U.S. patent application number 13/408002 was filed with the patent office on 2012-10-04 for method of forming patient specific implants with improved osseointegration.
This patent application is currently assigned to ZIMMER DENTAL, INC.. Invention is credited to Jeffrey A. Bassett, Sean Cahill, Michael Collins.
Application Number | 20120251980 13/408002 |
Document ID | / |
Family ID | 43017127 |
Filed Date | 2012-10-04 |
United States Patent
Application |
20120251980 |
Kind Code |
A1 |
Bassett; Jeffrey A. ; et
al. |
October 4, 2012 |
Method of Forming Patient Specific Implants with Improved
Osseointegration
Abstract
A patient-specific bone implant has a porous body with a core
material covered with tantalum. It is made with unique outer
dimensions selected to match a specific patient.
Inventors: |
Bassett; Jeffrey A.; (Vista,
CA) ; Collins; Michael; (San Marcos, CA) ;
Cahill; Sean; (Temecula, CA) |
Assignee: |
ZIMMER DENTAL, INC.
Carlsbad
CA
|
Family ID: |
43017127 |
Appl. No.: |
13/408002 |
Filed: |
February 29, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12501163 |
Jul 10, 2009 |
|
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13408002 |
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Current U.S.
Class: |
433/201.1 |
Current CPC
Class: |
A61L 27/30 20130101;
A61C 8/0012 20130101; A61F 2310/00161 20130101; A61F 2/30942
20130101; A61F 2002/30929 20130101; A61L 27/08 20130101; B33Y 80/00
20141201; A61F 2002/3092 20130101; Y10T 29/49568 20150115; A61F
2002/30962 20130101; A61F 2310/00544 20130101; A61F 2250/0023
20130101; A61L 27/56 20130101; A61F 2/2803 20130101; A61L 2430/02
20130101; A61F 2002/30011 20130101; A61F 2/3094 20130101; A61F
2002/30952 20130101; A61C 8/0013 20130101 |
Class at
Publication: |
433/201.1 |
International
Class: |
A61C 8/00 20060101
A61C008/00 |
Claims
1-31. (canceled)
32. A method of forming an implant configured for a bone defect of
a patient, comprising: determining anatomical information of an
area of the patient that includes the bone defect, including
obtaining dimensions of the bone defect; generating a digital model
of at least the dimensions of the bone defect based on the
anatomical information; planning a three dimensional implant model
using virtual structures generated in the digital model; shaping a
block of porous material into a body based on the three dimensional
implant model, the body having outer dimensions matching the
dimensions of the bone defect, the porous material including a core
material at least partially coated with a layer of biocompatible
metal.
33. The method of claim 32, in which determining anatomical
information of the area of the patient includes taking a
computerized axial tomography (CAT) scan of the area.
34. The method of claim 32, in which determining anatomical
information of the area of the patient includes taking an
impression of the area.
35. The method of claim 32, in which determining anatomical
information of the area of the patient includes taking a visible
light scan of the area.
36. The method of claim 32, in which generating the digital model
includes combining CAT scan and visible light scan data.
37. The method of claim 32, in which shaping the block of porous
material includes machining driven by computer aided design (CAD)
or computer aided manufacturing (CAM).
38. The method of claim 32, in which the implant is a root-form
dental implant that corresponds to the root of a single tooth, the
method further comprising coupling at least one dental prosthesis
to the body.
39. The method of claim 32, further comprising coupling a plurality
of dental prosthesis to the body.
40. The method of claim 32, in which the bone defect includes
multiple tooth root sockets, and in which shaping the block of
porous material includes dimensioning the body to conform to the
multiple tooth root sockets.
41. The method of claim 32, in which shaping the block of porous
material includes forming in the body at least one cavity, the
method further comprising coupling at least one post to the cavity,
and coupling at least one prosthetic tooth to the post.
42. A method of forming an implant configured for a bone defect of
a patient, comprising: determining anatomical information of an
area of the patient that includes the bone defect, including
obtaining dimensions of the bone defect; generating a digital model
of at least the dimensions of the bone defect based on the
anatomical information; planning a three dimensional implant model
using virtual structures generated in the digital mode, the three
dimensional implant model including mathematical representations of
the bone defect surface; shaping a block of porous material into a
body based on the mathematical representations of the bone defect
in the three dimensional implant model, the body having outer
dimensions matching the dimensions of the bone defect, the porous
material including a core material at least partially coated with a
layer of biocompatible metal.
