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Title:
ESTHETIC INDIVIDUAL POST AND CORES IN FIBER REINFORCED RESIN MATRIX
Document Type and Number:
WIPO Patent Application WO/1998/055041
Kind Code:
A1
Abstract:
A passive post, realizable indirectly, i.e., in the technician's laboratory, and therefore absolutely individual, presents not only the requisites of elasticity similar to the radicular dentine but also a good esthetic appearance. The materials used for the realization of posts and cores are based on fibers bound in a resinous matrix already directly assembled by the constructor to make up pre-shaped structures to be adapted individually and therefore cured, or separated from resinous and glass fiber materials which are then combined in order to realize the material to be shaped for the creation of individual posts and cores.

Inventors:
PAOLI MIRKO (IT)
Application Number:
PCT/IT1998/000143
Publication Date:
December 10, 1998
Filing Date:
May 29, 1998
Export Citation:
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Assignee:
PAOLI MIRKO (IT)
International Classes:
A61C13/30; A61C9/00; A61C19/00; (IPC1-7): A61C9/00; A61C13/30; A61C13/20
Domestic Patent References:
WO1996026686A11996-09-06
WO1996015731A11996-05-30
Foreign References:
US5518399A1996-05-21
US4913508A1990-04-03
US4695254A1987-09-22
Attorney, Agent or Firm:
Benettin, Maurizio (116, Padova, IT)
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Claims:
CLAIMS
1. L Passive post and core obtained from an individual model characterized by the fact that it has been realized in resinous material reinforced with fibers.
2. Passive post and core obtained from an individual model, as per claim 1, characterized by the fact that the prepolymerized takes place between two silicone moulds at least one of which is transparent and where the light that crosses through the transparent silicone makes it possible for the material to be preself cured.
3. Passive post and core obtained from an individual model, as per claim 1,2 characterized by the fact that it includes the following phases: * preparation of the radicular canal according to the clinical needs of the single case; * impression of the prepared tooth with conventional elastic material (elastomers) or with resinous materials; development of the impression, construction of the model and its treatment with conventional techniques; realization on the model of a pair of posts and cores (or replica) using photo curing a/o selfcuring acrylic resin; * mixture of laboratory silicone material to form a cylindrical sausagelike shape on which the replica is placed and made to penetrate so that both the post and the core are immersed in the silicone material for more than half of the entire thickness of the replica; after hardening occurs, grooves or cuts are made on the surface of the silicone near, but not in contact with, the replica. preparation and application over the suitably boxed silicone/replica system, of a second silicone material (set up by us, circa 1015 mm thick and rigorously transparent) prior to isolation of the contact surface with suitable material; after hardening occurs, separation of the two silicone materials and verification of the correct reciprocal re positioning of the two silicone halfmoulds; collection and application of the material, and where the material is manipulated and applied with instruments for composite materials, inserted into the hollow left by the replica on the first silicone and subsequently adapted, if desired, with an application of material in the core area. repositioning of the transparent silicone over the first silicone mould, exerting a slight pressure for the purpose of producing a light deformation of the material and verifying that the latter is slightly in excess; curing by means of light and pressure depending on the characteristics of the material; removal of the excessive material with a resin bur. Finishing of the excess with sandpaper (with decreasing particle size) up to the complete removal of the excessive material. positioning of the post and core on the model, checking the exact fit and passive insertion.
4. Passive post and core obtained from an individual model, characterized by the fact that it has been realized with fibers in resinous material and where the combination phase of the said fibers and resin occurs immediately before insertion into the mould. Passive post and core obtained from an individual model, as per claim 4 characterized by that fact that, after having realized the model and replica in acrylic resin: * two halfmoulds in nonelastic material (e. g. stone) are executed: * fibers and resinous matrix are combined and inserted into the space left by the replica in the mould, exerting a certain pressure. Polymerization is then carried out according to the characteristics of the material, followed by the final step: the finishing.
Description:
TITLE <BR> <BR> <BR> <BR> ESTHETICINDIVIDUAL POSTAND CORES<BR> <BR> <BR> <BR> <BR> IN FIBER REINFORCED RESIN MATRIX DESCRIPTION This patent pertains to the sector of the treatment of teeth and in particular concerns the operations, materials and systems for the prosthetic reconstruction of teeth, the realization of which requires the construction of posts and cores connecting the natural part of the tooth and the prosthetic structure.

