. In one form, the coupling is
attached to the porous metal portion in a threaded connection so
that the coupling is removable from the porous portion without
significantly damaging the porous metal portion sufficiently to
re-engage another metal coupling.
Inventors: |
Collins; Michael; (San
Marcos, CA) ; Bassett; Jeffrey; (Vista, CA) ;
Gervais; Chris; (San Marcos, CA) |
Assignee: |
Zimmer Dental
Carlsbad
CA
|
Family ID: |
44993958 |
Appl. No.: |
13/030283 |
Filed: |
February 18, 2011 |
Current U.S.
Class: |
433/173 |
Current CPC
Class: |
A61C 8/0006 20130101;
A61C 13/2656 20130101; A61C 8/0018 20130101; A61C 8/0022 20130101;
A61C 8/0048 20130101; A61L 27/047 20130101; A61C 8/0068 20130101;
A61C 8/0053 20130101; A61C 8/0012 20130101 |
Class at
Publication: |
433/173 |
International
Class: |
A61C 8/00 20060101
A61C008/00 |
Claims
1. A dental implant device comprising: an implant portion for being
placed in a bore in bone and having a coronal end portion and a
porous metal portion; and a metal coupling having a coronal end
configured for connection to a denture support piece, and an apical
end integrally formed with the coronal end and engaging the porous
metal portion, wherein the coupling is removable from the porous
metal portion without significantly damaging the porous metal
portion sufficiently to re-engage a coupling to support a denture
support piece.
2. The dental implant device of claim 1 wherein the porous metal
portion comprises tantalum or niobium.
3. The dental implant device of claim 1 further comprising a
threaded connection between the coupling and the porous metal
portion having a pitch allowance no greater than about 0.000844
inches.
4. The dental implant device of claim 1 further comprising a
threaded connection between the coupling and the porous metal
portion wherein the porous metal portion has threads with a thread
depth at most about 70% of the thread depth of corresponding
threads on the coupling.
5. The dental implant device of claim 1 wherein the implant portion
is at most about 4.0 mm in total height.
6. The dental implant device of claim 1 wherein the implant portion
is about 2.3 to 3.3 mm in total height.
7. The dental implant device of claim 1 wherein the coronal end of
the coupling is configured to snap-fit to the denture support
piece.
8. The dental implant device of claim 1 wherein the coronal end of
the coupling comprises at least one of: male connection structure,
female connection structure, a ball, a recess opening coronally for
receiving a projection of the denture support piece, and a recess
opening laterally relative to a coronal-apical direction for
receiving a bar to support a denture.
9. The dental implant device of claim 1 wherein the porous metal
portion forms a first bore and the coupling comprises an extension
received within the first bore.
10. The dental implant device of claim 9 wherein the extension is
integrally formed with the coupling.
11. The dental implant device of claim 9 wherein the porous metal
portion comprises a wall defining the first bore and having
pre-formed threads for engagement with the extension.
12. The dental implant device of claim 9 wherein the apical end of
the coupling defines a second bore, and wherein the extension
comprises a separately formed shaft received by the second bore for
securing the implant portion to the coupling.
13. The dental implant device of claim 12 wherein the shaft has a
first end threadedly attached to the coupling, and a second end
threadedly attached to the porous portion.
14. The dental implant device of claim 12 wherein the porous
portion comprises an outer surface forming an opening to the first
bore, and wherein the shaft comprises a radially extending shoulder
facing apically for engaging with the outer surface.
15. The dental implant device of claim 1 wherein the implant
portion comprises a block of the porous metal portion, the dental
implant device comprising a plurality of the couplings mounted on
the block and spaced from each other.
16. The dental implant device of claim 15 wherein the block
comprises bore for receiving each coupling, and the dental implant
device having a sleeve disposed in at least one bore for receiving
one of the couplings.
17. The dental implant device of claim 16 wherein the sleeve is
bonded to the block and has internal threads.
18. The dental implant device of claim 1 comprising a locking
member extending through the porous metal portion and engaging the
coupling for securing the coupling to the porous metal portion.
19. The dental implant device of claim 1 wherein the porous metal
portion comprises a bore for receiving the coupling, and wherein
the coupling is secured within the bore by a friction fit.
20. The dental implant device of claim 1 wherein the implant
portion comprises a non-porous apical end portion disposed apically
of the porous metal portion, and wherein the coupling comprises an
extension extending through the porous metal portion to engage the
apical end portion.
21. The dental implant device of claim 1 wherein the coronal end
portion is non-porous.
22. The dental implant device of claim 1 wherein the coronal end
portion has a threaded exterior surface.
23. The dental implant device of claim 1 comprising a plurality of
the couplings, the apical end of each coupling being configured for
alternative connection to the implant, and the coronal end of each
coupling being configured for connection to a differently shaped
denture support piece.
