Dental implant

A dental implant has a two-sided taper of the head part which is formed by bevels tapering down on both sides of the threaded bore toward the edges of the jaw bone. The bevels form lines of intersection with the circumference of the head part, starting from the edge areas of an end face of the head part and running at a variable height, corresponding to the shape of the upper edges of the jaw bone. A contact body connected to the crown is adapted to the taper at the upper edge of the head of the implant. The two-sided taper may be asymmetrical in design. The surface of the contact body facing the crown corresponds in shape to the head part and has bevels with a corresponding complementary shape. This yields a simplified prosthetic system with integrated security against twisting which has improved mechanical stability in both buccal and lingual directions.

SCOPE OF THE INVENTION 
The invention relates to an enosseous dental implant which includes a 
rotationally symmetrical bottom part, a head part and a threaded bore 
emanating from the head part to accommodate a fastening screw for 
fastening directly or through a intermediate member a dental crown, and 
which includes a device for securing the dental crown against twisting on 
the head part. 
STATE OF THE ART 
There are known dental implants for a tight-fitting denture consisting of a 
cylindrical or conical base body having a recess suitable for ingrowth in 
the jaw on its outside diameter, such as a roughened surface, cylindrical 
or conical thread, stepped grooves and the like. The head of the implant 
is polished and has a central bore which is designed as a threaded hole 
and serves to receive a threaded pin on which the crown is attached 
(German Patent No 40 28 855 C2, German Patent No. 39 17 690 C2). The crown 
is secured against twisting by a device connected to the fixation, such as 
a square or elliptical fitting. The crown is supported in a plane on the 
implant There is no adaptation of the implant the natural shape of the 
bone. 
It is also known that a spacer sleeve which can be provided between the 
crown and the head of the implant has a peripheral shoulder on its 
circumference to which the lower edge of the crown is attached (German 
Patent application DE-A 195 09 762) The shoulder runs at an inclined angle 
to the upper edge of the implant head at a distance that varies over its 
circumference, to thereby achieve an improved adaptation of the transition 
between the crown and the implant to the anatomical conditions through an 
appropriate choice of the base height of the shoulder The spacer sleeve 
here serves as the implant head. It is designed so that it is closed at 
the bottom and is screwed into the base body of the implant by a thread 
and it has a central threaded bore to accommodate the threaded pin to 
which the crown is attached. A centering collar on the lower end of the 
spacer sleeve is provided with vertical projections which engage in 
corresponding recesses in the base body and serve to orient the crown and 
secure it against twisting. 
Again with this device, the crown is again supported in one plane without 
adapting to the natural shape of the bone. 
SUMMARY OF THE INVENTION 
The dental implant according to the invention, as defined in the patent 
claims, provides for a two-sided taper of the head part which is formed by 
bevels arranged on both sides of the threaded bore and extending crosswise 
to the direction of the row of teeth. The bevels form lines of 
intersection with the circumference of the head part, emanating from the 
edge areas of an end face of the head part and running at a variable 
height, corresponding to the shape of the upper edges of the jaw bone. A 
contact body connected to the crown is adapted to the taper at the upper 
edge of the head of the implant. 
The two-sided taper may be asymmetrical in design. For this purpose, an 
shallower bevel is provided on the lingual side and a steeper bevel is 
provided on the bucal side. Lines of intersection of the different bevels 
with the circumference of the head part extend in this embodiment on both 
sidles at different heights in accordance with the shape of the jaw bone. 
The implant according to the invention permits an improved adaptation to 
the anatomy of the jaw bone as well as the soft tissue above the bone. Due 
to the shape of the implant, an adaptation to differences in level between 
the buccal and lingual heights and the approximate height of the bone is 
achieved, and a natural upper edge of the jaw bone is reproduced. In this 
way it is possible to avoid removing of bone tissue to establish a uniform 
base for the prosthetic system, and the natural bone shape can be mostly 
preserved and can regrow when the implant heals in. Furthermore, the 
nature shape of the bone determines the natural shape of the soft tissue, 
so that an interimplant papillary structure develops. 
