Method of Making a Denture With Nature Bite and Wear Properties and Denture

Abstract

The present invention to a method of denture manufacture that incorporates CAM-formed occlusal inserts, crowns, or overlays made of zirconia, resulting in a natural fit, feel, and wear essentially equivalent to the wear properties of natural teeth.

Claims

1. A method for making dentures with natural bite and feel and improved wear properties, said method comprising the steps of: a. Evaluating a patent to determine desired denture parameters; b. Fabricating a first denture according to said desired denture parameters, wherein said first denture comprises at least one occlusal portion; c. Electronically storing the three-dimensional shape and size of said first denture; d. Preparing at least one tooth within said first denture to receive at least one of at least one zirconium crown and at least one zirconium overlay; e. Preparing at least one of at least one zirconium crown and at least one zirconium overlay for attachment to said at least one tooth, where each said zirconium crown and zirconium overlay is sized and shaped to create a denture with parameters approximating the desired denture parameters when attached to the said at least one prepared tooth; and f. Attaching said at least one of at least one zirconium crown and at least one zirconium overlay to said at least one prepared teeth to create a second denture, where said second denture approximates said desired denture parameters; g. wherein, said second denture has improved wear properties compared to dentures comprising plastic artificial teeth.

2. The method of claim 1, further comprising the steps of: a. Test fitting said second denture to the patient; b. Assessing the patient; and c. Shaping at least one of said zirconium crowns, said zirconium overlays, or both, responsively to said assessment.

3. The method of claim 2, further comprising the step of permanently attaching said at least one of at least one zirconium crown and at least one zirconium overlay to said at least one tooth.

4. The method of claim 3, wherein said step of preparing said at least one tooth comprises at least one of milling, cutting, and forming one tooth.

5. The method of claim 3, wherein said step of preparing said at least one tooth comprises at least one of milling, cutting, and forming two teeth.

6. The method of claim 3, wherein said step of preparing said at least one tooth comprises at least one of milling, cutting, and forming three teeth.

7. The method of claim 3, wherein said step of preparing said at least one tooth comprises at least one of milling, cutting, and forming four or more teeth.

8. The method of claim 3, wherein said step of electronically storing the three-dimensional shape and size of said first denture comprises storing the three-dimensional shape and size of said first denture in a CAD program.

9. The method of claim 8, wherein at least one of the step of fabricating a first denture and the step of forming a holding area is performed by a CAM mill.

10. The method of claim 9, wherein the step of preparing a zirconia crown or overlay comprises the substeps of: a. Forming said crown or overlay to a first shape and a first size; and b. Sintering said crown or overlay to a first shape and a second size, wherein said first shape and second size are selected to create a second denture approximating said desired denture parameters.

11. The method of claim 10, wherein the substep of forming said crown or overlay to a first shape and a first size is performed by a CAM mill.

12. The method of claim 11, wherein said first shape and first size are determined using the electronically stored three-dimensional shape and size of said first denture.

13. The method of claim 12, wherein the substep of sintering further comprises sintering said occlusal insert at approximately 1500 degrees Celsius.

14. The method of claim 13, wherein the substep of sintering further comprises sintering said occlusal insert for between approximately 8 and approximately 12 hours.

15. The method of claim 14, wherein the substep of sintering further comprises sintering said occlusal insert for approximately 10 hours.

16. The method of claim 15, wherein said first size is approximately 15% to approximately 20% larger than said second size.

17. The method of claim 16, wherein said first size is approximately 17.8% larger than said second size.

18. A custom denture with natural bite and feel and improved wear properties and with one or more of one or more zirconium crowns and one or more zirconium overlays, said denture comprising: a base portion configured to overfit at least a portion of a patient's gums, said base portion comprising one or more sockets; plastic artificial teeth attached to said sockets, at least one of said teeth prepared to receive at least one of at least one zirconium crown and zirconium overlay; and one or more of one or more zirconium crowns and one or more zirconium overlays attached to said at least one prepared tooth; wherein said custom denture has desired parameters improved wear properties compared to dentures comprising plastic artificial teeth.