The present day noted techniques provide for the realization of individual metallic posts and cores in fused alloy or the use of prefabricated metallic posts.

Owing to their rigidity, these various metallic posts have the disadvantage of determining a strong concentration of stress at the level of the tooth root, appreciably increasing the risk of radicular fractures and consequent loss of the tooth.

Recently standard size posts have been proposed, i. e. based on carbon fiber and created industrially, with a module of elasticity similar to that of the radicular dentine. However, they present a problem: they cannot be shaped to the needs of each single radicular canal. Moreover, due to their black color they are quite frankly anti-esthetic in the event the subsequent prosthetic reconstruction is to be realized with materials lacking metal.

To resolve these problems a type of passive post has been studied, realizable indirectly, i. e.- in the technician's laboratory,

and therefore absolutely individual, presenting not only the requisites of elasticity similar to the radicular dentine but also a good esthetic appearance.

The materials used for the realization of posts and cores are based on fibers bound in a resinous matrix already directly assembled by the constructor to make up pre-shaped structures to be adapted individually and therefore cured, or separated from resinous and glass fiber materials which are then combined in order to realize the material to be shaped (with the techniques described below) for the creation of individual posts and cores.

The constructive technique-similar in the basic principles- presents slight differences, which will be described later on, depending on whether one or the other of the two basic materials are used.

Following are the various phases of the execution of individual posts and cores with resinous materials and fibers assembled by the constructor: Preparation of the radicular canal depending on the clinical needs of the single case and knowing that the diameter of the canal lumen is preferably at least 1.2 cm.

Impression of the tooth prepared with conventional elastic materials (elastomers) or with resinous materials.

Development of the impression, construction of the model and its treatment with conventional techniques.

Realization on the model of a copy of the post and core (hereinafter called"replica") using photo-curing a/o self-curing acrylic resin for models.

Mixture of a laboratory silicone material to form a sausage-like shape on which the replica is placed and made to penetrate so that both the post and the core are immersed in the silicone material for more than half of the thickness of the replica On hardening, a V-groove ca. 2 mm deep is made on the surface of the silicone, near, but not in contact with, the replica.

Preparation and application above the suitably boxed silicone/replica system of a second silicone material, rigorously transparent, for a thickness of ca, 10-15 mm prior to isolation of the contact surface with suitable material.

On hardening, the two silicone materials are separated and a verification is made of the correct reciprocal repositioning of the two silicone half-moulds.

Collecting and applying material. An equal length is applied, cutting away the excess with suitable clippers at the maximum length of the post and core to be realized. The material is manipulated and applied with instruments for composite materials, inserted in the hollow left by the replica of the first silicone and subsequently adapted. In the event that the core is particularly voluminous, (e. g. premolars or molars) it will be necessary to apply more material in the core area.

Repositioning of the transparent silicone above the first silicone mould, exercising a minimal pressure for the purpose of producing an adaptation of the resinous material and checking that it is moderately in excess.

Curing by light and pressure depending on the characteristics of the material.

Removal of the larger excess material by resin burs and finishing with sandpaper (with decreasing particle size) up to the complete removal of the excess material.

Positioning of the-post and core in the model, verifying the exact fit and the passive insertion.

Variants to the above-described system are foreseeable-for example, the possibility that the core is not completely made of fiber-reinforced material in the first phase but only a cylindrical lengthening is made, of a suitable height and diameter corresponding to the endocanal diameter of the post. The core will subsequently be constructed by stratifying a composite material with individual esthetic characteristics.

Following are the various technical phases in the execution of individual posts and cores in laboratory-assembled resinous material and fibers: After having made the model and replica in acrylic resin as described, the two half-moulds are executed but, in this case, using a non-elastic material, e. g. stone.

Combine fibers and resinous matrix, placing it into the space left free by the replica in the mould and exercising a certain pressure.

Curing follows, according to the characteristics of the material.

Finishing is carried out by the procedure described previously.

Any modifications of the core in shape or color may be made later with composite material of a suitable color.

This type of material can be worked directly on the model without executing the replica and the moulds. In this case the material, appropriately prepared, is applied directly into the canal lumen and the reconstruction of the core follows.

The final step is polymerization of the entire unit.

The foregoing schematic methods are sufficient for an expert to realize, therefore, that in a concrete application the concept can be subject to variants without prejudicing the substance of the innovative idea.

With reference to the preceding description, we wish to make the following claims: