WO2013174524A1 - Method for manufacturing of a dental product - Google Patents

Method for manufacturing of a dental product Download PDF

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Publication number
WO2013174524A1
WO2013174524A1 PCT/EP2013/001542 EP2013001542W WO2013174524A1 WO 2013174524 A1 WO2013174524 A1 WO 2013174524A1 EP 2013001542 W EP2013001542 W EP 2013001542W WO 2013174524 A1 WO2013174524 A1 WO 2013174524A1
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WO
WIPO (PCT)
Prior art keywords
dental
dental prosthesis
hole
cavity
replica
Prior art date
Application number
PCT/EP2013/001542
Other languages
French (fr)
Inventor
Stefan JAGELID
Simon JEGOU
Nicolai Bernhard
Original Assignee
Nobel Biocare Services Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nobel Biocare Services Ag filed Critical Nobel Biocare Services Ag
Publication of WO2013174524A1 publication Critical patent/WO2013174524A1/en

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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
    • 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
    • A61C13/08—Artificial teeth; Making same
    • A61C13/081—Making teeth by casting or moulding
    • 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
    • A61C13/08—Artificial teeth; Making same
    • A61C13/083—Porcelain or ceramic teeth
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y70/00—Materials specially adapted for additive manufacturing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y80/00—Products made by additive manufacturing