The shape of the head of the implant, adapted to the differences in level 
in the bone, prevents circular inflammation. Osteolysis develops on a 
different level, as is also the case with a normal tooth. 
In addition, this arrangement has a positive effect on controlled bone 
regeneration when using the membrane technique. Due to the tapered head of 
the implant, the membrane conforms to the shape of the head of the 
implant, and folding is prevented in applying the membrane. 
The surface of the contact body facing the crown corresponds in shape to 
the head part and has bevels with a corresponding complementary shape. 
This yields a simplified prosthetic system with integrated security 
against twisting which has improved mechanical stability in both buccal 
and lingual directions. The bevels on the head of the implant and the 
corresponding bevels on the contact body absorb the forces acting 
laterally on the implant and prevent shearing forces from occurring in the 
area of the securing screw.

DETAILED DESCRIPTION OF THE EMBODIMENT ILLUSTRATED IN FIGS. 1 THROUGH 9 
The embodiment illustrated here shows an enosseous dental implant having a 
cylindrical implant body 1 which consists of an implant root 2 and an 
implant head 3. Implant head 3 and implant root 2 may be designed in one 
piece, as shown in the figures, or may consist of two parts that are 
joined together in a suitable manner. On its perimeter, the implant root 2 
is provided with a thread 4 with which the implant is screwed into a 
predrilled hole in the jaw bone. 
A passage 9 on the lower end of the implant root 2 serves to facilitate 
settling and healing of the implant in the bone. When inserted, the top 
edge of the jaw bone runs in the area of the implant head 3. As shown by 
FIGS. 2 through 5, the implant head 3 has on its top end a two-sided taper 
formed by bevels 5 and 6. Due to this design, the top end of implant head 
3 is adapted to the shape of the jaw bone. 
Bevels 5 and 6 are asymmetrical in design. Therefore, bevel on the lingual 
side of the inserted implant runs at a shallower angle than the bevel 6 on 
its opposite side. Bevel 6 thus forms a more acute angle with the 
longitudinal axis of the implant body 1 than does the bevel 5, thus 
forming arc-shaped lines of intersection 7 and 8 with the cylindrical 
circumference of head part 3, running at different heights on both sides 
of the implant head 3 (FIGS. 3 and 4). In this way, the edge of the 
implant facing the crown can be largely adapted to the different shape of 
the edge of the jaw bone on the lingual and buccal sides. 
The top view in FIG. 5 shows that the bevels 5, 6 form straight top edges 
11, 12 with the end face 10 of the implant head. When the implant is 
inserted, the edge areas 13 and 14 of end face 10 are approximately at the 
level of the upper edge of the jaw bone between adjacent teeth and thus 
are at a different distance from the lines of intersection 7, 8 forming 
bevels 5, 6. 
After the healing and settling phase, a contact body 20 is placed on 
implant head 3 and is held in this position by a threaded pin 21 which is 
screwed into a concentric threaded hole 19 in the implant root (FIGS. 1 
and 3). The contact body 20 has a guide part 22 which in this embodiment 
is designed as a cylinder that engages in a corresponding recess 23 in the 
implant head 3. The lower side of the contact body 20 is adapted with a 
shape that is complementary to the asymmetrical shape of the implant head. 
For this purpose, on both sides of the guide cylinder 22, the contact body 
20 has inclined faces 24, 25 that correspond to the bevels 5 and 6 on 
implant head 3 and are in form-fitting contact with them. The faces 24, 25 
also serve as security against axial twisting of contact body 20 with 
respect to implant body 1. 