43. The method of claim 42, in which determining anatomical
information of the area of the patient includes taking a
computerized axial tomography (CAT) scan of the area.
44. The method of claim 42, in which determining anatomical
information of the area of the patient includes taking an
impression of the area.
45. The method of claim 42, in which determining anatomical
information of the area of the patient includes taking a visible
light scan of the area.
46. The method of claim 42, in which generating the digital model
includes combining CAT scan and visible light scan data.
47. The method of claim 42, in which shaping the block of porous
material includes machining driven by computer aided design (CAD)
or computer aided manufacturing (CAM).
48. The method of claim 42, in which the implant is a root-form
dental implant that corresponds to the root of a single tooth, the
method further comprising coupling at least one dental prosthesis
to the body.
49. The method of claim 42, further comprising coupling a plurality
of dental prosthesis to the body.
50. The method of claim 42, in which the bone defect includes
multiple tooth root sockets, and in which shaping the block of
porous material includes dimensioning the body to conform to the
multiple tooth root sockets.
51. The method of claim 42, in which shaping the block of porous
material includes forming in the body at least one cavity, the
method further comprising coupling at least one post to the cavity,
and coupling at least one prosthetic tooth to the post.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. patent
application Ser. No. 12/501,163, filed on Jul. 10, 2009.
FIELD OF THE INVENTION
[0002] The present application is directed to endosseous implants
and, more particularly to implants customized for specific patients
and that have features for improved integration with surrounding
bone.
BACKGROUND OF THE INVENTION
[0003] One form of implant is the root-form dental implant which is
placed in extraction site cavities or drilled holes in the mandible
or maxillae to support one or more tooth-shaped prosthesis. The
root-form implant generally has a cylindrical outer surface to
engage bone. While such dental implants may be provided in a
limited number of different lengths and diameters, these sizes may
not match the exact size needed to sufficiently fill an extraction
site to provide prosthesis with proper structural support and
proper aesthetic appearance. This is particularly true if the
extraction site is an irregular shape or is in an area where there
is a ridge defect.
[0004] Another form of dental implant is the plate-form or
blade-form implant which has a flat plate as the anchor to be
placed in the mandible or maxillae, and typically has posts to
support one or more prosthetic teeth or crowns either individually
or structurally interconnected by a bridge. A plate-form implant
may be more stable than a root-form implant in areas where multiple
teeth are missing, facial-lingual bone width is small and/or
alveolar ridge height is limited. The location of the posts on the
implant, however, is preset and may not correspond with the optimal
location of the crowns (or bridge) on the jaw. Special allowances
then need to be made in the crowns or bridge to account for this
which may result in aesthetic compromises. Also, the flat area of
the plate faces facially and lingually and is manually bent at the
time of surgery to conform to the curvature of the jaw. This
procedure is inexact and may damage the implant. A non-fitting
curvature of the plate may also cause gaps between the plate and
adjacent bone that could compromise healing or may require further
time consuming shaping of the bone.
[0005] Furthermore, the blade-form implant has been known to
promote fibro-osseous integration as opposed to osseointegration.
Osseointegration is defined as a direct connection between the
implant and viable bone that results in a very immobile implant. In
fibrous integration, the implant is surrounded by a membrane like
layer of less mineralized tissue that does not hold the implant as
well as bone tissue. While fibrous tissue connection may be
beneficial because it stimulates the periodontal ligament which
cushions the implant from occlusal loads, some degree of
osseointegration must occur to provide adequate support to the
implant. A total fibrous encapsulation of the implant isolates the
implant mechanically from the viable bone of the jaw and endangers
the long term survival of the implant.
[0006] Yet another form of implant is a bone graft. Sometimes it
may be necessary to perform some type of a bone restoring process
before a tooth implant can be placed. For instance, if the patient
has poor dental health and the patient has been wearing non-implant
supported dentures for many years, defects or holes may exist in
the bone. The best treatment option in such cases is to repair the
bone defects. Larger bone defects are currently treated by
harvesting the patients own bone or by using specially treated
cadaver bone. The bone harvesting surgery, however, can be more
invasive then the bone grafting surgery and adds to the patients
discomfort and healing time. Also, whether harvested or cadaver
bone is used, the surgeon must shape these bone pieces by hand at
the time of surgery to fit the defect. Hand shaping is not exact
and gaps between the graft and defect (i.e., bone surface) may
compromise heating. Finally, even if an implant customization
process could be used, it would be difficult to pre-shape natural
bone using automated machining processes without damaging the
bone.