19. The custom denture of claim 18, wherein said denture is a full denture.

20. The custom denture of claim 19, wherein said denture is a partial denture.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description and accompanying drawings, where:

[0035] FIG. 1 shows a perspective view of a full denture according to one embodiment of the present invention;

[0036] FIG. 2 shows a perspective view of a partial denture according to one embodiment of the present invention;

[0037] FIG. 3 shows a perspective view of a full denture according to one embodiment of the present invention prior to the step of forming holding areas within the denture;

[0038] FIG. 4 shows a perspective view of a full denture according to one embodiment of the present invention after the step of forming holding areas within the denture and prior to the step of attaching an occlusal insert;

[0039] FIG. 5A shows a perspective view of an occlusal insert manufactured according to the one embodiment of this invention prior to the substep of reducing the size by sintering;

[0040] FIG. 5B shows a perspective view of an occlusal insert manufactured according to one embodiment of this invention after the substep of reducing the size by sintering;

[0041] FIG. 6 shows a perspective view of a full upper denture according to the teachings of the present invention after the step of forming the holding areas within the denture and prior to the step of attaching an occlusal insert;

[0042] FIG. 7 shows a perspective view of a full upper denture according to the teachings of the present invention after the step of attaching an occlusal insert;

[0043] FIG. 8 shows a perspective view of an occlusal insert for an upper denture manufactured according to the teachings of the present invention;

[0044] FIG. 9 shows a perspective view of denture prepared to receive zirconium crowns and zirconium crowns prepared for connection to the prepared denture, all manufactured according to the teachings of the present invention;

[0045] FIG. 10 shows a perspective view of a denture prepared to receive zirconium overlays and zirconium overlays prepared for installation, manufactured according to the teachings of the present invention.

DETAILED DESCRIPTION

[0046] The present invention teaches a method of manufacturing dentures using zirconium occlusal inserts, crowns, or overlays, and dentures made by such methods of manufacture.

[0047] Embodiments of the present invention apply equally to full and partial dentures. In all embodiments, the method and, denture made using the method incorporate occlusal inserts, crowns, and/or overlays made of zirconia. Zirconia has high thermal resistance, low thermal conductivity, chemical stability, and high fracture strength. It is a high-performance material with excellent biocompatibility and mechanical properties. Zirconia has extreme hardness and wear resistance. Notably, zirconia wears at a rate similar to the wear rate of natural tooth enamel. Zirconia is also colorable and stainable, and can with relative ease be stained to match the esthetics of natural teeth. Zirconia is easily shapeable, and can be readily milled by CAM mills and similar machinery. Zirconia also does not unduly abrade or wear opposing natural teeth.

[0048] The first step in manufacturing a denture according to the teachings of the present method is determining the desired parameters of the denture. Parameters include the overall shape and size of the denture and the shape, size, and relative location and orientation of each denture component, including the base, the teeth, and any occlusal inserts. Preferably, the desired parameters are all of those parameters that relate to obtaining the desired fit and feel when the denture is used by the patient, preferably a natural bite feel.

[0049] The determination of desired parameters is preferably reached through evaluation of the patient by a dentist. This is particularly the case when the desired parameters are those that will result in a natural bite feel. Methods of evaluation the patient to determine the desired parameters are well known to the art, and result in the generation of a substantial amount of information about the patient's landmark oral structures, resting jaw position, muscle, jaw, and tooth movement during normal mastication and speech, the spacing and orientation of teeth, and general bite registry and occlusion characteristics. Approximating these parameters when a denture is in use is, as known to those skilled in the art, essential to preserving the preferred and desired natural bite feel.

