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  Methods for making provisional and long-term dental crowns and bridgesUSPTO Application #: 20080085493Title: Methods for making provisional and long-term dental crowns and bridges Abstract: The invention provides methods of making provisional and long-term dental restorations, particularly dental veneers, crowns and bridges. In one embodiment, the restoration can be fabricated indirectly by a dental laboratory. In another version, a dental practitioner can make the restoration chairside for a patient in a dental office. A polymerizable dental composite material, which is dimensionally shape-stable in its uncured state, is used to make the restoration. The material includes a polymerizable acrylic compound, polymerization initiator system capable of being activated by light or heat, and a filler material. The resulting dental restoration has good aesthetics, mechanical strength, and margins and contacts. (end of abstract) Agent: Dentsply International Inc - York, PA, US Inventors: Benjamin Jiemin Sun, Andrew Mathias Young, Andrew M. Lichkus USPTO Applicaton #: 20080085493 - Class: 433223000 (USPTO) Related Patent Categories: Dentistry, Method Or Material For Testing, Treating, Restoring, Or Removing Natural Teeth, Crown, Method Of Fabricating The Patent Description & Claims data below is from USPTO Patent Application 20080085493. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Patent Application 60/848,117 having a filing date of Sep. 29, 2006, the entire contents of which are hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates generally to methods for making provisional and long-term dental crowns, bridges, inlays, onlays, veneers, and other dental restorations. A polymerizable composite resin having good dimensional shape-stability is used to make the dental restoration. In one method, the restoration can be fabricated indirectly by a dental laboratory and sent to a dentist for placing in the mouth of a patient. In another version, the dentist can make the restoration in the dental office directly. The restoration can be made at the side of the dental chair where the patient is seated. [0004] 2. Brief Description of the Related Art [0005] Dental restorations, such as crowns and bridges, are used to restore or replace lost tooth structure, teeth, or oral tissue. Provisional (or temporary) restorations are intended to be used for a relatively short time. For example, a dentist will often use a provisional crown, until a permanent crown is ready to be placed in the mouth of a patient. Following one conventional procedure, the dentist makes the provisional crown for the patient at the dental office and a dental laboratory makes the permanent crown. The dentist mounts the provisional crown to protect the tooth while the permanent crown is being made. Later, the dentist removes the provisional crown and replaces it with the permanent crown. [0006] The provisional crown typically is made from a polymeric material such as an acrylic. In one method used to prepare a provisional crown, a polymerizable material is placed in a pre-formed impression which then is inserted into the patient's mouth. The polymerizable material is molded over the prepared tooth structure by pressing the impression thereon. Then, the impression containing the molded material, which may only be partially-cured at this point, is removed from the patient's mouth. The material is fully cured by a self (chemical)-curing, light-curing, or heat-curing mechanism, which may occur outside of the mouth, to form the ultimate provisional crown. Finally, the dental practitioner places the provisional crown over the prepared tooth and bonds the crown to the tooth using temporary dental cement. The provisional crown helps maintain the health and function of the tooth while the dental laboratory manufactures the permanent crown. At a subsequent office visit, the dentist removes the provisional crown and checks the color, occlusion, and fit of the permanent crown. If satisfactory, the dentist affixes the permanent crown to the tooth using permanent dental cement. [0007] Dental compositions containing polymerizable resins and filler particles often are used to prepare provisional crowns, bridges, and other restorations. Such dental compositions can be self (chemically)-curable, light-curable, or dual-curable. The dental compositions are cured and hardened by different chemical mechanisms to form a strong and durable material. In one example, a dentist uses a self-curing composition, which is prepared from two paste components. One component used to make the composition is a base paste and the other component is a catalyst paste. The base paste typically contains polymerizable monomers such as methacrylate or acrylate monomers; a free-radical polymerization accelerator such as a tertiary amine; and fillers such as silica, glasses, or alumina. Meanwhile, the catalyst paste typically includes a polymerizable monomer, a free-radical polymerization initiator such as dibenzoyl peroxide, and fillers. [0008] To prepare the composition, the amine-containing base and peroxide-containing catalyst pastes are combined and mixed together. Typically, the respective pastes are stored separately in side-by-side auto-mix cartridges. When a dentist is ready to prepare the composition, the pastes are extruded through a dispensing tip attached to the cartridges. The dispensing tip normally contains a static mixing element. As the pastes are mixed together, the catalyst system (amine and peroxide) react with each other and initiate polymerization and hardening of the composition. The polymerization process involves a reaction between the reducing agent (amine) and oxidizing agent (peroxide). This mechanism is commonly referred to as a redox mechanism. [0009] Compositions that can be used to make temporary crown and bridges are described generally in the patent literature. For example, May et al., U.S. Pat. No. 5,376,691 discloses dental cement for making temporary crowns and bridges. The dental cement is prepared from a first paste comprising a difunctional acrylate such as urethane diacrylate, an activator such as a tertiary amine, and radiopaque filler such as barium and/or strontium glasses. The second paste includes no substance having active double bonds, a catalyst such as dibenzoyl peroxide, a silicon dioxide material, and a softener that cannot be polymerized along with the other components but is sufficiently insoluble in the mouth. The softeners can be selected from such compounds as liquid paraffins, long-chain glycols, and inert alkylphthalates. [0010] Tateosian et al., U.S. Pat. No. 5,554,665 discloses a dental composition that is formed by the static mixing