U.S. patent application number 10/240549 was filed with the patent office on 2003-08-21 for implant provided with attachment and hole-insert parts, and a method for producing such an implant.
Invention is credited to Hall, Jan.
Application Number | 20030158554 10/240549 |
Document ID | / |
Family ID | 20279140 |
Filed Date | 2003-08-21 |
United States Patent
Application |
20030158554 |
Kind Code |
A1 |
Hall, Jan |
August 21, 2003 |
Implant provided with attachment and hole-insert parts, and a
method for producing such an implant
Abstract
An implant (4) is provided with attachment and hole-insert parts
(2, 3) with surfaces which have different degrees of finishing
and/or degrees of roughness and/or porosities (2f, 2g). Arranged on
the surfaces there is at least one dozen (A-B) in which the degree
of finishing and/or the degree of roughness and/or the porosity is
continuously changed. The changes in porosity in said zones can
mirror continuous or discontinuous changes in the bone in question,
for example the jaw bone or tooth bone. The continuously changed
zones can be obtained with the aid of electrolyte (15) and,
connected to the latter, an anode and cathode arrangement (13, 14).
When establishing the porosity, it is possible to mask different
portions of the respective implant and to control the temperature
of the implant.
Inventors: |
Hall, Jan; (Goteborg,
SE) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ LLP
SUITE 800
1990 M STREET NW
WASHINGTON
DC
20036-3425
US
|
Family ID: |
20279140 |
Appl. No.: |
10/240549 |
Filed: |
April 17, 2003 |
PCT Filed: |
April 3, 2001 |
PCT NO: |
PCT/SE01/00728 |
Current U.S.
Class: |
433/174 ;
438/584 |
Current CPC
Class: |
A61C 8/0022 20130101;
A61F 2002/30859 20130101; A61F 2002/30871 20130101; A61F 2250/0025
20130101; A61F 2002/30321 20130101; A61F 2002/30925 20130101; A61F
2002/30011 20130101; A61F 2002/30873 20130101; A61C 2008/0046
20130101; A61F 2250/0023 20130101 |
Class at
Publication: |
606/72 |
International
Class: |
A61B 017/56 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 4, 2000 |
SE |
0001202-1 |
Claims
1. Implant (4) provided with attachment and hole-insert parts (2,
3) with surfaces (2d, 3a', 3b') which have different degrees of
finishing and/or degrees of roughness, characterized in that the
surfaces are provided with at least one zone (A, B, C, D or E) in
which the degree of finishing and/or the degree of roughness and/or
the porosity (2f, 2g) is continuously changed.
2. Implant according to patent claim 1, characterized in that the
surfaces are provided with two or more zones (A, B, C, D, E) with
continuously changed degrees of finishing and/or degrees of
roughness and/or porosities.
3. Implant according to patent claim 1 or 2, characterized in that,
in the case where there is one zone, the latter extends in the
longitudinal direction of the implant, for example along a
substantial part (B) of the longitudinal direction of the
implant.
4. Implant according to patent claim 1 or 2, characterized in that,
in the case where there are two or more zones (A, B), these extend
in the longitudinal direction of the implant.
5. Implant according to patent claim 1, 2 or 3, characterized in
that, in the case where there is one zone, the latter extends in
the circumferential direction of the implant, e.g. over a
substantial part of the circumferential direction (C', D' or E') of
the implant.
6. Implant according to patent claims 1, 2, 4 or 5, characterized
in that, in the case where there are at least two zones (C', D',
E'), these extend along parts of the circumferential direction (2h)
of the implant.
7. Implant according to any of the preceding patent claims,
characterized in that each zone (C-E or C'-E') has a longitudinal
extent in the longitudinal direction or circumferential direction
(H, 2h) of the implant which is 5% or more of the respective extent
(H, 2h).
8. Implant according to any of patent claims 1, 2, 4, 6 or 7,
characterized in that, in the case where there are two or more
zones (C-E), two zones are arranged next to each other with the
porosity modifications oriented towards or away from each
other.
9. Implant according to any of the preceding claims, characterized
in that the hole-insert part (3) of the implant has one or more
threaded portions, for example a cylindrical threaded portion (4')
and a conical threaded portion (4") at the tip of the implant.