[0050] As known to the art, the dentist may use a haptic bite pad or other electronic device to obtain computer assistance in calculating the desired parameters and modeling the desired denture, from which a physical denture may be made using known techniques such as CAD/CAM or 3D printing. Alternatively, a dentist may evaluate the patient using known methods, may determine desired parameters based on that evaluation with or without computer assistance, and may input selected data or parameters into a CAD Or similar computer modeling program to generate a three-dimensional model of the desired parameter denture, from which a physical denture may be made using known techniques such as CAD/CAM or 3D printing. Preferably, the dentist evaluates the patient using known methods, determines desired parameters based on that evaluation with or without computer assistance, and those parameters are used to by the dentist or a denturist to create a physical denture. This physical denture, whether created in the preferred manner or by some other method, will be referred to as a “first denture.”

[0051] After evaluation of the patient and determination of the desired denture parameters, the next step herein is to fabricate a first denture. A first denture according to the teachings of this invention comprises a base portion with a first side configured to overfit at least a portion, of the patient's gums and a second side comprising one or more sockets configured to contain artificial teeth. This base portion is typically made of acrylic. The base portion can be purchased commercially and optionally modified, or, preferably, can be made from stock materials by known methods, such as by CAD/CAM, 3D printing, or by hand, to match as closely as possible the desired parameters.

[0052] The step of fabrication of the first denture further includes selecting and inserting artificial teeth into the sockets. These artificial teeth can be custom fabricated or molded to approximate or match the desired parameters, or can be purchased commercially. In preferred embodiments hereof, such artificial teeth are made of plastic, most preferably polymethylmethacrylate plastics. Because the occlusal fit of the finished denture will be determined by a separate occlusal insert, crown, or overlay, the artificial teeth in dentures of the present invention do riot need to be selected to result in a first denture precisely matching all of the desired parameters, particularly occlusal parameters. The artificial teeth may optionally be permanently attached to the denture base during this step. Preferably, this is accomplished by adhesive bonding, as would be appreciated by one skilled in the art.

[0053] The fabricated first denture comprises at least one occlusal portion. The occlusal portion, as that term is used herein, refers to that portion or portions of the surface of the attached artificial teeth that is anticipated be an occlusal surface when the patient uses the denture. The location of the occlusal surface or surfaces will, as would be appreciated, vary on a patient b patient basis depending on the particular characteristics of that patient's oral structures, jaw, jaw musculature, and teeth. Also, depending on whether the denture is upper or lower, and whether it is full or partial, the denture may have one occlusal portion, or may have more than one occlusal portion. The Figures above, and particularly FIG. 3, show common locations for occlusal portions.

[0054] After fabrication of the first denture, its three-dimensional size and shape is determined and stored electronically, preferably by use of a CAD scanner in conjunction with a CAD software program. Alternatively, the size and shape of the first denture may be manually inputted into a CAD program or drawn using CAD based on manually determined measurements.

[0055] In one embodiment of the present invention, the first denture is then prepared for occlusal inserts by forming one or more holding areas within the denture. These holding areas, as can be seen in FIG. 3, comprise voids or other apertures, and preferably slots, formed into the occlusal portions of the artificial teeth. These holding areas are configured to retain custom-made occlusal inserts. These occlusal inserts will ultimately be inserted be mated with the holding area and permanently bonded there. Holding areas may be formed by a variety of mechanical processes. Holding areas may be cut, milled, drilled, or sanded out of the occlusal portions. The location, size, and depth of the holding area may be determined manually, and the holding area may be formed manually. Preferably, however, particularly given the relatively small size of the holding area, the holding area is milled at a desired location, in a desired shape, to a desired depth, using a CAM mill. As would be appreciated by one skilled in the art, one, two, three, four or more holding areas may be desired to be formed into a first denture. Further, a single holding area may be formed across multiple occlusal surfaces. In that case, the holding area may be formed into both occlusal and non-occlusal surfaces of the first denture. Preferably, after the holding, area or areas are formed, the first denture is placed in a CAD scanner once again and a new three-dimensional model is made. In the preferred embodiment hereof, this second three-dimensional model can be compared to the first three-dimensional model to ensure that alignment and orientation of the first denture has not been inadvertently or undesirably altered by the formation of holding areas. If such alteration has occurred, comparison of the first and second three-dimensional models can be used to determine what adjustments should be made to bring the first denture back to the desired alignment and orientation.