Definitions

  • This invention relates to a method for manufacturing of a dental product.
  • the invention relates to manufacturing of a dental prosthesis comprising a glass-ceramic material and being intended for attachment to a dental implant.
  • Dental implant products are well known and relates typically to a dental implant made of titanium screwed into the jawbone combined with a dental prosthesis fastened to the implant.
  • the dental prosthesis contains often a shaped dental material in the form of a crown cap (coping) provided onto an abutment that in turn is fastened to the implant.
  • Such an abutment comprises an upper part that extends inside the dental material and supports it, and a lower part provided with connection means, such as threads, for connection to the implant.
  • a suitable dental material for such applications is glass ceramics.
  • a common glass ceramic material in dental applications is lithium disilicate as disclosed in e.g. US 6342458.
  • Such a material is suitable for processing a shaped dental product, such as a crown cap (coping), and provides the dental prosthesis with suitable physical properties (tooth-like appearance, high bending fracture strength, high fracture toughness value, etc.).
  • An object of this invention is to provide a method for manufacturing of a dental product that exhibit improved possibilities of making use of glass ceramic materials compared to conventional methods. This object is achieved by the method defined by the technical features contained in independent claim 1.
  • the dependent claims contain advantageous embodiments, further developments and variants of the invention.
  • the invention concerns a method for manufacturing of a dental product, said method comprising the step of producing a replica of a dental prosthesis intended for connection to a dental implant with a lower side of the dental prosthesis facing towards the implant and an upper side of the dental prosthesis facing away from the implant.
  • the invention is characterized in that the method comprises the steps of: providing the replica with a through hole that extends between the upper side and the lower side of the intended dental prosthesis such as to allow for the formation of a corresponding through hole through the intended dental prosthesis; and placing into the through hole a heat resistant and removable object having a shape corresponding to that of said through hole.
  • the inventive method makes it possible in practice to make use of a whole crown glass-ceramic dental prosthesis, which is difficult to fasten properly to implants without screws.
  • a dental prosthesis does not require any intermediate abutment.
  • the inventive method can also be used to produce copings with preformed screw holes that can be fastened to abutments or insert fittings by screwing. Screwing, as compared to adhesive or pressing means, is in some cases a more reliable fastening method.
  • the dental prosthesis is made of a lithium disilicate glass-ceramic dental material, wherein the replica has an outer shape that resembles that of a tooth.
  • the removable object exhibits shape permanence in such a way that it has substantially the same shape before forming of the dental prosthesis around the object as well as after removal of the object from the solidified dental prosthesis.
  • the object is a form of massive, integrated object that can be removed as a whole from the solidified dental prosthesis.
  • a suitable material for the object is metal.
  • To facilitate removal of the object it is preferably provided with a layer of an agent that reduces the adhesion between the object and the solidified dental prosthesis.
  • the through hole has a lower portion and an upper portion, wherein the lower portion is positioned closer to the lower side of the intended dental prosthesis, wherein the lower portion is more narrow than the upper portion, and wherein the through hole is provided with a flange that connects said portions.
  • the screw channel formed in the final dental prosthesis will resemble the shape of the through hole in the replica, this provides a seat for a screw positioned in the screw channel for connecting the dental prosthesis directly or indirectly to the dental implant.
  • the method comprises the step of providing the replica with a cavity positioned in connection to the through hole and to the lower side of the dental prosthesis, said cavity resembling the shape of a connecting member for connection to the dental implant.
  • the object also comprises the step of placing into the cavity a heat resistant object having a shape corresponding to that of said cavity.
  • This object can be a connecting member for connection to the dental implant that is fixed to the dental prosthesis during its production in the mould.
  • the object placed in the cavity can be removable and only resemble the shape of a connecting member, such as a standard insert fitting, that can be fixed to the dental prosthesis in a later stage.
  • Connecting members are commonly used to prevent rotation in relation to the dental implant (such that the screw to be placed in the screw channel only needs to press the prosthesis towards the implant). Fixing the connecting member inside the cavity during formation of the solid glass ceramic body is an efficient way of attaching the connecting member to the dental prosthesis.
  • the connecting member is ring-shaped, which means that it has a centrally located through hole that allows insertion of the screw to be used for fastening of the dental product.
  • the replica is produced in a plastic material by rapid prototyping, such as three-dimensional printing, and by automation according to a predefined shape described in a computer-readable form.
  • rapid prototyping such as three-dimensional printing
  • automation according to a predefined shape described in a computer-readable form.
  • the through hole extends in a substantially straight direction from a central position of the upper side to a central position of the lower side of the intended dental prosthesis. This forms a straight screw channel adequately positioned in the dental prosthesis.
  • Figs 1-3 show, in a schematic view, a first embodiment of the inventive method for production of a first type of dental product
  • Figs 4-6 show, in a schematic view, a second embodiment of the inventive method for production of a second type of dental product
  • Figs 7-8 show the second type of dental product
  • Figs 9-10 show dental products of the first and second type produced according to the inventive method and attached to dental implants.
  • Figures 1-3 show a first preferred embodiment of the inventive method for manufacturing of a dental product 1 of a first type.
