Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C13/00—Dental prostheses; Making same
  • A61C13/0003—Making bridge-work, inlays, implants or the like
  • A61C13/0022—Blanks or green, unfinished dental restoration parts
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C13/00—Dental prostheses; Making same
  • A61C13/0003—Making bridge-work, inlays, implants or the like
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K6/00—Preparations for dentistry
  • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
  • A61K6/884—Preparations for artificial teeth, for filling teeth or for capping teeth comprising natural or synthetic resins
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C13/00—Dental prostheses; Making same
  • A61C13/20—Methods or devices for soldering, casting, moulding or melting
  • A61C13/206—Injection moulding

Definitions

• This invention broadly relates to a mill blank assembly used in the field of dentistry to create an inlay, onlay, crown, veneer, coping, bridge, bridge framework, implant, implant abutment or other restoration or restoration component. More specifically, the present invention is directed to a mill blank assembly that is especially adapted for use with computer-aided design and machining processes to create a dental prosthesis. The present invention is also directed to a method for making a dental mill blank assembly.
• a variety of dental procedures are known for replacing or repairing damaged, weakened or missing tooth structures.
• a dental prosthesis commonly known as a filling is often used to fill cavities in teeth caused by tooth decay or caries.
• Somewhat larger prosthetics also used to fill cavities are known as inlays and onlays. Fillings, inlays and onlays may also be utilized to restore the shape of teeth that have been chipped or broken.
• bridges Other types of dental prosthetics include bridges, full crowns and partial crowns. Typically, these prosthetics are much larger than fillings and as a result are often more visible in the oral cavity. Full and partial crowns may be supported by remaining portions of the original tooth structure and/or by a post extending toward the bony region of the jaw.
• Bridges are structures that connect to adjacent tooth structure and provide an artificial tooth or tooth crown to replace corresponding, missing structure.
• amalgam In the past, fillings and some inlays and onlays were often made of a silver-colored metal alloy known as amalgam due to its relatively long life and relatively low cost. Another advantage offered by amalgam is that it allows a dental practitioner to fit and fabricate the restoration during a single session with a patient. Unfortunately, amalgam is not considered aesthetic since its silver color sharply contrasts to the appearance of natural teeth in the oral cavity. Another material used for dental prosthetics, and particularly for larger inlays and fillings, is gold. However, like amalgam, the color of gold sharply contrasts with the appearance of natural teeth and is highly visible in the oral cavity. In addition, gold is relatively expensive in comparison to other dental materials. As a consequence, many dental practitioners are increasingly turning to ceramic or polymer-ceramic composite materials for use to make dental prosthetics. Dental ceramic materials and dental polymer-ceramic composite materials can provide an appearance that closely matches the appearance of natural teeth. Such materials are also available in various color shades so that the practitioner can select a color that closely matches the color of adjacent tooth structure.
• the laboratory procedure for making the prosthetic may be somewhat involved, depending on the type of prosthetic that is needed.
• a wax replica of the desired crown is built on the stone model.
• the wax replica is then embedded in a refractory investment material and fired to create another negative physical image of the oral structure of interest.
• Porcelain is then forced into the investment material under pressure and heat in order to make the crown.
• a dental prosthesis using a computer-aided machining system typically involves the use of a "mill blank", a block of material from which the prosthetic is cut.
• Dental mill blocks are often made of a ceramic material.
• Commercially available dental mill blanks include VITA CELAYTM porcelain blanks from Vita Zahn Fabrik, VITA NCERAMTM ceramic blanks from Vita Zahn Fabrik, MACORTM micaceous ceramic blanks from Corning, and DICORTM micaceous ceramic blanks from Dentsply.
• An improved ceramic dental mill blank is described in applicant's co-pending PCT application entitled "CERAMIC DENTAL MILL BLANKS", PCT USOO/19887, filed August 26, 1999.
• Dental mill blanks may also be made of resinous materials.
• An example of a dental mill blank made of a polymeric resin and a filler is described in applicant's co- pending PCT patent application entitled “DENTAL MILL BLANKS", PCT US99/10966, filed January 8, 1999.
• Dental mill blanks made of such material exhibit superior milling characteristics such as hardness and cutting properties relative to previously known dental mill blanks.
• dental mill blanks are made of a two-piece construction that comprises a support stub section and a milling blank section.
• the support section is cylindrical and adapted to fit into a collet or a Jacobs chuck of a milling machine.
• the support section is made of metal, since the support section is ultimately detached from the milling section and does not form part of the finished prosthetic.
• the support section is typically made of a relatively soft metallic material such as an aluminum alloy that is easy to machine to precise tolerances.
• the milling section of conventional two-piece dental mill blank assemblies is often made of one of the aesthetically-pleasing restorative materials described above so that the resulting prosthetic provides a natural appearance once placed in the oral cavity.
• the milling section of conventional assemblies has a flat face that is joined to a flat face of the support section by an adhesive.
• An example of one type of two-piece construction is described in U.S. Patent No. 4,615,678.
• a dental mill blank assembly includes a milling section and a support section, and the support section is also part of a mold assembly that is used to form and make the milling section during manufacture of the assembly.
• the milling section is fixed to the support section by a chemical bond that begins to form within the mold cavity, such that the milling section and the support section are adhered to each other at the time that the mold assembly is opened for removal of the mill blank assembly.
• the use of an additional adhesive component to bond the milling section to the support section is unnecessary.
• the dental mill blank assembly of the present invention is especially suitable for use in computer-aided machining systems such as the machining systems described above.
• the mill blank assembly presents an enhanced resistance to fracture during the time that the milling section is machined in a milling system, and safely resists forces exerted by a milling tool in lateral directions so that the dental prosthetic can be fully machined.
• the chemical bond between the support section and the milling section greatly reduces the likelihood that the milling section is detached from the support section during a machining operation.
• the present invention in one aspect is directed to a mill blank assembly for a dental prosthesis that comprises a milling section made of a material suitable for making a dental prosthesis.
• the mill blank assembly also comprises a support section having a shaft for releasably supporting the mill blank assembly in a milling machine.
• the support section is bonded to the milling section by a chemical bond directly between the material of the support section and the material of the milling section.
• Another aspect of the invention is directed toward a dental mill blank assembly that consists essentially of a milling section and a support section.
• the milling section is made of a material having a composition that is different than the composition of the support section.
• the present invention is also directed toward a dental mill blank assembly that includes a support section having a shaft for releasably supporting the mill blank assembly in the milling machine.
• the support section includes a through passageway.
• the mill blank assembly also includes a hardened restorative material connected to the support section. A portion of the hardened restorative material is located within the passageway. Another portion of the hardened restorative material is located externally of the passageway, serves as a milling section and is integrally connected to the portion of hardened restorative material that is located within the passageway.
• Another aspect of the present invention is directed toward a method of making a dental mill blank assembly.
• This method includes the act of providing a mold assembly that includes a first mold component, a second mold component and a mold cavity defined at least in part by the first mold component and the second mold component.