[0007] Thus, an endosseous implant made of a material that is
easily shaped yet provides strong and rapid osseointegration is
desired.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is an enlarged fragmentary view of a porous metal
portion for any of the embodiments herein and in accordance with
one aspect of the present invention.
[0009] FIG. 2 is a side view of a two-stage, root-form dental
implant according to one aspect of the present invention;
[0010] FIG. 3 is a lateral view of a one-piece, root-form dental
implant according to another aspect of the present invention;
[0011] FIG. 4 is a lingual view of the one-piece dental implant of
FIG. 3 shown implanted in a jaw bone;
[0012] FIG. 5 is a lingual view of an alternative one-piece dental
implant according to an aspect of the present invention and shown
implanted in a jaw bone;
[0013] FIG. 6 is a lingual view of a plate-form dental implant
according to another aspect of the present invention;
[0014] FIG. 7 is a lateral view of a post of the plate-form dental
implant of FIG. 6;
[0015] FIG. 8 is a top view of the plate-form dental implant of
FIG. 6;
[0016] FIG. 9 is a lingual view of a plate-form implant according
to another aspect of the present invention;
[0017] FIG. 10 is an anterior, upper view of a mandible shown with
a surgical guide for the placement of the plate-form implants of
FIG. 6 or 9;
[0018] FIG. 11 is an anterior, upper view of a mandible with a
porous block implant to be placed in the mandible in accordance
with another aspect of the present invention;
[0019] FIG. 12 is an anterior view of a mandible and a multi-tooth,
alveolar ridge implant according to another aspect of the present
invention;
[0020] FIG. 13 is an anterior view of a skull and a maxillary,
multi-tooth implant according to another aspect of the present
invention;
[0021] FIG. 14 is a flow chart showing a simplified process for
forming an implant in accordance with the present invention;
[0022] FIG. 15 is a flow chart showing alternative steps for the
process of FIG. 14;
[0023] FIG. 16 is a flow chart showing further alternative steps
for the process of FIG. 14;
[0024] FIG. 17 is a perspective view of an alternative implant in
accordance to another aspect of the invention; and
[0025] FIG. 18 is a side cross-sectional view of yet another
alternative implant in accordance to another aspect of the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] The solution to the problems mentioned above is an
endosseous implant with a porous material that integrates strongly
with bone and may be easily shaped to match the dimensions of a
specific patient. In one form, the porous material is useful as a
bone substitute and/or cell and tissue receptive material. An
example of such a material is produced using Trabecular Metal.RTM.
technology generally available from Zimmer, Inc., of Warsaw, Ind.
Trabecular Metal.RTM. is a trademark of Zimmer Technology, Inc.
Such a material may be formed from a foamed polymer (such as
polyurethane, as one example) that is reduced to a reticulated
vitreous carbon foam substrate or skeleton. The carbon skeleton is
infiltrated and coated with a first layer of biocompatible metal,
such as tantalum, to produce a low density material, and then
plated with a second layer of tantalum to produce a high density
material. The metal is plated on the carbon substrate by a chemical
vapor deposition (CVD) process in the 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 alone, with one another, or with
other metals may also be used.
[0027] Referring to FIG. 1, an example of the porous metal
structure 10 includes a large plurality of ligaments 12 defining
open spaces 14 therebetween, with each ligament 12 generally
including a carbon core 16 covered by a thin film of metal 18 such
as tantalum, for example. The open spaces 14 between ligaments 12
form a matrix of continuous channels having no dead ends, such that
growth of cancellous bone through porous metal structure 10 is
uninhibited. The porous tantalum may include up to 75%-85% or more
void space 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 an implant into the surrounding bone of a
patient's jaw which increases stability (herein, jaw generally
refers to both the mandible and maxillae).
[0028] The rough exterior surface of such porous metal portion has
a relatively high friction coefficient with adjacent bone forming
the bore or cavity that receives the implant to further increase
initial stability. Thus, 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.
[0029] More specifically, for implants that are press-fit into a
bore or cavity in bone, the high level of friction between the
porous material and the bone provides immediate stability post
surgery. The tantalum struts 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.
[0030] 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 press-tit 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
since the implant device does not have the clearance to rotate out
of the indents and within the bore.
[0031] 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,
plate-form, or a larger implant block as described in detail
below).
[0032] Porous structure 10 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 material as follows.
