U.S. patent application number 13/862608 was filed with the patent office on 2013-11-07 for dental implant set.
This patent application is currently assigned to DENTSPLY INTERNATIONAL INC.. The applicant listed for this patent is Daniel MAGNUSSON, Brita OLSSON. Invention is credited to Daniel MAGNUSSON, Brita OLSSON.
Application Number | 20130295521 13/862608 |
Document ID | / |
Family ID | 46062052 |
Filed Date | 2013-11-07 |
United States Patent
Application |
20130295521 |
Kind Code |
A1 |
OLSSON; Brita ; et
al. |
November 7, 2013 |
DENTAL IMPLANT SET
Abstract
The present invention relates to a dental implant set comprising
a fixture for insertion into a bore hole arranged in bone tissue
having first indexing means, a dental component having second
indexing means and being adaptable to the fixture in an engaged
position where the first and second indexing means mate and in an
intermediate position where the dental component and the fixture
are in contact with each other but the first and the second
indexing means do not mate, and a fixation screw being adapted for
fixating the dental component to the fixture. The present invention
also relates to a method for attaching a dental component to a
dental fixture.
Inventors: |
OLSSON; Brita; (Goteborg,
SE) ; MAGNUSSON; Daniel; (Hono, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OLSSON; Brita
MAGNUSSON; Daniel |
Goteborg
Hono |
|
SE
SE |
|
|
Assignee: |
DENTSPLY INTERNATIONAL INC.
York
PA
|
Family ID: |
46062052 |
Appl. No.: |
13/862608 |
Filed: |
April 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61635345 |
Apr 19, 2012 |
|
|
|
Current U.S.
Class: |
433/173 |
Current CPC
Class: |
A61C 8/0066 20130101;
A61C 8/0089 20130101; A61C 8/008 20130101; A61C 8/0068 20130101;
A61C 8/0069 20130101; A61C 8/0074 20130101; A61C 8/0013
20130101 |
Class at
Publication: |
433/173 |
International
Class: |
A61C 8/00 20060101
A61C008/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 19, 2012 |
EP |
12164822.4 |
Claims
1. A dental implant set comprising: a fixture for insertion into a
bore hole arranged in bone tissue having first indexing means, a
dental component having second indexing means and being adaptable
to the fixture in an engaged position where the first and second
indexing means mate and in an intermediate position where the
dental component and the fixture are in contact with each other but
the first and the second indexing means do not mate, and a fixation
screw being adapted for fixating the dental component to the
fixture, wherein in the intermediate position: a first contacting
surface of the fixation screw is arranged to abut a second
contacting surface of the dental component and a third contacting
surface of the dental component is arranged to abut a fourth
contacting surface of the fixture, and wherein the dental implant
set is arranged such that the maximum capacity to transmit torque
is greater between the first and second contacting surfaces than
between the third and fourth contacting surfaces, so that when the
fixation screw is subject to a torque and an axial force applied by
a user, the dental component will rotate with the fixation
screw.
2. A dental implant set according to claim 1, wherein in the
engaged position the dental component is arranged such that the
fixation screw may rotate relative the dental component.
3. A dental implant set according to claim 1, wherein the fixture
further comprises an axis, and at least one of the first and second
contacting surfaces forms a smaller angle to the axis than at least
one of the third and fourth contacting surfaces.
4. A dental implant set according to claim 1, wherein the fixture
further comprises an axis, and wherein the first and second
contacting surfaces forms an essentially equal first angle to the
axis, and wherein the third and fourth contacting surfaces forms an
essentially equal second angle to the axis.
5. A dental implant set according to claims 3, wherein at least one
of the first and second contacting surfaces forms a first angle of
5.degree.-30.degree. relative to the axis of the fixture, and
wherein at least one of the third and fourth contacting surfaces
forms a second angle of 50.degree.-70.degree. relative to the axis
of the fixture.
6. A dental implant set according to claims 4, wherein at least one
of the first and second contacting surfaces forms a first angle of
5.degree.-30.degree. relative to the axis of the fixture, and
wherein at least one of the third and fourth contacting surfaces
forms a second angle of 50.degree.-70.degree. relative to the axis
of the fixture.
7. A dental implant set according to claim 1, wherein at least one
of the contacting surfaces have different surface characteristics
from the others in order to modify the coefficient of friction
between the first and second contacting surfaces or between the
third and fourth contacting surfaces.
8. A dental implant set according to claim 1, wherein at least one
of the contacting surfaces is coated with a material in order to
modify the coefficient of friction between the first and second
contacting surfaces or between the third and fourth contacting
surfaces.
9. A dental implant set according to claim 1, wherein at least one
of the contacting surfaces are surface treated in order to modify
the coefficient of friction between the first and second contacting
surfaces or between the third and fourth contacting surfaces.
10. A dental implant set according to claim 1, wherein the
contacting surfaces are provided such that a first frictional force
between the first and second contacting surfaces is larger for a
given applied axial force than a second frictional force between
the third and fourth contacting surfaces for the same applied axial
force.
11. A dental implant set according to claim 1, wherein the fixture
further comprises a bore provided with an internal thread, and
wherein the fixation screw further comprises an external thread
adapted to engage said thread of the bore of the fixture, and
wherein the length of the fixation screw is adapted such that the
external thread of the fixation screw is positioned coronally to
the thread of the bore of the fixture in said intermediate
position.
12. A dental implant set according to claim 1, wherein the length
of the fixation screw is adapted such that the external thread of
the fixation screw can engage the thread of the bore of the fixture
when the fixture and the dental component are arranged in the
engaged position.
13. A dental implant set according to claim 1, wherein the first
indexing means comprises indexing depressions extending in the
radial direction from a first surface of the fixture and the second
indexing means comprises indexing projections extending in the
radial direction from a second surface of the dental component, and
wherein the indexing depressions and projections are distributed
along the circumference of the first and second surfaces of the
fixture and the dental component respectively, such that the dental
component can only mate in certain specific rotational orientations
with respect to the fixture.
14. A dental implant set according to claim 13, wherein the dental
component further comprises at least one first indexing projection
having an apical end, and at least two second indexing projections,
each one having an apical end, and wherein the fixture further
comprises at least one first indexing depression having a coronal
end, and at least two second indexing depressions, each one having
a coronal end, wherein the apical ends of said at least two second
indexing projections are located apically of the apical end of the
first indexing projection and/or the coronal ends of said at least
two second indexing depressions are located coronally of the
coronal end of the first indexing depression, wherein the first and
second indexing projections and the first and second indexing
depressions are distributed along the circumference of the dental
component and the fixture, respectively, in such way that the
dental component can only mate in one rotational orientation with
respect to the fixture, wherein the first indexing projection is
only enabled to mate with the first indexing depression after said
at least two second indexing projections have mated with said at
least two second indexing depressions.
15. A method for the connection of a dental component to a fixture
having first indexing means by means of a fixation screw, said
dental component having second indexing means and being arranged to
engage the fixture in an engaged position when the first and second
indexing means mate, said method comprising the steps of:
positioning the dental component in an intermediate position in
which the dental component and the fixture are in contact with each
other but the first and second indexing means do not mate, and
applying a torque and an axial force to the fixation screw and
thereby rotate the fixation screw in relation to the fixture,
wherein the dental component rotates accordingly.
16. A method according to claim 15, wherein, a first torque may be
transferred from the fixation screw via a first pair of contacting
surfaces to the dental component, and a second torque may be
transferred from the dental component via a second pair of
contacting surfaces to the fixture, wherein the maximum capacity of
transferring torque at said first pair of contacting surfaces being
larger than the maximum capacity of transferring torque at said
second pair of contacting surfaces, thereby allowing the dental
component to rotate with the fixation screw.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This patent application claims the benefit of and priority
to EP Application Ser No. 12164822.4, filed on Apr. 19, 2012 and
U.S. Provisional Patent Application Ser. No. 61/635,345, filed on
Apr. 19, 2012, which are herein incorporated by reference for all
purposes.
TECHNICAL FIELD OF THE INVENTION
[0002] The present invention relates to a dental implant set
comprising a fixture, a dental component and a fixation screw. The
invention also relates to a method for the connection of a dental
component to a fixture by the means of a fixation screw.
BACKGROUND OF THE INVENTION
[0003] A frequent way today to restore a damaged or lost tooth is
to install a dental implant comprising a fixture in the adjacent
jawbone tissue (maxilla or mandible) and replace the damaged or
lost tooth with a dental prosthesis. A superstructure, such as an
abutment, may be used as a connection between the dental prosthesis
and the installed fixture.
[0004] A common technique to fasten the abutment to the fixture is
by using an abutment screw. Usually the abutment screw has an
externally threaded portion and a screw head and may thereby be
screwed into the fixture which has an internal bore with a
corresponding threaded portion. When fastening the abutment to the
fixture, the abutment is first mated to the fixture and then the
abutment screw is inserted into a through-hole of the abutment so
that the threaded portion of the abutment screw engages the
internal threading of the fixture and the screw head is seated on a
seat in the through-hole of the abutment.
[0005] Other dental components may also need to be attached to the
fixture during the process of preparing and installing a dental
prosthesis. Such dental components may e.g. be healing caps and
impression elements. Together with the fixture, the different
components may be referred to as a dental implant set.
[0006] Furthermore, there are various fixture configurations. For
instance, a fixture may have a flat topped coronal head portion,
which may be installed in any rotational position relative the jaw
bone. Another type of fixture configuration is a fixture having a
sloped coronal end portion in which the length of the fixture is
greater on the lingual side than the buccal side in order to match
the contour of the jawbone. Similarly, to the above described
fixture/jawbone-interface, for a superstructure, such as an
abutment, there may be an abutment/fixture-interface in which the
abutment should only be positioned in one way relative to the
fixture, e.g. an abutment having a sloped portion matching the
sloped head portion of a fixture. This is one type of asymmetrical
superstructure, in which the asymmetrical feature should be
positioned in a desired rotational relationship to either or both
of the fixture and the jawbone with surrounding teeth. Thus, with
regard to these interfaces, it would be desirable to ensure that
the dentist connects the superstructure with a correct rotational
orientation relative to certain fixtures or jawbone features. Also
for patient-specific or customized superstructures, such as a
customized abutment, such superstructure may often be made with a
certain intended rotational orientation relative to the fixture and
surrounding contours. Thus, also in these cases it would be
desirable to ensure that the dentist connects the superstructure
with a correct rotational orientation relative to the fixture and
other features in the oral cavity.
[0007] In order to be able to correctly position and/or hold a
dental component in a fixed rotational position indexing means are
generally used. However, positioning of small components in correct
rotational position to the dental implants is difficult, especially
in narrow and challenging situations with limited space, such as a
patient's mouth. The user may for example experience difficulties
to see which the correct orientation is and he/she may also have to
rotate the abutment for a while before the correct rotational
position is located. Furthermore, there may be long-term
consequences for the patient if the dental component is either
oriented rotationally incorrect, or if the indexing means of the
dental component and the fixture are not engaged with each other.
