Dentistry – Method or material for testing – treating – restoring – or... – Crown
Patent
1997-08-20
1999-04-06
Wilson, John J.
Dentistry
Method or material for testing, treating, restoring, or...
Crown
A61C 508
Patent
active
058909044
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a tooth post made of composite material presenting an opacity allowing easy location thereof by radiography.
It is known that, in the dental art, in order to strengthen a tooth, posts are employed which are mostly made of metal. Although these posts are easily locatable by the conventional means of radiography, they nonetheless present the drawback of presenting moduli of elasticity very different from those of the teeth in which they are fixed, so that they tend, during use, to injure the dentin, thus bringing about their release after a more or less long time.
In order to avoid this drawback, it has been proposed to employ posts made of composite materials of which the moduli of elasticity are close to those of the dentin, so that they preserve the latter, consequently ensuring a long-lasting hold of the post.
Such posts are mostly constituted by elements transparent to X-rays, so that they are difficult to locate, which is deterimental, on the one hand, from the medical standpoint, particularly in the case of an accidental ingestion, and on the other hand, from the administrative standpoint if it is desired to prove that these posts have been positioned.
It is, of course, possible, in order to ensure opacity of a post, to incorporate in the resin of which it is constituted, radio-opaque fillers which one attempts to distribute regularly in its mass. Now, it has been ascertained that, even when these fillers were relatively well distributed, the contour of the post obtained in X-radiography was not perfectly defined, particularly when the outer face of the post had undergone a specific machining. In order to avoid this drawback, a solution would be to increase the quantity of the fillers used. However, it has been ascertained that, in order to obtain a post whose contour under X radiography is perfectly defined, it was necessary to add a quantity of fillers such that the mechanical qualities of the post were then reduced.
It is an object of the present invention to propose a means for making a tooth post whose contour, obtained under X-radiography, is perfectly defined without its mechanical qualities being reduced.
The present invention thus has for its object a tooth post made of composite material, characterized in that it comprises a central core constituted by a matrix of hardenable resin in which are embedded fibers which give the post its main mechanical qualities, this central core being surrounded by a sheath constituted by at least one layer of fibers made of a radio-opaque material.
The fibers constituting the sheath may preferably be constituted by continuous fibers which extend substantially from one end of the post to the other. Furthermore, the fibers of the central core may be constituted by fibers transparent to X-rays.
In one embodiment of the invention, the peripheral sheath is constituted by at least two layers of intersecting fibers.
The fibers constituting the peripheral sheath are advantageously fibers of silica, ceramics, silicon carbide, or glass fibers with a high content of calcium oxide.
An embodiment of the present invention will be described hereinafter by way of non-limiting example, with reference to the accompanying drawings, in which:
FIG. 1 is a view in axial and longitudinal section of a post according to the invention.
FIG. 2 is an enlarged partial view in elevation of the post shown in FIG. 1.
FIG. 3 is an enlarged partial view in elevation of a variant embodiment of a post according to the invention.
FIGS. 1 and 2 show a tooth post 1 comprising a central core 3 formed by a matrix of epoxy resin in which are embedded fibers transparent to X-rays such as glass fibers 5 which extend over the whole length of the post 1. The nature of these fibers, their diameter and their quality are determined by the mechanical qualities that it is desired to give the post 1.
The periphery of the post comprises a sheath 6 formed by a layer of radio-opaque fibers 7 which are disposed longitudinally over the whole length of the post 1.
These fibers 7 are
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patent: 5074792 (1991-12-01), Bernadat
patent: 5328372 (1994-07-01), Reynaud et al.
patent: 5518399 (1996-05-01), Sicurelli, Jr. et al.
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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