24. A dental implant device comprising: an implant having a porous
metal portion with passages through the porous metal portion for
engaging bone; a coupling configured for supporting a dental
restoration; and a metal shaft connecting the coupling to the
implant and having a threaded apical end directly engaging the
porous metal portion in a separable threaded connection and a
threaded coronal end for engaging the coupling.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to porous implants and, in
particular, to a porous dental implant with improved
osseointegration features and that anchor dentures.
[0003] 2. Description of the Related Art
[0004] Conventional dentures have prosthetic teeth shaped and
colored to appear like natural teeth. The base of the denture is
colored to match gingival or soft tissue, and is fixed upon a
patient's gingiva by an adhesive. Oftentimes, however, the denture
does not adhere well to the patent's gum causing significant
discomfort and malfunction of the denture as well as embarrassment
to the patient when the denture slips out of the patient's
mouth.
[0005] In this case, endosseous implants may be used to anchor the
denture to support multiple prosthetic teeth. A denture that fits
over implants, or shortened natural teeth if preserved, is called
an overdenture.
[0006] Endosseous dental implants are typically threaded or
press-fit into pre-drilled bores in the mandible or maxilla to
support one or more prosthetic teeth. A number of implants spaced
along the mandible or maxillae may be used to support a full or
partial overdenture. The overdenture is used when the mandible or
maxilla of a patient has insufficient bone mass or strength to hold
an implant for each tooth, or when such a surgery for so many
implants is cost prohibitive or otherwise harmful to the patient. A
full denture with prosthetic teeth for an entire upper or lower jaw
is usually anchored by two to four implants. The denture may be
permanently fixed to the implants or may be removable in a snap-fit
arrangement. More stable systems have bars interconnecting adjacent
implants and that are covered by an overdenture snapped onto the
bars.
[0007] However, many years of denture use often result in a reduced
alveolar ridge or bone resorption caused by reduced impact from
occlusal forces. The localized impact of occlusal forces on the
mandible or maxilla is reduced because the denture causes the
forces to be impacted by the soft tissue throughout the mandible or
maxilla. In this case, further support systems may be needed to
hold the denture in a stable position. However, installing even a
reduced number of implants for supporting a denture may be too
expensive because the alveolar ridge may need to be built up by
grafts for example to adequately support a full size implant. Also,
grafting procedures often require harvesting bone from other parts
of the body or using animal or cadaver bone. The grafting procedure
can be painful, the grafts may fail to integrate, and the procedure
has some risks such as infection or disease transmission if animal
or cadaver bone is used. In other high risk cases such as smokers,
diabetics, or osteoporotics that have substantially reduced or
missing bone mass, low bone density, and/ or abnormally slow bone
growth, obtaining adequate support for conventional, full size
dental implants may be impossible. Thus, a desire exists to
increase the strength of the osseointegration, increase the rate of
growth of the osseointegration, and reduce the required size of the
dental implant.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a side, cross-sectional and exploded view of an
implant device with a first denture support system;
[0009] FIG. 2 is a close-up, fragmentary view of a porous material
on the implant device of FIG. 1;
[0010] FIG. 3 is a side, cross-sectional, and exploded view of a
second denture support system;
[0011] FIG. 4 is a side, cross-sectional, and partially exploded
view of a third denture support system;
[0012] FIG. 5 is a side, cross-sectional, and partially exploded
view of an implant with a fourth denture support system;
[0013] FIG. 6 is an exploded, side view of an alternative implant
and a denture support piece;
[0014] FIG. 7 is an exploded, side view of a further alternative
implant and a denture support piece; and
[0015] FIG. 8 is a perspective view of a block implant supporting
multiple denture support posts.
DETAILED DESCRIPTION
[0016] Referring to FIG. 1, an implant device 10 has an implant or
implant portion 12 that supports a denture support system 14.
Herein, denture refers to a dental prosthetic appliance that
distributes occlusal forces along the mandible or maxillae, and
through the gingiva or gums, rather than having a single tooth
shaped prosthesis supported by a single implant to directly impact
occlusal forces. A denture, and specifically an overdenture, also
may distribute the occlusal forces among one or more implants
supporting the denture. The denture may have one or more prosthetic
teeth supported by a gum colored base, usually made of a polymer
that is placed over the top and sides of the gums to distribute the
occlusal forces thereon. The denture may also be adhered to the
gums. This denture may be a full or complete denture that covers an
entire mandible or maxillae or may be a shortened partial denture
that only supports one or more prosthetic teeth. In the illustrated
form, the denture is supported by both soft tissue and one or more
implants.