In the latter situation, the dental component may be positioned
axially incorrect. Owing to the conditions occurring during the
installation of a dental implant set, i.e. a very limited space and
limited visibility, the industry is in need of improvements
entailing a simpler connection of a dental component to a
fixture.
SUMMARY OF THE INVENTION
[0008] An object of the invention is to overcome the above
problems, and to provide a dental implant set which facilitates the
connection procedure of a dental component to a fixture. This and
other objects, which will become apparent in the following, are
accomplished by means of a dental implant set and a method defined
in the accompanying claims.
[0009] According to at least a first aspect of the present
invention, a dental implant set is provided. The dental implant set
comprises: a fixture for insertion into a bore hole arranged in
bone tissue having first indexing means, a dental component having
second indexing means and being adaptable to the fixture in an
engaged position where the first and second indexing means mate and
in an intermediate position where the dental component and the
fixture are in contact with each other but the first and the second
indexing means do not mate, and a fixation screw being adapted for
fixating the dental component to the fixture, wherein in the
intermediate position: a first contacting surface of the fixation
screw is arranged to abut a second contacting surface of the dental
component and a third contacting surface of the dental component is
arranged to abut a fourth contacting surface of the fixture, and
wherein the dental implant set is arranged such that the maximum
capacity to transmit torque is greater between the first and second
contacting surfaces than between the third and fourth contacting
surfaces, so that when the fixation screw is subject to a torque
and an axial force applied by a user, the dental component will
rotate with the fixation screw.
[0010] If the maximum capacity of transferring torque at the
contacting surfaces of two bodies is higher than an applied torque,
the applied torque will be transferred from one body to the other,
and the two bodies will rotate together. Conversely, if the maximum
capacity of transferring torque at the contacting surfaces of two
bodies is lower than an applied torque, the two bodies will rotate
in relation to each other.
[0011] Owing to this, the first aspect of the invention is based on
the insight that the contacting surfaces between the different
components can be arranged such that when the dental component and
the fixture are in the intermediate position, in which position the
first and second contacting surfaces are in contact with each other
and the third and fourth contacting surfaces are in contact with
each other, applying a torque and an axial force directed in the
apical direction of the dental implant set to the fixation screw by
means of e.g. a driver operated by a user, will result in that the
dental component is rotated along with the fixation screw, when the
applied torque reaches the maximum capacity of torque transfer
between the third and fourth contacting surfaces and is lower than
the maximum capacity of torque transfer between the first and
second contacting surfaces. The dental component is rotated with
the fixation screw until it reaches the engaged position in which
the first and second indexing means mate. Thus, the user, e.g. a
dentist, can during the installation of the dental component to the
fixture reposition the dental component from the intermediate
position to the engaged position simply by applying a torque and an
axial force directed in the apical direction of the dental implant
set to the fixation screw. Hereby, the user does not need one hand
to hold and position the dental component and another hand to
tighten the screw. The dental component may for example be held in
position by applying an axial force directed in the apical
direction of the fixation screw to the fixation screw by means of
the driver and subsequently, the user may locate the correct
rotational position between the dental component and the fixture by
rotating the fixation screw together with the dental component.
Thus, the dental component will rotate relative to the fixture and
together with the fixation screw until the first and the second
indexing means mate. Hereby, the user can fixate the dental
component to the fixture by means of the fixation screw using one
hand only.
[0012] It should be noted that the expression that the dental
component rotates with the fixation screw does not mean that the
dental component must rotate along with the fixation screw in every
rotation but may sometime slip or have a different angular
velocity.
[0013] It should be noted that the dental implant set may comprise
additional components. The additional components may be arranged to
rotate with the fixation screw or not, as long as the dental
component rotates along with the fixation screw. Thus, according to
some example embodiments, the fixation screw is an abutment screw.
According to other example embodiments, the dental component is a
healing cap, an abutment, an abutment replica or an impression
element such as a pickup or transfer coping, respectively. The
dental component may be a one piece component, but it may also be
constituted of two or more parts that together form a dental
component.
[0014] During the installation of the dental component to the
fixture, the fixation screw is in contact with the dental component
via the first and second contacting surfaces. Hereby, at least a
part of the fixation screw may abut at least a part of the dental
component allowing torque to be transferred from the fixation screw
to the dental component. Similarly, the dental component is in
contact with the fixture via the third and fourth contacting
surfaces. Hereby, at least a part of the dental component may abut
at least a part of the fixture allowing torque to be transferred
from the dental component to the fixture.
[0015] According to one exemplary embodiment, the dental component
is moved in the apical direction of the fixture when moving from
the intermediate position to the engaged position. Hence, the user
may need to apply the axial force in the apical direction of the
dental implant set as well as said torque to said dental component
in order to rotate and move the dental component in the apical
direction of the fixture once the correct rotational position
between the dental component and the fixture is achieved.
[0016] According to at least one example embodiment, the dental
component and the fixation screw is pre-connected to each other.
Hereby, the positioning of the dental component to the fixture is
especially facilitated since the user does not need one hand to
hold the dental component and another hand to place the fixation
screw in position. According to at least one example embodiment,
the dental component and the fixation screw are held together by
means of a threaded engagement. According to at least yet another
example embodiment, the dental component and the fixation screw is
pre-connected by means of adhesive.
[0017] According to at least one example embodiment, in the engaged
position, the dental component is arranged such that the fixation
screw may rotate relative the dental component. That is, in the
engaged position, the dental component is rotationally locked
relative to the fixture while the fixation screw is allowed to
freely rotate. Consequently, tightening of the fixation screw is
possible and thereby, the fixation of the dental component to the
fixture.
[0018] According to at least one example embodiment, the fixation
screw comprises a non-threaded first contacting surface located
coronally of a threaded portion of the fixation screw, wherein the
first contacting surface forms a first non-zero angle in relation
to an axis of the fixture during and after installation of the
dental component to the fixture. The first contacting surface of
the fixation screw is configured and dimensioned to provide a first
friction against the second contacting surface of the dental
component. Similarly, according to at least one example embodiment,
the dental component comprises a non-threaded third contacting
surface, wherein said third contacting surface forms a second
non-zero angle in relation to the axis of the fixture during and
after installation of the dental component to the fixture. The
third contacting surface of the dental component is configured and
dimensioned to provide a second friction, against the fourth
contacting surface of the fixture.
[0019] According to at least one example embodiment, the fixture
further comprises an axis, and at least one of the first and second
contacting surfaces forms a smaller angle to the axis than at least
one of the third and fourth contacting surfaces. Consequently,
different frictions based on different inclinations may be provided
between the first and second contacting surfaces and the third and
fourth contacting surfaces. By providing a smaller angle between at
least one of the first and second contacting surfaces and the axis
compared to an angle between at least one of the third and fourth
contacting surfaces and the axis, the maximum capacity of torque
transfer via the first and second surfaces may, everything else
being equal, be larger compared to the maximum capacity of torque
transfer via the third and fourth surfaces, due to different
friction.
[0020] According to at least one example embodiment the first and
second contacting surfaces forms an essentially equal first angle
to the axis, and the third and fourth contacting surfaces forms an
essentially equal second angle to the axis. This means that the
contact between the first and the second contacting surfaces and
the contact between the third and fourth contacting surfaces may be
provided along an extension of the surfaces, and not only in a
single point. This has the implication that the torque may be
transferred by a larger area.
[0021] According to at least one example embodiment, the dental
component further comprises an axis coinciding with the axis of the
fixture during and after installation of the dental component to
the fixture. According to at least one example embodiment, the
fixation screw further comprises an axis coinciding with the axis
of the fixture during and after installation of the dental
component to the fixture. According to at least one example
embodiment, the axis of the fixture, the dental component and the
fixation screw coincides during and after installation of the
dental component to the fixture.
[0022] According to at least one example embodiment, at least one
of the first and second contacting surfaces tapers in the apical
direction. According to at least one example embodiment, at least
one of the third and fourth contacting surfaces tapers in the
apical direction.
[0023] According to at least one example embodiment, at least one
of the first and second contacting surfaces forms a first angle of
5.degree.-30.degree. relative to the axis of the fixture, and at
least one of the third and fourth contacting surfaces forms a
second angle of 50.degree.-70.degree. relative to the axis of the
fixture. By providing the first angle steeper than the second
angle, the maximum capacity of torque transfer between the first
and second contacting surfaces is larger than the maximum capacity
of torque transfer between the third and fourth contacting
surfaces, provided that other features of the surfaces are the
same. According to at least one example embodiment, the first angle
is about 5-11.degree. and the second angle is about 60.degree.,
respectively.
[0024] According to at least one example embodiment, a dental
implant set is provided in which mating portions of the first and
second contacting surfaces form a first contacting area and mating
portions of the third and fourth contacting surfaces form a second
contacting area, and wherein the first contacting area is larger
than the second contacting area.
[0025] In other words, according to at least one example
embodiment, the first contacting surface of the fixation screw has
a larger area which is intended for contact with the second
contacting surface of the dental component than the area of the
third contacting surface of the dental component intended for
contact with the fourth contacting surface of the fixture.
[0026] According to at least one example embodiment at least one of
the contacting surfaces has different surface characteristics than
the others in order to modify the coefficient of friction between
the first and second contacting surfaces or between the third and
fourth contacting surfaces. Hereby, an alternative way to provide
for a different maximum capacity to transfer torque between the
contacting surfaces is provided. Thus, the maximum capacity to
transfer torque between the different components via the contacting
surfaces may be altered by means of different surface
characteristics.
[0027] According to at least one example embodiment at least one of
the contacting surfaces is coated with a material in order to
modify the coefficient of friction between the first and second
contacting surfaces or between the third and fourth contacting
surfaces. Hereby, yet an alternative way to provide for a different
friction and thereby different level of maximum capacity of torque
transfer between the contacting surfaces is provided. The coating
may e.g. be TiN (titanium nitride) or AlTiN (aluminium titanium
nitride) which both increase the friction. The coating may e.g.
also be a-C:H (amorphous hydrogenated carbon) which reduces the
friction.
[0028] According to at least one example embodiment, at least one
of the contacting surfaces is surface treated in order to modify
the coefficient of friction between the first and second contacting
surfaces or between the third and fourth contacting surfaces.
Hereby, yet another alternative manner to provide for a different
coefficient of friction and thereby different level of maximum
capacity of torque transfer between the contacting surfaces is
provided.
[0029] According to one exemplary embodiment, the material of at
least one of the first, second, third or fourth contacting surfaces
is chosen such that it has different frictional characteristics
than at least one of the other surfaces. It is for example
conceivable that one of the components of the dental implant set is
made of titanium, while another component is made of a ceramic
material such as zirconia, and the third component may be made of
e.g. gold. It is in this embodiment not necessary that an entire
component is made of the same material, it is for example
conceivable with a dental component such as an abutment that is
made of zirconia and titanium. In that case, the second contacting
surface may be made of zirconia while the third contacting surface
may be made of titanium.
