A method for the manufacture of a prosthesis, a machine milled plastic material intermediate and the prosthesis

Abstract

A method for the manufacture of a prosthesis of individual pre-formed denture prosthesis teeth (14) and of a plastic material for forming a prosthesis base (12) wherein the teeth are embedded in pockets (20) and adhesively bonded, wherein the prosthesis base (12) is made by a CAD / CAM process, characterized in that the method comprises: - a first milling step (MS1), wherein an occlusal side (17) of the prosthesis base (12) is milled down so as to form the pockets (20) therein, wherein the pockets remain closed at their base after the first milling step for the insertion of the teeth; - an insertion step (IS), following the first milling step (MS1), wherein each tooth (14) is inserted, such as manually inserted, and fixed in a distinct pocket (20) for said tooth without prior trimming of said tooth; -a second milling step (MS2), following the insertion step (IS), wherein the basal side (18) of the prosthesis base (12) is subsequently milled down, such as for wear; wherein at least the first and second milling steps (MS1, MS2) occur in an automated milling machine, and wherein in the first milling step (S1) the pockets are milled such that the inner surface of each pocket conforms to the substantially entire contour of the base of a corresponding preformed tooth for receiving said tooth therein.

Description

[0001] A method for the manufacture of a prosthesis, a machine milled plastic material intermediate and the prosthesis

[0002] Field of the Invention

[0003] This invention relates generally to the field of denture prostheses and, more particularly, to methods and systems for producing denture prostheses in which artificial teeth are secured within a prosthetic base.

[0004] Description of Related Art

[0005] For several decades, dental prostheses, including partial and full dentures, have been manufactured by embedding artificial teeth into a gum-simulating base. Conventional methodologies have sought to optimize the placement of prosthetic teeth by considering gnathological principles. In particular, traditional approaches rely on manual positioning, articulator adjustments, and subsequent modifications, such as occlusal grinding, to ensure a suitable fit within a patient ' s oral cavity.

[0006] A variety of techniques exist for fabricating denture prostheses using milling (CAD / CAM) processes to shape the prosthesis base and install artificial teeth. For instance, EP2742907 Bl hereinafter the " Prior Art Reference", discloses a denture prosthesis and manufacturing method wherein through-hole cavities are milled in the denture base to accommodate preformed artificial teeth. The teeth may protrude below the basal surface of the denture base and are subsequently ground or milled flush with the underside. This prior art reference establishes a basis for computer-controlled prosthetic manufacturing and tooth positioning optimization but leaves room for further advancements in precision, efficiency, and adaptability in prosthetic fabrication.While the Prior Art Reference addresses certain challenges in aligning and anchoring prosthetic teeth. However, further improvements are desirable to increase the durability of prostheses and to prevent additional human workmanship postautomated milling or grinding processes to arrive at the final product. Additionally, it has been observed that when milling transitions occur between materials of differing hardness, whether the process is automated or manual, defects can result. The current invention aims to reduce manufacturing complexity, improve accuracy, and increase patient comfort. Thus, there remains a need for a denture prosthesis fabrication method that reduces the amount of post manufacture manual milling or grinding, and which process is less cumbersome for dental technician.

[0007] Summary of Invention

[0008] According to a first aspect of the invention there is provided a method according to claim 1.

[0009] The invention allows itself to be summarized by a method for the manufacture of a prosthesis of individual pre-formed denture prosthesis teeth and of a plastic material for forming a prosthesis base in which the teeth are embedded in pockets and adhesively bonded. The prosthesis base is made of the plastic material by a CAD / CAM process.

[0010] The CAD / CAM process is so well understood by the skilled person, namely a 'Dental Technician', that it needn' t be addressed. It is commonplace for Dental Technicians to be proficient in delivering dental technology with the latest materials and techniques, this includes CAD design, 3d printing and CAM using milling machines. However, for completeness sake the basics of a CAD / CAM process are described herein below.A CAD / CAM process may begin with the acquisition of digital data representing the patient ' s oral anatomy. In a further design stage, computer-aided design (CAD) software may be utilized to create a virtual prosthesis base. Following the design stage, a manufacturing process is carried out using computer-aided manufacturing (CAM). A finalized digital design may be transmitted to a milling machine, which fabricates the prosthetic base from a plastic blank, such as composed of polymethyl methacrylate (PMMA). This summarizes the basics.