[0017] Denture support system 14 includes a base or coupling 16
(also referred to as an abutment portion) that connects to a
coronal end portion 18 of the implant 12, a locator element 20 that
snap-fits onto a coronal end portion 22 of the coupling 16, and a
cap 24 that snap-fits onto a coronal end portion 26 of the locator
element 20.
[0018] With such a system, a denture or appliance has one or more
recesses arranged along an arc on the underside of the appliance to
align with a patient's mandible or maxillae. Each recess receives a
cap 24. In the patient's mouth, implants 12 are press-fit or
threaded into bores spaced along the mandible or maxillae 80. A
coupling 16 is then mounted on each implant 12. Then, to mount the
appliance on the jaw (jaw herein refers to either the maxillae or
mandible), each locator element 20 is either snap-fit onto a
coupling 16 or into the cap 24. The appliance is then snap-fit onto
the couplings 16 in the patient's mouth by pressing the locator
elements 20 onto the other piece (coupling 16 or cap 24) it
snap-fits onto. The locator element 20 is typically made of a
resilient material for this purpose such as an elastic polymer.
This type of system provides an easily removed appliance that is
more secure than dentures solely adhered to the top and sides of
the gums, and lower cost than a more permanent system that has bars
to support the denture or appliance. As explained in greater detail
below, a number of different denture support systems may be used
with implant 12.
[0019] Referring to FIGS. 1-2, to improve osseointegration, the
implant 12 includes a porous metal portion 40, and specifically, a
porous tantalum portion which is a highly porous biomaterial useful
as a bone substitute and /or cell and tissue receptive material. An
example of such a material is produced using TRABECULAR METAL.TM.
technology generally available from Zimmer, Inc. of Warsaw, Ind.
TRABECULAR METAL.TM. is a trademark of Zimmer Technology, Inc. Such
material may be formed from a reticulated vitreous carbon foam
substrate which is infiltrated and coated with a biocompatible
metal, such as tantalum, etc., by a chemical vapor deposition
("CVD") process in a manner disclosed in detail in U.S. Pat. No.
5,282,861, the disclosure of which is fully incorporated herein by
reference. Other metals such as niobium, or alloys of tantalum and
niobium with one another or with other metals may also be used.
[0020] As shown in FIG. 2, porous tantalum structure 40 includes a
large plurality of members 42 (also called ligaments, branches, or
struts) defining open spaces 44 therebetween, with each member 42
generally including a carbon core 46 covered by a thin film of
metal 48 such as tantalum, for example. The open spaces 44 between
members 42 form a matrix of continuous channels having no dead
ends, such that growth of cancellous bone entirely through porous
tantalum structure 40 is uninhibited. The porous tantalum may
include up to 75%-85% or more voids therein. Thus, porous tantalum
is a lightweight, strong porous structure which is substantially
uniform and consistent in composition, and closely resembles the
structure of natural cancellous bone, thereby providing a matrix
into which cancellous bone may grow to anchor implant 12 into the
surrounding bone of a patient's jaw which increases stability. The
rough exterior surface of such porous metal part has a relatively
high friction coefficient with adjacent bone forming the bore that
receives the implant to further increase initial stability as
alluded to above. This structure can produce superior aesthetic
results by restricting movement of the implant. These implants can
be placed without supplementary surgical procedures, such as bone
grafting, and can be placed in areas where traditional implants
have been less successful, such as with reduced or decayed alveolar
sections.
[0021] More specifically, the high level of friction between the
porous material and the bone provides immediate stability post
surgery. The tantalum members or struts 42 that extend from the
surface of the material create a rasping action that may stimulate
bone growth and anchor the implant at the time of placement. The
extremely biocompatible tantalum metal that the porous material is
made from allows bone to directly oppose the material. The tantalum
forms a porous scaffolding that allows bone to grow into the
material providing a rapid osseointegration response that quickly
augments the initial mechanical fixation to secure the implant. The
implant with in-grown bone may have stability greater than a
comparably sized implant with only on-grown bone. Finally, the
composite of in-grown bone and such a porous material has elastic
properties much closer to bone than a solid metal implant, creating
a loading environment that is conducive to maintaining bone near
the implant.
[0022] Regarding the initial stability, as an implant with the
porous material is inserted into the bore or cavity in bone, the
porous material will bite into the bone by grating, chipping and/
or flaking bone pieces off of the bone sidewalls against which the
implant device is being placed. When the implant is placed into the
bore or cavity, this "rasping" action may form slight recesses or
indents within the sidewall. This restricts rotational or twisting
motion of the implant device within the bore or cavity when the
implant device does not have the clearance to rotate out of the
indents and within the bore.