[0033] The porous structure may be infiltrated at least partially
with solid filler material such as a non-resorbable polymer or a
resorbable polymer to provide additional initial mechanical
strength and stability in high arcs of mechanical stress. 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), polymethyl methacrylate (PMMA),
polyetherimide, polysulfone, and polyphenolsulfone. Examples of
resorbable polymers may include poly lactic acid (PLA), poly
glycolic acid (PGA), poly lactic co-glycolic acid (PLGA),
polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV), and
copolymers thereof, polycaprolactone, polyanhydrides, and
polyorthoesters. The resorbable material would resorb as the hone
grows in and replaces it, which maintains the strength and
stability of the implant.
[0034] Referring to FIG. 14, a process 140 is provided to use the
porous material 10 which is fabricated in the process described
above (and indicated as 142 on FIG. 14) for a variety of
patent-specific, porous bone implants. These implants are created
by using imaging technologies that allow either radiographic or
visible light scan of the human body, such as the jaw and
dentition, that can be combined with computer aided design and
computer aided manufacturing (CAD, CAM), and rapid prototyping
technologies to make patient-specific dental products.
[0035] First, a computerized axial tomography (CAT) scan is taken
144 of the area of the patient's body to receive the implant in
order to obtain the patient's dimensions and particularly the
dimensions of the defect or cavity to be filled by the implant.
While the example of a dental implant or jaw implant is used below,
it will be understood that the bone implants may be formed for many
other bones in the body. In the present example, to obtain the
dimensions of the patient, a CAT scan of the patient's head is
taken including the defect and adjacent dentition. This may require
the patient to wear scanning appliances during the scan. Such
appliances may have markers or pins that are detected by the
scanner to indicate the location and shape of important dentition
such as the position of each tooth. For dental applications, the
patient is typically scanned using cone beam CAT technology.
[0036] The CAT scan outputs data in a format known as Diatom data.
Each voxel or 3D element (pixel) is recorded in the Diatom file
with 3D position data and radio-opacity data. A process known as
segmentation is used to create separate 3D rendering of each tissue
type based on the degree of radio-opacity. The resulting rendering
separates areas of hard and soft tissue by portraying the tissue as
different colors on the computer screen and/or by filtering the
tissue types by layers that can be selected on or off in a computer
program. With this technology, the captured data includes
information on structure underlying outer bone surfaces to be
avoided such as nerve location, sinus cavities, and tooth roots.
This information also may include bone density which is important
for further determining the size, shape, and location of the
implant.
[0037] Alternatively, an impression taking technique utilizing an
alginate, silicone, polyvinyl siloxane, polyether, zinc oxide
eugenol paste or other impression material typically used in
dentistry could be used to capture the shape of the bony defect.
The impression material would be injected into a mold around the
defect and then removed to form a negative of the defect. The
impression might also be used to capture the form and location of
adjacent detention to establish "reference" geometry to locate the
defect. A visible light scanner can then be used on the model to
create the digital data to form the 2D or 3D computer
representation of patient anatomy.
[0038] Optionally, a visible light scanner may be used to scan
directly in the mouth, skipping the impression taking step. These
intra-oral scanners create the digital data directly from a scan of
patient anatomy.
[0039] Visible light scans can be used to create point cloud, STL
or IGES data formats that are readily used by computer software to
create 21) or 3D models similar to the models created from the
Diacom data from the CAT scan. These models lack the bone density
data but have an advantage because visible light scans do not
suffer from the starburst or scatter effect created when x-ray
interact with metal fillings in the teeth. It is possible to
combine CAT scan and visible light data to create a composite
digital images of both the dentition and the bone.
[0040] Software then uses the scan data and mathematical algorithms
to create and display 146 a 2D and 3D representation of patient
anatomy and the area to be repaired. Software capable of portraying
the 21) and 3D renderings include, for example, Simplant by
Materialize, Co-Diagnostic by IVS and si-CAT by Sirona. Any of
these, or custom software, could render the non-edentulous area or
defect in the face or jaw that is to be restored. Optionally, once
the virtual existing structure is established, an actual physical
model may be produced 148 if it is deemed helpful to locate
existing dentition, shape the final prosthesis, and/or to help with
surgical planning This may be performed by rapid prototyping
technology. Alternatively, or additionally, a stone model developed
from impressions of the implant may be used in conjunction with the
virtual models.
[0041] After the non-edentulous area or defect, and surrounding
bone, are properly dimensioned on the models, the programs may be
used to build virtual structures inside of the rendered 2D or 3D
environment. Building virtual structures using the rendered
anatomical data as a reference is similar to CAD systems that use
parametric modeling capabilities. Examples of such CAD systems are
Unigraphics or Solidworks. Pointing devices such as trackballs or
mice are used to "pick" elements on the rendered patient anatomy
and then extend from these elements flat and curved surfaces that
are then sewn together into a solid.