[0011] A more detailed CAD / CAM process may see the acquisition of digital data representing the patient ' s oral anatomy achieved either by direct intraoral scanning or by scanning a physical impression to generate a precise digital model. The digital data includes key anatomical parameters such as jaw structure, occlusion, and prosthetic base dimensions, which serve as the foundation for the subsequent design stage.

[0012] In the design stage, computer-aided design (CAD) software may be utilized to create a virtual prosthesis base, and uniblock of teeth and prosthesis base. The digital models are tailored to ensure an optimal fit for the patient' s gums and denture teeth. Adjustments can be made to account for occlusal clearance, retention, and anatomical contours, optimizing both function and comfort. The design may be further refined to maximize milling efficiency and minimize material waste while preserving structural integrity.

[0013] Following the design stage, the manufacturing process is carried out using computer-aided manufacturing (CAM). The finalized digital design is transmitted to a milling machine, which fabricates the prosthetic base from a plastic blank, such as composed of polymethyl methacrylate (PMMA). The milling process may be performed using a high-precision CNC milling machine, such as featuring 4- or 5-axis capabilities. This ensures theaccurate shaping of the prosthesis base, with precise detailing of the basal fit and borders while eliminating excess material.

[0014] The invention sets itself apart from known CAD / CAM processes in the field of dental prostheses in that the method comprises:

[0015] A first milling step. In this step an occlusal side of the prosthesis base is milled down so as to form the pockets. These pockets remain closed at their base after the first milling step for the insertion of the teeth.

[0016] An insertion step, following the first milling step. This step is also called embedding. Here each tooth is inserted and fixed in a distinct pocket for said tooth without prior trimming of said tooth. The distinct pocket in this step too is closed at its bottom.

[0017] A second milling step, following the insertion step, wherein the basal side of the prosthesis base is subsequently milled down - generally for wear by an end user.

[0018] In the new method at least the first and second milling steps occur in an automated milling machine. In the first milling step the pockets are milled such that the inner surface of each pocket, particularly the bottom part of the inner surface, conforms to the contour of the base of a corresponding preformed tooth so as to leave substantially no excess accommodating space, such as for excess adhesive, within said pocket.

[0019] Milling machines are exceedingly accurate these days, with impressive milling resolution. Particularly snug fits are achieved by milling with a machine allowing for a milling resolution in the range of 0.5–0.1 micrometers, such as 0.15 micrometers. Such resolution may be achieved with the imes-icore CORiTEC 350i-series, particularly the Pro Mill. The personskilled in the art will understand that there are also other suitable CNC-machines. This allows for highly accurate milling.

[0020] In one example, the pocket is digitally designed so that the corresponding tooth will fit within said pocket with an average of 10-15 micrometers of spacing from a pocket wall along the circumference of the tooth - e. g. the pocket follows the overall shape of the tooth, but is just 20-30 micrometers larger. This leaves substantially no excess accommodating space upon milling (in the first milling step), and provides for an exceedingly snug fit. Excess accommodating spaces are generally a millimeter sized void that depart from the tooth' s base shape for excess adhesive to move to when an insertion step occurs. This feature may be combined with every other aspect and embodiment of the invention.

[0021] Having substantially no excess accommodating space upon milling traditional adhesives may have undesirable effects, if not used sparingly. Problems may include overflow, which will need to be corrected for in a later milling step, or displace a tooth within its pocket such that it assumes a suboptimal position. Ordinary PMMA acrylic glues tend to be prohibitively viscous. In order to prevent the above issues a self-curing, two-component MMA-based adhesive system may be used, wherein a first component comprises methyl methacrylate (MMA) 70 - 80 wt. %, acrylic polymer based on methyl methacrylate 15 - 25 wt. %, and preferably triethylene glycol dimethacrylate 0.5 - 4 wt. % and dibenzoyl peroxide 0.5 - 2 wt. %; wherein a second component comprises methyl methacrylate 95 – 99,5 wt.% and 0,5 – 5 wt.% N,N-dimethyl-p-toluidine. This is applicable to every embodiment of the invention.

[0022] A two-component system self-hardens when the two components are combined and applied as adhesive.In a preferred embodiment the substantially the entire inner surface of each pocket is provided with a two-component MMA-based adhesive system prior to insertion of a corresponding tooth. This may be done by swabbing the inner surface with a small brush.