• the method also includes the act of directing a quantity of restorative material into the mold cavity.
• the method further includes the act of reacting the restorative material with the second mold component in order to establish a chemical bond between the restorative material and the second mold component.
• the method also includes the act of hardening the restorative material located in the mold cavity.
• Another aspect of the present invention is directed toward a method of making a dental prosthesis.
• the method includes the act of providing a mold assembly that includes a first mold component, a second mold component and a mold cavity defined at least in part by the first mold component and the second mold component.
• the method also includes the acts of directing a quantity of restorative material into the mold cavity, and establishing a bond between the restorative material and the second mold component.
• the method further includes the acts of hardening the restorative material located in the mold cavity, and separating the first mold component from the restorative material.
• the method additionally includes the acts of mounting the second mold component in a milling machine, and milling the hardened restorative material at least partially into a prosthesis.
• the present invention is also directed in an additional aspect to a method of making a dental mill blank assembly.
• the method includes the act of directing a quantity of restorative material through a passageway of a support section.
• the method also includes the act of hardening restorative material located within the passageway as well as restorative material located externally of the passageway, such that the hardened restorative material located externally of the passageway serves as a milling section and the hardened restorative material located within the passageway resists detachment of the milling section from the support section.
• Fig. 1 is a side cross-sectional view of a mold assembly according to certain embodiments of the invention, wherein the mold assembly is shown as it initially appears and before such time as restorative material has been directed into a mold cavity of the assembly;
• Fig. 2 is a view somewhat similar to Fig. 1 except that a quantity of restorative material has been introduced into the mold cavity and an inner mold component has shifted relative to an outer mold component in response to the introduction of the restorative material into the mold cavity;
• the inner mold component 14 includes a shaft 22 as well as a flange 24.
• the shaft 22 and the flange 24 are integrally joined together and form a single, unitary body.
• an outer end of the shaft 22 has a chamfered section for facilitating insertion of the shaft 22 in a chuck of a milling machine as will be described in the paragraphs that follow.
• the inner mold component 14 has moved a substantial distance away from the end wall 18, but the space between the flange 24 and the end wall 18 is occupied by the restorative material.
• the cylindrical shapes of the outer edge of the flange 24 and the inner face of the outer wall 16 have nearly equal diameters and present a close mating fit so that the inner mold component 14 slides within the outer mold component 12 without undue lateral movement or "slop".
• the front face of the flange 24 is closely adjacent to the inner side of the end wall 18 before restorative material is introduced into the mold cavity. More preferably, the flange 24 is in contact with the inner side of the end wall 18 as shown in Fig. 1 before restorative material is introduced into the mold cavity. In this orientation of the components 12, 14, the volume of space in the mold cavity (ignoring the space in the passageway 20) is essentially zero. As the mold cavity is filled, the flowing dental restorative material bears against the front face of the flange 24, thereby helping to ensure air bubbles are not created in the mass of restorative material in the mold cavity as the mold cavity enlarges in volume. Avoidance of air bubbles in the restorative material is desired so that the resulting milling section is strong and does not have voids that might otherwise appear within or on the surface of the resulting prosthetic.
• a limited amount of back pressure is applied to one or both of the components 12, 14 as the mold cavity is filled. In this manner, the likelihood of air bubbles in the resulting milling section is reduced. If, for example, the outer mold component 12 is held stationary while the mold cavity is filled, pressure is applied to the inner mold component 14 so that the inner mold component 14 does not freely move in a direction away from the passageway 20.
• an outer end of the milling section 32 that is remote from the second mold component 14 is ground, sanded, machined or otherwise finished to a smooth surface.
• the smooth surface is not needed for subsequent machining operations during a process for making a dental prosthetic, but does improve the overall appearance of the assembly 30 as may be desired to facilitate the promotion and sale of the assembly 30 to a dental practitioner or a dental laboratory. Finishing the end wall to a smooth surface is desired in instances where a portion of the restorative material 28 has entered the passageway 20 and hardened to leave visually apparent gate or a protrusion, especially in instances where there is a protrusion with a relatively rough outer end.
• the resin may be made from a material comprising a monomer, oligomer or polymer comprising a free radically curable functionality and a cationically curable functionality.
• Alternative polymers for the restorative material 28 include thermoplastic polymers, such as polycarbonates, nylon, polyetheretherketones, polyurethanes, polyimides and polyamides. The polymer material may be filled with one or more types of filler as described below.
• the restorative material 28 also includes a filler which may be either organic or inorganic in character.
• the filler is preferably a finely divided material that may optionally have an organic coating. Suitable coatings include silane or encapsulation in a polymeric matrix.
• the filler may be selected from one or more of many materials suitable for incorporation in compositions used for medical or dental applications, such as fillers cu ⁇ ently used in dental restorative compositions and the like.
• the second mold component 14 may be made of a material that does not establish a strong chemical bond with the restorative material 28.
• examples of such other materials include metals (e.g., aluminum) and other types of polymers (such as nylon, polycarbonate, polyethylene and polypropylene and ABS).
• the outer wall 16 of the first mold component 12 is preferably made of a material that transmits actinic radiation.
• the first mold component 12 is a unitary body that is made of a clear or translucent material that does not significantly hinder passage of actinic radiation.
• the first mold component 12 is preferably made of a material that does not react with the restorative material 28 and form a bond.
• the curing chamber may include a multiple number of light sources that are a ⁇ anged in a row along interior walls of the curing chamber.
• the resulting milling section 32 of the mill blank assembly 30 is suitable for fabricating a wide variety of restorations, including inlays, onlays, crowns, veneers, bridges, implant abutments, copings and bridge frameworks.
• Various means of machining the milling section 32 may be employed to create a custom-fit dental prosthesis having a desired shape.
• the prosthesis is milled by computer-aided milling equipment, such as machines sold under the trade names CEREC 2TM or CEREC 3TM from Sirona,
• the third mold component 15b is movable within the hollow interior of the first mold component 12b.
• the third mold component 15b includes an end wall 17b as well as a hollow, cylindrical outer wall 19b that is integrally joined to the end wall 17b.
• the diameter of the outer wall 19b is just slightly smaller than the inner diameter of the first mold component 12b, so that the third mold component 15b is smoothly slidable within the first mold component 12b without undue lateral movement or slop.
• the third mold component 15b as well as the first mold component 12b are preferably made of the same materials described above in connection with the first mold component 12. Fig.
• FIG. 6 is a view for exemplary purposes that shows an example of an initial position of the third mold component 15b within the first mold component 12b before restorative material is introduced into the mold cavity.
• the end wall 17b in that orientation is in flat, face-to-face contact with the face of the flange 24b.
• the volume of the mold cavity (ignoring the passageway 23b) is essentially zero.
• Flowable restorative material is introduced into the mold cavity through the passageway 23b that extends through the second mold component 14b. Once the restorative material enters the mold cavity, the third mold component 15b and the second mold component 14b move relatively away from each other in a direction along the reference axis 26b.