[0042] One planning strategy that may be used in the dental field
is to first design 150 the final tooth shape prosthesis and/or any
support posts or abutments on the virtual model, and then size,
shape, and locate 152 the implant or implants on the virtual model,
needed to support those prosthesis. The virtual teeth also can be
used to assess proper bite and chewing function. Rapid prototyping
may then be used to form a coping to build a final prosthesis, and
the posts may be formed by machining as described below. Once the
implant or 3D volume is formed in the model, it can be isolated for
fabrication.
[0043] Referring to FIG. 15, in an alternative procedure 172, the
implant is designed 152a on the 3D model, and then a physical model
of the jaw with the implant is produced 148a from the 3D model. The
abutments and final prosthesis are then formed 150a on the physical
model.
[0044] Referring to FIG. 16, in yet another alternative procedure
174, the abutment, posts, and or final prosthesis are formed 150b
on a physical model made 148b from impressions and/or the 3D
virtual model. The pieces are then scanned and digitized 176 to
place them on the 3D model. Once the supports and virtual teeth are
properly sized and located on the 3D model, the porous implant is
designed 152b.
[0045] Regardless of which procedure is used, once the 3D
representation of the porous block or implant is formed, the
mathematical representations of the surface and 3D volumes are
easily transferred from 3D modeling programs to a Computer Assisted
Manufacturing (CAM) program. CAM programs trace machine paths over
the imported 3D model that will eventually guide any number of
types of machines during the fabrication process. The output of
these programs is computer numerical control (CNC) code that can be
processed by the electronic controls of fabrication equipment.
[0046] To shape 156 a block of porous material, any of the
precursor stages of the porous material can be shaped before the
metal layers are deposited by traditional machining operation
driven by (CAD/CAM) technology. Alternatively, the 3D volume data
may be used to form a mold, and the foam is initially created in
the mold so that the foam is already in a near-net shape (i.e.,
near the final implant shape), it may also be possible to shape the
foamed polymer with desired dimensions by using rapid prototype
processes such as 3D printing or selective laser sintering.
[0047] As another alternative, the carbon or polymer foam can be
shaped by CNC milling equipment such as that made by HAAS
Automation, Inc. This may occur either before or after the first
coating of metal is deposited on the foam. This near-net shaped
carbon foam is then plated or replated with tantalum to create the
porous implant.
[0048] Alternatively, a high density body of the foam already
plated with both layers of the metal could then be cut to the
designed dimensions using CNC controlled EDM (Electrical Discharge
Machining). In this case, the porous material may be provided as a
cube, rectangular prism, or cylinder that is shaped by the EDM
process. The EDM process avoids the tendency to close pores on the
surface of the porous material as occurs with other more
traditional machining and milling.
[0049] In one form, after the porous block is shaped as described
above, it is ready to be implanted. This type of implant may be
used on the jaw when the implant will not directly support teeth
for example. This may occur if the implant is used to build up bone
loss or bone defect areas spaced away from the alveolar such as
when dentures, bridges, or other appliances that do not require
drilling into the implant are to be placed over the area of the jaw
with the implant. It will be appreciated that the implant may be
sufficient for bones other than the jaw.
[0050] In an alternative form, after the porous block is shaped,
other parts of the implant such as support posts and prosthesis are
fixed 158 to the porous block to complete the implant. The CAM
software can add holes to the porous block model if needed to hold
the underlying structures or post that hold the prosthetic teeth.
The CAM software also produces CNC data of both the porous block
with holes and the tooth supporting structures.
[0051] It will be understood that any of the posts in any of the
embodiments described herein can be made of the porous metal
structure 10, such as Trabecular Metal.RTM.. In this case, the
block may be a single piece shaped with integral posts.
Alternatively, the porous metal posts may be formed separately and
subsequently attached to the block.
[0052] It also will be understood that any of the posts in any of
the embodiments described herein, whether or not made of porous
material, may be partially embedded in the porous block during or
after the shaping of the porous block such that the implant is
provided as a single, unitary component.
[0053] In one form, the tooth supporting structures or posts are
made of a solid, strong metal such as titanium that is
biocompatible. CNC machine tools may be used to fabricate these
metal parts. Diffusion bonding, CVD bonding, and the like may be
used to bond the porous metal and titanium elements. It will be
understood, however, that other materials such as metals, ceramics,
and composites, or porous materials as mentioned above, may be used
to form the posts instead. In this way, the entire implant
structure of defect filling porous block and tooth support is
fabricated as a single piece for implantation.