[0030] By providing contacting surfaces which are surface treated
and/or coated with a material, made of different materials and/or
by any other means differed, the coefficient of friction may be
provided such that it differs between the different contacting
surfaces. Thus according to at least one example embodiment at
least one of the contacting surfaces has a different coefficient of
friction compared to the other contacting surfaces. The difference
in coefficient of friction may, for instance, be achieved by
surface modification, surface roughening by etching or blasting,
anodization or surface coating.
[0031] According to at least one example embodiment, the contacting
surfaces are provided such that a first frictional force between
the first and second contacting surfaces is larger for a given
applied axial force directed in the apical direction of the dental
implant set than a second frictional force between the third and
fourth contacting surfaces for the same applied axial force.
[0032] Thus, if the surfaces in contact between the different
components are either modified, differed or arranged such that the
frictional force between the fixation screw and the dental
component is larger than the frictional force between the dental
component and the fixture, the maximum capacity to transfer torque
from the fixation screw to the dental component may, everything
else being equal, be larger compared to the maximum capacity to
transfer torque from the dental component to the fixture. Hereby,
the dental component will be able to rotate along with the fixation
screw in the intermediate position.
[0033] Furthermore, according to at least one example embodiment,
the first contacting surface of the fixation screw is surface
modified in one way, while the second contacting surface of the
dental component is not modified at all or modified in another way.
According to at [east yet another example embodiment the first
contacting surface of the fixation screw is not modified at all,
while the second contacting surface of the dental component is
surface modified. According to at least one example embodiment the
third contacting surface of the dental component is surface
modified in one way, while the fourth contacting surface of the
fixture is not modified at all or modified in another way.
According to at least yet another example embodiment the third
contacting surface of the dental component is not modified at all,
while the fourth contacting surface of the fixture is surfaced
modified.
[0034] According to at least one example embodiment, the
coefficient of friction between the first and second contacting
surfaces (i.e. between the fixation screw and the dental component)
is larger than the coefficient of friction between the third and
fourth contacting surfaces (i.e. between the dental component and
the fixture).
[0035] If the difference in coefficient of friction is provided by
different surface roughness, this may be accomplished by means of
e.g. blasting, etching or any other suitable process known in the
art. The surface roughness of at least one of the contacting
surfaces may be greater than the others.
[0036] It is also conceivable to further differentiate the friction
provided by the first, second, third and fourth contacting surfaces
by combining various friction increasing and/or friction reducing
measures. Thus, according to at least one example embodiment, at
least one of the contacting surfaces is provided with friction
increasing measures. According to at least yet another example
embodiment, at least one of the contacting surfaces is provided
with friction reducing measures. According to at least one example
embodiment, at least one of the contacting surfaces is provided
with friction increasing measures while at least one of the other
contacting surfaces is provided with friction reducing measures.
Thus, the first or second contacting surface may be provided with
friction increasing measures while the third or fourth contacting
surface may be provided with friction reducing measures in order to
allow the dental component to rotate with the fixation screw in the
intermediate position.
[0037] It is also conceivable that the fixation screw is provided
with friction reducing measures in order for the threaded portion
of the fixation screw to more easily mate with a threaded bore of
the fixture. Hereby, other means to increase the maximum capacity
of torque transfer between the first and second contacting surface
are needed (e.g. a steep inclination of the first and second
contacting surfaces as seen in relation to the axis of the fixture)
in order to provide for a higher maximum capacity of torque
transfer between the first and second contacting surfaces compared
to the maximum capacity of torque transfer between the third and
the fourth contacting surfaces.
[0038] It should be noted that any type of combinations regarding
surface angle relative the axis and surface modifications between
the contacting surfaces are conceivable in order to enable the
dental component to rotate together with the fixation screw in the
intermediate position. For instance, the first or the second
contacting surface may provide for a high degree of maximum
capacity of torque transfer by providing a steep inclination while
the third and fourth contacting surfaces may provide for a low
degree of maximum capacity of torque transfer by being provided
with friction reducing measures.
[0039] However, in order for the dental component to rotate along
with the fixation screw in the intermediate position, other
connection means between the different components are conceivable.
Thus, according to at least one example embodiment, at least one of
the contacting surfaces is provided with projections or ribs.
According to at least one example embodiment, the contacting
surfaces are provided with threads. According to at least one
example embodiment, at least one of the contacting surfaces is
provided with grooves. Thus, the projections e.g. formed as ribs,
on one of the contacting surfaces may connect with another
contacting surface possibly provided with grooves which may
interconnect with said projections. Consequently, if the first
contacting surface of the fixation screw is provided with ribs and
the second contacting surface of the dental component is provided
with corresponding grooves, the interconnecting ribs/grooves may
allow the dental component to rotate along with the fixation screw
until the dental component falls into the engaged position with the
fixture. The threads may also provide for the dental component to
rotate along with the fixation screw until the dental component
falls into the engaged position with the fixture. In the engaged
position, the interconnection force between the contacting surfaces
by the ribs/grooves or threads is overcome and the fixation screw
is able to rotate in relation to the dental component.
[0040] According to at least one other example embodiment, at least
one of the contacting surfaces is provided with an adhesive.
Hereby, the fixation screw, the dental component and/or the fixture
may be interconnected in a similar manner as by the ribs and
grooves described above. Consequently, if the first contacting
surface of the fixation screw is provided with an adhesive, the
dental component may rotate along with the fixation screw until the
dental component falls into the engaged position with the fixture.
In the engaged position, the interconnection force between the
contacting surfaces by the adhesive is overcome. Of course, other
alternatives providing interconnection between the different
components are conceivable, such as magnetic forces. Thus,
according to at least yet another embodiment, at least one of the
contacting surfaces is magnetic.
[0041] According to yet another further embodiment, the third
and/or fourth contacting surfaces slopes downward in the direction
of rotation. By this arrangement, the reaction force from the
contact between the third and fourth contacting surfaces will have
a component in the direction of rotation. Thereby, the maximum
capacity of torque transfer is reduced. Hence, less torque will be
required to move the third and fourth contacting surfaces in
relation to each other and the dental component will thereby easier
rotate in relation to the dental fixture until it reaches the
engaged position.
[0042] In the exemplary embodiments described above, several
different alternative manners for affecting the maximum capacity of
torque transfer to the dental component via the first and second
contacting surfaces and the maximum capacity of torque transfer to
the fixture via the third and fourth contacting surfaces have been
described. However, in general terms the maximum capacity of torque
transfer between the first and second contacting surfaces should be
greater than the maximum capacity of torque transfer between the
third and fourth contacting surfaces in the intermediate position,
as is explained in conjunction with the first aspect of the present
invention. The capacity to transfer torque is a function of the
force applied and the length of the lever arm. In the present case,
the potential peripherally directed force which can be applied to
each one of the contacting surfaces is the normal force exerted on
the respective surface by the force being applied by the user
multiplied with the coefficient of friction between the surfaces.
As the normal force is perpendicular to the surface, the normal
force for each one of the surfaces is the force being applied by
the user divided with sine for the angle between the respective
surface and the axis of the fixture. The length of the respective
lever is the distance from the axis of the dental implant set or
fixture and the respective contact surface. Hence, in order for the
maximum capacity of torque transfer between the first and second
contacting surfaces to be larger than the maximum capacity of
torque transfer between the third and fourth contacting surfaces,
the integral of the function: normal force times coefficient of
friction times lever integrated over the contact surface, should be
larger at the first and second contacting surfaces than at the
third and fourth contacting surfaces. Mathematically, this could be
expressed as:
.intg.F.sub.N.mu..sub.1r.sub.1dA.sub.1>.intg.F.sub.N2.mu..sub.2r.sub.-
2dA.sub.2.
[0043] wherein,
[0044] F.sub.N1 is the normal force acting at the first and second
contact surfaces of the dental component;
[0045] .mu..sub.1 is the coefficient of friction between the first
and second contact surfaces;
[0046] r.sub.1 is the distance from the first and second contact
surfaces to the axis of the implant set or the fixture;
[0047] A.sub.1 is the contact area of the first and second
contacting surfaces;
[0048] F.sub.N2 is the normal force acting at the third and fourth
contact surfaces of the fixture;
[0049] .mu..sub.2 is the coefficient of friction between the third
and fourth contact surfaces;
[0050] r.sub.2 is the distance from the third and fourth contact
surfaces to the axis of the implant set or the fixture;
[0051] A.sub.2 is the contact area of the third and fourth
contacting surfaces.
[0052] Hence, the above-described exemplary embodiments describe
different measures for affecting either the normal force being
exerted on the respective contacting surfaces or the coefficient of
friction of the respective contacting surfaces. According to at
least one example embodiment, a dental implant set is provided
wherein the fixture further comprises a bore provided with an
internal thread, and wherein the fixation screw further comprises
an external thread adapted to engage said thread of the bore of the
fixture, and wherein the length of the fixation screw is adapted
such that the external thread of the fixation screw is positioned
coronally to the thread of the bore of the fixture in the
intermediate position. Thus, the fixation screw may not engage the
thread of the fixture until the indexing means mate. Hereby, the
intermediate position provides for the possibility to allow the
dental component to rotate along with the fixation screw since the
dental component, in the intermediate position, is rotationally
free relative the fixture. That is, the fixation screw is not able
to fixate the dental component to the fixture since the fixation
screw may not engage the thread of the fixture in the intermediate
position.
[0053] According to at least one example embodiment, the exterior
of the dental component is arranged to be in contact with the
interior of the fixture, while the interior of the dental component
is arranged to be in contact with the fixation screw. Hence, in
this embodiment, the dental component comprises an internal bore
arranged to receive the fixation screw.
[0054] According to at least one example embodiment, the length of
the fixation screw is adapted such that the external thread of the
fixation screw may engage the thread of the bore of the fixture
when the fixture and the dental component are arranged in the
engaged position. In this way, the dental component may freely
rotate until it is in the engaged position. In the engaged
position, the dental component is rotationally locked in relation
to the fixture by means of the indexing means and the force
entailing the interconnection between the dental component and the
fixation screw (e.g. frictional force) is overcome. That is, in the
engaged position when the fixation screw is able to engage the
threaded bore of the fixture the dental component is rotationally
locked in relation to the fixture by means of the indexing means
and thus, the force entailed by the threading is greater than the
force entailed by the interconnection between the dental component
and the fixation screw. Hereby, the external thread of the fixation
screw may engage the threaded bore of the fixture. On the contrary,
in the intermediate position, the dental component and the fixation
screw are in contact with, but not engaged with, each other. That
is, in the intermediate position, the dental component may rotate
along with the fixation screw, and the threaded portion of the
fixation screw is not allowed to mate with the thread of the bore
of fixture.