10. Implant according to any of the preceding patent claims,
characterized in that a surface (2d) situated on the attachment
part (2) has a degree of finishing which is obtained by machining,
and in that the degree of roughness/porosity increases continuously
therefrom out towards the tip (9d) of the implant.
11. Method for establishing different degrees of finishing and/or
degrees of machining of outer surfaces (2d, 3a', 3b') of an implant
(4) with attachment and hole-insert parts (2, 3a, 3b),
characterized in that the implant (4) is applied wholly or
partially in or near an electrolyte (15), in that the temperature
of the implant can be controlled, and in that voltage (U) is
applied to an anode and cathode arrangement (8, 14) where a current
(I) initiated by the voltage is passed through the implant.
12. Method according to patent claim 11, characterized in that an
anode (8) included in the arrangement is arranged in a cooling
device, for example in a container (6) which is filled with liquid
nitrogen (7), and in that the implant (4) is connected to the anode
(B) via a boundary surface (6a) in the cooling device, and in that
the cooling of the anode effected by the cooling device (7) is
transmitted to the implant.
13. Method according to patent claim 11 or 12, characterized in
that parts of the implant (4) are masked, and in that the porosity
(2g) is initiated by means of said electrolyte (15) and voltage (U)
on the exposed portions of the implant.
14. Method according to patent claim 13, characterized in that each
zone (C-D) with respective continuously changed degree of finishing
and/or degree of roughness and/or porosity (2g) is initiated with
the aid of voltage and current generated in the anode and cathode
arrangement (8, 14).
15. Method according to patent claim 13 or 14, characterized in
that each zone (C-D) with respective continuously changed degree of
finishing and/or degree of roughness and/or porosity (2g) is
initiated with the aid of the degree of immersion or degree of
application of the implant in the electrolyte (15).
16. Method according to patent claim 13, 14 or 15, characterized in
that each zone with respective continuously changed degree of
finishing and/or degree of roughness and/or porosity is initiated
with the aid of the degree of masking of the implant.
17. Method according to patent claim 13, 14 or 15, characterized in
that each zone with respective continuously changed degree of
finishing and/or degree of roughness and/or porosity is initiated
by voltage and current generated in the anode and cathode
arrangement, the degree of immersion or degree of application in
the electrolyte, the degree of masking and temperature control,
preferably vigorous cooling.
18. Arrangement for providing an implant with different degrees of
finishing and/or machining and/or degrees of porosity (2f, 2g) on
the surfaces (4', 4") of the implant, characterized in that the
range includes implants with continuously decreasing or increasing
porosity in one or more zones (C-D).
19. Arrangement according to patent claim 18, characterized in that
the continuously decreasing or increasing porosity in each zone is
varied between different implants in the range.
20. Arrangement according to patent claim 15 or 16, characterized
in that the implants in the range have different continuously
decreasing zones in the longitudinal and/or circumferential
directions (H, 2b) of the implant.
Description
[0001] The present invention relates to an implant provided with
attachment and hole-insert parts which have surfaces with different
degrees of finishing and/or degrees of roughness and/or porosities.
It also relates to a method for establishing different degrees of
finishing and/or degrees of machining and/or porosities on outer
surfaces of an implant with attachment and hole-insert parts. The
invention also relates to an arrangement for providing a range of
implants which are optimized for different dental situations.
[0002] It is already known to use implants which have upper parts
for attachment of spacer elements or other superstructures and,
below said upper parts, lower parts which are intended to be
inserted in a hole in the bone, for example in the jaw bone or
tooth bone. The attachment part in question is arranged on the jaw
bone which, after the implant has become incorporated, is exposed
for connection of the spacer or superstructure in question. Said
lower parts can be designed with threads and it is possible to use
straight cylindrical thread portions which at the bottom merge into
a cone-shaped threaded portion at the tip of the implant.
[0003] For examples of implants, reference may be made inter alia
to WO 97/43976 and WO 97/03621.
[0004] It is also already known to provide the different surfaces
of the implant with different finishes and/or machine treatments
and/or porosities. In this connection reference may be made to,
inter alia, the Swedish applications 9901971-3, 9901973-9 and
9901974-7 filed by the same applicant as the present application.
Reference may also be made to U.S. Pat. Nos. 5,571,017, 5,829,978,
5,842,865, 5,885,079, 5,947,735 and 5,989,027.