[0054] Once the implant and any required posts and prosthesis are
complete, a surgical guide may be formed 154 as described below,
and the appropriate bores or shaping of the defect or extraction
site may be performed 160 to receive the implant. The implant and
prosthesis are then implanted 162 and 164.
[0055] Referring to FIG. 2, using the methods described above, the
porous material may be shaped to form a number of different
patient-specific dental and maxillofacial implants that provide
excellent integration with surrounding bone. In one example form, a
root-form, two-stage, dental implant 20 is provided to be press-tit
or threaded into a bore in the alveolar ridge to support a
prosthetic tooth. Implant 20 may be fabricated using the
patient-specific design and manufacturing process described above.
Parameters such as the implant length, taper angles, and diameter
anywhere along the taper can be specifically selected for the
individual patient's anatomy. Further the exact location of the
porous material of the implant and other surface roughening can be
specifically selected. The prosthetic section can also be
specifically designed to optimally accommodate the prosthetic
tooth.
[0056] The implant 20 has a body 22 with an apical or anchor
portion 24 and a collar portion 26. The apical portion 24 has a
diameter (d) and body length (l), while the collar portion 26 has a
diameter (cd) and collar length (cl) that were all set or
customized according to the real dimensions of the bore or
extraction site on the patient. In this example, the porous metal
material 28 extends through-out the entire apical portion 24. It
will be appreciated, however, that the porous material may extend
only on parts of the apical portion 24 (e.g., upper, lower, inner,
or outer portions). Likewise, the porous material may or may not
extend on all or part of the collar portion 26. In one form,
implant 20 may have a prosthetic interface 21, such as the Zimmer
Dental, Inc. friction fit hexagon, within a coronal cavity 23
(shown in dash line) and accessible on the collar portion 16 to
assemble and attach an abutment to the implant 20. It will be
understood that while the root-form implant typically has a
generally cylindrical outer surface, in the case of
patient-specific implants here, the implant 20 may have an
irregular shape 25 (shown in dash line) to properly fit a
particular extraction site. It will be appreciated that the shape
is limited only by practicality and structure on the bone to be
avoided (e.g., nerves, blood vessels, etc.).
[0057] Referring to FIGS. 3-4, a one-piece, root-form, dental
implant 30 has an integrally formed anchor portion 32, abutment
portion 34, and collar portion 36. In addition to the dimensions
customized on the two-stage implant 20, here the one-piece implant
30 has additional dimensions that are set depending on the
dimensions of the patients bone and soft tissue. For example, the
implant 30 can be further customized by selecting features such as
the facial (f), lingual (ll), mesial (m) and distal (dl) heights of
the margin or cuff 40 to correspond to the actual height of the
patient's soft tissue. Similarly, the cuff diameter (cud), the cone
height (ch) and angulation (a) may be customized to correspond to
the size and orientation of the prosthetic tooth to be
supported.
[0058] If a non-viable natural tooth is removed though an
atraumatic extraction, it is possible to place an implant very near
the time of extraction with little modification to the extraction
site. Using many of the imaging technologies discussed above, it is
possible to digitize the shape of the extraction socket. The
implant 30 is shown after being press-fit into extraction socket
38. In this case, the anchor portion 32 and the collar 34 may have
an irregular shape to match the shape of the extraction socket 38
as with the implant 20. The high friction between the porous metal
material of the anchor portion 32 and adjacent bone holds the
implant 30 in place during healing.
[0059] Referring to FIG. 5, an implant 50 is provided that is
similar to implant 30 except that here a collar portion 52 of the
implant 50 has outer surfaces 54 that meet at corners or joints 56
(e.g., polygonal) white teeth or barbs 58 are provided on an anchor
portion 51 of the implant 52 to increase retention strength of the
implant within the extraction site. In one form, the barbs 58 are
annular and have a pointed edge pointing coronally.
[0060] Referring to FIGS. 6-8, a plate-form implant 60 may be made
by the process for patient-specific design and manufacturing
described above. The implant 60 has an apical blade or plate
portion 62 for endosseous attachment and that is partially or
substantially made of the porous metal material described herein.