  • Producing a replica in the form of a three-dimensional plastic model of a dental prosthesis can be done by rapid prototyping (such as 3D-printing or stereo-lithography) or machining and is well known as such.
  • rapid prototyping such as 3D-printing or stereo-lithography
  • machining such as a dental prosthesis can be formed that resembles the shape and dimensions of the plastic model.
  • Figure 1 shows a plastic model (replica) 2 used in the first embodiment.
  • the plastic model 2 resembles a full-contour crown dental prosthesis 12 for connection to a dental implant 9 (see figures 3 and 9).
  • a lower side 2a (12a) of the plastic model 2 (dental prosthesis 12) faces downwards towards the intended position of the implant 9 and an upper side 2b (12b) of the plastic model 2 (dental prosthesis 12) faces away from the implant 9.
  • the plastic model 9 comprises sprues 3 that, after having been burnt out, form channels 4 (figure 2) for introducing hot-pressed glass ceramic material into a mould in a subsequent investment-casting step.
  • the number, shape and position of the sprues 3 may of course differ from what is shown here.
  • the plastic model 2 is provided with a through hole 50 that extends between the upper side (surface) 2b and the lower side (surface) 2a such as to allow for the formation of a corresponding through hole (screw channel) in the intended dental prosthesis 12.
  • the plastic model 2 is in this example also provided with a cavity 60 positioned in connection to the through hole 50 and to the lower side 2a of the plastic model 2.
  • the cavity 60 is intended to form a space for an upper part 6b of a connector 6 used for connecting the dental prosthesis 12 to the implant 9 (figures 2, 3 and 9).
  • This arrangement may be regarded such that the through hole 50 in this example forms part of a larger cavity, wherein an elongated part of the larger cavity is intended to form the through hole screw channel, and wherein a lower part of the larger cavity forms the cavity 60.
  • the elongated through hole/screw channel cavity 50 has a lower portion 50a and an upper portion 50c, wherein the lower portion 50a is positioned closer to the lower side 2a of the plastic model 2.
  • the lower portion 50a is more narrow than the upper portion 50c and the through hole 50 is provided with a flange or narrowing/broadening portion 50b that connects the lower and upper portions 50a, 50b (figure 1 ).
  • a corresponding flange 50b will thus be formed in the intended dental prosthesis (figure 9).
  • the purpose of this corresponding flange 50b in the dental product 1 is to provide a surface onto which a head of an implant engagement screw 15 can press when engaging the dental product 1 to the implant 9 (see figure 9).
  • a removable metallic pin 5 screwed onto a metallic connector 6 are positioned in the through hole 50 and the lower cavity 60.
  • the pin 5 has a shape and dimension corresponding to the elongated through hole 50 (as well as to a part of the lower cavity 60) and the upper part 6b of the connector 6 has a shape and dimension corresponding to the lower cavity 60 (except for the part occupied by the pin 5 that extends into the lower cavity 60) such that the entire cavity 50, 60 becomes completely filled.
  • the pin 5 is made of stainless steel and the connector 6 is made of titanium.
  • Such materials can withstand the contact with e.g. a glass- ceramic ingot during a hot-pressing process so that the shape, dimension and position of the pin 5 and the connector 6 will remain.
  • the material of the connector 6 is suitable for forming part of the dental product 1.
  • the pin 5 Since the pin 5 is intended to be removed in a later stage its surface is preferably treated such as to prevent or reduce adhesion to the glass ceramic material.
  • the connector 6 is intended to form a connection to the dental implant 9 and is therefore intended to be fastened (fused) to the glass ceramic material as to form an integral part of a solid body of glass ceramic material.
  • the connector 6, or at least its upper part 6b, is therefore preferably treated such as to enhance adhesion to the glass ceramic material.
  • the connector 6 has an upper part 6b intended to be fastened to the glass ceramic material and a lower part 6a forming a standard connector for various implants. Both parts of the connector 6 have cross sections that prevent rotation, i.e a non-circular cross section, such as a polygonal cross section.
  • the connector 6 is ring-shaped and has a centrally located hole that allows a screw 15 to extend through the hole from an upper part of the dental prosthesis 12 to the implant 9 (figure 9).
  • a mould is then formed in a conventional way by arranging a refractory investment material (plaster) 7 around the plastic model 2 containing the pin 5 and connector 6.
  • the plastic model 2, including the sprues 3, is then burned out prior to hot-pressing of the glass-ceramic at 800°C - 900°C.
  • Figure 2 shows the step of introducing the formable glass-ceramic dental material into a mould that has a shape and dimension resembling that of the plastic model 2 and in which the pin 5 and the connector 6 are positioned,
  • a glass-ceramic ingot 8 e.g. of the lithium disilicate-type
  • the casted dental crown 12 is divested by sand blasting, the sprues 3 are cut and the pin 5 is removed to form the screw channel, see figure 3.
  • the connector 6 has now been fused to the glass-ceramic dental material. If a lithium disilicate material is used the surface of the dental prosthesis is preferably acid etched with hydrofluoric acid to remove the thin (max 100 pm) reactive layer formed between the glass-ceramic material and a silica containing investment material.
  • Figures 4-6 shows a second preferred embodiment of the inventive method for manufacturing of a dental product 10 of a second type.
  • the principle of the example shown here is similar to the first embodiment.
  • a difference is the shape of the lower cavity in the replica/plastic model and, thus, in the corresponding cavity in the dental prosthesis. Accordingly, also the shape of the object arranged in the cavity when forming the solid glass-ceramic material differs.
  • the connector which now has the form of a standard insert fitting, is not fused to the glass-ceramic dental material during manufacturing of the dental prosthesis. Instead the standard insert fitting is fastened to the dental material at a later stage, e.g by fusing or cementing.
  • FIG. 4 shows, in line with figure 1 , a plastic model 20 resembling a full- contour crown dental prosthesis 120 (fig 6) for connection to a dental implant 9 with a lower side 20a (120a) of the plastic model 20 (dental prosthesis 120) facing towards the intended position of the implant 9 and an upper side 20b (120b) of the plastic model 20 (dental prosthesis 120) facing away from the implant 9.