[0023] Providing adhesive to the pocket differs from providing the adhesive to the tooth, as this prevents excess adhesive from contaminating the coronal portion of the tooth. It also beneficially allows a tooth to become fixed within the pocket along its lateral circumference, such as the dental cervix -also known as the neck of the tooth. This further beneficially allows a tooth to remain fixed regardless of whether a second milling step effects the pocket or not.

[0024] Wherever the two-component MMA-based adhesive system is mentioned an alternative adhesives may be used, such as an MMA-based adhesives with a low viscosity of 1 – 5000 mPa·s at 20°C before mixing - such as when the adhesive is a two-component adhesive system - or curing. It is pointed out that conventional MMA or PMMA based adhesives with a high viscosity o 10,000 – 100,000 mPa·s at 20°C are not suitable to obtain the desired beneficial effect. For two-component MMA-based adhesive systems viscosity the viscosity as mentioned above is an upper limit for the more viscous component prior to mixing.

[0025] Very satisfactory results were achieved for MMA-based adhesives systems such as the two-component VITA VIONIC® BOND:

[0026] https: / / web.archive.org / web / 20241108025206 / https: / / www.vita-zahnfabrik.com / en / Removable-prosthetics / Digital-prosthetics / VITA-VIONIC-BOND-48155,27568.htmlThe person skilled in the art may understand "conforms" in the context of this application as "to give the same shape, outline, and contour to." By conforming the pockets such that the corresponding preformed teeth fit snugly into the pockets, they may be appropriately fitted and embedded to ensure they are constrained.

[0027] The insertion step is optionally performed manually. Removal may even be preferred for the sake of preventing particulate contamination from remaining in the pockets prior to inserting the teeth. Accordingly, the insertion step may comprise the removal of the prosthesis base from the milling machine for cleaning after which each tooth is inserted and fixed in its distinct pocket.

[0028] The removal of the prosthesis base yield complications when it comes to manufacturing. As such, the milling steps are preferably performed using an automated milling machine, such as an imes-icore CORiTEC 350i Pro Mill, using a zero-point clamping system for holding the prosthesis base in a removable support structure. This beneficially allows for the intermediate removal and return of the support structure along with the prosthesis base for a manual execution of the insertion step. The machine may subsequently return to its second milling step without aberrant milling behavior, due to any offsets that might otherwise have been introduced in the positioning of the support structure and in turn the prosthesis base. Any deviation in positioning may lead to discrepancies in the alignment between the basal side and the jaw structure, potentially causing misalignment of the jaw, which may subsequently result in physical discomfort or pain.

[0029] The prosthesis base may be milled from a monolithic polymer object, such as comprising PMMA. A disc shaped object is most suitable for the current application. The zero-point clampingsystem as used by the invention will comprise a reversibly removable support structure with which the polymer object can be assembled for the first and second milling steps, and with which it will remain assembled during the intermediate insertion step.

[0030] A computer is associated with the automated milling machine, and the method comprising a computer implemented method step in which the inner surface of each pocket is calculated and defined for the first milling step in the CAD / CAM process by said computer:

[0031] - calculating a virtual material buffer volume around a base of a corresponding tooth;

[0032] - forming a virtual combination volume from the virtual buffer volume and a virtual model of the prosthesis base;

[0033] - and subtracting a virtual volume of the corresponding tooth from the combination volume for forming a first virtual model for the first milling step.

[0034] This not only creates the pocket within the CAD model but also serves as the foundation for the CAM model to establish the starting and stopping points for milling during the initial milling step.

[0035] The second milling step may comprise trimming the base end of only those teeth of which the virtual buffer volume extends beyond the virtual model of the prosthesis base. This is very rarely the case. The extent to which the basal end of the teeth is trimmed is determined by the shape of the reference for the prosthesis base, which varies depending on the specific reference jaw provided by the end user. Advantageously, since this step is not restricted to manual trimming alone, is achieved in shaping the teeth. As a result, the teeth are better adapted to fit the prosthesis base, which in turn improves the overall fit of the prosthesis within the end user ' s jaw, in turn, providing a greater comfort for the end user.The computer implemented method step is mediated by a series of predefined program settings, such as provided within an preprogrammed XML file, and such a XML file is user selectable within a CAD environment on said computer. An XML file in a CAD / CAM process provides a standardized, machine-readable format that enables efficient data exchange between design and manufacturing systems. It ensures consistency and automation by structuring design parameters for direct processing in computer-aided fabrication. The XML file in this context may be added manually, or may be provided automatically in the CAD / CAM environment. In essence, the XML file provides the instructions that enable the separation of the method for forming the prosthesis, into the separate first milling step, the insertion step and the second milling step.