[0055] If the fixation screw is allowed to engage the threaded bore
of the fixture when the dental component and the fixture are in the
intermediate position, the dental component will be fixated to the
fixture by means of the fixation screw in an axially incorrect
position. By adapting the length of the fixation screw such that
the fixation screw may engage the threaded bore of the fixture in
the engaged position, and not in the intermediate position, such
erroneous axial positions may be avoided.
[0056] According to at least one example embodiment, the fixation
screw comprises a non-threaded portion located coronally of a
threaded portion. In this way, the threaded portion of the fixation
screw may be configured and dimensioned to mate with the threaded
bore of the fixture while the interior of the non-threaded portion
may be arranged such that it may receive a driver or any other
object suitable for applying a torque and an axial force directed
in the apical direction of the dental implant set to the fixation
screw.
[0057] According to at least one example embodiment, a dental
implant set is provided wherein the first indexing means comprises
indexing depressions extending in the radial direction from a first
surface of the fixture and the second indexing means comprises
indexing projections extending in the radial direction from a
second surface of the dental component, and wherein the indexing
depressions and projections are distributed along the circumference
of the first and second surfaces of the fixture and the dental
component respectively, such that the dental component can only
mate in certain specific rotational orientations with respect to
the fixture.
[0058] Owing to this, a various number of correct rotational
orientations may be provided by a suitable placement of
corresponding indexing projections and depressions. For example,
according to at least one example embodiment, the corresponding
indexing projections and depressions may be arranged such that four
rotational orientations allow mating of the dental component with
the fixture. Hereby, the fixation screw together with the dental
component may have to rotate 89.degree. before the dental component
may move in the apical direction and thereby achieve mating of the
dental component with the fixture. The dental component may move in
the apical direction e.g. due to gravity or by an axial force
directed in the apical direction of the dental implant set being
applied by the user.
[0059] A rotational orientation where the indexing projections and
depressions do not mate implies that the dental component and the
fixture are in the intermediate position. In the intermediate
position, the dental component is in a first axial position. A
rotational orientation where the indexing projections and
depressions mate implies that the dental component and the fixture
are in the engaged position. In the engaged position, the dental
component is in a second axial position which may be different to
the first axial position. That is, the engaged position may entail
a different axial position of the dental component compared to the
axial position of the dental component in the intermediate
position.
[0060] Hereby, according to at least one example embodiment, at
least two axially spaced, as seen in a coronal-apical direction,
relative positions between the dental component and the fixture are
possible, one position occurring in at least one rotational
orientation wherein the dental component engages the fixture in an
engaged position, and at least one position occurring in at least
one rotational orientation wherein the dental component and the
fixture are in contact with, but not engaged with, each other in an
intermediate position.
[0061] According to at least one example embodiment, in the
intermediate position, the third contacting surface is provided by
a portion of the second indexing means of the dental component.
According to at least one example embodiment, in the intermediate
position, the fourth contacting surface is provided by a portion of
the first indexing means of the fixture. According to at least yet
another example embodiment, in the intermediate position, the
second indexing means of the dental component rests on the first
indexing means of the fixture. For example, the second indexing
means may be designed as rib portions while the first indexing
means may be designed as a surrounding wall portion or as a shelf.
Thus, according to at least one example embodiment, in the
intermediate position, the rib portions of the dental component
rest on the surrounding wall or shelf of the fixture. Of course,
other shapes of the indexing means are conceivable.
[0062] According to at least one example embodiment, a dental
implant set is provided wherein the dental component further
comprises at least one first indexing projection having an apical
end, and at least two second indexing projections, each one having
an apical end, and wherein the fixture further comprises at least
one first indexing depression having a coronal end, and at least
two second indexing depressions, each one having a coronal end,
wherein the apical ends of said at least two second indexing
projections are located apically of the apical end of the first
indexing projection and/or the coronal ends of said at least two
second indexing depressions are located coronally of the coronal
end of the first indexing depression, wherein the first and second
indexing projections and the first and second indexing depressions
are distributed along the circumference of the dental component and
the fixture, respectively, in such way that the dental component
can only mate in one rotational orientation with respect to the
fixture, and wherein the first indexing projection is only enabled
to mate with the first indexing depression after said at least two
second indexing projections have mated with said at least two
second indexing depressions.
[0063] According to this example embodiment, the corresponding
indexing projections and depressions are arranged such that only
one rotational orientation allows mating of the dental component
with the fixture. Thus, the fixation screw together with the dental
component may have to rotate 359.degree. before it can move in the
axial direction and thereby mate with the fixture. The movement in
the axial direction may be achieved by either gravity or by an
axial force being applied by the user in the apical direction of
the dental implant set.
[0064] Since the at least two second indexing projections are
located coronally of the first indexing projection, the at least
two second indexing projections will mate with the corresponding
indexing depression before the first indexing projection mates with
the corresponding first indexing depression. Also, by having the at
least two second depressions configured and dimensioned to only
enable mating with the at least two second projections, erroneous
mating of the indexing projections and depressions is avoided.
Thus, the dental component may rotate along with the fixation screw
until the indexing projections and indexing depressions correctly
mate, i.e. until the engaged position occurs. Erroneous mating of
the indexing projections and indexing depression could otherwise
result in that the dentist would have to withdraw the dental
component and retry to find a correct mating position.
[0065] According to at least one example embodiment, the first
indexing means comprises the at least one first indexing depression
and the at least two second indexing depressions. According to at
least one example embodiment, the second indexing means comprises
the at least one first indexing projection and the at least two
second indexing projections.
[0066] According to at least a second aspect of the present
invention, a method is provided for the connection of a dental
component to a fixture having first indexing means by means of a
fixation screw, the dental component having second indexing means
and being arranged to engage the fixture in an engaged position
when the first and second indexing means mate, said method
comprising the steps of positioning the dental component in an
intermediate position in which the dental component and the fixture
are in contact with each other but the first and second indexing
means do not mate, and applying a torque and an axial force to the
fixation screw and thereby rotate the fixation screw in relation to
the fixture, wherein the dental component rotates accordingly.
[0067] Hereby, the user can easily position the dental component
and the fixation screw and then, by using one hand only, rotate the
fixation screw by applying a torque and an axial force directed in
the apical direction of the dental component and the fixation
screw, thereby enabling the first and second indexing means to
mate. Effects and features of this second aspect of the present
invention are largely analogous to those described above in
connection with the first aspect of the invention.
[0068] According to at least one example embodiment, a first torque
may be transferred from the fixation screw via a first pair of
contacting surfaces to the dental component, and a second torque
may be transferred from the dental component via a second pair of
contacting surfaces to the fixture, wherein the maximum capacity of
transferring torque at said first pair of contacting surfaces being
larger than the maximum capacity of transferring torque at said
second pair of contacting surfaces, thereby allowing the dental
component to rotate with the fixation screw.
[0069] According to at least one example embodiment, the method may
be executed by means of an implant set according to any one of the
exemplary embodiments of the first aspect of the present invention.
In that case, the first pair of contacting surfaces may be
constituted of the first and second contacting surfaces and the
second pair of contacting surfaces may be constituted of the third
and fourth contacting surfaces.
[0070] According to at least a third aspect of the present
invention, a method for preparing a dental implant set is provided.
The method comprises the steps of: providing a fixture having first
indexing means, and providing a dental component having second
indexing means and being arranged to engage the fixture in an
engaged position where the first and second indexing means mate and
being arranged to not engage the fixture in an intermediate
position where the first and the second indexing means do not mate
but where the dental component and the fixture are in contact with
each other, and providing a fixation screw for connecting said
dental component to said fixture, and providing a first contacting
surface of the fixation screw to abut a second contacting surface
of the dental component and a third contacting surface of the
dental component to abut a fourth contacting surface of the
fixture, and providing said contacting surfaces such that when a
torque and an axial force directed in the apical direction of the
fixation screw is applied to the fixation screw, in the
intermediate position, the fixation screw rotates in relation to
the fixture and the dental component rotates accordingly.
[0071] According to at least one example embodiment, the method may
be utilized for preparing an implant set according to any one of
the exemplary embodiments of the first aspect of the present
invention.
[0072] According to at least one example embodiment, the method
further comprises providing the contacting surfaces such that the
maximum capacity of transferring torque between said first and
second contacting surfaces is larger than the maximum capacity of
transferring torque between said third and fourth contacting
surfaces.
[0073] According to at least one example embodiment the method may
be utilized for preparing an implant set wherein the fixture
further comprises an axis, and at least one of the first and second
contacting surfaces is provided to form a smaller angle to the axis
than at least one of the third and fourth contacting surfaces.
[0074] According to at least one example embodiment, the method
further comprises providing mating portions of the first and second
contacting surfaces to form a first contacting area and providing
mating portions of the third and fourth contacting surfaces to form
a second contacting area.
[0075] According to at least one example embodiment, the method
further comprises providing at least one of the contacting surfaces
to have different surface characteristics from the others in order
to modify the friction between the first and second contacting
surfaces or between the third and fourth contacting surfaces.
[0076] According to at least one example embodiment, the method
further comprises coating at least one of the contacting surfaces
with a material in order to modify the friction between the first
and second contacting surfaces or between the third and fourth
contacting surfaces.
[0077] According to at least one example embodiment, the method
further comprises surface treating at least one of the contacting
surfaces in order to modify the friction between the first and
second contacting surfaces or between the third and fourth
contacting surfaces.
[0078] The described dental implant set is particularly suitable
and intended for medical and dental applications, and is
particularly suited for use in the field of dental implant
dentistry and related applications. Dental implants are used to
support the restoration of missing teeth. Dental implant fixtures
are surgically implanted by a dentist. These dental implants
typically will be provided with abutments and crowns; that is,
following successful dental implantation of dental implant fixtures
into the jaw of the patient, complementary components including
abutments and crowns will be affixed to the dental implanted
fixtures to provide the patient with a restoration of the patient's
natural teeth.
[0079] A dental implant may comprise a dental fixture and a
superstructure, such as an abutment.
[0080] A dental fixture is for use as the anchoring member of a
dental prosthesis. To this end, the dental fixture is insertable
into a pre-prepared bore hole in the bone tissue of a jawbone
(maxilla or mandible) at a site where the dental prosthesis is
required. The dental fixture is normally rotated into the bore
hole.
[0081] For screw-type dental fixtures the bore hole may be provided
with internal threads in advance or may be left un-tapped with the
dental fixture provided with a self-tapping capacity, e.g. by the
provision of one or more axially-extending cutting recesses, edges
or notches, etc in the fixture thread. For instance, an apical end
portion of the fixture may be provided with 2-4 cutting recesses,
such as 3 cutting recesses. Other number of cutting recesses are
readily conceivable.
