Note: Descriptions are shown in the official language in which they were submitted.
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SPECIFICATION
CONE-SHAPED IMPLANT
The invention is directed to an enossal single tooth implant for a firmly
seated tooth replacement, comprising an essentially cylindrical base member
s introducable into a bore introduced into a jaw bone that comprises a blind
bore open at its coronal end, a spacer sleeve attachable twist-resistant to
the
coronal end edge of the base member that comprises a cervical centering
color that is introducable into a hollow-cylindrical ring recess provided at
the
cororial end of the base member, comprises a shoulder adjoining the
to centering color in coronal direction and capable of being placed onto the
coronal end edge of the base member, and that is provided with a bore open
toward its coronal end for the acceptance of the implant post, whereby a
connecting means for twist-protected connection of the spacer sleeve to the
base member is formed in that the hollow-cylindrical ring recess of the base
15 member comprises at least one base member positive locking element
effective in circumferential direction and the centering color of the spacer
sleeve comprises at least one spacer sleeve positive locking element
complimentary to the base member positive locking element or elements, an
implant post directly or indirectly introducable into the blind bore of the
base
2 o member and at least partially penetrating the spacer sleeve and a
fastening
head for the tooth replacement, whereby the base member positive locking
element or elements islare provided at an inside wall of the ring recess in a
positive locking region thereof directly following the end edge of the base
member; whereby a guide surfacelguide surfaces of the positive locking
2 s region lying immediately adjacent to the longitudinal axis of the ring
recess
lies/lie on a cylindrical surface whose diameter corresponds to that of a
guide
region of the ring recess having an essentially smooth circumferential wall
and cervically adjoining the positive locking region; whereby a centering
region of the ring recess having a reduced diameter compared to the guide
3 o region cervically adjoins the guide region of the ring recess; whereby the
spacer sleeve positive locking element or elements islare provided cervically
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following the shoulder of the spacer sleeve at the cylindrical outside wall of
the centering collar in a positive locking section thereof; whereby the
circumferential surface or surfaces of the positive locking section lying
radially closest to the longitudinal center axis of the centering collar lie
on a
cylindrical surface whose diameter essentially corresponds to the inside
diameter of the guide region of the base member; whereby a cylindrical
guide section cervically adjoins the positive locking section, the outside
diameter thereof essentially corresponding to the inside diameter of the
guide region of the base member; and whereby a cylindrical centering
to section whose outside diameter essentially coincides with the inside
diameter of the centering region of the base member cervically adjoins the
guide section. Such an implant is disclosed by DE 195 34 979 C1, which is
referenced with respect to further details of this implant of the species.
Given the known implant, the base member, which can either be
smooth or provided with an outside screw thread, comprises an essentially
constant cross-section over its length. This geometry has in fact generally
proven itself but, given implants in the molar tooth region, leads thereto due
to the higher forces acting on the implant thereat a comparatively large
diameter of the base member is required for a stable anchoring of the
2 o implant structure. This in tum requires a greater removal of bone tissue
for
the insertion of the base member into the bone.
United States Letters Patent 5,205,745 discloses a multi-part single
tooth implant, whereby the base member comprises two cylindrical sections
that are connected to one another by a conical section, whereby the
2 5 cervically lying section comprises a smaller outside diameter than the
coronally lying section. For improving the strength, a reinforcing core is
introduced in this base member, a connecting screw for fastening the tooth
crown being capable of being screwed thereinto. The crown put in place on
the base member comprises no component parts that engage into a blind
3 o bore of the base member.
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The object of the invention is to create an implant of the species
initially cited, whereby a stable anchoring of the implant structure is
possible
with less damage to the bone tissue of the patient.
This object is inventively achieved by an implant according to the
preamble of claim 1 wherein the base member, with reference to its
longitudinal direction, comprises a first section that forms the cervical end
of
the base member and also comprises a second section adjoining the first
section at the coronal end thereof wherein the outside diameter is enlarged
to in the direction toward the coronal end of the base member, and the outside
diameter in the first section with respect to the longitudinal direction of
the
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base member does not change significantly or at least changes less strongly
then in the second section, and the first section is preferably free of a
thread.
The first section can thereby be essentially cylindrical and the second
section can be essentially conical. The first section can comprise recesses
s of any geometry, for example the standard lacunae, given what is otherwise
an essentially constant outside diameter.
The invention can also comprise a third, essentially cylindrical section
that adjoins the second section in the direction toward the coronal end of the
base member, whereby the outside diameter of the first section is smaller
over its entire length then the outside diameter of the third section.
It can also be provided that the third, essentially cylindrical section of
the base member is provided with a preferably self tapping outside screw
thread.
The outside diameter of the base member at its cervical end can
is amount to 65% through 85%, preferably 70% through 75%, of the outside
diameter at its coronal end.
The distance between the coronal end of the base member and the
coronal end of the first section can lie in a range between 4 mm and 7 mm,
preferably at approximately 6.5 mm, according to a preferred embodiment.
2 o The invention can also provide that the cone angle a of the second
section lies in a range from 25° through 50°, preferably in a
range from 30°
through 45°.
