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Method of manufacturing dental restorationsRelated Patent Categories: Dentistry, Prosthodontics, Tooth ConstructionMethod of manufacturing dental restorations description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20080108015, Method of manufacturing dental restorations. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Application No. 60/445,923, filed Feb. 6, 2003, which is incorporated herein by reference. FIELD OF THE INVENTION [0002] This invention relates to the manufacture of posts and obturators and more specifically to the manufacture of single-unit posts and obturators having a filling material attached thereto. The invention further relates to the bonding of filling materials to posts and obturators and to the bonding of veneers to dental understructures. BACKGROUND OF THE INVENTION [0003] Gutta percha and gutta percha-like natural and synthetic rubbers and thermoplastics do not adhere well to posts and obturators. Many posts and obturators are made of glass fiber-reinforced dental resins and their components are dissimilar to gutta percha and other thermoplastics that are molded onto the appliance. The surface wettability of the post and obturator are low due to at least two reasons: a) the matrix resins used to make the fiber-reinforced composite of the post and obturator are of a hydrophobic rather than hydrophilic nature; and b) the surface is precured leaving an insufficient number of unsaturated chemical bonding for further reaction. Both of these factors will work against good adhesion between the post or obturator and the gutta percha or other hydrophobic thermoplastic or other material. [0004] Similar bonding problems exist between dental substructure materials and overlayer veneer materials. The general practice is to partially light cure the fiber-reinforced composite substructure and to keep an oxygen-inhibited layer for better wetting of the subsequent overlayer materials. However, the oxygen-inhibited layer itself is expected to be weak in strength and consequently poor adhesion along this layer is likely. To eliminate this weak layer, a higher degree of conversion in the absence of oxygen is required. This practice, however, limits the availability of unsaturated bonds on the surface for any future adhesive procedures. [0005] The application of additional layers of material to an understructure has been taught in the art whereby plasma deposition is used to apply the layers to the understructure. U.S. Pat. No. 5,873,725 is directed to a dental post having a layer of ceramic material deposited over and bonded to the outside surface to facilitate adhesion of the post to a dental adhesive. The surface of the post is first roughened to increase the surface area of the post and thereafter a layer of ceramic material is applied by sputtering or plasma spray deposition. The layer of ceramic material does not alter the surface of the post, but adds an additional layer of material, namely ceramic, to the post. Similarly, U.S. Pat. No. 5,480,301 is directed to an orthodontic appliance whereon particles of stainless steel, ceramic, ceramic-metal composite, or metal-metal composite materials are applied to the surface of the orthodontic appliance by plasma spray coating, arc spray coating, flame spray coating or vacuum sputtering. [0006] It has also been known to use plasma deposition for enhancing the bond strength of fibers to the matrix material in a fiber reinforced composite material. Commonly owned U.S. Pat. No. 6,200,136 is directed to a fiber-reinforced dental bridge material wherein the material comprises fibers embedded in a polymeric base material. In order to enhance the bond between the reinforcing fibers and the base material, thereby enhancing the reinforcing effect, the patent teaches silanizing or otherwise treating the fibers by etching, chemically grafting, plasma treating, or ion-bombarding. U.S. Pat. No. 5,829,979 is directed to a reinforcing material for dental appliances and prostheses. The reinforcing material is sometimes pretreated with a cold gas plasma or other such process that will increase the wetability and chemical activity of the material and thereby enhance the ability of the material and the resin to adhere. [0007] The aforementioned prior art has been limited to bonding processes used during the impregnation of fibers in a polymeric matrix or to the actual addition of layers to an understructure. [0008] Attempts have been made to improve the bonding between posts and obturators and gutta percha by applying silane or a silane/resin mixture to the post and obturator. Nevertheless, the bond is still quite weak. [0009] It is desirable to increase the bond strength between posts and obturators and gutta percha or gutta percha-like natural or synthetic rubbers and thermoplastics. It would be beneficial to improve the bond strength between dental substructures and composite veneering materials. SUMMARY OF THE INVENTION [0010] Dental posts and obturators are manufactured herein having a filling material applied to the apical end of the post and obturator such that the adherence strength between the filling material and the post or obturator is very high. The filling material is adhered to the post and obturator by applying one or more corona or plasma treatments to the surface of the post and obturator and thereafter applying the filling material to the surface-treated post and obturator. The surfaces of the post and obturator are modified by the corona or plasma treatments to create a highly adherent surface for the application of the filling material thereto. [0011] Dental restorations are manufactured herein wherein a veneer is applied to a dental substructure and the adherence strength of the veneer to the dental substructure is very high. The veneer is adhered to the dental substructure by applying one or more corona or plasma treatments to the surface of the dental substructure and thereafter applying the veneer to the dental substructure. The surface of the dental substructure is modified by the corona or plasma process to create a highly adherent surface for the application of the veneer thereto. BRIEF DESCRIPTION OF THE DRAWINGS [0012] The present invention will be more fully understood and appreciated by reading the following DESCRIPTION OF THE INVENTION in conjunction with the accompanying drawings, in which: [0013] FIG. 1 is a perspective view of a post with filling material made in accordance with the present invention; [0014] FIG. 2 is a perspective view of an obturator with filling material made in accordance with the present invention; and [0015] FIG. 3 is a schematic view of a post made in accordance with the present invention being tested in a pull out shear test. DESCRIPTION OF THE INVENTION [0016] As will be appreciated, the present invention provides a method of bonding gutta percha and gutta percha-like thermoplastic materials to posts and obturators to provide a combined endodontic post and tip of filling material in a single unit, or an endodontic obturator having filling material in an integral, single unit. [0017] FIG. 1 shows a post unit 10 comprising a post section 11 and a cone or tip section 14. Post section 11 contains a main body 12 and a carrier or apical portion 13. Carrier portion 13 is preferably an extension of main body 12 of post section 11 and may be of very fine diameter to accommodate tip section 14 of filling material. Tip section 14 comprises a flexible rod or cone of biocompatible material for filling the apex of the canal. The cone of biocompatible filling material is attached to carrier portion 13 of post section 11 at the apical end 10a of post unit 10. Carrier 13 may be formed during the actual manufacture of main body 12 or thereafter by grinding, cutting or similar means. [0018] FIG. 2 shows an obturator 20 having a carrier 22 with a cone of biocompatible filling material 24 attached thereto. As shown in the drawings, post section 10 and carrier 22 are each tapered to provide ease of placement into the canal. Continue reading about Method of manufacturing dental restorations... Full patent description for Method of manufacturing dental restorations Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method of manufacturing dental restorations patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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