[0023] The rasping action also accelerates osseointegration onto
the implant device and into the pores of the porous material due to
the bone compaction into the pores. First, the grating of the bone
structure causes the bone to bleed which stimulates bone growth by
instigating production of beneficial cells such as osteoblasts and
osteoclasts. Second, the bone pieces that fall into the pores on
the porous material assist with bone remodeling. In the process of
bone remodeling, osteoblast cells use the bone pieces as
scaffolding and create new bone material around the bone pieces.
Meanwhile osteoclast cells remove the bone pieces through
resorption by breaking down bone and releasing minerals, such as
calcium, from the bone pieces and back into the blood stream. The
osteoblast cells will continue to replace the grated bone pieces
from the pores and around the implant device with new and healthy
bone within and surrounding the extraction site. Thus, the porous
material has increased resistance to twisting or rotation, allows
for immediate or very early loading, and increases long-term
stability due to the improved osseointegration. Such an implant
with ingrown bone has stability greater than a comparably sized
implant with only on-grown bone. These advantages may be realized
no matter the form of the porous implant (e.g., root-form or a
larger implant block as described in detail below).
[0024] Porous tantalum structure 40 may be made in a variety of
densities in order to selectively tailor the structure for
particular applications. In particular, the porous tantalum may be
fabricated to virtually any desired porosity and pore size, whether
uniform or varying, and can thus be matched with the surrounding
natural bone in order to provide an improved matrix for bone
in-growth and mineralization. This includes a gradation of pore
size on a single implant such that pores are larger on an apical
end to match cancellous bone, and smaller on a coronal end to match
cortical bone, or even to receive soft tissue ingrowth. Also, the
porous tantalum could be made denser with fewer pores in areas of
high mechanical stress. Instead of smaller pores in the tantalum,
this can also be accomplished by filling all, or some of the pores
with a solid filler material.
[0025] To provide additional initial mechanical strength and
stability to the porous structure, the porous structure may be
infiltrated with a filler material such as a non-resorbable polymer
or a resorbable polymer. Examples of non-resorbable polymers for
infiltration of the porous structure may include a polyaryl ether
ketone (PAEK) such as polyether ketone ketone (PEKK), polyether
ether ketone (PEEK), polyether ketone ether ketone ketone (PEKEKK),
polymethylacrylate (PMMA), polyetherimide, polysulf one, and
polyphenolsulfone.
[0026] Examples of resorbable polymers may include polylactic
co-glycolic acid (PLGA), polylactic acid (PLA), polyglycolic acid
(PGA), polyhydroxybutyrate (PHB), and polyhydroxyvalerate (PHV),
and copolymers thereof, polycaprolactone, polyanhydrides, and
polyorthoesters. By providing additional initial mechanical
strength and stability with a resorbable filler material, a
titanium reinforcing implant core may not be required when directly
impacting mastication forces from a single prosthetic tooth. The
resorbable material would resorb as the bone grows in and replaces
it, which maintains the strength and stability of the implant.
[0027] This strong porous structure is particularly beneficial when
reduced alveolar ridges are present. In this case, the implant 12
may be less than about 4 mm in total height (along the
apical-coronal direction), and in one form is about 2.3 to 3.3 mm
in total height. Otherwise, the implant may have typical sizes such
as up to about 16 mm in total height.
[0028] Referring again to FIG. 1, the coupling 16 has an apical end
portion 28 that engages the implant 12. In one form, the apical end
portion 28 is integrally formed with the coronal end portion 22 of
the coupling 16, but could be separate. The coupling 16 as well as
the cap 24 may be made of a biocompatible metal such as titanium,
titanium alloy, stainless steel, zirconium, cobalt-chromium
molybdenum alloy, polymers such as polyether ketone ketone (PEKK)
for one example, ceramic, and/or composite material.
[0029] The apical end portion 28 may be configured for temporary or
permanent attachment to the porous metal portion 40 of the implant
12. In the illustrated form, the apical end portion 28 has an
apical engagement surface 30 and a shaft or extension 32 extending
apically from the engagement surface 30. The porous metal portion
40 has an axially extending bore 34 to receive the shaft 32. A wall
36 defines the bore 34 with pre-formed internal threads 38 to
engage exterior threads 50 on the shaft 32. To form the threads 38,
a steel coil is rotated into the bore 34 to cut into the porous
wall 36 to form the threads 38 thereon. Alternatively, the thread
38 may be formed by a pre-tapped or machined insert typically made
of Ti, or by electro discharge machining. In one example form, the
maximum diameter of the bore 34 is about 1 to 2 mm to the base of
the threads 38, and the threads 38 may be sized as type 1-72 with a
pitch of about 0.014 inches. The pitch is measured as the axial or
longitudinal length between adjacent single lead thread peaks. The
threads 38 may alternatively be triple lead threads with a pitch of
0.042 inches. The axial length of the threads is at least about 1
mm although the threads may have other lengths as desired to
withstand pull-out of the coupling 16.
