Dentistry – Method or material for testing – treating – restoring – or... – Crown
Patent
1997-12-15
2000-01-11
Lewis, Ralph A.
Dentistry
Method or material for testing, treating, restoring, or...
Crown
4332281, A61K 6087, A61K 6027, A61L 2700
Patent
active
060129247
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a section of composite material intended to constitute a prosthetic element, and particularly a tooth post, as well as to a process for manufacturing such a section.
BACKGROUND OF THE INVENTION
It is known that, in the dental domain, in order to ensure the perennity of the dental substance of a tooth, metal posts are called upon, which are screwed or sealed therein. Such metal posts present a certain number of drawbacks, which are principally associated with the great difference which exists between the mechanical characteristics of these posts and those of the dentine in which they are disposed.
In order to avoid such drawbacks, it has been proposed to employ posts made of composite material, constituted in particular by a matrix of bio-compatible resin, and particularly an epoxy resin, in which carbon or glass fibers are embedded.
In certain embodiments, the fibers are longitudinal fibers which extend over the whole length of the post and which are under equal tension therein. The posts thus constituted, by reason of their mechanical characteristics close to those of the dentine, considerably reduce the drawbacks set forth hereinabove.
However, such posts present the drawback of being transparent to X-rays, so that their positioning is particularly difficult to establish with the aid of the conventional apparatus available to practitioners.
These posts are usually manufactured by pultrusion, i.e. by a process of extrusion in which both the fibers, particularly the carbon or glass fibers, and a resin matrix are passed in the same die at the same time, the fibers being, all along the operation, maintained under tension. This operation of pultrusion is sometimes difficult to carry out by reason of the problems of obturation of the die of the extruder which occur during operation.
In the prior state of the art, products, or charges, are known, which are added to the dental reconstitution pastes, in order to give them a certain opacity to X-rays. U.S. Pat. No. 4,503,169 thus proposes to that end to include zirconium, oxides in dental reconstitution pastes.
Patent GB-A-2 028 855 also discloses a settable composition exempt of mercury based on a carboxylic polyacid and which contains, inter alia, filling elements which may possibly comprise fibrous elements which may be coated with metal oxides capable of reacting with the carboxylic polyacid in order to promote bond with the matrix.
SUMMARY OF THE INVENTION
The present invention has for its object to propose a means for solving both the problems associated with carrying out the pultrusion operation and those connected with the lack of opacity of the prosthetic elements used in the dental art, which are constituted by composite materials based on resins, particularly epoxy resins, reinforced by fibers, particularly long, unidirectional carbon fibers.
The present invention thus has for an object a section of composite material intended to constitute a prosthetic element, particularly a dental post, comprising a core, constituted by longitudinal fibers, which is embedded in a matrix of resin, characterized in that this resin matrix contains at least one metal oxide.
Applicants have in fact observed that the implementation of pultrusion was largely facilitated when metal oxides were added to the resin matrix. In fact, the added metal oxide behaves like a sliding agent which reduces the adhesion of the resin and promotes flow of the product in the die of the extruder. Implementation is even easier when the metal oxides are in the form of granules or microballs. It is also possible, in order to facilitate the pultrusion operation further, to use metal oxides which are contained in microballs, particularly glass microballs.
Under these conditions, the metal oxides introduced in the resin perform two functions, namely a first function of slide provoking the extrusion and a second function of opacity.
As set forth hereinafter, when one is obliged to add a relatively large quantity of metal oxides in the res
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Chu Mahn
Reynaud Marc
Reynaud Pierre-Luc
Lewis Ralph A.
Reynaud Marc
Reynaud Pierre-Luc
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