[0036] A second virtual (uniblock) model may be formed for the second milling step by merging a virtual model of the teeth and a virtual model of the prosthesis base. In the context of CNC milling for dental prostheses, a uniblock refers to a single, continuous block of material that is treated as an integrated unit during the machining process. By merging the virtual model of the teeth with the virtual model of the prosthesis base, the CNC machine processes the base as an unified uniblock model, ensuring that all features are milled with precise alignment. This approach guarantees that the basal side is milled to the appropriate depth, such that an accurate fit of the prosthesis onto the reference jaw of the end user is achieved.

[0037] The method may comprises a third milling step (S3) following the second milling step (S2), such as without intermediate removal from the milling machine, wherein the occlusal side of the prosthesis with teeth is retraced by a milling tool, such as a 0, 6 mm milling bit, in which a corresponding milling toolpath exclusively follows an exact final surface, with negligible stock allowance. After the second milling step, misalignment ofthe occlusion may occur, potentially causing discomfort for the end user. To address this, the method comprises a third milling step following a tracing step, during which measurements are taken to ensure that the teeth have the correct length and do not protrude excessively. The method may therefore exclude a roughing (oversized) milling of the teeth.

[0038] A person skilled in the art will understand that negligible stock allowance pertains to removing a negligible amount of material (often in the range of microns or a few thousandths of an inch) is left for a final pass of a milling tool to achieve precise dimensions and surface finish. This particular step as applied to the preformed teeth is performed without any prior rough milling of the occlusal side of the teeth. The entire method of the invention in fact may very well omit any rough milling of the occlusal side of the teeth at all, also separate of this specific option. A synergistic effect is achieved when

[0039] The teeth may be selected from a digital library. This approach enables the selection of suitable teeth based on the reference teeth of the end user, ensuring an accurate replication that is crucial for user comfort.

[0040] The prosthesis base may be formed entirely from a material disk, preferably an acrylic polymer disc. The use of such a disc may allow for efficient machining using CAD / CAM technigues, enabling precise shaping and adaptation to the patient' s oral structure. The polymer material may ensure strong adhesive bonding with the embedded teeth, and may enhance the overall stability of the prosthesis. The acrylic polymer disc may further allow for customized basal milling of prefabricated teeth, which may ensure optimal occlusal alignment and reduce the need for manual adjustments. Additionally, the material may be color-matched to simulate natural gum tissue, improving the aesthetic appearance of the prosthesis.The first milling step and second milling step may each comprise the sequential use of milling tools with decreasing diameters to achieve a progressively finer machining process. The sequential use of milling tools with decreasing diameters may allow for a progressively refined machining process, enabling more precise shaping of the prosthesis base and embedded teeth. By initially removing material with larger tools, efficient machining may be achieved while maintaining structural integrity. Subsequent milling with smaller tools may provide finer detail and improved surface quality, reducing the need for additional finishing. Furthermore, this may minimize mechanical stress on the material, thereby reducing the risk of fractures and ensuring a high level of precision in the final prosthesis.

[0041] In an exemplary embodiment the prosthesis is at least a partial denture comprising at least one tooth. Where the invention discusses teeth, it can be understood that this does not intend to convey a plural by definition, but may pertain to a prosthesis in which only one tooth is present. Teeth may, for the purpose of claim 1-3 refer to at least one tooth, and for claim 4 "those teeth" may refer to the at least one tooth in particular.

[0042] As a result of the first milling step or the embedding step, an intermediate piece may be formed. This is referred to as a machine milled plastic material intermediate prosthesis base fabricated by a CAD / CAM process. After the embedding step, the base is provided with individual pre-formed teeth embedded and adhesively bonded in individual corresponding pockets comprised in the occlusal side of the prosthesis base. Only the occlusal side of the intermediate prosthesis base is formed, namely by means of a milling machine, and the pockets may be closed at their base, and each pocket conforms to the contour of substantially the entire embedded part of an untrimmed base of a corresponding preformed tooth. Keeping the pockets closed is a deliberate choice in this method, as the milling of a occlusalside and the milling a basal side of the prosthesis are kept as separate actions of separate method steps.