[0082] A superstructure for connecting a prosthetic part to the
fixture may comprise an abutment, spacer or other transmusosal
component which engages to the dental fixture to bridge the gingiva
overlying the maxilla or mandible. The prosthetic part, e.g. a
crown, bridge or denture may be secured to the abutment. There are
various other forms that the superstructure can take. For instance,
the prosthetic part may be secured directly to the dental fixture.
A dental implant may thus comprise an abutment connected to the
dental fixture, or the dental fixture without an abutment.
[0083] The term "coronal" is here and throughout this application
used to indicate a direction towards a head end or trailing end of
the dental implant. For instance, in a situation where an abutment
is connected to a dental fixture, the coronal direction of the
abutment would be a direction towards the part of the abutment
being directed away from the fixture. Conversely, the term "apical"
indicates a direction towards an insertion or leading end of the
component. Thus, apical and coronal are opposite directions.
Furthermore, the terms "axial", "axial direction" or "axially" are
used throughout this application to indicate a direction taken from
the coronal end to the apical end, or vice versa. The terms
"radial", "radial direction" or "radially" indicate a direction
perpendicular to the axial direction.
[0084] A blind bore or socket may extend apically into the fixture
body from the coronal end to an end surface in-between the apical
and coronal ends of the fixture body for a superstructure to be
secured to the fixture. The socket may comprise an
internally-threaded section for screw connection of the
superstructure to the fixture. A rotational lock for the
superstructure may be provided in the socket, such as an internal
polygonal side wail, e.g. hexagonal, or alternatively one or more
protrusions from or indentation in the wall of the socket. A
section of the socket, such as the coronal section; may be tapered
towards the apical end. The tapered section is suitably arranged
coronally of the internally-threaded section.
[0085] The fixture may be used in a one stage procedure or a two
stage procedure. In a one stage procedure a healing or temporary
abutment is connected to the fixture to form the gingival tissue,
and after a healing period the healing or temporary abutment is
replaced by a permanent abutment. For a two stage procedure the
fixture is provided with a healing cap and the gingival tissue is
sutured over the fixture and healing cap, and after a healing
period the tissue is opened up and an abutment is connected to the
fixture after removal of the healing cap.
[0086] A conceivable alternative to having an abutment connected to
the fixture is to have a one-piece dental implant, wherein a
portion of the dental implant is embedded in bone tissue, while
another portion of the dental implant extends from the bone tissue
across the gingiva.
[0087] The fixture may have a conically tapering end portion which
tapers towards the coronal end. The axial extent of this coronal
end portion is small compared to the total length of the fixture,
as an example no more than 4% of the total length, such as in the
range of 1.5%-3.7%. The coronal end portion may suitably be
provided without a threaded surface, e.g. having a smooth or a
roughened (such as blasted) surface.
[0088] The fixture may have a substantially flat coronal end
surface which is perpendicular to the longitudinal axis of the
fixture. Alternatively, the coronal end surface may have a sloped
contour relative to the longitudinal axis of the fixture, e.g. such
that when positioned within the jawbone the length of the fixture
is larger on a lingual side and shorter on a buccal side of the
fixture. Another alternative is a saddle-shaped or wave-like
coronal end surface.
[0089] The length of the dental fixture may be in the range of 5-19
mm, depending on the clinical situation. The outer diameter of the
dental fixture may suitably be in the range of 2-6 mm, such as 3-5
mm.
[0090] The fixture may be substantially cylindrical or slightly
tapering from the coronal end towards the apical end. If the
fixture has a slight tapering, the core of the fixture and the
outer periphery defined by e.g. thread tops may have the same or
different angle of taper. Furthermore, the core of the fixture may
be cylindrical while the thread tops describe a conicity or,
conversely, the core of the fixture may be tapered while the thread
tops describe a generally cylindrical geometry. Alternatively, the
fixture may comprise a combination of one or more cylindrical
and/or one or more tapering portions. Thus, one or more portions of
the fixture may have e.g. thread tops lying in a common imaginary
cylindrical surface, which cylindrical surface is parallel with the
longitudinal axis of the fixture. Alternatively or additionally,
one or more portions of the fixture may have thread tops lying in
an imaginary conical surface which in the apical direction is
tapering towards the longitudinal axis.
[0091] The externally threaded fixture may comprise one or more
thread spirals.
[0092] The term "pitch" is used to indicate the axial distance
between adjacent tops of a threading. The term "lead" is used to
indicate the distance advanced parallel to the longitudinal axis
when the fixture is turned one revolution, i.e. it corresponds to
the pitch multiplied with the number of thread spirals. For a
single thread spiral having a constant pitch, the lead is equal to
the pitch; for a double thread spiral, the lead is twice the
pitch.
[0093] The term "microthread" is used to indicate a thread having a
height which is no greater than 0.2 mm. According to at least one
example embodiment, the fixture is provided with microthreads
having a height in the range of 0.02-0.2 mm, such as 0.05-0.015 mm,
for instance 0.1 mm. The term "macrothread" is used to indicate a
thread having a height which is greater than 0.2 mm. According to
at least one example embodiment, the fixture is provided with
macrothreads having a height in the range of 0.25-0.35 mm, such as
0.3 mm.
[0094] Suitably, microthreads may be located coronally of
macrothreads. For instance, microthreads may be arranged to engage
dense cortical bone and macrothreads may be arranged to engage
porous spongious/cancellous bone. The lead of a microthread
suitably corresponds to the lead of a macrothread. The macrothread
pitch may, as an example, be 2-4 times, such as 3 times, the pitch
of the microthreads. The pitch (top-to-top spacing) at a fixture
portion provided with microthreads may be around 0.10-0.30 mm, for
instance 0.20-0.24 mm. The pitch (top-to-top spacing) at a fixture
portion provided with macrothreads may be around 0.30-0.90 mm, for
instance 0.60-0.72 mm.
[0095] Microthreads can be regarded as defined, oriented roughness.
A non-oriented roughness having smaller dimensions, for instance
obtained by blasting, etching, etc., may be superimposed on
microthreads as well as on macrothreads.
[0096] A thread profile may comprise two flanks, a top
interconnecting said two flanks, a bottom formed between two
adjacent threads, said flanks forming an acute angle v with a plane
which is perpendicular to the fixture axis and which angle v lies
in a plane containing the extension of the fixture axis, said
profile further having a height D. The top may be curved and may
have a top radius. Suitably, for 10.degree..ltoreq.v<35
.degree., the top radius is greater than 0.4.times.D and, for
35.degree..ltoreq.v<55.degree., the top radius is greater than
0.2.times.D.
BRIEF DESCRIPTION OF THE DRAWINGS
[0097] FIGS. 1-3 illustrate an implant set according to at least
one example embodiment of the present invention.
[0098] FIG. 4 illustrates surface modifications of components in a
dental implant set for obtaining desired friction-affecting
properties according to at least one example embodiment of the
present invention.
[0099] FIG. 5 illustrates surface modifications of components in a
dental implant set for obtaining desired friction-affecting
properties according to at least one other example embodiment of
the present invention.
[0100] FIG. 6 illustrates dental components according to example
embodiments of the present invention, wherein one dental component
is to be connected to a fixture in a specific rotational
orientation with respect to the fixture and one other dental
component which may be arranged in a number of different rotational
orientations with respect to the same fixture.
[0101] FIG. 6a is a top view of the fixture in FIG. 6
[0102] FIGS. 6b-6c are bottom views of the dental component in FIG.
6.
[0103] FIG. 7 schematically illustrates a dental component and the
factors affecting the transfer of torque between different
components.
DETAILED DESCRIPTION OF THE DRAWINGS
[0104] FIGS. 1, 2, 3, 4, 5 and 6 illustrate various dental implant
sets 1 comprising various dental components 2, 3a-3c, each dental
implant set 1 further comprises a fixture 4 and a fixation screw 6,
according to at least some example embodiments.
[0105] FIGS. 1-3 and 6, illustrate a dental implant set 1 during
installation of a dental component, such as a healing cap 2 or an
abutment 3b, 3c, to a fixture 4, 104 by means of a fixation screw
6. The fixation screw may be driven by a driver 80 as illustrated
in FIGS. 1-3. The fixation screw 6 is adapted to be joined to the
dental component 2, 3b, 3c in order to fasten the dental component
2, 3b, 3c to the fixture 4, 104. That is, the dental component 2,
3b, 3c is arranged to be in contact with both the fixation screw 6
and the fixture 4, 104.
[0106] In FIGS. 1-3 and 6, the fixture 4, 104 has a coronal portion
8, intended to engage the cortical bone tissue, extending apically
from a coronal end 12 of the fixture 4, 104, and an apical portion
10, intended to engage the cancellous bone tissue, extending
coronally from an apical end 14 (only shown in FIG. 6) of the
fixture 4, 104. The apical portion 10 may have a conicity tapering
towards the apical end of the fixture 4, 104 to ease insertion of
the fixture 4, 104 into a bore-hole in the jawbone. In the
illustrated example, the coronal portion 8 is apically tapered, it
may however also have a straight configuration. The coronal end 12
of the fixture 4, illustrated in FIGS. 1-3, has a sloped
configuration and the coronal end 12 of the fixture 104,
illustrated in FIG. 6, has a straight configuration.
[0107] The coronal portion 8 is herein illustrated as having an
exterior at least partly provided with relatively small threads, or
microthreads 16, e.g. having three thread spirals, although another
number is conceivable, such as 1, 2, 4 or more spirals. Although
microthreads 16 have been illustrated, according to at least an
alternative example embodiment the coronal portion 8 is at least
partly provided with relatively large threads, or macrothreads 18,
similarly to the apical portion 10, either as a separate thread
spiral or as a continuation of the thread spiral at the apical
portion 10. According to at least another alternative example
embodiment, instead of microthreads 16, the coronal portion 8 may
be provided with a plurality of annular ridges, which to the naked
eye could give the same visual appearance as microthreads 16. Other
conceivable alternatives are circumferential lines of beads or
non-oriented/randomly provided projections such as bulges.
[0108] In the illustrated example embodiment, the macrothreads 18
at the apical portion 10 has the same lead as the microthreads 16
at the coronal portion 8. However, the pitch of the macrothreads 18
is three times the pitch of the microthreads 16, since the
microthreads 16 comprise three thread spirals.
[0109] The apical portion 10 comprising macrothreads 18 is herein
illustrated as having one thread spiral, however, the apical
portion 10 may alternatively have two or more thread spirals.
[0110] The length of the herein illustrated coronal portion 8 may
be about 1-2 mm, such as 1.5 mm. However, shorter or longer lengths
are readily conceivable. The relative length of the coronal portion
8 may also be selected from a wide range, such as 5-50% of the
total length of the fixture 4, 104, e.g. 10-20%.