The first, second and, potentially, third section can be respectively
differently worked andlor coated, whereby, in particular, their surface can
2 s respectively be differently designed. For example, one or two of the
sections
can comprise a smooth surface and the remaining section or sections can
comprise a rough surface. When the third section is implemented with an
outside thread, it preferably comprises a rough surface produced with an
etching technique, whereas first and second sections are preferably provided
3 o with a titanium plasma coating.
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It can also be provided that the blind bore in the base member
comprises a plurality of coaxial, essentially cylindrical sections whose
inside
diameter decreases from the coronal end to the cervical end.
Inventively, the blind bore in the base member can comprise a larger
s inside diameter in the region of the third section then in the first
section.
Further, the inside diameter of the blind bore in the preferably cone-
like second section can lie between the inside diameter of the blind bore in
the third section of the base member and that in the first section of the base
member.
to The invention also provides positive locking elements for securing a
structure secured to the base member against twisting with respect to the
base member, these being capable of being particularly provided
immediately following the coronal end face of the base member.
The invention is based on the perception that, for dependable
15 anchoring of an implant structure even given the occurrence of greater
forces
as occur in the region of the molars, a comparatively large diameter of the
base member is required only in the region of the hard corticalis, whereas a
smaller cross-sectional area suffices in the region of the spongiosa.
Accordingly, the length of the section of the base member advantageously
2 o approximately corresponds to the thickness of the corticalis. A preferably
self-tapping outside thread in the thickened, third section can serve the
purpose of better anchoring of the base member in the corticalis.
Further features and advantages of the invention derive from the
following description of exemplary embodiments of the invention with
2 s reference to the attached drawings.
Fig. 1 shows a side view of a first embodiment of a base member of
the inventive implant.
Fig. 2 shows a longitudinal section of the base member shown in Fig.
1.
3 o Fig. 3 shows a front view of a second exemplary embodiment of the
inventive base member.
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Fig.4 shows a longitudinal section of the base member in the
embodiment of Fig. 3.
Identical component parts and component parts having the same
effect are provided with the same reference characters in the following
description.
Referring to Fig. 1, the base member of the implant successively
comprises three main sections from the cervical end to the coronal end,
namely a first cylindrical section 1, a conical transition section 3, as well
as
a second cylindrical section 5, whereby the outside diameter of the section
l0 5 is greater then that of the section 1, and the outside diameter of the
section
2 diminishes from the larger diameter of the section 5 to the smaller diameter
of the section 1 continuously, for example, conically, or along a curve that,
for example, can be hyperbolic or in the shape of a circular arc. Oval-
shaped depressions 7, what are referred to as lacunae, into which bone
material can grow for better anchoring during healing are fashioned in a
known way in the first cylindrical section 1. The length between the coronal
end of the section 5 and the cervical end of the section 3 in this exemplary
embodiment amounts to approximately 6.5 mm, whereas the length of the
section 1 can vary dependent upon application and, for example, can lie
2o between 5 mm and 11 mm and typically amounts to 1/2 through 2/3 of the
overall length of the base member. In the illustrated exemplary embodiment,
the outside diameter of the section 1 amounts to approximately 5.4 mm, and
the outside diameter of the section 5 amounts to approximately 4 mm,
whereby the cone angle a of the section 3 amounts to approximately 30°.
As proceeds from the sectional view of Fig. 2, the base member
shown in Fig. 1 comprises a blind bore 10 for the acceptance of an implant
post and comprises a spacer sleeve, as disclosed in German Patent 195 34
979 C1, which is referenced in view of further details. In agreement with the
teaching of this publication, the blind bore comprises a first and second
3 o inside thread 11 or, respectively 12, whereby the inside thread 11 has a
smaller diameter then the inside thread 12 and lies essentially in the section
1. The inside thread 12 is followed by a guide region 13 that lies in the
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section 5 and whose inside diameter is larger then the inside diameter of the
thread 11 and 12. In the direction toward the coronal end, the guide section
13 is followed by a positive locking section 14 that comprises a plurality of
positive lock recesses 15 for interaction with complementary positive locking
s elements of a spacer sleeve that are introduced into the base member
shown in Figs. 1 and 2 and through which an implant post can be introduced
into the base member and anchored with the inside thread 11. Three or fnnr
semicircular or rectangular recesses 15 are preferably present. DE 195 34
979 C1 is referenced in view of further details with respect to the positive
lock connection.
The second embodiment of the base member of the inventive implant
shown in Figs. 3 and 4 essentially corresponds to the base member shown
in Figs. 1 and 2. Differing from the embodiment of Figs. 1 and 2, however,
the first cylindrical section 5 here is provided with a self tapping outside
thread 20 that begins below the coronal end approximately at the level of the
guide section 13 and extends up to the beginning of the cone-like section 3.
The nominal diameter of the outside thread 20 thereby corresponds to the
outside diameter of the thread-free part of the section 5 at its coronal end,
whereby the thread depth amounts to approximately 1/6 of this outside
2 o diameter, i.e. 0.9 mm given an outside diameter of 5.4 mm. The conical
transition region is fashioned somewhat shorter here. The cone angle a at
a transition from an outside diameter or, respectively, nominal diameter of
the thread 20 from 5.4 mm to 4 mm lies at approximately 45°. Both
individually as well as in arbitrary combination, the features of the
invention
disclosed in the above specification, in the drawings as well as in the claims
can be critical for the realization of the various embodiments of the
invention.