  • the plastic model 20 comprises sprues 3 as described above.
  • the plastic model 20 is provided with a through hole cavity 500, 600 that, in line with the first embodiment, gives rise to a corresponding desired cavity in the final dental product 10 shown in figures 6 and 8.
  • An upper part 500 of the cavity is intended to form the screw channel through the intended dental prosthesis 120 and is pin-shaped.
  • a lower part 600 of the cavity, below the pin-shaped part 500, corresponds to the cavity 60 described above and resembles an upper part 66b of a standard insert fitting 66 (fig 7).
  • the entire cavity 500, 600 has the shape of a pin provided onto (or screwed partly into) a standard insert fitting connector (that occupies more space inside the dental prosthesis 120 than the connector 6 shown in figures 1-3).
  • the heat-resistant and removable object 55 used in the subsequent casting step has, of course, a shape similar to that of the cavity 500, 600 it is intended to form.
  • the object used to form the cavity is an integrated one-piece part, for instance a machined silica-free material such as alumina.
  • the object(s) can be a replica of the standard insert fitting 66 to be used, which replica is provided with an extended pin screwed into an upper screw hole of the replica.
  • the replica and the pin, as well as the one-piece object 55 can be made of stainless steel or another heat resistant metal alloy.
  • the removable object 55 has in this case a lower part 55a having a shape resembling the upper part 66b of the insert fitting 66, and an upper part 55b having the shape of a pin with a circular cross section (a circular cylinder).
  • the object 55 thus has a shape resembling that of a standard insert fitting provided with a pin protruding out from a central hole of the standard insert fitting.
  • the plastic model 20 is finished, the object 55 used to define the cavity is positioned in the through-hole cavity 500, 600 which then becomes completely filled.
  • a mould is then formed in a conventional way by arranging a refractory investment material (plaster) around the plastic model 20 containing the object 55.
  • the plastic model 20, including the sprues 3 is then burned out prior to hot-pressing of the glass-ceramic at about 800°C - 900°C.
  • Figures 5-6 correspond to figures 2-3 and show the step of introducing the formable glass-ceramic dental material 8 into the mould in which the object 55 is positioned (figure 5) and the step of finalizing the dental prosthesis 120 by cutting the sprues 3, removing the object 55, treating the surface etc. (figure 6).
  • Figures 7-8 show the second type of dental product 10 that in this example includes the insert fitting 66.
  • the insert fitting 66 has been introduced into the lower cavity 600 and fixed to the dental prosthesis 120.
  • a lower part 66a of the insert fitting 66 is available for connection to the dental implant 9.
  • Figure 8 also shows, in line with figure 3, the screw 15 to be inserted through the cavity/screw channel 500 for connection of the dental product 10 to the implant 9.
  • the insert fitting 66 is ring-shaped and has a centrally located hole that forms an extension of the screw channel/cavity 500 so as to allow the screw to be inserted from the upper side 120b of the dental prosthesis 120 all the way down to a flange 500b arranged in the insert fitting 66 that provides a seat for the screw head (see also fig. 10).
  • the standard insert fitting 66 is typically made of a titanium or zirconia based material and can be produced separately from the dental prosthesis.
  • the plastic model 2, 20 and the removable object 5, 55 forming the through hole 50, 500, 600 can be produced at a production site, whereas investing-casting, final treatment of the dental prosthesis 12, 120 and fastening of the insert fitting 66 to the glass-ceramic material can be made at a dental laboratory.
  • the standard insert fitting 66 is typically also produced at a production site but may be available from different suppliers.
  • Figures 9-10 show dental products 1 , 10 manufactured according to the inventive method fastened to dental implants 9.
  • the removable object 5, 55 should have a certain internal strength so it does not break or fall apart when removed from the through-hole cavity.
  • the Young's modulus for the material of the removable object 5, 55 should be at least 10 GPa, preferably at least 30 GPa, more preferably at least 50 GPa.
  • the removable object 5, 55 and the corresponding cavity/screw channel 50, 500, 600 extend in a substantially straight direction between a central position of the upper side (surface) 12b, 120b and a central position of the lower side (surface) 12a, 120a of the intended dental prosthesis 12, 120.
  • the (intended) dental prosthesis 12, 120 can have an outer shape that resembles more than one tooth, e.g. a bridge, since the inventive method and is applicable to multi-abutment restorations.
  • the lower cavity 60, 600 described above is open, i.e. it forms a hollow depression at the lower side 2a, 20a, of the replica 2, 20.
  • the invention is not limited by the embodiments described above but can be modified in various ways within the scope of the claims.
  • the connector 6 does not necessarily have to be integrated in the dental prosthesis 12 as shown in figures 1-3, instead it could for instance be cemented to the lower side of the dental prosthesis, but integrating the connector strengthens the adhesion and simplifies and improves the connection to the implant.
  • replica refers to an item that corresponds substantially in shape and dimensions to the part it is intended to resemble, in this case a dental prosthesis intended for connection to a dental implant. Some differences may exist though, such as the sprues.
  • plastic or wax material refers in this case to any material that is useful for forming a replica or plastic model of a dental prosthesis and that can be burnt-out in an investment casting process.
  • the pin-shaped parts 5, 55b forming the screw channels may have a slightly increasing diameter in the same direction as they are intended to be pulled out in order to simplify removal.
  • dental implant refers in this context to a part or fixture intended to be fastened to the jawbone whereas the term dental prosthesis refers to the glass-ceramic tooth-like part.
  • a dental prosthesis for connection to a dental implant means that the dental prosthesis can be connected directly or indirectly, e.g. via an abutment or a bridge, to the implant.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Veterinary Medicine (AREA)
  • Public Health (AREA)
  • Animal Behavior & Ethology (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Dentistry (AREA)
  • Epidemiology (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Dental Prosthetics (AREA)