[0111] The coronal portion 8 comprises a tapering end portion 20,
which tapers towards the coronal end 12 of the fixture 4. The
tapering end portion 20 is no more than 4% of the total length of
the fixture 4, 104. The surface of the tapering end portion 20 may
be non-threaded, either smooth or blasted (or otherwise
roughened).
[0112] Cutting recesses 22 (only shown in FIG. 6) or grooves extend
coronally from the apical end of the fixture 4, 104. The number of
cutting recesses may be one or more, such as two, three or four
cutting recesses, suitably symmetrically positioned about the
circumference of the apical end of the fixture 4, 104 for
self-tapping of the fixture 4, 104 when being screwed/rotated into
the bore-hole provided in the maxilla or mandible.
[0113] A socket 24 having an open end in the coronal end 12 of the
fixture 4, 104 is provided. The socket 24 extends apically into the
fixture 4, 104 and is configured and dimensioned for receiving the
dental component, such as the healing cap 2 as illustrated in FIGS.
1-3 and the abutment 3b, 3c as illustrated in FIG. 6. The socket 24
is further provided with an internally threaded apical section 34
intended for engagement with the fixation screw 6. The healing cap
2 in the embodiment shown in FIGS. 1-3, has a sloped configuration
and will, after being properly fixated to the fixture 4 by means of
the fixation screw 6, level with the fixture 4 and the surrounding
bone. The abutment 3b illustrated in FIG. 6 has a sloped
configuration and the abutment 3c illustrated in FIG. 6 has a
symmetrical configuration. The abutments 3b, 3c will extend through
the gingiva of the patient once properly installed in the fixture
104.
[0114] Although various alternative configurations are conceivable,
the socket 24 is herein illustrated as having a conical coronal
section 26 and a substantially cylindrical intermediate wall
section 28 located apically of the coronal section 26. Indexing
elements 30, herein illustrated as radially extending indexing
depressions 30, of which two are seen in FIGS. 1-3 are provided in
the intermediate wall section 28. The indexing depressions 30 are
herein illustrated as continuations of the conical coronal section
26 but are not apically tapering. Thus, in the illustrated examples
in FIGS. 1-3 and 6, the inclination of the conical coronal portion
26 and the indexing depressions 30 are different and connected by
means of a bending portion. As an alternative, the indexing
depressions 30 may be tapering. Further as an alternative, the
intermediate wall section 28 may be substantially conical. Between
the indexing depressions 30, the intermediate wall section 28 is
connected to the conical coronal section 26 by shelves 32.
[0115] The combination of the indexing depressions 30, the
intermediate wall section 28 and the shelves 32 is referred to as
first indexing means 100 of the fixture 4. The indexing means 100
are further described in relation to FIG. 6.
[0116] In FIGS. 1-3, the healing cap 2 comprises an engagement
portion 46 intended to engage with the indexing depressions 30 and
the intermediate wall section 28 of the fixture 4. The engagement
portion 46 is herein illustrated as having a generally cylindrical
enveloping surface, although other enveloping surfaces, such as
tapering, would be a conceivable alternative. The healing cap 2
further comprises a conical coronal portion 48 which extends
coronally of the engagement portion 46. Similar, in FIG. 6, the
abutments 3b, 3c comprises a respective engagement portion 46
intended to engage with the indexing depressions 30 and the
intermediate wall section 28 of the fixture 104. The engagement
portion 46 is herein illustrated as having a generally cylindrical
enveloping surface, although other enveloping surfaces, such as
tapering, would be a conceivable alternative. The abutments 3b, 3c
further comprises respective conical coronal portions 48 which
extends coronally of the engagement portion 46.
[0117] In FIGS. 1-3, the healing cap 2 is further provided with a
through-hole 44 extending from a coronal opening located at a
coronal end of the healing cap 2 to an apical opening located at
the apical end of the healing cap 2. The through-hole 44 is adapted
to receive the fixation screw 6. The abutments 3b, 3c in FIG. 6 are
each provided with a similar trough-hole, fulfilling the same
purpose.
[0118] Indexing elements 60, herein illustrated as radially
extending indexing projections 60, of which one is seen in FIGS.
1-3, are located at the cylindrical enveloping surface of the
engagement portion 46. Each indexing projection 60 has an apical
end 62 here illustrated as a shelf-like recess in the engagement
portion 46.
[0119] The combination of the indexing projections 60 with their
apical ends 62 and the intermediate wall sections of the
cylindrical enveloping surface located between the indexing
projections 60 of the engagement portion 46 is referred to as
second indexing means 200 of the healing cap 2. The indexing
projections 60 will be described in greater detail below in
relation to FIG. 6.
[0120] The fixation screw 6 comprises a threaded portion 6a having
a core provided with an external thread 6d. Furthermore, the
fixation screw 6 is provided with a shaft 6b and a head 6c, wherein
the threaded portion 6a is provided at an apical portion of the
shaft 6b. According to at least the embodiments shown in FIGS. 1-3
the circumference of the head 6c, located coronally of the threaded
portion 6a is apically tapered and thus forming an angle to a
longitudinal central axis C of the fixture. In FIG. 1 the
circumference of the head 6c is forming a first contacting surface
71 intended to be in contact with a second contacting surface 72
provided here by the interior of the conical coronal portion 48 of
the healing cap 2, once the healing cap 2 is connected to the to
the fixture 4. The first contacting surface 71 is forming an angle
.alpha. of about 11.degree. in relation to the axis C of the
fixture 4. The healing cap 2 with the corresponding second
contacting surface 72 is forming a seat for receiving the first
contacting surface 71 of the fixation screw 6. The second
contacting surface 72 of the healing cap 2 forms an angle .alpha.
of about 11.degree. in relation to the axis C of the fixture. Thus,
according to at least the embodiment shown here, when the fixation
screw 6 is inserted into the healing cap 2, the first contacting
surface 71 will come into contact with the second contacting
surface 72 of the healing cap 2. The fixation screw 6 is adapted to
extend through the through-hole 44 of a dental component and engage
the internal thread 34 of the fixture 4, 104 in order to fixate the
dental component to the fixture 4.
[0121] In FIG. 1 the apical ends 62 of the indexing projections 60
of the healing cap 2 is forming a third contacting surface 73
intended to be in contact with a fourth contacting surface 74
provided here by the shelf 32 of the fixture 4. The third
contacting surface 73 is forming an angle .beta. of about
70.degree. in relation to the axis C of the fixture. The fourth
contacting surface 74 of the fixture 4 forms an angle .beta. of
about 70.degree. in relation to the axis C of the fixture 4.
[0122] As is also illustrated in FIGS. 1-3, a part of the apical
end of the through-hole 44 is provided with threads 47, configured
and dimensioned to engage with the fixation screw 6 in order for
the healing cap 2 and the fixation screw 6 to be pre-connected to
each other prior to being connected to the fixture. The dimensions
of the head 6c of the fixation screw 6 and the corresponding
dimension of the fixation screw receiving portion of the healing
cap 2 will, together with an apical end of the threads 47 and a
coronal end of the threads 6d of the fixation screw 6, prevent the
fixation screw 6 and the healing cap 2 from being separated once
the fixation screw 6 has been threaded through the healing cap 2.
Hereby, the fixation screw 6 and the healing cap 2 will be held
together during installation of the healing cap 2 to the fixture
4.
[0123] The dental implant set 1 will now be further described in
use. FIGS. 1-3 show various stages of the installation process of
the healing cap 2 to the fixture 4. The fixture 4 has here
previously been inserted into a bore hole, arranged in bone tissue
while the healing cap 2 and the fixation screw 6, which are
pre-connected to each other, has been placed into the fixture 4, as
can be seen in FIG. 1. Furthermore, in FIG. 1, an intermediate
position is illustrated in which the fixation screw 6 and the
healing cap 2 is in contact but where the first and second indexing
means 100, 200 do not mate, while in FIGS. 2-3, an engaged position
is illustrated in which the first and the second indexing means
100, 200 mate and engages each other.
[0124] As can be seen in FIG. 1 the apical end 62 (the shelf-like
recess) of the indexing projection 60 of the healing cap 2 rests on
the shelf 32 of the first indexing means 100 of the fixture 4.
Thus, according to at least this example embodiment the third
contacting surface 73 of the healing cap 2 is provided by the
apical end 62 of the indexing projection 60, and is in contact with
the fourth contacting surface 74 of the fixture 4, here provided by
the shelf 32. Hereby, the healing cap 2 and the fixture 4 are in
contact with each other but the first and second indexing means
100, 200 do not mate. This position is referred to as the
intermediate position.
[0125] When the healing cap 2 is rotated relative the fixture 4,
the indexing projection 60 and its apical end 62 will move away
from the shelf 32 of the fixture 4 and eventually, in one or more
specific rotational orientations, meet an indexing depression 30
into which the indexing projection 60 is configured and dimensioned
to fit. In previous implant sets, the dentist would first have to
rotate the healing cap by one hand until it was correctly oriented
and thereafter tighten the implant screw to the fixture. However,
according to the present invention, the implant set 1 is provided
such that the torque applied by the driver 80 to the fixation screw
6 is transferred from the fixation screw 6 to the healing cap 2 via
the first and second contacting surfaces 71, 72 and from the
healing cap 2 to the fixture 4 via the third and fourth contacting
surfaces 73, 74, in such a manner that the maximum torque that can
be transferred via the first and second contacting surfaces 71, 72
is larger than the maximum torque that can be transferred between
the third and fourth contacting surfaces 73, 74. By this, the
healing cap 2 will rotate together with the fixation screw 6 in the
intermediate position. This will be further explained below. When
the indexing projections 60 are fit into the corresponding indexing
depressions 30, the first and second indexing means 100, 200 mate.
That is, the healing cap 2 will be able to move axially in the
apical direction of the fixture and engage with the fixture 4 in an
engaged position. The axial movement of the healing cap 2 is due to
an axial force being applied by the user in the apical direction of
the dental implant set or gravity. This can be seen in FIGS. 2-3
where the indexing projections 60 is fit into an indexing
depressions 30. Various axial positions of the dental component
relative the fixture are shown; in FIG. 2 the healing cap 2 and the
fixture 4 are in an early stage of the engaged position since the
indexing projections 60 are only slightly fitted into the indexing
depressions 30 while FIG. 3 show a late stage of the engaged
position where the indexing projections 60 are fully inserted into
the indexing depressions 30.
[0126] Furthermore, as is also illustrated in FIGS. 1-3, the length
of the fixation screw 6 is chosen such that the threads 6d cannot
engage the thread 34 when the healing cap is in the intermediate
position in FIG. 1, while it is able to engage it in the different
stages of the engaged position illustrated in FIGS. 2-3. After the
healing cap 2 has been arranged in the desired rotational position
relative the fixture 4 such that the indexing projections 60
engages with the indexing depressions 30 the healing cap 2 is
rotationally locked relative the fixture 4. This means that, in the
engaged position, the healing cap 2 is not able to rotate together
with the fixation screw 6, as in the intermediate position, due to
the rotational lock provided by the indexing means 100, 200.