[0056] In this embodiment, the first denture must represent, as closely as possible, an ideal occlusal relationship prior to the step of preparation of an occlusal insert. As would be appreciated by one skilled in the art, failure of the first denture to represent an ideal occlusal insert dramatically increases the odds that the second denture provided to the patient will not have a satisfactory fit and feel.

[0057] In this embodiment, for each holding area, a custom sized and custom shaped zirconium occlusal insert is prepared. Preparation of the occlusal insert includes selecting zirconium stock based on desired color and esthetic characteristics and forming the occlusal insert. The initial size and shape of the occlusal insert is selected so that when the occlusal insert or inserts are completely prepared and fitted within the holding area or areas, the result is a denture with an overall shape, size, and parameters that approximate the desired parameters.

[0058] In this embodiment, the occlusal insert is preferably formed by CAM milling from zirconium stock, most preferably by a CAM mill guided by the CAD electronic three dimensional model of the first denture such that the occlusal insert is shaped on one side to mate with the holding area and shaped on the other side to form tooth surfaces that result in a denture with the desired parameters. The CAM mill may be directed to form an occlusal insert of the shape and profile shown by the electronically stored three dimensional image, but oversized to account for shrinkage of the zirconia during the preferred sintering step. Preferably in this embodiment, the, occlusal insert is formed approximately 15% to approximately 20% oversized, with the precise degree of oversizing contingent on the specific sintering conditions intended to be used. Most preferably, the occlusal insert is formed approximately 17.8% oversized. In this embodiment, a separate occlusal insert is created for each holding area.

[0059] Preferably in this embodiment, the step of preparing the occlusal insert includes sintering the occlusal insert after forming. Sintering improves the properties of zirconia for use as an implant, and particularly improves flexural strength, as would be appreciated by one skilled in the art. Sintering for zirconia used in implants is typically performed at temperatures between 1,300 degrees Celsius and 1,700 degrees Celsius, with the greatest improvement in flexural strength occurring at around 1,500 degree Celsius. In preferred embodiments of the present invention, sintering is performed at temperatures of approximately 1,500 degrees Celsius. Time of sintering is dependent on volume, temperature, and method. Although microwave sintering, conventional sintering, and other sintering methods may be used, the occlusal insert of the present invention is preferably sintered using conventional sintering for between approximately 8 and approximately 12 hours, and most preferably for approximately 10 hours.

[0060] Optionally in this embodiment, the step of preparing the occlusal insert may include staining the occlusal insert to a desired shade, color, or tone, such as to match or simulate real teeth. Such staining, as would be appreciated by one skirled in the art, may occur at virtually any stage of the method. Preferably, staining occurs during sintering.

[0061] In this embodiment, after the occlusal insert is prepared, it is attached to the first denture by mating the occlusal insert with the holding areas to forma denture that as closely as possible approximates the desired parameters. This denture is referred to herein as a “second denture.” It should be noted that the second denture is t of a separate structure in this embodiment from the first denture; rather it is the revision of the first denture created by the formation of the holding areas and the attachment of the prepared occlusal inserts to those holding areas. If the of insert does not obtain the desired fit within its corresponding holding area, or if the occlusal insert does not mate with its corresponding holding area to form a second denture that adequately approximates the desired parameters, the occlusal insert may be removed and may undergo further preparation. Such further preparation may include, by way of example, additional sintering, milling, sanding, abrading, cutting, or other shaping.