Abstract

The invention concerns a method for manufacturing of a dental product (1, 10), said method comprising the step of: producing a replica (2, 20) of a dental prosthesis (12, 120) intended for connection to a dental implant (9) with a lower side (12a, 120a) of the dental prosthesis (12, 120) facing towards the implant (9) and an upper side (12b, 120b) of the dental prosthesis (12, 120) facing away from the implant (9). The invention is characterized in that the method comprises the steps of: providing the replica (2, 20) with a through hole (50, 500, 600) that extends between the upper side (12b, 120b) and the lower side (12a, 120a) of the intended dental prosthesis (12, 120) such as to allow for the formation of a corresponding through hole through in the intended dental prosthesis, and placing into the through hole (50, 500, 600) a heat resistant and removable object (5, 55) having a shape corresponding to that of said through hole (50, 500, 600).

Description

Method for manufacturing of a dental product TECHNICAL FIELD
This invention relates to a method for manufacturing of a dental product. In particular, the invention relates to manufacturing of a dental prosthesis comprising a glass-ceramic material and being intended for attachment to a dental implant.
BACKGROUND OF THE INVENTION
Dental implant products are well known and relates typically to a dental implant made of titanium screwed into the jawbone combined with a dental prosthesis fastened to the implant. The dental prosthesis contains often a shaped dental material in the form of a crown cap (coping) provided onto an abutment that in turn is fastened to the implant. Such an abutment comprises an upper part that extends inside the dental material and supports it, and a lower part provided with connection means, such as threads, for connection to the implant. A suitable dental material for such applications is glass ceramics. A common glass ceramic material in dental applications is lithium disilicate as disclosed in e.g. US 6342458. Such a material is suitable for processing a shaped dental product, such as a crown cap (coping), and provides the dental prosthesis with suitable physical properties (tooth-like appearance, high bending fracture strength, high fracture toughness value, etc.).
There are different known ways of attaching the glass ceramic material onto the abutment. An example is to form the glass ceramic material directly onto the abutment using e.g. investment casting. A glass ceramic material is desired in many dental applications but it is not used as often as desired because handling and forming of the material as well as attaching of glass ceramic copings properly onto abutments are relatively complicated and time-consuming processes. There is a need of improvements in this field.
SUMMARY OF THE INVENTION
An object of this invention is to provide a method for manufacturing of a dental product that exhibit improved possibilities of making use of glass ceramic materials compared to conventional methods. This object is achieved by the method defined by the technical features contained in independent claim 1. The dependent claims contain advantageous embodiments, further developments and variants of the invention.
The invention concerns a method for manufacturing of a dental product, said method comprising the step of producing a replica of a dental prosthesis intended for connection to a dental implant with a lower side of the dental prosthesis facing towards the implant and an upper side of the dental prosthesis facing away from the implant.
The invention is characterized in that the method comprises the steps of: providing the replica with a through hole that extends between the upper side and the lower side of the intended dental prosthesis such as to allow for the formation of a corresponding through hole through the intended dental prosthesis; and placing into the through hole a heat resistant and removable object having a shape corresponding to that of said through hole. This enables the production of a dental prosthesis with a pre-shaped through hole in, for instance, a conventional plastic model-based process involving an investment casting process using a glass-ceramic dental material. By placing a heat-resistant and removable object into the through-hole cavity before the investment casting process a screw channel for fastening the dental product to the dental implant is simply created by removing the object after the investing casting process. To make such a screw channel cavity afterwards in an already solidified glass-ceramic dental material is very costly since it is both time-consuming and tool-damaging. Thus, the inventive method makes it possible in practice to make use of a whole crown glass-ceramic dental prosthesis, which is difficult to fasten properly to implants without screws. Such a dental prosthesis does not require any intermediate abutment. The inventive method can also be used to produce copings with preformed screw holes that can be fastened to abutments or insert fittings by screwing. Screwing, as compared to adhesive or pressing means, is in some cases a more reliable fastening method. Preferably, the dental prosthesis is made of a lithium disilicate glass-ceramic dental material, wherein the replica has an outer shape that resembles that of a tooth.
Preferably, the removable object exhibits shape permanence in such a way that it has substantially the same shape before forming of the dental prosthesis around the object as well as after removal of the object from the solidified dental prosthesis. This means, for instance, that the object is a form of massive, integrated object that can be removed as a whole from the solidified dental prosthesis. A suitable material for the object is metal. To facilitate removal of the object it is preferably provided with a layer of an agent that reduces the adhesion between the object and the solidified dental prosthesis.
In an embodiment of the invention the through hole has a lower portion and an upper portion, wherein the lower portion is positioned closer to the lower side of the intended dental prosthesis, wherein the lower portion is more narrow than the upper portion, and wherein the through hole is provided with a flange that connects said portions. As the screw channel formed in the final dental prosthesis will resemble the shape of the through hole in the replica, this provides a seat for a screw positioned in the screw channel for connecting the dental prosthesis directly or indirectly to the dental implant. In an embodiment of the invention the method comprises the step of providing the replica with a cavity positioned in connection to the through hole and to the lower side of the dental prosthesis, said cavity resembling the shape of a connecting member for connection to the dental implant. Preferably, it also comprises the step of placing into the cavity a heat resistant object having a shape corresponding to that of said cavity. This object can be a connecting member for connection to the dental implant that is fixed to the dental prosthesis during its production in the mould. Alternatively, the object placed in the cavity can be removable and only resemble the shape of a connecting member, such as a standard insert fitting, that can be fixed to the dental prosthesis in a later stage. Connecting members are commonly used to prevent rotation in relation to the dental implant (such that the screw to be placed in the screw channel only needs to press the prosthesis towards the implant). Fixing the connecting member inside the cavity during formation of the solid glass ceramic body is an efficient way of attaching the connecting member to the dental prosthesis. The connecting member is ring-shaped, which means that it has a centrally located through hole that allows insertion of the screw to be used for fastening of the dental product.