[0030] It may be desirable to form a connection in the bore 34 that
permits the coupling 16 to be removed from the implant 12 and
replaced when the coupling 16 or support system 14 is damaged or
the type of denture support system is to be changed. Thus, damage
to the porous thread 38 should be prevented or limited when the
coupling 16 is removed from the bore 34 so that the implant 12 can
adequately support a denture with a replacement coupling that may
be metal, ceramic, or other material for long term placement and
not merely a coupling considered to be temporary, such as a
temporary polymer coupling for example. To limit such damage to the
thread 38, the thread is formed with relatively loose fitting
threads such as class 1 thread specifications under the ASME B.1.1.
standard. The measurement for the tightness or looseness of the
threaded connection is indicated by the pitch allowance, which is
the difference between the maximum pitch (or pitch length) of the
external threads and the minimum pitch of the internal threads with
respect to the pitch length tolerances.
[0031] Smaller diameters of class 1 threads are not defined as
standard threads in the thread specifications, but allowances for a
looser configuration of the thread can be calculated. When the
implant manufacturer designs and fabricates both the male and
female threads, an acceptable fit for the application can be
assured. For a 1-72, class 1 thread, the maximum pitch P1 (FIG. 1)
on the external threads 50 of the coupling 16 is no greater than
about 0.0143311 inches while the minimum internal thread pitch P2
(FIG. 1) on the implant 12 is no less than about 0.013467 inches,
for a maximum desired pitch allowance of about 0.000844 inches. In
another form, the minimum pitch allowance is at least about 0.0008
inches.
[0032] In order to further reduce the risk of damaging the internal
threads 38, the thread depth t2 (FIG. 1) of the internal threads 38
on the implant 12 is at most about 70% of the thread depth t1 (FIG.
1) of the external threads 50 on the coupling 16. In one form, the
coupling thread depth t1 is about 0.0075 inches and the implant
thread depth is at most about 0.00525 inches. This structure
reduces the amount of surface area on the threads 38 of the implant
that is susceptible to damage without significantly reducing the
strength of the threaded connection.
[0033] Typically, a stand-alone, single-tooth implant that receives
a full occlusive force, such as about 68 lb/sq. in (about 300 N)
cannot have a connection with such a wide tolerance because these
types of connections often do not withstand such relatively large
occlusive forces over long time periods. Here, however, for a
complete denture, four implants 12 will typically be used to
support four snap-fit locations, although less or more may be used
as desired. Thus, in this case, a single implant on such a denture
system should not receive the full occlusive force. At least some
of the force may be absorbed by the soft tissue, and in turn along
the jaw, and the remainder of the force may be spread at least
partially among the implants. The implants on the system, together,
may only be impacted by about 75%, 50%, or even 20% of the total
occlusive force. Even if the implants are found to impact 100% of
the occlusive force rather than partially impacted on the soft
tissue and the jaw, the force is spread among the implants of the
system so that a single implant substantially does not receive 100%
of the force.
[0034] Alternatively, a more permanent connection can be provided
between the coupling 16 and the porous metal portion 40 of the
implant 12. This may include self-tapping threads on the shaft 32
that cuts into the porous wall 34 of the implant to form a
permanent threaded connection. Otherwise, a friction fit may be
used between a non-threaded shaft 52 (shown in dash line on FIG. 1)
that is generally cylindrical and may have an axially extending
morse taper as shown. The shaft 52 is press-fit into a bore 54
(also shown in dash line) on the implant 12. In this case, the
outer diameter of the shaft 52 is about 10/1000 inches wider than
the inner diameter of bore 54.
[0035] As another alternative, a shrink fit may be used with a Ti
shaft that will shrink upon exposure to liquid nitrogen, for
example, and is then cooled to expand within bore 54 resulting in a
tight fit within the bore 54. Also, the shaft 32 or 52 may be
respectively locked into the bore 34 or 54 by a separate member
such as a cross-pin or set screw 56 (shown in dashed line). Such a
pin or screw may or may not pass entirely through the coupling
shaft and to the porous material on the other side of the shaft.
Otherwise, the apical end portion 28 may be connected to the porous
metal portion 40 by a diffusion bond or a chemical vapor deposition
bond. In this case, the coupling 16 may have a relatively short,
central locating shaft 58 (shown in dashed line on FIG. 1) received
by a short bore 60 (also shown in dashed line) on the implant 12
for centering the coupling 16 on the implant 12. The bonding takes
place between the shaft 58 and the bore 60, or between the
engagement surface 30 and the coronal end portion 18, or both.
[0036] An apical end portion 62 of the porous metal portion 40 may
be similarly bonded to a non-porous anchor or stem 64 forming an
apical end 66 of the implant 12. In one form, the anchor 64 is made
of titanium, titanium alloy, stainless steel, zirconium,
cobalt-chromium molybdenum alloy, polymers such as polyether ketone
ketone (PEKK) for one example, ceramic, and/ or composite material.