[0005] From the above references it is already known to use
different degrees of porosity on the surfaces in question. There
are different opinions concerning the sizes of the pores and their
applications. Thus, it has previously been proposed that the
surface of the attachment part be made of a machined smooth
surface, while the threads on the lower parts of the implant can be
made with porosities of different sizes, i.e. different degrees of
roughness. From the above references it is also already known to
provide different parts along the longitudinal extent of the
implant with different degrees of porosity. It is known that one
zone with a first degree of porosity on the surface changes
abruptly into a second or adjacent zone having a second degree of
porosity.
[0006] In the case of implants, for example in dentistry, it is
preferable to avoid abrupt changes between different zones with
different degrees of porosity and instead provide one or more
marked or extended zones in which the change of porosity is
continuously modified. Thus, in a marked or extended zone, a first
porosity can be present at one end of the zone and can condense or
decrease towards the other end of the zone. In one embodiment, the
zone in question will be able to extend along at least the greater
part of the longitudinal extent of the implant. Thus, for example,
a porosity of zero, or close to zero, will be present on the
surface at the attachment part of the implant, i.e. the degree of
finishing and/or degree of machining is high on this surface.
Thereafter, i.e. on the surface of the thread(s) of the implant,
the porosity will start with a low value and will increase
gradually in the longitudinal direction of the implant towards the
tip of the implant, or vice versa. The increase in the porosity of
the implant along the longitudinal extent of the implant can be
made linear or progressive. Implants will alternatively be able to
be provided with two or more such marked zones where the porosity
is linearly or progressively increasing or decreasing from one end
of the respective zone to the other end of the zone. In a further
alternative embodiment, the porosity or the porosities will be able
to increase linearly or progressively in the circumferential
directions of the implant. In a further alternative, the porosities
will be able to form marked islands on the outer surfaces of the
implant, which islands are thus situated on finished and/or
machined surfaces.
[0007] The variations in the degrees of finishing and/or machining
and/or the porosities will be able to meet different requirements
of dental situations, for example, where implants must be able to
be applied in different types of bone, for example tooth bone and
jaw bone in the upper jaw, tooth bone and jaw bone in the front and
inner areas of the lower jaw, etc. The porosities must be able to
provide different possibilities of introducing or anchoring the
implant in tooth bones or jaw bones of different degrees of
softness or hardness. In some cases the porosities are also
intended to be used as depots for bone-growth-stimulating or
bone-growth-promoting agents, and the movement of these agents from
the depots to the surrounding bone must be controlled and varied
according to the different dental situations The porosities must
therefore be able to mirror the tooth bone structure and provide
optimum insertion and anchoring functions for the implant in the
respective bone and optimum functions concerning the release of the
bone-growth-stimulating agents.
[0008] There is therefore a need to be able to provide implants
with optimum porosities, and the continuous or soft transitions in
the marked zones are dictated by the fact that the changes or
differences in the different bone types or bone conditions consist
of indistinct transitions or changes, i.e. the hardness or softness
of a bone's structure often represents a soft or continuous change
in the patient's jaw bone or tooth bone. From the purely technical
aspect, there are great problems in providing said continuously
decreasing or increasing changes in the degrees of porosity in
marked zones of the implant. The main object of the present
invention is to solve this problem.
[0009] There is a need to be able to make available a range of
implants which have different decreasing porosity functions in
marked zones, i.e. there is a need for differently structured
porosity arrangements on different implants. The invention also
solves this problem. By virtue of having a range of implants with
different porosity changes in one or more zones, an optimum implant
can be used for the respective dental situation. It is known that
the porosity affords a greater surface for union with surrounding
bone. In the case of especially soft bone structures, it is of
interest to be able to offer the large surfaces for union which
high porosities afford. In some situations it may be of interest
also to provide the outer surface of the attachment part with
porosity.
[0010] The feature which can principally be regarded as
characterizing an implant according to the invention is that the
surfaces are provided with at least one zone in which the degree of
finishing and/or the degree of roughness and/or the porosity is
continuously changed.
[0011] In embodiments of the inventive concept, the implant has a
single zone with continuously decreasing or increasing porosity.
Some of the surface or surfaces, for example the surface of the
attachment part, can be formed with a low, minimal porosity. In
further illustrative embodiments, two or more zones can be arranged
along the longitudinal and/or circumferential directions of the
implant. In a preferred embodiment, each zone will take up a
longitudinal or circumferential value which is 5% or more of the
respective extent. The invention is preferably used in connection
with implants having an outer thread or threads.