Hereby, the fixation screw 6 may be tightened and the healing cap 2
fixated to the fixture 4. As can be seen in FIG. 3, in the fully
engaged position, the conical coronal portion 26 of the fixture 4
is forming a seat for the exterior of the conical coronal portion
48. Thus, the shape of the conical coronal portion 48 is conical
similar to the conical coronal portion 26 of the fixture 4.
[0127] Turning back to FIG. 1, it should be noted that the apical
end 62 of the indexing projections 60 is still in contact with the
shelves 32 of the fixture 4 when the healing cap 2 is rotated
relative the fixture 4 in the intermediate position. Thus, a
frictional force will counteract the rotation of the healing cap 2
relative the fixture 4.
[0128] Furthermore, when rotating the fixation screw 6 a frictional
force will counteract the rotation of the healing cap 2. Thus, at
least two different frictional forces are affecting the rotation of
the fixation screw 6 and the healing cap 2 when rotated together in
the intermediate position shown in FIG. 1; a first frictional force
between the first contacting surface 71 of the fixation screw 6 and
the second contacting surface 72 of the healing cap 2, and a second
frictional force between the third contacting surface 73 of the
healing cap 2 and the fourth contacting surface 74 of the fixture
4. When the fixation screw 6 is rotated, e.g. by applying a torque
by the driver 80, a different torque is allowed to be transferred
via the first and second contacting surfaces 71, 72 than via the
third and fourth contacting surfaces 73, 74 if the first and the
second frictional forces are different, provided everything else
equal. That is, the applied torque to the fixation screw 6 is
transferred from the fixation screw 6 to the healing cap 2 via the
first and second contacting surfaces 71, 72, and from the healing
cap 2 to the fixture 4 via the third and fourth contacting
surfaces, 73, 74, until the maximum capacity of torque transfer is
reached for either one of the pairs of contacting surfaces.
[0129] The first frictional force between the first and second
contacting surfaces 71, 72 and the second frictional force between
the third and fourth contacting surfaces 73, 74 may be altered by
different means. For example, a steeper inclination entails a
higher frictional force. As can be seen in the example embodiment
shown in FIGS. 1-3, the inclination a of the circumference of the
head 6c of the fixation screw 6 and the interior of the conical
coronal portion 48 providing the first and second contacting
surfaces 71, 72 are steeper compared to the inclination .beta. of
the apical ends 62 of the indexing projections 60 and the shelf 32
of the fixture providing the third and fourth contacting surfaces
73, 74, respectively. Hereby, assuming other characteristics of the
contacting surfaces 71-74 being the same, a larger torque can be
transferred between the fixation screw 6 and the healing cap 2 than
between the healing cap 2 and the fixture 4.Thus, the healing cap 2
will rotate along with the fixation screw 6 relative the fixture 4
in the intermediate position even though the distance, and thereby
the lever, is larger from the axis of the dental fixture to the
third and fourth contacting surfaces 73, 74 than from the axis of
the dental fixture to the first and second contacting surfaces 71,
72.
[0130] Rather than, or in addition to, providing dental components
2, 3a, 3b, 4, 6, of the implant set 1 with different angles for the
different contacting surfaces 71-74 for achieving different
frictional properties, the maximum capacity of torque that can be
transferred may also be affected by variations in surface
properties, thereby modifying the friction of coefficient between
the respective contacting surfaces. Turning to FIGS. 4-5
alternative manners to differentiate the frictional forces between
the contacting surfaces 71, 72, 73, 74 for a given axially applied
force are illustrated.
[0131] The same reference numerals as used in relation to FIGS. 1-3
and 6 denotes corresponding features in FIGS. 4 and 5. For sake of
clarity, only features differing from the embodiments described in
FIGS. 1-3 and 6 will be elaborated upon in the following
description of FIGS. 4 and 5. In FIG. 4 it is illustrated where the
fixation screw 6 and the dental component, here illustrated as a
custom-shaped abutment 3a, are surface modified for obtaining the
desired friction-affecting properties. Another example is
illustrated in FIG. 5 where the fixture 4 and the dental component,
here illustrated as an sloped abutment 3b, are surface modified for
obtaining the desired friction-affecting properties.
[0132] Thus, FIG. 4 illustrates an example in which the
circumference of the head 6c of the fixation screw 6 has been
provided with a surface roughness and similarly, the interior of
the conical coronal portion 48 of the abutment 3a has been provided
with a surface roughness. The surfaces provided with surface
roughness are here indicated by grey-coloured areas. When the
fixation screw 6 is inserted into the abutment 3a during and after
installation of the abutment 3a to the fixture 4, the circumference
of the head 6c is forming the first contacting surface 71 intended
to be in contact with the second contacting surface 72 provided
here by the interior of the conical coronal portion 48 of the
abutment 3a. Hence, the first and second contacting surfaces 71, 72
are provided with a surface roughness to provide for a higher
friction than if the contacting surfaces 71, 72 would have been
smooth surfaces.
[0133] FIG. 5 illustrates an example in which the contacting
surfaces 73, 74 between the abutment 3b and the fixture 4 have been
provided with some frictional reducing manner. That is, in this
embodiment, it is the apical ends 62 of the indexing projections 60
acting as the third contacting surface 73 and the shelves 32 in the
socket 24 acting as the fourth contacting surface 74, that have
been provided with frictional reducing measures, indicated by the
grey-coloured areas, to provide for a lower friction than if the
contacting surfaces 73, 74 would have been untreated surfaces.
[0134] It should be noted that to achieve a higher friction between
the first and second contacting surfaces 71, 72 it is not necessary
that both components are provided with the greater surface
roughness. Similar, to achieve a lower friction between the third
and fourth contacting surfaces 73, 74, it is not necessary that
both components are provided with frictional reducing measures.
Providing one of the components, e.g. the fixation screw 6 in FIG.
4 with roughened surface 71 while keeping the second contacting
surface 72 of the abutment 3a smooth will still result in a higher
friction than if both components would have smooth contacting
surfaces 71, 72. Of course providing at least one of the third and
fourth contacting surfaces 73, 74 with frictional reducing
measures, as in FIG. 5, will increase the relative frictional force
between that of the first and second contacting surfaces 71, 72 and
that of the third and fourth contacting surfaces 73, 74. Hence the
maximum capacity of torque transfer to the fixture 4 from the
abutment 3a, 3b will be smaller than the maximum capacity of torque
transfer to the abutment 3a, 3b from the fixation screw and
therefore allowing the abutment 3a, 3b to rotate along with the
fixation screw 6 in the intermediate position.
[0135] Other surface modification alternatives are of course
conceivable for affecting the frictional coefficients. Thus,
instead of surface roughening, an alternative would be to provide
the contacting surfaces 71-74 with a surface coating, another
alternative would be anodization of the contacting surfaces 71-74
(or of the entire components).
[0136] In order to clarify the different factors explained above,
reference is now made to FIG. 7 which schematically illustrates a
dental component and the factors affecting the capacity of torque
transfer between different components. The schematic dental
component in FIG. 7 corresponds to contacting surface 71 of the
fixation screw 6 and has the shape of a regular truncated cone. It
is in the following explanation assumed that the force per surface
area unit is constant over the cone surface. The lateral area of
the contacting surface 71 is
(R+r).pi.S
and the lateral surface area of an infinitesimal element is
2 ( r + ( R - r ) x H ) .pi. ( xS H ) ##EQU00001##
wherein S is the lateral height of the truncated cone, R and r are
the respective radiuses of the respective bases of the truncated
cone, x is the distance from the lower base of the cone and H is
the total height of the cone. The apically directed force per unit
area F.sub.A is
F ( ( R + r ) .pi. S ) , ##EQU00002##
where F is the force applied by the user. The normally directed
force per unit area F.sub.N is
F ( ( R + r ) sin ( .alpha. ) .pi. S ) , ##EQU00003##
where .alpha. is the angle between the contacting surface 71 and
the axis of the dental implant set. The lever L between each unit
area and the axis of the dental implant set is
r + ( R - r ) x H . ##EQU00004##
The coefficient of friction between the first and second contacting
surfaces is not illustrated in the picture but is denoted .mu.. The
torque is thereby
T = .intg. 0 H ( F ( R + r ) sin ( .alpha. ) .pi. S ) .mu. ( 2 ( r
+ ( R - r ) x H ) .pi. ( xS H ) ) ( ( r + ( R - r ) x H ) ) ,
##EQU00005##
i.e. the normally directed force per unit area times the
coefficient of friction times the lateral surface area of an
infinitesimal element times the lever integrated over the height of
the dental component. Hence, the torque becomes
T = 2 .mu. F ( R 2 + Rr + r 2 ) 3 sin ( .alpha. ) ( r + R ) .
##EQU00006##
[0137] It is from the above explanation clear that the factors
affecting the maximum torque transfer is the angle .alpha. the
coefficient of .mu. and the lever L. Even though FIG. 7
schematically illustrates the fixation screw 6, the same reasoning
applies to the capacity of transferring torque between the healing
cap and the fixture as well, but in that case it is the angle
.beta., please refer to FIG. 1, that should be used.
[0138] In FIG. 6 the first and the second indexing means are
illustrated in greater detail. The same reference numerals as
previously used denotes corresponding features. For sake of
clarity, only features differing from previously described
embodiments will be elaborated upon in the following description.
Most features of the dental implant set 1 are similar to the dental
implant set 1 illustrated in the previous figures.
[0139] FIG. 6 illustrates a sloped abutment 3b which is to be
connected to a symmetrical fixture 104 in a specific rotational
orientation with respect to the fixture 104, by means of a fixation
screw 6. The abutment 3b, the fixture 104 and the fixation screw 6
together represent a dental implant set 1 according to at least one
example embodiment of the invention. FIG. 6 also illustrates a
straight symmetrical abutment 3c which may be arranged in a number
of different rotational orientations with respect to the same
fixture 104. The abutments 3b, 3c further comprise dental
crown-receiving or prosthesis-receiving portions 148 which in use
extend coronally of the fixture 104 above the gingiva. Extension
portions 50, herein illustrated as coronally flaring up to a
shoulder 52, is intended to extend through the gingiva and is
provided between the fixture engagement portion 46 and the
prosthesis-receiving portion 148.