Preferably, the replica is produced in a plastic material by rapid prototyping, such as three-dimensional printing, and by automation according to a predefined shape described in a computer-readable form. This is an efficient method that provides for a high quality.
Preferably, the through hole extends in a substantially straight direction from a central position of the upper side to a central position of the lower side of the intended dental prosthesis. This forms a straight screw channel adequately positioned in the dental prosthesis. BRIEF DESCRIPTION OF DRAWINGS
In the description of the invention given below reference is made to the following figure, in which:
Figs 1-3 show, in a schematic view, a first embodiment of the inventive method for production of a first type of dental product,
Figs 4-6 show, in a schematic view, a second embodiment of the inventive method for production of a second type of dental product,
Figs 7-8 show the second type of dental product, and
Figs 9-10 show dental products of the first and second type produced according to the inventive method and attached to dental implants.
DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION
Figures 1-3 show a first preferred embodiment of the inventive method for manufacturing of a dental product 1 of a first type.
Producing a replica in the form of a three-dimensional plastic model of a dental prosthesis can be done by rapid prototyping (such as 3D-printing or stereo-lithography) or machining and is well known as such. By using e.g. an investment casting process a dental prosthesis can be formed that resembles the shape and dimensions of the plastic model.
Figure 1 shows a plastic model (replica) 2 used in the first embodiment. The plastic model 2 resembles a full-contour crown dental prosthesis 12 for connection to a dental implant 9 (see figures 3 and 9). A lower side 2a (12a) of the plastic model 2 (dental prosthesis 12) faces downwards towards the intended position of the implant 9 and an upper side 2b (12b) of the plastic model 2 (dental prosthesis 12) faces away from the implant 9. The plastic model 9 comprises sprues 3 that, after having been burnt out, form channels 4 (figure 2) for introducing hot-pressed glass ceramic material into a mould in a subsequent investment-casting step. The number, shape and position of the sprues 3 may of course differ from what is shown here.
As shown in figure 1 the plastic model 2 is provided with a through hole 50 that extends between the upper side (surface) 2b and the lower side (surface) 2a such as to allow for the formation of a corresponding through hole (screw channel) in the intended dental prosthesis 12.
The plastic model 2 is in this example also provided with a cavity 60 positioned in connection to the through hole 50 and to the lower side 2a of the plastic model 2. The cavity 60 is intended to form a space for an upper part 6b of a connector 6 used for connecting the dental prosthesis 12 to the implant 9 (figures 2, 3 and 9). This arrangement may be regarded such that the through hole 50 in this example forms part of a larger cavity, wherein an elongated part of the larger cavity is intended to form the through hole screw channel, and wherein a lower part of the larger cavity forms the cavity 60.
The elongated through hole/screw channel cavity 50 has a lower portion 50a and an upper portion 50c, wherein the lower portion 50a is positioned closer to the lower side 2a of the plastic model 2. The lower portion 50a is more narrow than the upper portion 50c and the through hole 50 is provided with a flange or narrowing/broadening portion 50b that connects the lower and upper portions 50a, 50b (figure 1 ). A corresponding flange 50b will thus be formed in the intended dental prosthesis (figure 9). The purpose of this corresponding flange 50b in the dental product 1 is to provide a surface onto which a head of an implant engagement screw 15 can press when engaging the dental product 1 to the implant 9 (see figure 9).
When the plastic model 2 is finished, a removable metallic pin 5 screwed onto a metallic connector 6 (see figures 2 and 3) are positioned in the through hole 50 and the lower cavity 60. The pin 5 has a shape and dimension corresponding to the elongated through hole 50 (as well as to a part of the lower cavity 60) and the upper part 6b of the connector 6 has a shape and dimension corresponding to the lower cavity 60 (except for the part occupied by the pin 5 that extends into the lower cavity 60) such that the entire cavity 50, 60 becomes completely filled.
In this example, the pin 5 is made of stainless steel and the connector 6 is made of titanium. Such materials can withstand the contact with e.g. a glass- ceramic ingot during a hot-pressing process so that the shape, dimension and position of the pin 5 and the connector 6 will remain. Further, the material of the connector 6 is suitable for forming part of the dental product 1.
Since the pin 5 is intended to be removed in a later stage its surface is preferably treated such as to prevent or reduce adhesion to the glass ceramic material. On the other hand, the connector 6 is intended to form a connection to the dental implant 9 and is therefore intended to be fastened (fused) to the glass ceramic material as to form an integral part of a solid body of glass ceramic material. The connector 6, or at least its upper part 6b, is therefore preferably treated such as to enhance adhesion to the glass ceramic material.
The connector 6 has an upper part 6b intended to be fastened to the glass ceramic material and a lower part 6a forming a standard connector for various implants. Both parts of the connector 6 have cross sections that prevent rotation, i.e a non-circular cross section, such as a polygonal cross section. The connector 6 is ring-shaped and has a centrally located hole that allows a screw 15 to extend through the hole from an upper part of the dental prosthesis 12 to the implant 9 (figure 9).
A mould is then formed in a conventional way by arranging a refractory investment material (plaster) 7 around the plastic model 2 containing the pin 5 and connector 6. The plastic model 2, including the sprues 3, is then burned out prior to hot-pressing of the glass-ceramic at 800°C - 900°C. Figure 2 shows the step of introducing the formable glass-ceramic dental material into a mould that has a shape and dimension resembling that of the plastic model 2 and in which the pin 5 and the connector 6 are positioned, In this case a glass-ceramic ingot 8 (e.g. of the lithium disilicate-type) is hot- pressed at about 900°C such as to generate a viscous flow through the sprue-channels 4 into the mould.
Thereafter, the casted dental crown 12 is divested by sand blasting, the sprues 3 are cut and the pin 5 is removed to form the screw channel, see figure 3. The connector 6 has now been fused to the glass-ceramic dental material. If a lithium disilicate material is used the surface of the dental prosthesis is preferably acid etched with hydrofluoric acid to remove the thin (max 100 pm) reactive layer formed between the glass-ceramic material and a silica containing investment material.