The anchor 64 also has external threads for strong connection to
cancellous bone and may be self-tapping threads for screwing the
implant 12 into a bore in bone. As with the bonded connection to
the coupling 16, the anchor 64 may also have a short locating shaft
68 received in a central bore 70 on the apical end portion 62.
[0037] When a more permanent connection is used, implant 12 is
effectively a one-piece implant that extends through the gingiva
once implanted. Whether the connection between the coupling 16 and
implant 12 is a more temporary connection or a permanent
connection, the implants 12 can be fully loaded with the denture
immediately after surgery since the occlusal loads are reduced as
explained above. In other cases, where appliances apply a more
direct load on the implant, an overdenture that is not tightly
secured to the implants may be used during a healing period.
[0038] As mentioned above, the coupling 16 may be disconnected from
implant 12 without significantly damaging the porous metal portion
40. The coupling 16 may be removed to replace it if it is damaged.
Also, other interchangeable couplings may be provided, each for a
different denture support system. Each of the couplings has an
apical end the same or similar to the apical end 28 on the coupling
16 for connection to the implant 12 so that the type of support
system on the implant 12 may be changed.
[0039] For example, support system 14 (FIG. 1) is similar to the
LOCATOR.RTM. support system provided by Zest Anchors, Inc. Coupling
16 may be removed from implant 12 to replace it with a support
system 100 (FIG. 3) or a support system 200 (FIG. 4). In the
illustrated example, support system 100 may be similar to the
ERA.RTM. system provided by Sterngold, Inc. Support system 100
includes a coupling 102 with an apical end portion 104 for
connection to the implant 12 and a coronal end portion 106 for
connection to a female element 108 in a snap-fit. A male, resilient
cap 110 is mounted on the female element 108. The cap 110 may be
placed directly in a recess in a denture as explained above for cap
24.
[0040] Referring to FIG. 4, an alternative denture support system
200 also may be mounted on the implant 12. The support system 200
has a coupling 202 with an apical end portion 204 for engagement
with the implant 12 and a coronal end portion 206 configured for
connection to a connector element 208. A cap or female element 210
is mounted on the connector element 208 and fits within a recess on
a denture. Instead of the couplings 16 and 102 described above with
a recess opening coronally for receiving a projection of the
denture support piece, the coupling 202 has a male connector, and
in one specific example, a ball 212 that fits within a socket 214
formed on the connector element 208. In turn, the connector element
208 has a spherical outer surface 216 that fits within a socket 218
in the cap 210 to form a second ball joint.
[0041] Also with support system 200, a separate shaft 220 is
received in a bore 222 open on an apical surface 224 of the
coupling 202, thereby forming a female connector on the coupling
rather than an integral male connector as with couplings 16 and
102. The shaft 220 may be threaded on both its coronal end 226 and
its apical end 228 to connect the coupling 202 to the implant 12.
In the illustrated form, the coronal end 226 may have a larger
outer diameter than its apical end 228 to form a shoulder 230
therebetween. The shoulder 230 sits on a coronal surface 72 of the
porous metal portion 40 of the implant 12 (FIG. 1) so that
advancement of the shaft 220 into the bore 34 is limited to ensure
a sufficient amount of the coronal end 226 extends above the
implant 12 for connection to the bore 222 and the coupling 202. It
will be understood that any of the support systems described herein
may be provided with such a separate shaft rather than the integral
shaft as provided with couplings 16 and 102.
[0042] Referring to FIG. 5, the coupling 16 may also be removed to
replace the temporary support systems 14, 104, or 204 with a more
permanent bar support system. This system provides bars or beams
that extend from implant to implant spaced along an arch on the
mandible or maxilla. A denture then snaps on and off of the bars.
The bars, however, remain extending horizontally and coronally of
the soft tissue. Although such a permanent system is more costly,
it may reduce slight shifting of the denture in the mouth to
provide a more stable and comfortable feeling because the denture
can attach to the fixed bars in a relatively large number of
locations.
[0043] In the illustrated form, a denture support system 300 has an
implant 302, similar to implant 12, including a stem 332 like stem
64. The system 300 also has a coupling 304 mounted on the implant
302. The coupling 304 has an apical end portion 306 configured to
engage a porous metal portion 330 of the implant 302 and has an
axially extending through-bore 308. A fastener 310 extends through
the through-bore 308 and into an internal bore 312 on the implant
302 to retain the coupling 304 on the implant 302. The internal
bore 312 may be longer than the bore 32 on implant 12 to
alternatively receive both the longer fastener 310 as well as the
couplings 16, 102, or 202 for example. For this purpose, the
internal bore 312 may also have an axial section with a larger
diameter (a more coronal section for example) and an axial section
with a smaller diameter (such as a more apical section) to
accommodate different diameters on both the fastener 310 and the
shaft 32 and 220 from the other couplings.