[0043] As a result of the second milling step, the plastic material of the base may be milled from a polymer disc such that the disk forms a collar. The plastic material of the base is monolithic with the collar through remaining supports, and the disk itself is assembled with a reversibly removable support structure of a zero-point clamping system, so that the intermediate prosthesis base is able to be returned to the milling machine for milling the basal side of the intermediate prosthesis base so as to form a prosthesis. This in essence, comprises the same effect as previously discussed, keeping the milling of the occlusal side and the milling the basal side of the prosthesis separate actions of separate method steps.

[0044] For the sake of clarity, the definition of a "zero-point clamping system" will be explained. A "zero-clamping system" (also known as "zero-point clamping system") may allow for precise and repeatable positioning of the prosthesis base during machining, ensuring accurate alignment throughout the manufacturing process. In other words, the intermediate prosthesis base may be removed from the CNC-machine after the first milling step, the embedding step may be executed, and the intermediate prosthesis base may be returned to the CNC-machine, and due to the zero-clamping system, the intermediate prosthesis base will be returned to the exact same position so that that CNC machine starts at exactly the same position, and no inaccuracy occurs due to a misalignment of the position of the prosthesis base at the first milling step with reference to the position of the prosthesis base at the second milling step.

[0045] The final product as a result of the second milling step comprises a prosthesis of individual pre-formed denture prosthesis teeth and of a plastic material for forming aprosthesis base fabricated by means of the method described in the description above.

[0046] The accompanying drawings illustrate the present invention and, together with the description, serves to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more embodiments of the invention and is not to be construed as limiting the invention.

[0047] The invention is hereinafter described using the following drawings:

[0048] - figure la displays a side perspective of a reference teeth and reference base for said teeth;

[0049] - figure lb displays a side perspective of a prosthesis of an individual pre-formed denture prosthesis tooth and a prosthesis base wherein the tooth us embedded in a pocket; - figures 2a, 2b and 2c respectively display a side perspective of the prosthesis base as a result of the first milling step, the insertion step and the second milling step;

[0050] - figures 3a and 3b respectively display a side perspective of the prosthesis base with the prosthetic teeth before the third milling step and the prosthetic teeth corrected as a result of a third milling step.

[0051] Whenever in the figures the same reference numerals are applied, these numerals refer to the same parts.

[0052] With reference to Figures la, a side perspective of a reference tooth is displayed with a reference base for said teeth of an end-user. Figure lb displays a side perspective of a prosthesis of individual pre-formed denture prosthesis teeth 14 and of a plastic material for forming a prosthesis base 12 wherein the teeth are embedded in pockets 20 and adhesively bonded, wherein the prosthesis base 12 is made by a CAD / CAM process.Figures 2a, 2b and 2c respectively display the individual steps of the method comprising a first milling step, an insertion step and a second milling step. With reference to figure 2a, the first milling step MSI is shown, wherein an occlusal side 17 of the prosthesis base 12 is milled down so as to form the pockets 20 therein, wherein the pockets remain closed at their base after the first milling step for the insertion of the teeth.

[0053] With reference to figure 2b, the insertion step IS is shown, following the first milling step (MS1), wherein each tooth 14 is inserted, such as manually inserted, and fixed in a distinct pocket 20 for said tooth without prior trimming of said tooth. With reference to figure 2c, the second milling step (MS2) is shown, following the insertion step IS, wherein the basal side 18 of the prosthesis base 12 is subsequently milled down, such as for wear. It should be noted that this figure displays a case wherein the teeth is trimmed.

[0054] At least the first and second milling steps MSI, MS2 occur in an automated milling machine. If present, a third milling step will also occur therein. However, a third milling step is not strictly necessary. In the first milling step SI the pockets are milled such that the inner surface of each pocket conforms to the substantially entire contour of the base of a corresponding preformed tooth for receiving said tooth therein.

[0055] Optionally, at least the first (as shown in figure 2a) and second (as shown in figure 2c) milling steps MSI, MS2 occur in a singular automated milling machine, such as an imes-icore CORiTEC 350i Pro Mill, using a zero-point clamping system for holding the prosthesis base 12 in a removable support structure, so as to allow for the intermediate removal and return of the support structure along with the prosthesis base 12 for an, optionally manual, execution of the insertion step IS. The thirdmilling step MS3 will also occur in the same automated milling machine, if present.