[0012] The feature which can principally be regarded as
characterizing a method according to the invention is that the
implant is applied wholly or partially in or near an electrolyte,
and that the implant is subjected to cooling which is preferably
substantial and that voltage is applied to an anode and cathode
arrangement where the implant is arranged so that a current
produced by the voltage is passed through the implant to establish
said porosity. Liquid nitrogen can be used for cooling, and the
implant can be connected to an anode included in the anode and
cathode arrangement at a boundary surface in the container. The
anode is situated in the nitrogen in the container and the cooling
of the anode effected by the nitrogen is transmitted to the implant
by means of its mechanical contact with the anode. The implant is
immersed wholly or partially in electrolyte and a continuous
transition zone is obtained by the fact that, in parts of the
implant not immersed, the electrolyte is taken up in a decreasing
amount along the height of the implant and by the fact that the
decreasing amount gives rise to the continuous change in the
porosity. In alternative embodiments, parts of the implant can be
masked so that the electrolyte is prevented from gaining access to
the masked portions and is thus prevented from forming porosities.
Different sizes of porosities are determined inter alia by means of
the electrolyte composition and/or changes in voltage and/or
current.
[0013] The novel arrangement is characterized mainly by the fact
that a number of implants are provided with different continuously
decreasing changes in porosity in one or more zones and by the fact
that the different implants in the range can be used to achieve
optimum solutions to different dental situations.
[0014] Further embodiments of the implant, method and arrangement
according to the above will be evident from the attached subclaims
relating to the independent claims for the implant, method and
arrangement, respectively.
[0015] By means of what has been proposed above it is possible to
offer new types of implants which open up new approaches to and
optimum solutions for dental situations. By means of the invention
it is also possible, in an economically advantageous manner, to
manufacture implants with porosities of the type in question in
marked zones. It is therefore not necessary to use the abruptly
changing zones in the known arrangements, with the different
degrees of roughness/porosity which characterize the prior art.
There are a great many possible variations for producing implants
of this type and the novel method makes available a production
technique which permits said variations in an advantageous manner.
The invention also permits greater or lesser porosity on the
surface of the attachment part if the priority is to eliminate
risks of infection on the surface and to promote bone union
(greater surfaces for incorporation of bone).
[0016] The main characteristics of an implant, a method and an
arrangement according to the invention will be described below with
reference to the attached drawings, in which:
[0017] FIG. 1 is a diagram showing the porosity or roughness as a
function of the implant length L, and a curve indicating a porosity
continuously increasing towards one end of the implant,
[0018] FIG. 2 is a side view showing an implant related to the
diagram in FIG. 1, and where the implant has a certain degree of
finishing on its left part (attachment part) and where the porosity
or roughness increases as the curve rises in FIG. 1 towards the
free end of the implant,
[0019] FIG. 3 is a diagram showing voltage and current parameters
in an applied electrochemical process,
[0020] FIG. 4 is a side view and schematic representation showing
an electrolyte used in the electrochemical process, and an anode
and cathode arrangement arranged in this,
[0021] FIG. 5 is a schematic representation, enlarged in relation
to FIG. 4, showing the application of the implant in relation to a
suitable cooling unit and electrolyte, and where the implant has
been masked on parts of its length,
[0022] FIG. 6 is a side view showing another masking in relation to
the example in FIG. 5,
[0023] FIG. 7 is a side view showing the implant with a number of
different zones with continuously decreasing porosity and zones of
very low porosity,
[0024] FIG. 8 is a vertical section showing decreasing zones in the
circumferential direction of the implant,
[0025] FIG. 9 is a vertical section showing the application of the
implant to an anode part which extends into the cooling
unit/container unit according to FIG. 4, and where the porosity
increases towards the free or lower end of the implant,
[0026] FIG. 10 is a vertical section/vertical view showing a
further design of the connection of the implant to the cooling unit
and maskings for establishing substantial porosity-free zones,
[0027] FIG. 11 is a vertical section/vertical view showing a
reverse application to the cooling unit compared to the embodiment
according to FIG. 10,
[0028] FIG. 12 is a vertical section/vertical view showing the
application of the implant to the cooling unit with the implant
lying in such a way that a varied porosity is obtained in the
circumferential direction of the implant, and
[0029] FIG. 13 shows an example of a dental implant produced
according to the invention.