[0140] Although various alternative configurations are conceivable,
the socket 24 of the fixture 104 is herein illustrated as having a
conical coronal section 26 and a substantially cylindrical
intermediate wall section 28 similar to the fixture 4 illustrated
in FIGS. 1-3. The first indexing means of the fixture 104 comprises
seven indexing elements 30a-30g, herein illustrated as radially
extending indexing depressions 30a-30g provided in the intermediate
wall section 28 (illustrated in detail in FIG. 6a). The
intermediate wall section 28 and the radially extending indexing
depressions 30a-30g act as a component engagement portion of the
fixture 104. The coronal end of the intermediate wall section 28
forms a shelf 32 with gaps formed by said seven indexing
depressions 30a-30g. Six of the indexing depressions 30a-30e, 30g
are equidistantly distributed along the circumference of the
intermediate wall section 28. The seventh indexing depression 30f
is interposed between two (30e, 30g) of said six equidistantly
distributed indexing depressions. This is clearly illustrated in
the top view of FIG. 6a.
[0141] The second indexing means of the abutment 3b comprises seven
indexing elements 60a-60g, herein illustrated as radial indexing
projections 60a-60g, provided sequentially in the circumferential
direction of the cylindrical enveloping surface of the fixture
engagement portion 46 (illustrated in detail in FIG. 6b). Similarly
to the distribution of the radial indexing depressions 30a-30g in
the fixture 104, there are six equidistantly distributed radial
indexing projections 60a-60e, 60g on the abutment 3b, while the
seventh radial indexing projection 60f is interposed between two
(60e, 60g) of said six equidistantly distributed radial indexing
projections. With this configuration, the seventh radial indexing
projection 60f and its two neighbouring radial indexing projections
60e, 60g can only mate in one correct way with the seventh radial
indexing depression 30f and its two neighbouring indexing
depressions 30e, 30g. Thus, there is only one rotational
orientation possible for the abutment 3b to be connected with
respect to the fixture 104. This means that the abutment 3b may
have to be rotated 359.degree. before the indexing projections 60
correctly mates with the corresponding indexing depressions 30.
[0142] Four of the radial indexing projections can be regarded as
first indexing elements 60a-60d, each having an apical end (in FIG.
6 the apical end of the indexing projection 60d is designated with
reference numeral 62d). The other three radial indexing projections
60e-60g, namely said seventh radial indexing projection 60f and its
two neighbouring indexing projections 60e, 60g, can be regarded as
second indexing elements 60e-60g having apical ends 62e-62g located
apically of the apical ends of the first indexing elements 60a-60d.
This facilitates for the dentist to connect the abutment 3b to the
fixture 104 in the correct rotational orientation.
[0143] When the abutment 3b is to be connected to the fixture 104,
the projections forming said second indexing elements 60e-60g may
come in contact with the shelf 32 in the fixture 104. The
projections forming said first indexing elements 60a-60d will still
be spaced from the shelf 32. The abutment 3b is then rotated so
that the second indexing elements 60e-60g fall into the designated
indexing depressions 30e-30g of the fixture 104, i.e. into the
seventh indexing depression 30f and its two neighbouring indexing
depressions 30e, 30g.
[0144] Thus, the second indexing elements 60e-60g will first engage
with the seventh indexing depression 30f and its two neighbouring
indexing depressions 30e, 30g which represent fourth indexing
elements 30e-30g, and thereafter having already found the correct
rotational position, the first indexing elements 60a-60d of the
abutment 3b can engage with the third indexing elements 30a-30d
(the other four indexing depressions 30a-30d) of the fixture
104.
[0145] If only a single one (for example 60f) of the seven indexing
projections 60a-60g of the abutment 3b would have an apical end
located apically of the other six indexing projections, that single
one (for example 60f) of the indexing projections 60a-60g could
have mated with any one of the seven indexing depressions 30a-30g
of the fixture 104. However, only one (in this example 30f) of
those seven indexing depressions 30a-30g of the fixture is the
correct one which allows the trailing indexing projections of the
abutment 3b to also mate with the corresponding indexing
depressions in the fixture. If the dentist would place said single
one (e.g. 60f) of the seven radially projecting indexing
projections 60a-60g into one of the six incorrect radially intended
indexing depressions (e.g. 30a-30e, 30g), the trailing indexing
projections (e.g. 60a-60e, 60g) of the abutment 3b would not find a
mating indexing depression in the fixture 104 but would abut the
shelf 32. By additionally letting another one (for example 60g) of
the seven indexing projections (60a-60g) have an apical end
extending apically of the apical ends of the other indexing
projections, said indexing projection (in this example 60g) will be
in contact with the shelf 32 of the fixture reducing the risk of
the other indexing projection (in this example 60f) falling into
the incorrect depression in the fixture 104. Thus, having an
abutment 3b with at least one first indexing element and at least
two second indexing elements having apical ends apically of the
apical end of the first indexing element reduces the risk of the
second indexing elements falling into the incorrect indexing
depressions in the fixture. Hereby, the abutment 3b may rotate
together with the fixation screw 6 in the intermediate position
until the indexing projections 60a-60g falls into the correct
indexing depressions 30a-30g. Nevertheless, if the dentist brings
the abutment 3b towards the fixture 104 in a slightly inclined
direction, one of said second indexing elements may still be able
to reach into an incorrect indexing depression in the fixture,
albeit not very deeply because of the other second indexing element
contacting the shelf 32 preventing further advancement. Because the
second indexing element cannot fall deeply into an incorrect
indexing depression, a rotating motion will easily lift the second
indexing element and after continued rotation the correct position
will be found. Thus, the abutment 3b and the fixture 104 will stay
in the intermediate position until the indexing elements 60a-60g
correctly mates with the corresponding indexing depressions
30a-30g.
[0146] Having three radially projecting second indexing elements
with longer apical extensions than the trailing first indexing
element further facilitates correct alignment of the indexing
elements of the abutment 3b with those of the fixture. FIG. 6
illustrates an advantageous distribution of three second indexing
elements 60e-60g interposed between two (60a, 60d) of the first
indexing elements 60a-60d. The middle one (60f) of the second
indexing elements 60e-60g cannot fall into an incorrect indexing
depression (30a-30e, 30g) in the fixture 104, because of the other
two (60e, 60g) second indexing elements provided on either side
thereof. When the abutment 3b is to be connected to the fixture
104, the second indexing elements 60e-60g will with high likelyhood
land on the shelf 32, thus requiring the dentist to rotate the
abutment 3b into the correct orientation. During such rotation,
unless the dentist holds the abutment 3b absolutely straight, one
of the two outer second indexing elements (60e, 60g) might just
slightly drop into an incorrect indexing depression in the fixture
104. Since the drop is so small, the dentist can easily continue
the rotation until the correct alignment is found.
[0147] As illustrated in the bottom view of FIG. 6b, the first
indexing elements 60a-60d are somewhat wider than the second
indexing elements 60e-60g. In the fixture 104, however, the third
and fourth indexing elements 30a-30g have substantially the same
width. This has the effect that due to a larger width difference
between the second indexing elements 60e-60g and the fourth
indexing elements 30e-30g, there will be a lateral play between
these indexing elements facilitating the finding of the correct
rotational orientation. In other words, because the radially
projecting second indexing elements 60e-60g are
laterally/transversely underdimensioned with respect to the
radially indenting fourth indexing elements 30e-30g, they will more
easily fall into place than if they were of substantailly the same
dimensions. The radially projecting first indexing elements 60a-60d
are dimensionally closer matched to the radially indenting third
indexing elements 30a-30d, reducing potential lateral play, and
instead ensuring a substantially well-defined rotational position
of the abutment 3b with respect to the fixture 104. It should be
understood that rather than making the second indexing elements
60e-60g narrower than the first indexing elements 60a-60d, an
option would be to make them of equal width and instead make the
fourth indexing elements 30e-30g wider than the third indexing
elements 30a-30d. Thus, the relatively large lateral play between
the second and fourth indexing elements can be accomplished with
various designs of the abutment 3b and/or fixture 104.
[0148] In FIG. 6, the second indexing elements 60e-60g have been
illustrated as extending all the way to the apical end of the
abutment 3b, however, other alternatives are conceivable. For
instance, the second indexing elements 60e-60g may extend somewhat
shorter, as long as the apical ends 62e-62g thereof are located
apically of the apical ends of the first indexing elements 60a-60d,
or they may extend longer, i.e. beyond the apical end of the
abutment 3b.
[0149] Furthermore, it should be noted that the coronal extension
of the second indexing elements 60e-60g may also be shorter. In
fact, it should be understood that, for the radially projecting
second indexing elements 60e-60g to fall into connection with the
radially indenting fourth indexing elements 30e-30g, the second
indexing elements 60e-60g could be designed as substantially flat
plates projecting from the surface of the fixture engagement
portion 46 of the abutment 3b. Once the flat plates are received by
the associated indexing depressions 30e-30g, the whole abutment 3b,
including the following indexing elements 60a-60d (i.e. the other
radial projections which have the purpose to provide a rotational
lock) will be guided in the desired direction for completing the
insertion of the abutment 3b into the fixture 104.
[0150] It should also be noted that, although second indexing
elements 60e-60g have been presented in FIG. 6 as the seventh
radial projection 60f and its two neighbouring radial projections
60e, 60g, other alternatives are possible. For instance, the
seventh radial indexing projection 60f and a non-neighbouring
indexing projection (such as projection 60a, 60b or 60c) could have
their apical ends located apically of the apical ends of the other
radial projections. These two radial projections would be leading
and be the first ones to abut the shelf 32 provided between the
indexing depressions in the fixture 104. They can only fall down
from the shelf when the seventh radial indexing projection 60f is
aligned with the seventh radial indexing depression 30f. Thus, in
general terms, according to at least one example embodiment, the
distribution of the second indexing elements around the fixture
engagement portion is asymmetrical relative to the distribution of
the first indexing elements. In other words there is at least one
pair of second indexing elements (for instance corresponding to the
illustrated positions of 60f/60g, or 60f/60a, or 60f/60b) spaced
differently than the spacing between any pair of first indexing
elements.
[0151] FIG. 6 and FIG. 6c also illustrate another abutment 3c. It
has six equally-dimensioned and equidistantly distributed indexing
elements in the form of radial indexing projections 70. Unlike the
first abutment 3b, this other abutment 3c lacks a seventh indexing
projection. Thus, this other abutment 3c may be connected to the
fixture 104 in six different rotational orientations. This means
that the abutment 3c may have to be rotated 59.degree. before the
indexing projections 70 correctly mates with the corresponding
indexing depressions 30.
[0152] Throughout the detailed description, a healing cap 2
abutments with sloped surfaces 3a, 3b and an abutment with a
straight surface 3c have been used as examples of dental
components. It should be noted that other types of dental
components may be used with the present invention. For example, the
dental component may, in addition to the illustrated embodiments,
be an abutment replica, a driver, a healing cap, an impression
pick-up element, a digital transfer coping, a healing abutment, a
soft tissue former, etc.
[0153] The person skilled in the art realizes that the present
invention by no means is limited to the embodiments described
above. For example dental implant sets 1 with other indexing means
100, 200 may be used. Furthermore, the different embodiments may be
combined with each other in any suitable manner. For example, the
indexing means Illustrated in one embodiment may readily be used in
another embodiment.
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