[0056] In this embodiment, a computer is associated with the automated milling machine, the method comprising a computer implemented method step in which the inner surface of each pocket is calculated and defined for the first milling step in the CAD / CAM process by said computer:

[0057] - calculating a virtual material buffer volume around a base of a corresponding tooth;

[0058] - forming a virtual combination volume from the virtual buffer volume and a virtual model of the prosthesis base; and

[0059] - subtracting a virtual volume of the corresponding tooth from the combination volume for forming a first virtual model for the first milling step.

[0060] The second milling step MS2 comprises trimming the base end of only those teeth which virtual buffer volume extends beyond the virtual model of the prosthesis base.

[0061] The computer implemented method step is mediated by a series of predefined program settings, such as provided within a preprogrammed XML file, and wherein such XML file is user selectable within a CAD environment on said computer.

[0062] A second virtual (uniblock) model is formed for the second milling step by merging a virtual model of the teeth and a virtual model of the prosthesis base.

[0063] With reference to figures 3a and 3b, a third milling step (S3) following the second milling step S2 is shown, such as without intermediate removal from the milling machine, wherein the occlusal side of the prosthesis with teeth is retraced by a milling tool, such as a 0, 6 mm milling bit, in which a corresponding milling toolpath exclusively follows an exactfinal surface, with negligible stock allowance. Figure 3a displays the prosthetic teeth before application of the third milling step MS3 and figure 3b displays the prosthetic teeth after the application of the third milling step MS3.

[0064] In this example, the method excludes a roughing (oversized) milling of the teeth.

[0065] The teeth are selected from a digital library.

[0066] The prosthesis base 12 is formed entirely from a material disk, preferably an acrylic polymer disc.

[0067] The first milling step MSI and second milling step MS2 each comprise the sequential use of milling tools with decreasing diameters to achieve a progressively finer machining process. The first, and optionally also milling step, comprises three milling steps terminating at a drill diameter of 1, 2 mm; whereas the third milling step retraces the uniblock with a drill having a 0, 6 mm diameter.

[0068] According to a second aspect of the invention and with reference to figures 2a, 2b and 2c, a machine milled plastic material intermediate 100 prosthesis base fabricated by a CAD / CAM process is provided, wherein the base is provided with individual preformed teeth 14 embedded and adhesively bonded in individual corresponding pockets comprised in the occlusal side of the prosthesis base, wherein only the occlusal side of the intermediate 100 prosthesis base is formed, namely by means of a milling machine, and wherein the pockets are closed at their base, and wherein each pocket follows the contour of substantially the entire embedded part of an untrimmed base of a corresponding preformed tooth.According to any embodiment of the second aspect of the invention, and with reference to figures 2a, 2b and 2c, the intermediate prosthesis base is provided, wherein the plastic material of the base is milled from a polymer disc such that the disk forms a collar, wherein the plastic material of the base is monolithic with the collar through remaining supports, and wherein the disk itself is assembled with a reversibly removable support structure of a zero-point clamping system, so that the intermediate prosthesis base is able to be returned to the milling machine for milling the a basal side of the intermediate 100 prosthesis base so as to form a prosthesis.

[0069] According to a third aspect of the invention, a prosthesis of individual pre-formed denture prosthesis teeth 14 and of a plastic material for forming a prosthesis base 12 fabricated by means of the method described in the first aspect of the invention is provided. This may be a partial denture or a full denture.

[0070] Although the invention has been discussed in the foregoing with reference to an exemplary embodiment of the invention, the invention is not restricted to this particular embodiment which can be varied in many ways without departing from the invention. The discussed exemplary embodiment shall therefore not be used to construe the appended claims strictly in accordance therewith. On the contrary the embodiment is merely intended to explain the wording of the appended claims without intent to limit the claim to this exemplary embodiment. The scope of protection of the invention shall therefore be construed in accordance with the appended claims only, wherein a possible ambiguity in the wording of the claims shall be resolved using this exemplary embodiment.

[0071] Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to coverin the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above are hereby incorporated by reference. Unless specifically stated as being "essential" above, none of the various components or the interrelationship thereof are essential to the operation of the invention. Rather, desirable results can be achieved by substituting various components and / or reconfiguration of their relationships with one another.

