Extracoronal holding member for dental prostheses

A holding member assembly comprises a shell-like female part with an annular cavity and a male part with a torus adapted to mate with the cavity. The torus contains a slot with an annular spring which, on insertion of the male into the female, engage in a holding slot of the female part. The female part is embedded into a tooth crown, whereas the male part is connected to a dental prosthesis part. Through constructing the female part with the cavity, it is possible to produce holding members with reduced overall height compared with the known holding members, but which still have an excellent stability.

This invention relates to an extracoronal holding member for dental 
prostheses and especially to such an article which is in two parts, namely 
a male part and a female part, with the parts being held together by an 
annular spring when the dental prosthesis is inserted. 
BACKGROUND OF THE INVENTION 
Increasing use is being made of the possibility of the wearers of dental 
prostheses being able to detach the prosthesis from its anchoring 
themselves and remove it, e.g., for cleaning purposes. To this end, an 
attaching member is known (Swiss Pat. No. 343,061) comprising a cap-like 
member, which includes two screwed-together portions forming an assembly 
called the female part and a cooperating member also formed by two 
screwed-together portions and called the male part. The male and female 
parts are held together without clearance by an annular spring or circular 
clip. Both for releasing and attaching the dental prosthesis, the annular 
spring or clip is elastically widened at its holding surface provided on 
the male part, so that there is a certain resistance when releasing and 
attaching the dental prosthesis. 
However, it is a disadvantage of the known holding member that it has a 
relatively large overall height due to the two spaced, superimposed 
guidance surfaces necessary for obtaining adequate stability of the hold 
member. Due to the relatively large number of individual components of 
this known hold member, it is also complicated in construction and 
therefore expensive. 
BRIEF SUMMARY OF THE INVENTION 
An object of the present invention is to provide a holding member of the 
aforementioned type in which its construction can be considerably 
simplified and its overall height made considerably less than that of the 
known devices without loss of stability. 
Briefly described, the invention includes a holding member assembly for 
dental prostheses comprising a female member having means defining a 
generally annular cavity therein, a male member having a generally 
toroidal portion shaped and dimensioned to be closely received in said 
female member, an annular spring for releasably holding said members 
together and means for securing one of said members to at least one tooth 
of a wearer and the other of said members to a prosthesis. 
Thus, the shortcomings of the prior art are overcome by a structure in 
which the female part is provided with an annular cavity and the male 
member is shaped as a ring for insertion in the annular cavity. Thus, the 
male part is supported on faces of the female part which are relatively 
remote from the central axis of the holding member assembly, thereby 
ensuring a high degree of stability of the assembly, accompanied by 
significantly reduced overall height.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As previously indicated, the device of the present invention is formed in 
two cooperating parts, a female part and a male part which interfit but 
which are shown separately in the figures. 
The female part 1 shown in FIG. 1 is molded in a conventional manner, not 
further described, onto a schematically indicated tooth corona or crown 2. 
Female part 1 is constructed as a hollow shell and has an annular cavity 3 
forming a closed (i.e., endless) channel. The inner wall 4 of cavity 3 
forms a central projection 5 bounded by a cover 6 in which a central 
rinsing opening 7 is provided. The outer wall 8 of the female part extends 
upwardly higher than the cover 6 of central projection 5 and has at its 
end an outwardly extending flange 9 which reinforces outer wall 8. On the 
outer side of cavity 3, outer wall 8 has a holding slot 10 corresponding 
to an outwarly protruding rib 10 which functions as an anchoring means on 
the outside of outer wall 8. 
The male part 11 shown in FIG. 2 is constructed as a torus 12 having a 
central recess 14. A wall or base 13 extends across one side of torus 12, 
closing that side of the recess. Base 13 has a radially outwardly 
extending flange 15 projecting beyond torus 12 and is provided on its top 
face with an anchoring plate 16, having shouders with inclined sides which 
permit perfect anchoring with a dental prosthesis part schematically 
illustrated at 17. 
In order that the male part 11 can be inserted without clearance into 
female part 1, torus 12 has the same cross-sectional shape as cavity 3 of 
female part 1. A circumferential slot 19 is formed approximately in the 
center of outer wall 18 of torus 12 and receives an annular spring 20. As 
is illustrated in FIGS. 3 to 5, different contructions of annular spring 
20 are possible. 
When male part 11 is inserted into female part 1, annular spring 20 is 
initially somewhat compressed and then engages in the holding slot 10. By 
using corresponding construction on the sloping slot walls and because of 
the arrangement of slot 10, it is possible to ensure that annular spring 
20 holds the male part in clearance-free manner in cavity 3 of the female 
part. 
Due to the fact that annular spring 20 is mounted in male part 11, it is 
removed at the time of removing dental prosthesis part 17 and the male 
part from female part 1 and hold slot 10 consequently becomes accessible, 
e.g., for cleaning. To ensure that the bristles of the brush used for 
cleaning do not stick to the annular spring ends and consequently tear the 
spring 20 out of slot 19, those ends are constructed in accordance with 
FIGS. 3 to 5. 
In FIG. 3, annular spring 20 is a bent wire, round in cross-section, whose 
ends 21 are bent inwardly. Holding slot 10 in female part 1 has 
corresponding depressions, not shown, into which ends 21 project. Annular 
spring 20a in FIG. 4 is constructed as a flat ring with a smooth outer 
edge 22. Inner edge 23 has a plurality of recesses 24 which form areas or 
points having increased flexibility and elasticity. Annular spring 20b in 
FIG. 5 is made from a round wire and is shaped in indulating manner, its 
ends 25 being appropriately bent inwardly. 
As can be gathered from FIG. 1, walls 4 and 8 of female part 1 conically 
converge towards the bottom of cavity 3. Therefore, torus 12 of male part 
11 also has a conical shape. However, cavity 3 and torus 12 need not be 
conical, e.g., the walls could be approximately parallel. If the walls 
slope, the slope should only be sufficiently great to ensure perfect 
supporting of male part 11 in female part 1 by annular spring 20. 
The construction of the holding member assembly formed from female part 1 
and male part 11 is extremely simple. The essential point is that no 
screwed-together parts need be used. Despite the extremely limited overall 
height, very good stability of the holding member is obtained. 
In FIGS. 1 and 2, the two parts are shown on a greatly increased scale. In 
reality, the greatest diameter of female part 1 is approximately 5 mm, 
while the overall height of female part 1 and male part 11 is 
approximately 2.5 mm, i.e., only about half that of known holding members. 
With limited adaptation, the previously described extracoronal holding 
member can so be used as an intracoronal holding member. The uses of the 
known holding members also exist in the present case. Thus, the holding 
member can be arranged in a plastic web for holding purposes. The gold 
construction for soldering to a tooth root is also possible. It can also 
be used as an intracoronal insert, i.e., the male part and female part are 
inserted into the tooth. Gold, platinum and alloys thereof are used as 
materials for the hold member. 
While certain advantageous embodiments have been chosen to illustrate the 
invention, it will be understood by those skilled in the art that various 
changes and modifications can be made in accordance with the invention as 
defined in the appended claims.