[0030] The varying or continuously modified porosity in the zone or
zones concerned can be obtained in different ways. In the present
case, an electrochemical method is preferably used which can be of
a type known per se. As the electrochemical method which is
described in the Swedish patent applications 9901971-3 and
9901974-7 is highly suitable for use in this context, reference is
made to these patent applications which were filed by the same
applicant as that of the present patent application. As will be
evident from the electrochemical method already described, the
oxide layer on the surface of the implant can be formed and varied
by adjusting various parameters in the process, which parameters
can include the composition of the electrolyte, the voltage and
current in the anode and cathode arrangement used, the electrode
geometry, the treatment time, etc. To obtain the features according
to the present invention, the implant requires to be applied to and
acted on by the electrolyte in the manner described below. However,
the electrochemical process will not be described in detail here,
and instead reference is made to said patent applications
[0031] In FIG. 1, a curve 1 indicates a continuously modified
roughness/porosity along the length of an implant. The change here
is assumed to be obtained along a zone or zones of the implant. In
the present case, a low degree of roughness/porosity is used at one
end of the implant, which low degree of roughness can have a value
of 0.7 .mu.m. After a predetermined extent along the implant, the
roughness in this case changes distinctly to a value of 1.0 .mu.M,
for example. Thereafter, the roughness increases in the zone or
zones in question up to a value of 1.5 .mu.m. This increase
represents a continuous change and can be linear and can have a
progressiveness in accordance with the line of the curve 1.
[0032] The implant shown diagrammatically in FIG. 2 is related to
the diagram according to FIG. 1 such that a distance A on the
implant corresponds to the distance 1 in the diagram. The length or
distance B corresponds to the curve length 1 to 1'. As will be seen
from FIG. 2, the distance A represents an attachment part 2 for a
spacer element, and the distance B represents a hole-insert part 3
of an implant 4. The implant 4 has a design characteristic to the
invention. In this case, the distances A and B form two different
zones in which there is a continuous or progressive
roughness/porosity. For example, the attachment part 2 can have
less roughness/porosity along its length or a roughness/porosity
which is lowest at an end surface 2a and increases gradually
towards the bottom surface 2a'. The lower degree of
roughness/porosity established at the end surface 2a is indicated
by 2b, while the gently increasing roughness/porosity at the bottom
surface 2a' is indicated by 2c. Thus, the outer surface 2d can be
considered to have a low and gently increasing roughness/porosity
viewed from the end surface 2a. According to the invention, the
degree of roughness/porosity can be varied, and in one illustrative
embodiment the outer surface 2d can be entirely without porosity
markings or can have extremely low porosity, i.e. the outer surface
2d is very finely machined. In the illustrative embodiment, the
extent B of the implant is arranged such that there is a single
zone, in which zone therefore a low roughness/porosity is present
at the upper end 3a of the hole-insert part 3 and a relatively high
(cf. FIG. 1) roughness/porosity is present at the end 3b of the
hole-insert part.
[0033] FIG. 3 shows typical current and voltage values in the
electrochemical process (see also said Swedish patent
applications). To establish high degrees of roughness and porosity,
a current value of 0.2 ampere is used in this case, and the voltage
value can extend up to a level of 300 volts, for example. The
current curve is indicated by I and the voltage curve by U. The
horizontal axis represents a time axis t. In accordance with the
previously known method according to said Swedish patent
applications, a certain spark formation occurs in the area 5 on the
voltage curve U. The spark formation occurs along the whole of the
implant surface and gives rise to pore formation and increased
surface roughness.
[0034] FIG. 4 is a diagrammatic representation showing an
electrolyte 15 used in the electrochemical process, and an anode
and cathode arrangement applied in the latter. The anode 8 which
can be formed by the implant itself or can consist of a part which
is mechanically coupled to the implant 9 is connected to the
positive potential 10 of an energy source 11. The positive
connection of the anode and cathode arrangement is indicated by 13.
The negative potential 12 of the energy source is correspondingly
connected to the cathode 14 of the anode and cathode arrangement.