Claims

CLAIMS1. A method for the manufacture of a prosthesis of individual pre-formed denture prosthesis teeth (14) and of a plastic material for forming a prosthesis base (12 ) wherein the teeth are embedded in pockets (20) and adhesively bonded, wherein the prosthesis base (12) is made by a CAD / CAM process,characterized in that the method comprises:- a first milling step (MS1), wherein an occlusal side (17) of the prosthesis base (12) is milled down so as to form the pockets (20) therein, wherein the pockets remain closed at their base after the first milling step for the insertion of the teeth; - an insertion step (IS), following the first milling step (MS1), wherein each tooth (14) is inserted, such as manually inserted, and fixed in a distinct pocket (20) for said tooth without prior trimming of said tooth;- a second milling step (MS2), following the insertion step (IS), wherein the basal side (18) of the prosthesis base (12) is subsequently milled down, such as for wear;wherein at least the first and second milling steps (MSI, MS2) occur in an automated milling machine, and wherein in the first milling step (SI) the pockets are milled such that the inner surface of each pocket, particularly the bottom part of the inner surface, conforms to the contour of the base of a corresponding preformed tooth so as to leave substantially no excess accommodating space, such as for excess adhesive, within said pocket.

2. The method according to claim 1, wherein at least the first and second milling steps (MSI, MS2, MS3) occur in a singular automated milling machine using a zero-point clamping system for holding the prosthesis base in a removable support structure, so as to allow for the intermediate removal and return of the support structure along with the prosthesis base for an, optionally manual, execution of the insertion step (IS).

3. The method according to claim 1 or 2, wherein a computer is associated with the automated milling machine, the method comprising a computer implemented method step in which the inner surface of each pocket is calculated and defined for the first milling step in the CAD / CAM process by said computer: - calculating a virtual material buffer volume around a base of a corresponding tooth;- forming a virtual combination volume from the virtual buffer volume and a virtual model of the prosthesis base; and- subtracting a virtual volume of the corresponding tooth from the combination volume for forming a first virtual model for the first milling step.

4. The method according to claim 3, wherein the second milling step comprises trimming the base end of only those teeth of which the virtual buffer volume extends beyond the virtual model of the prosthesis base.

5. The method according to claim 3 or 4, wherein the computer implemented method step is mediated by a series of predefined program settings, such as provided within an preprogrammed XML file, and wherein such XML file is user selectable within a CAD environment on said computer.

6. The method according to any of claims 3-5, wherein a second virtual (uniblock) model is formed for the second milling step by merging a virtual model of the teeth and a virtual model of the prosthesis base.

7. The method according to claim 6, comprising a third milling step (S3) following the second milling step (S2 ), such as without intermediate removal from the milling machine, wherein the occlusal side of the prosthesis with teeth is retraced by a milling tool, such as a 0, 6 mm milling bit, inwhich a corresponding milling toolpath exclusively follows an exact final surface, with negligible stock allowance.

8. The method according to any one of claims 1-7, wherein the method excludes a roughing (oversized) milling of the teeth.

9. The method according to any one of claims 1-8, wherein the teeth are selected from a digital library.

10. The method according to any one of claims 1-9, wherein the prosthesis base (12) is formed entirely from a material disk, preferably an acrylic polymer disc.

11. The method according to any one of claims 1-10, wherein the first milling step (MS1) and second milling step each comprise the sequential use of milling tools with decreasing diameters to achieve a progressively finer machining process.

12. The method according to any one of claims 1-11, wherein the prosthesis is at least a partial denture.

13. A machine milled plastic material intermediate (100) prosthesis base fabricated by a CAD / CAM process, wherein the base is provided with individual pre-formed teeth (14) embedded and adhesively bonded in individual corresponding pockets comprised in the occlusal side of the prosthesis base, wherein only the occlusal side of the intermediate (100) prosthesis base is formed, namely by means of a milling machine, and wherein the pockets are closed at their base, and wherein each pocket conforms to the contour of substantially the entire embedded part of an untrimmed base of a corresponding preformed tooth.

14. The intermediate prosthesis base according to claim 13, wherein the plastic material of the base is milled from a polymer disc such that the disk forms a collar, wherein the plastic material of the base is monolithic with the collar through remaining supports, and wherein the disk itself is assembled with a reversibly removable support structure of a zero-point clamping system, so that the intermediate prosthesis base is able to be returned to the milling machine for milling the a basal side of the intermediate (100) prosthesis base so as to form a prosthesis.

15. A prosthesis of individual pre-formed denture prosthesis teeth (14) and of a plastic material for forming a prosthesis base (12 ) fabricated by means of the method according to any one of claims 1-12.

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