of two complementary pastes. A catalyst paste includes a polymerizable methacrylate, a peroxide, and a stabilizer such as butylated hydroxytoluene. The stabilizer is effective at preventing polymerization for at least 180 days at 23.degree. C. A complementary accelerator and radiation-cure initiator paste includes a polymerizable methacrylate and a reducing agent for the peroxide such as dihydroxyethyl-p-toluidine. According to the '665 patent, the paste compositions preferably have substantially the same viscosity and are mixed in a volume ratio between 1:1 and 1:5. [0011] Xie, U.S. Pat. No. 5,977,199 discloses a delivery system for delivering dental cement material for making temporary crowns and bridges. A catalyst paste and base paste are dispensed from a dual cartridge and mixed in a static mixer to form a polymerizing material. The catalyst paste comprises at least one polymerizable monomer, polymerization initiator, polymerization inhibitor, and filler. The base paste comprises at least one polymerizable monomer, at least one polymerization accelerator, polymerization inhibitor, and filler. According to the '199 patent, the viscosity of the catalyst paste must be substantially greater than the viscosity of the base paste in order for the mixture to cure effectively. [0012] Conventional temporary dental restorations, such as provisional crowns and bridges, are used by patients for a relatively short period of time. As discussed above, the provisional crown is used by the patient while a permanent crown is made. Today, provisional crowns and bridges typically are used by a patient for a period of about three to six months. In general, such provisional restorations are effective, but there is a need in the dental field for restorations that can be used for longer periods. [0013] The present invention provides methods for making such dental restorations. A dental practitioner can use the resulting dental restoration as a provisional expecting that it will remain in the patient's mouth for a time period of about 1 to about 12 months. On the other hand, if the dental practitioner wishes to use the dental restoration as a long-term product, expecting that it will remain in the patient's mouth for a period of time longer than about 12 months, he or she can do so. The dental restorations of this invention can be used as either provisional or long-term dental products because of their advantageous properties. Particularly, the restorations are strong and durable and do not break or fracture easily. Because of their mechanical strength, the restorations can withstand hard occlusion forces. In addition, the restorations have pleasing aesthetics matching the shade of natural teeth. Moreover, the restorations have good margins and contacts, providing the patient with comfort while promoting dental health. The restoration covers and supports the tooth structure sufficiently so that it protects the tooth's pulpal portion. [0014] One object of the present invention is to provide a method that a dental laboratory can use to make dental crowns, bridges, inlays, onlays, veneers, and other dental restorations having good mechanical strength, aesthetics, and occlusal fit. [0015] Another object of this invention is to provide a method that a dental practitioner can use to design and fabricate the crown, bridge, or other dental restoration "chairside." This would help make the crown manufacturing and fitting process less time-consuming and costly. The dentist may be able to mount the crown on the patient's tooth in a single office visit. [0016] These and other objects, features, and advantages of this invention are evident from the following description and illustrated embodiments. SUMMARY OF THE INVENTION [0017] This invention provides methods for making provisional and long-term dental crowns, bridges, inlays, onlays, veneers, and other dental restorations. In one version, a dental laboratory can make the restoration. This method involves dispensing a heated polymerizable composite material into a matrix and positioning the matrix over an area of a pre-formed dental model that will receive the restoration. The composite material may comprise polymerizable acrylic compound, polymerization system capable of being activated by light or heat for polymerizing the composition, and filler material. [0018] The composite material is allowed to set and cool and form a dimensionally shape-stable uncured restoration on the dental model. The matrix is then removed, while the composite material, in the shape of the restoration, remains seated on the model. Light is used to irradiate the composite material so that it cures and forms a hardened restoration directly on the model. Finally, the restoration is removed, finished, and polished. A visible light-curing sealant can be applied to provide a stain-resistant and glossy surface finish to the restoration if desired. The restoration is now ready to be mounted on a patient's tooth. [0019] In another embodiment, a dental practitioner can make the dental restoration at the patient's chair in the dental office. This method involves dispensing a heated polymerizable composite material into a hardened dental impression. The same composite material as described above can be used in this method. The practitioner positions the impression containing the composite material in the mouth of a patient so that the material is molded over the targeted area that will receive the restoration. The material is allowed to cool and form a dimensionally shape-stable, uncured restoration. The impression containing the composite material is removed from the mouth. Then, the restoration is irradiated with light so that it cures and hardens. The restoration can be maintained within the impression material while it is being light-cured. Alternatively, the restoration can be removed from the impression material before it is light-cured. [0020] Another chairside method involves removing the impression from the mouth, while leaving the shape-stable, uncured restoration over the targeted area inside of the mouth so that the restoration can be fitted. Then, the restoration is removed from the mouth and irradiated with light so that it cures and hardens. If desired, the uncured restoration can be irradiated with light while it is positioned in the mouth so that it partially cures. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Continue reading... Full patent description for Methods for making provisional and long-term dental crowns and bridges Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Methods for making provisional and long-term dental crowns and bridges 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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