Dentistry – Prosthodontics – Stress breaker
Patent
1994-08-23
1996-04-23
Bennett, Christopher A.
Dentistry
Prosthodontics
Stress breaker
433173, A61C 1328
Patent
active
055098045
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a base for dental prosthesis and the like for implantation in bone.
More specifically, the subject of the invention is a base for implantation in bone, including an outer body of rigid material, preferably a biocompatible metallic material, having means for anchoring it to the bony tissue and a cavity in which an inner body, also made of a rigid material, preferably a biocompatible metallic material, with a seat for holding a prosthesis is disposed with the interposition of a layer of resiliently shock-absorbent bonding material; an annular retaining element being connected to the edge of the cavity in the outer body and having an inner edge.
A base for implantation in bone of the type specified above is disclosed in WO-A-8 706 816 (FIG. 4).
In that prior implantation base the inner edge of the annular retaining ring merely overlies the upper portion of the resilient bonding material interposed between the outer body and the inner body. With this construction the resilient bonding material is not sealingly prevented from coming into contact with food and/or mouth fluids which can seep through the interspace between the retaining ring and the inner body and cause a degradation of said resilient bonding material.
Other bases for implantation in bone are described, for example, in U.S. Pat. No. 4 780 080, French patent application 2 580 169, and Dutch patent application 8200711.
The bases for implantation in bone described in these documents have the disadvantage that the resiliently shock-absorbent bonding material interposed between the inner and outer bodies extends to the top of the base and, in the condition of use, is in contact with the surrounding tissue, particularly the gum tissue. This material can thus come into contact with food and various liquids introduced into the mouth and may sooner or later become degraded.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a base for implantation in bone which overcomes the problem of the bases of the prior art described above.
According to the invention, this object is achieved by means of a base for implantation in bone of the type specified above, characterized in that the inner edge of the annular retaining element is in engagement with a corresponding outer collar on the inner body so as to be resiliently preloaded thereagainst.
In the base for implantation in bone according to the invention, the retaining ring connected to the outer body prevents the inner body from coming out of the cavity in the outer body and, in particular, isolates the layer of shock-absorbent material interposed between them from the outside environment. By virtue of the resilient preloading of the edge of the retaining element, the shock-absorbent material is isolated even when the inner body performs very small movements inwardly of the cavity in the outer body, resiliently compressing the shock-absorbent material between the bodies, during chewing.
BRIEF DESCRIPTION OF THE DRAWINGS
Further characteristics and advantages of the invention will become clear from the detailed description which follows with reference to the appended drawings, provided purely by way of non-limiting example, in which:
FIG. 1 is a perspective view of a base for dental prosthesis for implantation in bone according to the invention,
FIG. 2 is a section taken on the line II--II of FIG. 1,
FIG. 3 is a partial section showing a detail of the base according to the invention during the fixing of the retaining ring to the outer body, and
FIG. 4 is a view showing the same detail as FIG. 3 in a working condition.
DETAILED DESCRIPTION OF THE INVENTION
In the drawings, a base for implantation in bone according to the present invention is generally indicated 1.
The base has a monolithic structure including a substantially conical outer body 2 made of a rigid material, preferably a biocompatible metallic material such as titanium or an alloy thereof.
The outer body 2 has a cavity 3 (FIGS. 2 to 4) which is also substant
REFERENCES:
patent: 4881897 (1989-11-01), Franek et al.
patent: 5033962 (1991-07-01), Scatena
patent: 5040982 (1991-08-01), Stefan-Doger
patent: 5425639 (1995-06-01), Anders
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