Figures 4-6 shows a second preferred embodiment of the inventive method for manufacturing of a dental product 10 of a second type. The principle of the example shown here is similar to the first embodiment. A difference is the shape of the lower cavity in the replica/plastic model and, thus, in the corresponding cavity in the dental prosthesis. Accordingly, also the shape of the object arranged in the cavity when forming the solid glass-ceramic material differs. Another difference is that the connector, which now has the form of a standard insert fitting, is not fused to the glass-ceramic dental material during manufacturing of the dental prosthesis. Instead the standard insert fitting is fastened to the dental material at a later stage, e.g by fusing or cementing. The screw used to fasten such a dental product is introduced through a screw channel formed in similarity with the previous embodiment, but the screw head presses in this case onto an upper side of the insert fitting and not onto a flange in the glass-ceramic material (fig 9). Figure 4 shows, in line with figure 1 , a plastic model 20 resembling a full- contour crown dental prosthesis 120 (fig 6) for connection to a dental implant 9 with a lower side 20a (120a) of the plastic model 20 (dental prosthesis 120) facing towards the intended position of the implant 9 and an upper side 20b (120b) of the plastic model 20 (dental prosthesis 120) facing away from the implant 9. The plastic model 20 comprises sprues 3 as described above.
As shown in figure 4 the plastic model 20 is provided with a through hole cavity 500, 600 that, in line with the first embodiment, gives rise to a corresponding desired cavity in the final dental product 10 shown in figures 6 and 8. An upper part 500 of the cavity is intended to form the screw channel through the intended dental prosthesis 120 and is pin-shaped. A lower part 600 of the cavity, below the pin-shaped part 500, corresponds to the cavity 60 described above and resembles an upper part 66b of a standard insert fitting 66 (fig 7). Thus, in this case the entire cavity 500, 600 has the shape of a pin provided onto (or screwed partly into) a standard insert fitting connector (that occupies more space inside the dental prosthesis 120 than the connector 6 shown in figures 1-3). The heat-resistant and removable object 55 used in the subsequent casting step has, of course, a shape similar to that of the cavity 500, 600 it is intended to form. In the example shown here the object used to form the cavity is an integrated one-piece part, for instance a machined silica-free material such as alumina. As an alternative the object(s) can be a replica of the standard insert fitting 66 to be used, which replica is provided with an extended pin screwed into an upper screw hole of the replica. The replica and the pin, as well as the one-piece object 55, can be made of stainless steel or another heat resistant metal alloy. As shown in figure 6, the removable object 55 has in this case a lower part 55a having a shape resembling the upper part 66b of the insert fitting 66, and an upper part 55b having the shape of a pin with a circular cross section (a circular cylinder). The object 55 thus has a shape resembling that of a standard insert fitting provided with a pin protruding out from a central hole of the standard insert fitting. When the plastic model 20 is finished, the object 55 used to define the cavity is positioned in the through-hole cavity 500, 600 which then becomes completely filled. A mould is then formed in a conventional way by arranging a refractory investment material (plaster) around the plastic model 20 containing the object 55. The plastic model 20, including the sprues 3, is then burned out prior to hot-pressing of the glass-ceramic at about 800°C - 900°C.
Figures 5-6 correspond to figures 2-3 and show the step of introducing the formable glass-ceramic dental material 8 into the mould in which the object 55 is positioned (figure 5) and the step of finalizing the dental prosthesis 120 by cutting the sprues 3, removing the object 55, treating the surface etc. (figure 6).
Figures 7-8 show the second type of dental product 10 that in this example includes the insert fitting 66. In figure 8 the insert fitting 66 has been introduced into the lower cavity 600 and fixed to the dental prosthesis 120. A lower part 66a of the insert fitting 66 is available for connection to the dental implant 9. Figure 8 also shows, in line with figure 3, the screw 15 to be inserted through the cavity/screw channel 500 for connection of the dental product 10 to the implant 9.
The insert fitting 66 is ring-shaped and has a centrally located hole that forms an extension of the screw channel/cavity 500 so as to allow the screw to be inserted from the upper side 120b of the dental prosthesis 120 all the way down to a flange 500b arranged in the insert fitting 66 that provides a seat for the screw head (see also fig. 10). The standard insert fitting 66 is typically made of a titanium or zirconia based material and can be produced separately from the dental prosthesis.
Not all method steps of the inventive method must be carried out at a production site. Typically, the plastic model 2, 20 and the removable object 5, 55 forming the through hole 50, 500, 600 can be produced at a production site, whereas investing-casting, final treatment of the dental prosthesis 12, 120 and fastening of the insert fitting 66 to the glass-ceramic material can be made at a dental laboratory. The standard insert fitting 66 is typically also produced at a production site but may be available from different suppliers.
Figures 9-10 show dental products 1 , 10 manufactured according to the inventive method fastened to dental implants 9. The removable object 5, 55 should have a certain internal strength so it does not break or fall apart when removed from the through-hole cavity. The Young's modulus for the material of the removable object 5, 55 should be at least 10 GPa, preferably at least 30 GPa, more preferably at least 50 GPa. Generally, the removable object 5, 55 and the corresponding cavity/screw channel 50, 500, 600 extend in a substantially straight direction between a central position of the upper side (surface) 12b, 120b and a central position of the lower side (surface) 12a, 120a of the intended dental prosthesis 12, 120.
The (intended) dental prosthesis 12, 120 can have an outer shape that resembles more than one tooth, e.g. a bridge, since the inventive method and is applicable to multi-abutment restorations. The lower cavity 60, 600 described above is open, i.e. it forms a hollow depression at the lower side 2a, 20a, of the replica 2, 20. The invention is not limited by the embodiments described above but can be modified in various ways within the scope of the claims. For instance, the connector 6 does not necessarily have to be integrated in the dental prosthesis 12 as shown in figures 1-3, instead it could for instance be cemented to the lower side of the dental prosthesis, but integrating the connector strengthens the adhesion and simplifies and improves the connection to the implant. The term "replica" refers to an item that corresponds substantially in shape and dimensions to the part it is intended to resemble, in this case a dental prosthesis intended for connection to a dental implant. Some differences may exist though, such as the sprues. The term "plastic or wax material" refers in this case to any material that is useful for forming a replica or plastic model of a dental prosthesis and that can be burnt-out in an investment casting process.
The pin-shaped parts 5, 55b forming the screw channels may have a slightly increasing diameter in the same direction as they are intended to be pulled out in order to simplify removal.
The term (dental) implant refers in this context to a part or fixture intended to be fastened to the jawbone whereas the term dental prosthesis refers to the glass-ceramic tooth-like part. The expression "a dental prosthesis for connection to a dental implant" means that the dental prosthesis can be connected directly or indirectly, e.g. via an abutment or a bridge, to the implant.