[0062] In this embodiment, after the occlusal insert or occlusal inserts are determined to be suitably prepared, the occlusal insert or occlusal inserts may be permanently attached to the holding areas. Preferably, however, the prepared occlusal insert or inserts are first removably inserted into the holding areas for test-fitting with the patient. During test-fitting the dentist may assess whether the second denture creates the desired fit and feel for the patient, preferably a natural bite feel. The dentist may assess the patient objectively, including recording occlusal patterns ear data. The dentist may separately or additionally solicit or accept subjective feedback from the patient concerning the fit and feel of the second denture. Based on this further assessment, the second denture may be further shaped or altered responsively to the assessment, including the patient's preferences and the dentist's judgment of the patient's needs. This test-fitting and revision process may, as would be appreciated, be repeated until the second denture creates a fit and feel satisfactory to the patient and the dentist. This further test-fitting and further evaluation step may optionally and preferably be completed after the occlusal formation substep, but before the sintering substep.

[0063] After the second denture is determined to be satisfactory to the patient and the dentist—which preferably but optionally includes the further assessment discussed above the second denture is finished. In this embodiment, the occlusal insert or inserts are stained, if staining is desired and has not yet been performed, are sintered, if sintering is desired and has not yet been performed, and are permanently attached to the holding area or areas. Such permanent attachment can be accomplished through the use of adhesives or resins, using techniques known to the art. Preferably, permanent attachment is accomplished by cleaning the occlusal insert or inserts and holding area or areas with a solvent such as alcohol, applying a first primer to the surface of the occlusal insert that will contact the surface of the holding area, applying a second primer to the area of the surface of the holding area that will contact the surface of the occlusal insert, applying a bonding agent such as a dual-cure resin cement to both surfaces, attaching the occlusal insert to the holding area in the desired orientation, extravagating excess bonding agent, and allowing the bonding agent to finish curing. A wide variety of adhesives and adhesive attachment techniques may be used within the scope and spirit of this invention.

[0064] In alternate embodiments, after the step of fabricating the first denture, the method may comprise the step of preparing the first denture for at least one zirconium crown (100) or at least one zirconium overlay (101) by shaping or forming at least one of the artificial teeth of the first denture to receive such a crown (100) or overlay (101). Preferably, at least one artificial tooth is prepared to receive a zirconium crown (100) or a zirconium overlay (101) using a CAM mill. As would be appreciated by one skilled in the art, one, two, three, four, or more artificial teeth may be prepared to receive one, two, three, four, or more crowns, overlays, or mixtures of crowns and overlays. Further a multiple artificial teeth may be prepared to receive a single zirconium overlay (101). Preferably, after the step of preparing the first denture for at least one zirconium crown (100) or zirconium overlay (101), the first denture is placed in at CAD scanner once again and a new three-dimensional model is made. In the preferred version of this embodiment, this second three-dimensional model can be compared to the first three-dimensional model to ensure that alignment and orientation of the first denture has not been inadvertently or undesirably altered by the preparation to receive at least one crown (100) or overlay (101). If such alternation has occurred, comparison of the first and second three-dimensional models can be used to determine what adjustments should be made to bring the first denture back to the desired alignment and orientation.

[0065] In these embodiments, at least one zirconium crown (11), at least one zirconium overlay (101), or a mixture of zirconium crowns and overlays, are fabricated for attachment to the prepared first denture. Fabrication of such crown or crowns, overlay or overlays, includes selecting zirconium stock based on desired color and esthetic characteristics and forming the crown or the overlay. The initial size and shape of the at least one crown and/or overlay is selected so that when such crown and/or overlay is fabricated and fitted to the artificial teeth prepared to receive it, the result is a denture with an overall shape, size, and parameters that approximate the desired parameter.

