Dentistry – Method or material for testing – treating – restoring – or... – Endodontic
Patent
1997-08-20
1998-08-25
Wilson, John J.
Dentistry
Method or material for testing, treating, restoring, or...
Endodontic
433220, A61C 508
Patent
active
057977488
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a dental prothesis and more particularly a prothesis made of composite material adapted to control the directional distribution of the mechanical stress resistance exerted thereon. The present invention also concerns a method for manufacturing such a dental prothesis.
DESCRIPTION OF THE RELATED ART
It is known that, when a depulped tooth is reconstituted, it is essential to ensure the perennity of the residual dental substance, which is usually done by means of metal protheses, made of precious alloy or not, which are screwed or sealed in the dental canal.
It is also known that the great differences which exist between the mechanical characteristics of these metal protheses and the dentin of the tooth are the cause of most of the failures which occur in this type of intervention and which are translated by unsealings and/or cracks in the roots under the action of considerable stresses generated by the forces of chewing.
It has been proposed to overcome these drawbacks by replacing the metal protheses by protheses made of composite material, essentially constituted by carbon fibers disposed longitudinally along the axis of the prothesis which are embedded in a hardenable resin. Although the protheses of this type have overcome the principal drawbacks associated with metal protheses, nonetheless they are not totally satisfactory as their mechanical characteristics and in particular their maximum stress resistance, are the same whatever the applications envisaged.
Another drawback of this latter type of protheses is that, the carbon fibers being electrically conducting, the prothesis may constitute an electrode, vehicle of electrochemical corrosion.
Furthermore, tenons of this type employing carbon fibers are black in color, which limits their use in certain cases of aesthetic restoration.
The morphological studies carried out on the axes of insertion of the teeth in the mandibles have demonstrated that the angles of the occlusal stresses exerted thereon vary considerably. In fact, during chewing, the teeth are subjected to stresses which are applied thereon in various angular ranges and which depend in particular on the angles formed by the axes of insertion of the antagonistic teeth which meet.
In this way, for single-root teeth, these axes of insertion merge most of the time with the canal axes along which are inserted the protheses which will serve to reinforce the reconstituted teeth. For multi-root teeth, and more particularly for the molars, the canal axes of the different roots being divergent, it is known that it is no longer solely the axes of insertion of the teeth which will intervene in the stresses undergone thereby, but the different cusp slopes, the ridges, the cavities, in other words the anatomy of the triturating face, which will determine the angle of application of the occlusal forces to which the prothesis is subjected.
BRIEF DESCRIPTION OF THE INVENTION
The present invention has for its object to propose a means for making protheses of which the direction of the privileged axes of mechanical resistance may be adjusted to desired values, as a function of the direction of the stresses to which they are subjected and which depend on the type of teeth in which they are inserted.
The present invention thus has for its object a dental prothesis made of composite material, characterized in that it is constituted by a central core made of at least one bundle of fibers which is surrounded by a sheath constituted by at least one layer of fibers, isotropic or not, the fibers of the central core and those of the sheath being embedded in a hardenable resin, and the fibers of the sheath being oriented by a given angle with respect to the longitudinal axis of the prothesis.
In an embodiment of the invention, the sheath is constituted by at least two superposed layers of fibers, disposed symmetrically with respect to the longitudinal axis of the prothesis, the said two layers being able to be woven.
In a variant embodiment of the inven
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patent: 1649508 (1927-11-01), Carmichael
patent: 3318000 (1967-05-01), Paris
patent: 5074792 (1991-12-01), Bernadat
patent: 5165893 (1992-11-01), Thompson
patent: 5409378 (1995-04-01), Pohl
patent: 5564929 (1996-10-01), Alpert
Chu Manh
Reynaud Marc
Reynaud Pierre-Luc
Reynaud Marc
Reynaud Pierre-Luc
Wilson John J.
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