As has been indicated in the figure, the lower parts 9a of the
implant are dipped in the electrolyte 15. Capillary and other
suction and evaporation phenomena mean that electrolyte is taken up
in decreasing quantity upwards and along the outer surface parts 9b
of the implant which are situated above the immersed parts 9a of
the implant. The effect of this is that the immersed parts 9a are
exposed to a chemical treatment which gives a greater porosity than
the porosity of those parts 9b which are situated above the parts
9a. This has the effect that a zone is obtained on the parts 9b
where the porosity is continuously modified or decreases in the
upward direction.
[0035] The kinetics of the electrochemical process can be
controlled by varying the temperature of the implant. The porosity
and surface roughness of the parts 9b can thus be regulated by
cooling the implant. FIG. 4 shows a cooling arrangement 6 which in
this case consists of a container 6a for liquid nitrogen 7. In the
illustrative embodiment shown, the anode 8 of the anode and cathode
arrangement is arranged in or extends through the interior 8 of the
container and is in this way subjected to a cooling function
exerted by the liquid nitrogen.
[0036] It will be appreciated from the above and from FIG. 5 that
the position of the zone can be changed with the aid of the degree
of immersion of the implant in the electrolyte 15. In FIG. 5, the
degree of immersion can be adjusted in the directions of the arrows
16. It will also be appreciated that the suction forces along the
surface 9c of the implant mean greater electrolyte accumulation 15a
at the lower parts 9d of the implant than at parts 9b which are
situated higher up. The electrolyte can thus influence the implant
with a greater amount of electrolyte at said lower parts 9d than at
the parts 9c situated higher up, which also indicates said
continuous or progressive change or reduction of the porosity
towards the upper parts of the implant. In accordance with the
embodiment according to FIG. 5, masking functions are also used
which correspond to those indicated in said Swedish applications.
The maskings can consist of tube-shaped parts 17, 18 of Teflon,
latex, etc. Alternatively, lacquers can be used. The maskings are
intended to prevent porosity occurring on the masked parts during
the electrochemical process. In the present case, the tube part 17
or the like masks an area 9f which is situated under the spacer
attachment part 2d. The last-mentioned part is in turn masked by
the tube or the lacquer 18. Said areas 9f and 2d therefore have a
very low porosity or no porosity at all, depending on previous
treatment or working.
[0037] According to FIG. 6, it is also possible to use the masking
function to form islands or areas 9g, 9b which extend across parts
of the surfaces of the implant. In these areas 9g, 9h, the porosity
continuously changes from the lower parts of the implant in the
direction towards the upper parts of the implant. In this case the
masking has been done with a tube, a lacquer, etc. 19 leaving the
surface open for said areas. In the present case, the implant 9d is
thus given a porosity which continuously increases or changes from
the lower part up towards the masking 19, which increase or change
merges into said areas 9g, 9h.
[0038] According to the invention, masking functions can thus be
used, and during the total process of coating the implant 4 with
one or more zones of decreasing or increasing porosity, the
positions of the maskings can be rearranged or changed. According
to FIG. 7, several zones C, D and E can be established along the
longitudinal extent or height of the implant.
[0039] According to FIG. 8, different zones C', D' and E' can also
be established in the circumferential direction where each zone,
for example the zone 19, has a greater porosity at the end 19a than
at the end 19b and the porosity continuously decreases within the
zone.
[0040] It is also possible to influence the degree of
roughness/porosity by mechanical working after the electrochemical
treatment has been carried out.
[0041] FIG. 9 shows in more detail the mechanical connection
between the implant 4 and the anode part 8 according to FIG. 4 The
anode part 8 can have a recess for the spacer attachment part 2d of
the implant, which recess is indicated by 8a. The size of the
recess is adapted to the spacer attachment part so that the implant
is secured in the anode part 8. This arrangement also provides
masking for the outer surface 2d of the part 2. It will be evident
from this embodiment that a large mechanical contact surface is
present between the implant and the anode 8, which contact surface
is established by means of the top surface 2a of the implant and
the bottom surface 8a' of the recess 8a. The implant and the anode
must be pressed against each other with forces F and F'
respectively. Upon connection of the anode and cathode arrangement
13, 14 with a voltage according to the above, said porosity is
established at the lower parts of the implant, while at the same
time the implant is exposed to a very great cooling effect from the
liquid nitrogen in the container 6a. The cooling function is thus
established via the bottom part 6b of the cooling arrangement. The
anode part 8 and the bottom part 6b can be sealed by means of a
sealing ring 21 or the like.