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• Health & Medical Sciences (AREA)
• Oral & Maxillofacial Surgery (AREA)
• General Health & Medical Sciences (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Dentistry (AREA)
• Plastic & Reconstructive Surgery (AREA)
• Dental Prosthetics (AREA)
• Dental Preparations (AREA)
• Dental Tools And Instruments Or Auxiliary Dental Instruments (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Cited By (2)

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Citations (12)

Family Cites Families (33)

• 2000
  • 2000-12-18 US US09/741,249 patent/US6669875B2/en not_active Expired - Lifetime
• 2001
  • 2001-04-20 AU AU2001253717A patent/AU2001253717A1/en not_active Abandoned
  • 2001-04-20 DE DE60130139T patent/DE60130139T2/de not_active Expired - Lifetime
  • 2001-04-20 EP EP01927243A patent/EP1343431B9/en not_active Expired - Lifetime
  • 2001-04-20 WO PCT/US2001/012828 patent/WO2002049531A1/en not_active Ceased
  • 2001-04-20 AT AT01927243T patent/ATE370707T1/de not_active IP Right Cessation
  • 2001-04-20 JP JP2002550877A patent/JP4369119B2/ja not_active Expired - Fee Related
• 2003
  • 2003-10-03 US US10/678,538 patent/US7214435B2/en not_active Expired - Fee Related

Patent Citations (12)

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