[0066] In these embodiments, the crown and/or overlay is preferably formed by CAM milling from zirconium stock, most preferably by a CAM mill added by the CAD electronic three dimensional model of the first denture such that the crown and/or overlay is shaped on one side to mate to the artificial teeth prepared to receive it and shaped on the other side to form tooth surfaces that result in a denture with the desired parameters. The CAM mill may be directed to form a crown and/or overlay of the shape and profile shown by the electronically stored three dimensional image, but oversized to account for shrinkage of the zirconia during the preferred sintering step. Preferably in this embodiment, the crown an for overlay is formed approximately 15% to approximately 20% oversized, with the precise degree of oversizing contingent on the specific sintering conditions intended to be used. Most preferably, the crown and/or overlay is formed approximately 17.8% oversized.

[0067] Preferably in these embodiments, the step of preparing the at least one crown and/or overlay includes sintering after forming. Sintering improves the properties of zirconia for use as an implant, and particularly improves flexural strength, as would be appreciated by one skilled in the art. Sintering for zirconia used in implants is typically performed at temperatures between 1,300 degrees Celsius and 1,700 degrees Celsius, with the greatest improvement in flexural strength occurring at around 1,500 degree Celsius. In preferred embodiments of the present invention, sintering is performed at temperatures of approximately 1,500 degrees Celsius. Time of sintering is dependent on volume, temperature, and method. Although microwave sintering, conventional sintering, and other sintering methods may be used, the occlusal insert of the present invention is preferably sintered using conventional sintering for between approximately $ and approximately 12 hours, and most preferably for approximately 10 hours.

[0068] Optionally in these embodiments, the step of fabricating at least one crown and/or overlay may include staining the crown and/or overlay to a desired shade, color, or tone, such as to match or stimulate real teeth. Such staining, as would be appreciated by one skilled in the art, may occur at virtually any stage al the method. Preferably, staining occurs during sintering.

[0069] In these embodiments, after the at least one crown and/or overlay is fabricated, it is attached to the first denture by mating the crown and/or overlay with the artificial tooth or teeth prepared to receive each such crown and/or overlay, to form a denture that as closely as possible approximates the desired parameters. This denture is referred to herein as a “second denture.” It should be noted that the second denture is not a separate structure in this embodiment from the first denture; rather it is the revision of the first denture created by the preparation of a selected tooth or selected teeth within the first denture, and the attachment of the at least one zirconium crown or overlay to the prepared tooth or teeth. If the attached crown and/or overlay does not obtain the desired fit, or otherwise fails to form a second denture that adequately approximates the desired parameters, at least one crown and/or overlay may be removed and may undergo further preparation. Such further preparation may include, by way of example, additional sintering, milling, sanding, abrading, cutting, or other shaping.

[0070] In these embodiments, after the at least one zirconium crown or overlay is determined to be suitably prepared, such crown and/or overlay may be permanently attached to the prepared tooth or teeth. As with other embodiments herein, test-fitting of the second denture may occur prior to final fixation of the crown and/or overlay.

[0071] After the second denture is determined to be satisfactory to the patient and the dentist, the second denture is finished. In these embodiments, the crown and/or overlay are stained, if staining is desired and has not yet been performed, are sintered, if sintering is desired and has not yet been performed, and are permanently attached to the holding area or areas. Such permanent attachment can be accomplished through the use of adhesives or resins, using techniques known to the art. A wide variety of adhesives and adhesive attachment techniques may be used within the scope and spirit of this invention.

[0072] As will be apparent to one skilled in the art, these embodiments of the method, may incorporate one or more than one zirconium crown, one or more than one zirconium overlay, or a mixture of zirconium crowns and overlays that involves one or more of each. Further, as will be apparent to one skilled in the art, these embodiments of the method may be combined with embodiments of the method that utilize occlusal inserts.

[0073] Although the present invention has been described in considerable detail with reference to certain preferred versions thereof other versions are possible. For example, materials, shapes, sized, or configurations other than those described in detail herein may be used for the versions of this invention. Further, the method may include additional steps, intervening steps, or steps performed in an order other than those specified in the embodiments described above. Therefore, the spirit and scope of the claims should not be limited to the description of the preferred embodiments described herein.