Claims

1. Method for manufacturing of a dental product (1 , 10),
said method comprising the step of:
- producing a replica (2, 20) of a dental prosthesis (12, 120) intended for connection to a dental implant (9) with a lower side (12a, 120a) of the dental prosthesis (12, 120) facing towards the implant (9) and an upper side (12b, 120b) of the dental prosthesis (12, 120) facing away from the implant (9), characterized in
that the method comprises the steps of:
- providing the replica (2, 20) with a through hole (50, 500, 600) that extends between the upper side (12b, 120b) and the lower side (12a, 120a) of the intended dental prosthesis (12, 120) such as to allow for the formation of a corresponding through hole through in the intended dental prosthesis, and - placing into the through hole (50, 500, 600) a heat resistant and removable object (5, 55) having a shape corresponding to that of said through hole (50, 500, 600).
2. Method according to claim 1 ,
characterized in
that it comprises the step of producing the dental prosthesis (12, 120) by introducing a dental material into a mould that has a the shape and dimension resembling that of the replica (2, 20).
3. Method according to claim 2,
characterized in
that the dental prosthesis (12, 120) is produced in an investment casting process.
4. Method according to claim 1 and 2,
characterized in that it comprises the step of removing the object (5, 55) from the through hole (50, 500, 600) formed in the dental prosthesis (12, 120).
5. Method according to claim 2,
characterized in
that the dental material is a glass-ceramic dental material, preferably a lithium disilicate glass ceramic.
6. Method according to any of the above claims,
characterized in
that the replica (2, 20) has an outer shape that resembles that of a tooth.
7. Method according to any of the above claims,
characterized in
that the through hole (50) has a lower portion (50a) and an upper portion (50c), wherein the lower portion (50a) is positioned closer to the lower side (12a, 120a) of the intended dental prosthesis (12, 120), wherein the lower portion (50a) is more narrow than the upper portion (50c), and wherein the through hole (50) is provided with a flange (50b) that connects said portions (50a, 50c).
8. Method according to any of the above claims,
characterized in
that the method comprises the step of providing the replica (2, 20) with a cavity (60, 600) positioned in connection to the through hole (50, 500) and to the lower side (12a, 120a) of the intended dental prosthesis (12, 120), said cavity (60, 600) resembling the shape of a connecting member (6, 66) for connection to the dental implant (9).
9. Method according to claim 8,
characterized in that it comprises the step of placing into the cavity (60, 600) a heat resistant object (6, 55a) having a shape corresponding to that of said cavity (60, 600).
10 Method according to claim 2 and 9,
characterized in
that it comprises the step of fixing the object (6) placed in the cavity (60) to the dental material in the mould, wherein the object (6) is a connecting member for connection to the dental implant (9).
11. Method according to claim 2 and 9,
characterized in
that the heat resistant object (55a) placed into the cavity (600) is removable, wherein the method comprises the step of removing the object (55a) placed into the cavity (600) from the dental prosthesis (120).
12. Method according to claim 11,
characterized in
that it comprises the step of fixing a connecting member to the dental prosthesis (120), wherein the connecting member is an insert fitting (66) having a shape corresponding to the cavity (600).
13. Method according to claim 10 or 12,
characterized in
that the connecting member (6, 66) is ring-shaped.
14. Method according to any of the above claims,
characterized in
that the replica (2, 20) is produced by rapid prototyping, such as three- dimensional printing.
15. Method according to any of the above claims,
characterized in that the replica (2, 20) is produced by automation according to a predefined shape described in a computer-readable form.
16. Method according to any of the above claims,
characterized in
that the replica (2, 20) is made of a plastic or wax material.
17. Method according to any of the above claims,
characterized in
that that the through hole (50, 500) extends in a substantially straight direction from a central position of the upper side (12b, 120b) to a central position of the lower side (12a, 120a) of the intended dental prosthesis (12, 120).
PCT/EP2013/001542 2012-05-24 2013-05-24 Method for manufacturing of a dental product WO2013174524A1 (en)

Applications Claiming Priority (2)

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GB1209151.8 2012-05-24
GB1209151.8A GB2502331A (en) 2012-05-24 2012-05-24 A replica for moulding a dental implant with a through hole

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
US10111734B2 (en) 2013-10-01 2018-10-30 Nobel Biocare Services Ag Dental kit-of-parts and method of assembling the same
KR101913589B1 (en) 2017-06-01 2018-10-31 진순환 A method for manufacturing a laminate prosthesis

Citations (2)

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WO2000000103A1 (en) * 1998-06-30 2000-01-06 Astrazeneca Ab Dental implant component
WO2007111438A1 (en) * 2006-03-25 2007-10-04 Wan Young Jang Dental prosthesis and manufacturing method thereof

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Publication number Priority date Publication date Assignee Title
US2337036A (en) * 1938-10-22 1943-12-21 Dental Res Corp Resilient mold
US20070037127A1 (en) * 2005-08-05 2007-02-15 Den-Mat Corporation Method of forming pressable procelain restoration

Patent Citations (2)

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Publication number Priority date Publication date Assignee Title
WO2000000103A1 (en) * 1998-06-30 2000-01-06 Astrazeneca Ab Dental implant component
WO2007111438A1 (en) * 2006-03-25 2007-10-04 Wan Young Jang Dental prosthesis and manufacturing method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10111734B2 (en) 2013-10-01 2018-10-30 Nobel Biocare Services Ag Dental kit-of-parts and method of assembling the same
KR101913589B1 (en) 2017-06-01 2018-10-31 진순환 A method for manufacturing a laminate prosthesis

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GB2502331A (en) 2013-11-27

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