Abutments or posts 64 extend coronally from the plate portion 62 to
support prosthesis 66 such as crowns, bridges, or dentures. The
plate portion 62 is shaped to substantially match the lateral
curvature of the jaw of the specific patient, and the posts 64 may
be located on the plate portion 62 to correspond to the best
locations to support the prosthesis 66. Thus, for example, each
post 64 may have a different facial-lingual distance from the
facial surface 68 of plate portion 62 (FIG. 8), or may have
non-uniform mesial-distal spacing along the plate portion 62.
[0061] The porous metal material has unique properties that ideally
suit it for the blade implant 60 while eliminating the other
disadvantages of the conventional plate-form implant. As mentioned
above, the porous nature of the material allows bone to grow
through the outer surface of the implant and into the body of the
implant. The biologic response to the porous metal material is
relatively rapid and the bone in-growth begins to occur quickly.
These properties of the porous metal material encourage strong
osseointegration rather than fibrous encapsulation.
[0062] On the plate-form implant 60, the length (pl), width (pw),
and depth (ph) of the plate portion 62 were all set to correspond
to the dimensions of a specific patient's pre-planned implantation
site (or extraction site if such a cavity already exists). The
curvature (pc) of the plate portion 62 is set to substantially
match that of the specific patient's jaw. Variations in the depth
of the plate portion 62 may be made by one or more recesses 70 set
back from an outer surface 71 of the implant 60 to bypass anatomic
structures such as nerves or blood vessels on the particular
patient.
[0063] In order to effectively support the prosthesis 66, the posts
64 may be placed at different angles (from an apical-coronal axis
`a`) to maximize aesthetics as well as to properly align with bite
forces. In some forms, the post 64 may have a widened portion 73
forming a shelf or margin 72 extending radially outward from a base
78 for supporting the prosthesis 66. In one case, the margin 72 may
be offset a uniform distance from the alveolar ridge so that it
extends generally linear. Alternatively, the margin 72 may be
scalloped (FIG. 6) and the dimensions of the scalloping may be
different depending on the side of the post 64. Thus, in the
illustrated example, the widened portion 73 may be wider on the
facial side 74 than on the lingual side 76 of the post 64.
Likewise, the mesial and distal sides of the post 64 may also have
different dimensions.
[0064] Referring to FIG. 9, an implant 90, similar to implant 60,
has a base portion 92, and posts 94 (shown in dash line) where the
base portion 92 is at least partially made of the porous metal
material, and may be plate shaped or otherwise. The implant 90 also
was made with custom dimensions as with the other implants herein.
Here, however, crowns 96 are also designed on the 3D modeling
system and fabricated during the design and fabrication process
rather than solely by conventional impression mold procedures as
described previously. In this example, the patient-specific design
process models both the endosseous plate form section and the
prosthetic dentition 96 as well as the posts 94. The resulting
crowns 96 can be pre-assembled to the implant 90 or may be provided
in a kit so that the clinician need only cement or screw retain the
prosthesis 96 to the implant 90.
[0065] Referring to FIG. 10, the software used for shaping the
implants described above may also be used to form (154 on FIG. 14)
a surgical guide 100 by using the same patient-specific data used
to design the implant. For example, for guiding the plate-form
implant 60 into a mandible 102, saddle shaped surgical guide 100
may be formed and shaped with the CAD/CAM methods described above.
The surgical guide 100 is shaped to be located over the particular
mesial-distal/facial-lingual location along the mandible 102. The
surgical guide 100 also has an opening 104, such as an elongate
slot or groove, that is shaped to receive and guide a rotating
surgical burr. The groove 104 guides the burr to control the shape
and depth of the groove. Optionally, a sleeve, made of metal for
example, may fit the groove to further limit lateral motion of the
burr to ensure the burr is limited to within the boundaries of the
groove 104. Once the surgical guide 100, and sleeve if used, is in
place, a trough is cut through the groove 104 and into the bone
102. It will be understood that instead of an elongate groove,
opening 104 may be whatever shape is needed including circular
openings to form a bore for root-form implants or larger irregular
openings for bore-graft type implants described below.
[0066] Referring to FIG. 11, a porous block 110 of porous material
10 has been formed and shaped by the methods described above to fit
the dimensions of a particular defect site 112 on bone 114. Porous
block 110 is a non-edentulous, alveolar ridge implant to reinforce
decayed alveolar but be covered by a non-anchored section of a
denture or bridge, for example. The porous block 110 fits the site
112 better than a hand shaped block and eliminates the need for an
additional surgery to harvest bone. Also, typically when a bone
graft is placed at a site it must be allowed to heal preferably
before the area receives any significant loading and placement of
the denture or bridge over the area. Here, however, the improved
fit of the patient-specific porous block 110 and the unique
properties of the porous metal material permit immediate
restoration.