[0042] FIG. 10 shows another means of connection of the implant 4
to the anode part 8 which in this case does not have the recess
(cf. 8a) indicated in FIG. 9. In this case, the top surface 2a of
the spacer attachment member 2 is secured to the bottom surface 8a"
of the anode by securing means of a suitable type. In this case,
the anode part 8 is sealed off by sealing means or members 21' from
the inner wall 6a' of the container 6a. The arrangement can be
provided with guides 22 or equivalent acted on in the direction 23,
for example by means of actuating members 24 which can consist of
or comprise mechanical drive wheels (for example gear wheels). In
this case, the implant 4 is provided with masks 25, 26 of the type
indicated above. A characteristic of the zones is that the porosity
is greatest at the bottom of each zone and decreases upwards to the
spacer attachment part 2.
[0043] In FIG. 11, the implant is turned around compared to the
case in FIG. 10. The free end surface 9d' of the implant is in this
case secured in the recess 8a of the anode in the same way as in
FIG. 10. Alternatively, the anode in this case can comprise a
recess in the same way as in FIG. 9, which recess is adapted to the
tip (free end) of the implant 4. In this case too, the implant, the
anode, etc. are displaceable in the direction of the arrows 25 in
order to provide for immersion in the electrolyte 15 to a greater
or lesser extent. In this case, the coarse porosity is established
at the end surface 2a of the spacer attachment part 2 and decreases
towards the tree end 9d' of the implant. In this case there is
therefore only one zone.
[0044] In the embodiment according to FIG. 12, the implant is in
principle arranged horizontally in relation to the surface of the
electrolyte 15. In this case too, the anode 8 has a recess 8a in
which the spacer attachment part 2 is connected. The thus
horizontally arranged implant can be immersed to a greater or
lesser extent in the electrolyte 15 in the directions of the arrows
26. In this way, porosity of different sizes is present about the
circumferential direction of the implant, cf. FIG. 8.
[0045] In accordance with the above, the implant itself can only
form the anode in said anode and cathode arrangement. The implant
extends through the bottom part 6b of the container 6 according to
the example above. In FIG. 2, the outer surfaces of the hole-insert
part have been indicated by 3a' and 3b'. The degrees of porosity
have been symbolized by 2f and 2g, respectively. In FIG. 7, the
length or height of the implant is indicated by H. A marked or
extended zone, for example one of zones C, D or E, means that the
extent of the zone in the direction H of the implant must be at
least 5% of the value of H. Correspondingly, the decreasing
porosity or porosities in the circumferential direction, for
example the circumferential direction C' in FIG. 8, will assume a
value of at least 5% of the total circumference 2h in said extended
or marked zone. In FIG. 10, a first thread of a cylindrical portion
is indicated by 4' and a thread on the conical tipped part of the
implant is indicated by 4". The degree of immersion of the implant
in the electrolyte 15 depends on where and how long the marked or
extended zone for the continuously changed porosity is to be and/or
on the degree of masking of the implant. According to the
invention, it is also possible to provide a range of implants which
are basically the same, but with different porosity changes within
one or more marked zones, different zones, etc. Reference is made
here to the different embodiments according to the above, where it
is clear that implants can have different numbers of marked zones
with different porosity changes, i.e. changes with different sizes
of the porosities and different changes of these porosities. With
such a range, it is possible to choose the implant which in the
given dental situation is considered to give the best result or the
most optimum result in said dental situation. The choice can be
made on the basis of practical experience or by assigning different
dental situations to different implants.
[0046] FIG. 13 shows an example of a dental implant of a type known
per se (Brnemark System.RTM.) which has been provided with a
surface structure according to the invention The implant is made of
titanium and has a machined surface. The machined surface remains
on the spacer attachment part 2, the flange, while the threaded
part, the hole-insert part 3, has a roughness/porosity produced
according to the above method and continuously decreasing along the
length of the implant from the flange.
[0047] The figure also shows two enlargements taken on the threaded
part, and on the curved part at the spacer attachment part, where
the machined main surface has been acted on to a lesser extent by
the electrolyte treatment.
[0048] The invention is not limited to the embodiment shown above
by way of example, and instead it can be modified within the scope
of the attached patent claims and the inventive concept.
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