[0044] The coupling 304 also has a coronal portion 314 with one or
two recesses 316 and 318 that opens in a mesial or distal direction
(or laterally relative to the coronal-apical direction). In the
illustrated form, each recess 316 and 318 is placed on a horizontal
extension 320 or 322 respectively. Each of the recesses 316 and 318
receives an end 324 of a horizontally extending bar 326 that spans
from coupling to coupling 304 mounted on the implants 302 along the
mandible or maxillae. The overdenture has underlying structures
that snap onto each bar on one or more places and covers the bar
and the coupling.
[0045] In addition to these examples, any denture support system on
the implants herein may have any connection between the coupling
and the other support system pieces as long as the denture is
adequately supported, and the implant receives sufficiently reduced
occlusive forces if the coupling is directly attached to the porous
material by a threaded connection.
[0046] It will be understood that it is also possible to replace
the coupling 16 to have the implant support an abutment and a
single prosthetic tooth instead of the denture. The latter case,
however, would only be recommended in cases where the new coupling
can be permanently bonded to the implant, or the implant internal
bore can be modified to connect to the coupling in a configuration
sufficient to impact single-tooth occlusive forces without damaging
or displacing the implant in the mandible or maxilla.
[0047] Referring to FIG. 6, other alternative forms of the implant
12 are also contemplated. As shown, an implant 400 may support any
of the denture support systems described herein. Implant 400 is a
three piece implant with a coronal head portion 402, a porous metal
portion 404, and an apical anchor or stem portion 406. A non-porous
extension or core 408 extends apically from the coronal head
portion 402, and has an apical end portion 410 that extends into a
bore 412 on the anchor 406. The porous metal portion 404 is in the
shape of a collar or sleeve, and in one form, has a radial
thickness of about 0.03 inches (about 0.75 mm).
[0048] The porous metal portion 404 is mounted on the core 408 so
that once the core 408 is secured to the anchor 406, the porous
metal portion is secured to the implant 400 between the head
portion 402 and the anchor 406 without the need to bond or weld the
non-porous pieces to the porous metal portion. This avoids
challenges that may be experienced when bonding a porous structure
to a substrate due to the dissimilar materials, the reduced surface
area of the porous material, and changes in both the porous metal
material 40 and the coupling 16 caused by high temperature for
example.
[0049] In the illustrated form, the anchor 406 may be laser welded
to the apical end portion 410 of the core 408 thereby permanently
securing the porous metal portion 404 on the core 408.
Specifically, the apical end portion 410 and anchor 406 are welded
together along a seam 414 at the apical end 416 of the anchor 406.
It will be understood that many alternative configurations are
contemplated (such as the head being integral to the anchor 406 or
entirely separate instead of integral to the head portion 402) as
long as the porous metal portion 404 is secured over the core 408
on the implant 400.
[0050] The exterior of the head portion 402 may be provided with a
zone 418 of large threads 420 for insertion of the implant 400 into
a bore in bone as well as for improved osseointegration and initial
stability with cancellous bone. A more coronal zone 422 may have
small threads, circumferential grooves 440, or other surface
roughness structures or coating for the promotion of cortical bone
growth. In one form, the grooves 440 are barb shaped so that the
groove edges generally point coronally to bite into the surrounding
bone and limit pull-out of the implant 400. If the head portion 402
has a zone extending into the gingiva, the surface of that zone may
have a surface selected for promotion of soft tissue growth or
barriers to limit soft tissue or bacteria from extending into the
bone layers within the bore in bone.
[0051] As shown, implant 400 may also have an internal, axially
extending bore 424 within the head portion 402 to receive any of
the couplings described herein such as the coupling 16. In this
case, however, the bore 424 extends within the non-porous material
of the head portion 402. The head portion 402 may be made of the
same materials as that mentioned above for anchor 64.
Alternatively, the coupling may be welded to a coronal end 426 of
the head portion 402 to effectively form a one-piece implant that
supports a denture or bridge. In this case, the coupling 16 may
have a short centering shaft 428 (shown in dashed line) to center
the coupling on the implant 400. The shaft 428 is received in a
short bore 430 (shown in dashed line) on the implant 400. The
placement of the shaft 428 and the bore 430 on the coupling and
implant may be reversed, and the bore and shaft may be connected to
each other by friction fit, adherent, or other methods.
