Dental attachment for fixing dental prostheses

A dental attachment for fixing a dental prosthesis to healthy teeth comprising a male portion 1 which is rigidly fixed to a healthy tooth and a female portion 2 which is rigidly fixed to the dental prosthesis, the male portion 1 comprising two independent pins 7 which are intended to be engaged and sealed in a hole formed in a living tooth, and which have a spherical head 8, and the male portion further comprises a coupling portion 3 having an opening 5 which opens at a lower face and by way of an aperture 6 at its lateral face, the assembly being so arranged that the spherical coupling heads 8 of the pins 7 may be housed and sealed in the opening 5, the pins 7 extending from the coupling portion 3 through said aperture 6, the female portion 2 then being connected to the male portion 1.

The present invention relates to an attachment for fixing dental 
prostheses. 
The arrangements used hitherto for fixing dental prostheses require crowns 
to be fitted on to the healthy teeth on each side of the gap to be filled, 
to permit bridges and even partial dentures to be fixed on to the crowns. 
That procedure involves cutting healthy teeth which serve to carry the 
dental prostheses, thus making them much more vulnerable to infection and 
decay. It will be appreciated that that is not desirable, and systems have 
been developed, such as that described in Swiss Pat. No. 619,856, which 
use anchoring members comprising two teat elements which are intended to 
be fixed in a healthy tooth and which serve to carry a screwthreaded rod 
on to which are screwed studs which serve for fixing the prostheses. 
That arrangement is not satisfactory because it is necessary to drill two 
strictly parallel cavities to receive the test elements, and that cannot 
be achieved under pratical conditions. In fact, this arrangement also 
involves the necessity for forming substantial openings in the healthy 
teeth serving to carry the anchoring means, in order to be able to secure 
them in the required position. In addition, the use of irremovable 
screwthreaded rods cause problems for the user, particularly when fixing 
removable units. 
According to the present invention there is provided a dental attachment 
for fixing dental prostheses to healthy teeth, comprising a male portion 
which can be rigidly fixed to a healthy tooth and a female portion which 
is rigidly fixed to the dental prostheses, the male portion comprising two 
independent pins which are intended to be secured by one of their ends in 
a healthy tooth and which have at their other end a spherical head, and 
said male portion also comprising a coupling member having a cavity or 
opening which opens at a lower face and also by way of an aperture in its 
lateral face, the assembly being so arranged that the spherical coupling 
members of the pins may be housed and sealed in the cavity or opening, the 
pins extending from the connecting member through said aperture.

The attachment illustrated in the drawings comprises a male portion 1 which 
is intended to be fixed in a healthy tooth, and a female portion 2 which 
is intended to be incorporated in/or attached to a dental prostheses. 
In the embodiment illustrated in FIGS. 1, 2, 3 and 7, the male portion 1 
comprises a body 3 having a substantially conical outside surface and a 
rounded upper part, the body 3 flaring outwardly from the rounded upper 
part to its bottom end. The body 3 is provided with a cavity or opening 
having a cylindrical upper part 4 and a downwardly open, flared, lower 
part 5. A lateral aperture 6 provides access to the opening 4, 5, at the 
side of the body 3. 
The male portion 1 further comprises two pegs or pins 7 having a spherical 
head 8 intended to be positioned in the opening 4, 5, the diameter of the 
head 8 being larger than the width of the aperture 6. 
The free end of each of the pins 7 is intended to be sealed in a respective 
hole drilled in a healthy tooth. 
The pins 7 are displaceable angularly and axially with respect to each 
other, the heads 8 thereof always remaining in the opening 4, 5 and thus 
engaged with respect to the body 3. 
By virtue of this arrangement, the dentist can drill two small holes or 
recesses, the dimensions of which correspond to those of the pins 7, in a 
healthy tooth, for receiving the pins 7. The holes or recesses drilled in 
the tooth may be small in size and do not necessarily have to be parallel 
to each other nor spaced at a predetermined distance. In fact, as the pins 
7 are movable with a translatory movement and with an angular movement, 
they can be easily fitted into the two drillings and then sealed therein. 
The opening 4, 5 is also fitted with a sealing material when the body 3 is 
correctly oriented to permit the prosthesis to be fixed in position. 
The corresponding female portion 2 (FIG. 7) is formed by a conical cap 
member 9, the internal shape of which corresponds to the external shape of 
the conical body 3, and which has a side aperture 10. The cap 9 can thus 
be fitted over the conical body 3, once the body 3 has been fixed to a 
tooth in the mouth, as described hereinbefore, by means of the pins 7. 
The conical cap 9 has a lower lip portion 11 which co-operates with the 
lower edge of the conical body 3 to lock the cap 9 on the body 3 in the 
engaged position of use. 
The cap 9 may be made of a slightly elastic material such as a plastics 
material. 
The female portion 2 is incorporated in the dental prosthesis 12 by any 
known means. 
In the second embodiment illustrated in FIGS. 1, 4, 5 and 6, the male 
portion 1 comprises a body 12 which also has a cavity or opening 4, 5 
which is accessible through the rear side of the body 12 by way of an 
aperture 6 and which is inteded to receive the spherical heads 8 of two 
pins 7. 
The body 12 of the male portion 1 also has a coupling portion 13 having 
three conical millings or drillings 14, 15, 16 with their axes parallel. 
The conical drillings 14, 15 and 16 flare outwardly towards the upper face 
of the body 12 of the male portion 1. 
The coupling portion 13 is intended to co-operate with a female portion 2 
of the attachment, as illustrated in FIGS. 5 and 6, which comprises three 
pins 17, 18 and 19 mounted in a mass of plastics material 20, with an 
aperture 21. 
The pins 17, 18 and 19 are also conical and flare outwardly in an upward 
direction, and at their lower end are provided with a retaining lip or 
catch means 22. 
The female portion 12 is intended to be incorporated in a dental 
prosthesis. That may be effected for example by providing in the dental 
prosthesis, a cavity or opening which corresponds to the form of the mass 
of plastics material 20 of the female portion 2. The female portion 2 is 
then received in the manner of a press-stud in the cavity or opening in 
the dental prosthesis. It is retained in position in the prosthesis by a 
shoulder 20a co-operating with the walls of the cavity or opening formed 
in the dental prosthesis. 
To fix the dental prosthesis, it is sufficient to engage the pins 17, 18 
and 19 in the drillings 14, 15 and 16, which is extremely simple because 
of the conical configuration of the pins and the drillings. By pushing the 
pins right home into the drillings, the retaining lip portion 22 is moved 
into a position under the coupling portion 13 and holds the female and 
male portions 1 and 2 in the coupled position. 
This attachment is particularly attractive for the following reason: 
1. The interference with the healthy teeth serving as a carrier is 
minimised, as the drillings may be small and the position thereof is not 
critical, as also is the case with their orientation. 
2. The dental prosthesis may be removably fixed. 
3. The alignment of the two or more male portions serving to fix the 
prosthesis, and likewise in regard to the female portion, is not a 
critical consideration, by virtue of the tapered configuration of the 
drillings and the pins respectively of the body and the cap, as well as 
the elasticity of the mass of plastics material of the female portion, 
which permit the portions automatically to assume their proper positions 
when the prosthesis is set in place. 
4. It can be manufactured on a mass-production basis, and the cost price 
thereof can be kept very low.