The top side of the contact body also has a corresponding design. The 
angular position of the inclined top faces 26, 27 corresponds to that of 
the inclined bottom faces 24, 25. The outer end of faces 26 runs out in a 
horizontal collar 28. A corresponding collar 29 is also on the outer end 
of the inclined face 27. Faces 24 and 26 border an apron 30 with a 
downward slope 30 (FIG. 8), and faces 25 and 27 border an apron 31 with a 
downward slope (FIG. 9). Aprons 30, 31 run in the cylindrical part 33 of 
the contact body 20 below the edge areas 13, 14 of the end-face 10. The 
circumference of the contact body 20 increases in a conical shape toward 
the top, while circumference 33 has a slightly concave profile. Likewise, 
the circumference of the contact body 20 increases toward the top in the 
area of the aprons 30, 31 with a slightly concave profile 34, 35, which 
develops into the circumference 33 of the contact body 20 without edges. 
The contour of a crown 40 follows the slightly concave profile 33, 34, 35 
without a joint or a shoulder. On its lower side, the crown 40 is adapted 
to the shape of the contact body 20 and is attached to it. An extension 36 
of the contact body 20 having a shallow recess on its top end to 
accommodate the screw head 37 on pin 21 serves to orient and secure the 
crown 40. The extension 36 may be in the shape of a cylinder, as shown in 
the figures, or it may have a different shape such as the Shape of a 
pointed cone. The crown 40 is attached to the contact body 20 by cementing 
and/or by a transverse screw 38 which is guided through a hole in the 
crown and engages in a lateral threaded bore 39 in the extension 36 of the 
contact body 20. 
The thickness of aprons 30, 31 is such that they correspond approximately 
to the thickness of the soft tissue which forms on the jaw bone. This 
yields an adaptation to the anatomical conditions even in the area of the 
soft tissue. The shape of the soft tissue is determined by the natural 
course to which the implant head is adapted by the two-sided tapered 
design of the head part, so that an interimplant papillary structure also 
develops postoperatively. FIG. 10 shows the shape of the bone 41 and the 
gingiva 42 as well as the interdental papillae 43 with a natural dental 
arrangement. The corresponding view of a dental arrangement with a 
traditional implant system shows the loss of interdental papillae in the 
areas 44 between the implant and the neighboring natural teeth. FIG. 12 
shows the implant system according to FIGS. 1 and 8 with interdental 
papillae 45 between implant 46 and the neighboring natural teeth 47 which 
develops due to the adaptation of level to the natural shape of the bone 
and soft tissue. 
ALTERNATIVE EMBODIMENTS 
FIGS. 13 through 16 show alternative embodiments of the invention. In the 
embodiment according to FIG. 13, the asymmetrical taper of the implant 
head 50 on its upper end is achieved by beveled partial faces 51 and 52 
with a convex curvature, developing into end face 53 of the implant head 
without an edge. The contact body (not shown) which belongs with this 
embodiment is adapted to the top and bottom sides of the shape of the 
implant head 50, as explained above. 
FIG. 14 shows that in another embodiment of this invention, the implant 
head 60 has an end face 61 with an approximately elliptical shape on its 
upper end derived from a convex curve of the asymmetrical beveled faces 62 
and 63 in the radial direction. This permits an adaptation to particular 
anatomical conditions on the upper edge of the jaw bone. Again in this 
embodiment, the contact body (not shown) which belongs with it is adapted 
to the shape of the implant head 60 on its upper and lower sides. 
The top part of the contact body serving to secure the crown is to be 
adapted to the axial direction of the crown. FIGS. 15 and 16 show one 
embodiment where an extension 66 of a contact body 65 extending upward is 
bent at an acute angle to the axis 69 of the implant body in the direction 
of crown axis 68. The extension 66 is a friction body 70 which is designed 
concentric with crown axis 68 and is set on end face 67 of contact body 
65, and is open toward the axis 69 and has an inclination 71 which runs 
into the inclined face 72 on the buccal side of the contact body 65. The 
crown is attached to the contact body 65 in the direction of axis 68. Any 
other shapes of the extension of the contact body projecting upward are 
also possible.