[0052] Referring to FIG. 7, in yet another alternative, an implant
500 has a porous metal portion 502 with a bullet shape and without
a non-porous anchor part. In one form, the implant 500 may be made
entirely of the porous material. In the illustrated form, however,
a coronal non-porous portion 504 may be made of the same materials
as that mentioned above for anchor 64. The coronal portion 504 may
provide increased initial stability in the cortical bone and to
support the coupling 16 (in this example). Thus, the coronal
portion 504 may have small threads, circumferential grooves or
barbs 506, or other surface treatment to engage the surrounding
cortical bone.
[0053] The implant 500 has a number of different alternative
configurations for securing the coronal portion 504 to the porous
metal portion 502 and securing the coupling 16 to the coronal
portion 504. In one form, the implant 500 has an internal bore 508
(shown in dashed line) that at least extends axially into the
coronal portion 504, and in the illustrated form, also extends into
the porous metal portion 502. In this alternative, the shaft 510 of
the coupling 16 directly engages the porous metal portion 502
similar to that above described for bore 32 on implant 12. In this
case, the coronal portion 504 is welded or otherwise bonded to a
coronal surface 512 of the porous metal portion 504. In another
alternative, the coronal portion 504 has an apically extending stem
514 (shown in dashed line) that extends into a large bore 516
extending axially into the porous metal portion 502. In this case,
the stem 514 is secured in the larger bore 516 by friction fit,
bonding, threading, and/ or otherwise as mentioned above, and the
coupling shaft 510 is secured within the head portion 504 and the
non-porous stem 514 rather than the porous metal portion 502.
[0054] In yet another alternative form, the coupling 16 may be
bonded to the coronal surface 518 of the coronal portion 504 while
the coronal portion 504 is bonded to the coronal surface 512 of the
porous metal portion 502 to form a permanently formed, one-piece
implant. In this case, the coupling 16 may have the short shaft 58
(shown in dashed line) received by a short axial bore 522 (shown in
dashed line) open on the coronal end 520 of the coronal portion
504. Similarly, the porous metal portion 502 may have a short axial
bore 524 (shown in dashed line) that receives a short shaft 526
(shown in dashed line) extending from the coronal end portion 504.
It will be understood that the male-female orientation of the
shafts and short bores could be reversed.
[0055] Referring now to FIG. 8, an alternative is provided for
alveolar ridges with significant defects such as low bone mass
under multiple tooth locations. In this case, a single implant 600
may be used that is in the form of a block 602 of the porous metal
material 604, and that supports one or more denture support system
structures 606. In the illustrated form, the ball joint structure
is shown from the denture support system 200 (FIG. 4).
[0056] In this form, the block 602 is shaped to fit the defect or
the defect on the bone is shaped to receive the block. In either
case, such a block may be shaped with CAD design techniques to
provide a custom block that fits a particular patient's jaw if
desired. Otherwise, the block may be provided in a standard size
and subsequently shaped by the practitioner. The block 602 may have
one or more bores 608 (here two are shown) to receive a coupling
610 like coupling 202 for example. The bores 608 may be threaded or
otherwise provided for alternative connection to the couplings as
described above. This includes one or more bores 612 (shown in
dashed line) extending transverse to bores 608 and opening to bores
608 so that the coupling may be locked into bore 608 by a cross-pin
or set screw 614. Also, the orientation and spacing of the bores
608 may also be custom designed for the particular patient and type
of support system if needed.
[0057] In yet another approach, optional sleeves 616 may be
provided for insertion into the bores 608 (or at least one bore)
and that have internal threads 618 to engage the threads on the
coupling 610. In one form, the sleeves 616 are made of titanium or
other acceptable solid metal, and the sleeves 616 are fixed in the
bores 608 by diffusion bonding, chemical vapor deposition (CVD)
bonding, or other types of welding. Otherwise, the sleeves 616 may
be fixed in the bores by friction or taper fit, the set screw 614,
adhesives, and/ or any other attachment device used herein. The
sleeve 616 may even have external threads to act as an adapter.
[0058] It will be appreciated that any of the specific features of
any of the single or multiple implant devices described herein may
be used on any of the embodiments herein where it is consistent
with that embodiment structure. Thus, for example, a sleeve and/or
any of the attachment methods, such as bonding, used for the block
602 may also be used on any of the single implant embodiments of
FIGS. 1-7 and vice versa.
[0059] It will be understood that while the block 606 is shown to
only extend for a small arcuate section to support two couplings
610, the block 606 could extend mesially and distally to form a
compete arch to hold an entire denture.
[0060] While this invention has been described as having a
preferred design, the present invention can be further modified
within the spirit and scope of this disclosure. This application is
therefore intended to cover any variations, uses, or adaptations of
the invention using its general principles such as for other than
dental implants. Further, this application is intended to cover
such departures from the present disclosure as come within known or
customary practice in the art to which this invention pertains and
which fall within the limits of the appended claims.
* * * * *