[0067] It will be appreciated that the porous block may be formed
and shaped into many different shapes, as needed. For example, a
more plate shaped porous block 110a may be used to fill a shallow
or flat defect site 112a, or a generally saddle shaped porous block
110b may be used to build up reduced ridge areas 112b.
[0068] By another alternative, porous block 110 is one of a set of
blocks with pre-set dimensions where each block has different
dimensions to address a specific anatomical condition. In the
illustrated example, each block may be shaped to fit a particular
area of a mandible or maxilla. Thus, one block might be dimensioned
to build-up the alveolar ridge while another block might be
dimensioned to build up the alveolar margin on the mandible, and so
forth. Of course a single block may be dimensioned for multiple
positions on the mandible or maxilla. In this case, the patient is
scanned as described above to determine the dimensions of the
implantation site. Then, the pre-set implant that is the best fit
to the dimensions of the implantation site is selected for use.
[0069] In one form, the blocks are provided without integral
abutments so that the practitioner has the option to use each block
to support a prosthesis or position the block where it does not
support a prosthesis. When support is desired, the block may have a
bore to receive a post or the post may be attached to the block as
described above for the plate-form implant. It will be appreciated
that such pre-dimensioned blocks, or units of blocks, can be
provided for any of the embodiments described herein.
[0070] The implants described so far are designed to treat tooth
loss and bone loss of the alveolar ridge due to tooth decay, bone
atrophy, and minor injury. The same patient-specific design and
manufacturing process as described above can also be used to shape
porous metal implants that repair more severe bone loss due to
traumatic injury such as from automobile accidents, severe
diseases, and cancer that can result in large quantities of bone
being lost and most or all the teeth being lost.
[0071] Referring to FIG. 12, a patient-specific porous metal block
120 has integral posts 122 to support tooth prosthetics. Similar to
implant 60, the post 122 and prosthetic dentition can be modeled
using the same scan information used to create the block 120 and
can be provided pre-assembled or in a kit with the bone grafting
implant 120. Here, however, a much larger section of the mandible
is replaced or repaired including, for example, areas inferior to
the alveolar margin, and as inferior as, or forming, the mental
foramen, mental protuberance, or any other part of the
mandible.
[0072] Referring to FIG. 13, porous metal block 130 may be shaped
using the same patient-specific design and manufacturing processes
as described above. In the illustrated example, block 130 is an
implant 132 used to repair a large section of the maxillo-facial
area 136 of the skull. In this example, the implant includes
prosthetic dentition 134.
[0073] Referring to FIG. 17, various metal inserts can be placed
into the porous construct to join multiple sections of the porous
or solid material. For example, a female threaded insert or anchor
member 202 can be press fit into a porous body or block 200 to hold
a post 204 on which at least one tooth crown may be fastened or
supported thereon. In one form, a hole or window 206 extends from
an outer surface 208 of the porous block 200 and the threaded
insert is placed in the window while the post 204 is placed through
a cavity or bore 210 perpendicular to the window. The post 204 is
then threaded to the threaded bore 212 on the insert 202. It will
be appreciated that either the post 204 or insert 202 can have the
female threads while the other has male threads. It will also be
appreciated that instead of a window, the insert 202 could be
entirely embedded within the porous block by forming the porous
block around the insert.
[0074] Referring to FIG. 18, in another form, multiple pieces of
porous material 200a and 200b, each with the window 206 can be
secured to each other by first placing the first insert 202a and
joining it to post 204. The second porous piece 200b is then
inserted on the post 204 and secured to the post by a second female
threaded insert 202b. Such a construct of multiple porous blocks
and solid sections would allow some variability in the positioning
of the crown retaining posts which may be necessary to achieve
optimal prosthetic placement of the tooth crowns. Variability in
placement would allow the crown to be slightly shifted based on the
occlusion of the patient.
[0075] It will also be understood that an insert or anchor member
214 may extend to the outer surface of the porous body 200 forming
the opening 216 of the cavity 210. So configured, the post 204 is
still received by cavity 210 (shown in dash lines on FIG. 18).
Here, post 204 only engages the anchor member 202 without engaging
porous body 200.
[0076] Finally, it will be understood that the post or member 204
may be provided only to secure the porous bodies to each other
rather than also support a prosthetic tooth. In such a case, post
204 may not extend out of the porous body.
[0077] While this invention ma have 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 including non-dental
bone areas. 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.
* * * * *