Protocol for staged milling type computer aided manufacturing of surgical prosthetics

Abstract

A protocol for milling type computer aided manufacturing (CAM) of prosthetics, includes generating a semi-finished prosthetic and a boundary layer surrounding the semi-finished prosthetic in a puck of material forming the prosthetic, wherein supports extend from the boundary layer to the semi-finished prosthetic, wherein the semi-finished prosthetic has at least 5% by time of milling to be completed; generating a finished model of the prosthetic with a model of the boundary layer and overlying this with a model of the semifinished prosthetic and the model of a boundary layer surrounding the semi-finished model; generating an final milling profile for forming the prosthetic; and milling the final prosthetic in a final stage milling operation.

Description

PROTOCOL FOR STAGED MILLING TYPE COMPUTER AIDED MANUFACTURING OF SURGICAL PROSTHETICSBACKGROUND OF THE INVENTION

[0001] 1. FIELD OF THE INVENTION

[0002] The inventors developed this technology which generally relates to a protocol for staged milling type computer aided manufacturing (CAM) of surgical prosthetics, particularly oral prosthetics.

[0003] 2. BACKGROUND INFORMATION

[0004] A prosthetic within the meaning of this application is an artificial manmade device that replaces a missing body part (generally human body part), which may be lost through trauma, disease, or a condition present at birth such as a congenital disorder. A surgical prosthetic within the meaning of this application is a prosthetic that is installed or positioned by a clinician in a medical procedure. A prosthetic field within the meaning of this application is the area within the body, including related or adjacent tissue within which a prosthetic fits and operates, analogous, roughly, to an operative field in surgery. Prostheses are intended to restore the normal functions of the missing body part to the greatest extent possible. The present invention is described in connection with oral prosthetics, but can have broader application to fitting of any prosthetics associated with surgically altered physiologic parameters.

[0005] An oral prosthetic, also called a dental prosthetic or dental prosthesis, is an intraoral prosthetic used to restore / reconstruct intraoral defects, such as missing teeth, missing parts of teeth, and missing soft or hard structures of the jaw or palate and is considered herein as a subset of surgical prosthetics. The prosthetic field for oral prosthetics is the oral cavity and associated body structures. Prosthodontics is the dental specialty that focuses on dental prostheses. Such prostheses are used to rehabilitate mastication (chewing), improve aesthetics, and aid speech.

[0006] An oral prosthetic may be held in place by connecting to teeth, or via dental implants, by suction, or by being held passively by surrounding muscles. Like other types of prostheses, they can either be fixed permanently or removable. Fixed prosthodontics (permanent oral prosthetic) and removable oral prosthetic (such asdentures) are made in many variations. Permanently fixed oral prosthetic or dental prostheses typically use dental adhesive or screws, to attach to teeth or dental implants. Removable oral prosthetic or dental prostheses may use friction against parallel hard surfaces and undercuts of adjacent teeth or dental implants, suction using the mucous retention (with or without aid from denture adhesives), and by exploiting the surrounding muscles and anatomical contours of the jaw to passively hold in place.

[0007] Dentures (also known as false teeth) are a common oral prosthetic constructed to replace missing teeth, and are supported by the surrounding soft and hard tissues of the oral cavity. Conventional dentures are removable (removable partial denture or complete denture). However, there are many denture designs, some which rely on bonding or clasping onto teeth or dental implants (fixed prosthodontics). There are two main categories of dentures, the distinction being whether they are used to replace missing teeth on the mandibular arch or on the maxillary arch.

[0008] Dentures (also known as false teeth) are a common oral prosthetic constructed to replace missing teeth, and are supported by the surrounding soft and hard tissues of the oral cavity. Conventional dentures are removable (removable partial denture or complete denture). However, there are many denture designs, some which rely on bonding or clasping onto teeth or dental implants (fixed prosthodontics). There are two main categories of dentures, the distinction being whether they are used to replace missing teeth on the mandibular arch or alternatively on the maxillary arch.

[0009] Oral prosthetics have a long history, as early as the 7th century BC, Etruscans made partial dentures out of human or other animal teeth fastened together with gold bands. Wooden full dentures were invented in Japan around the early 16th century. In 1728, Pierre Fauchard proposed dentures using a metal frame and teeth sculpted from animal bone. The first porcelain dentures were made around 1770 (attributed to Alexis Duchateau). In 1791 , the first British patent was granted to Nicholas Dubois De Chemant, who was a previous assistant to Duchateau, for an artificial teeth forming composition, and also springs for fastening or affixing the same “which said teeth may be made of any shade or colour, which they will retain for any length of time and will consequently more perfectly resemble the natural teeth.” In 1820, Samuel Stockton, a goldsmith by trade, began manufacturing high-quality porcelain dentures mounted on 18-carat gold plates. Later dentures (from about the 1850s) were made of Vulcanite, a form of hardened rubber into which porcelain teeth were set. In the 20th century, acrylic resin and other plastics were used.

[0010] The present invention relates to the field known as CAD / CAM dentistry. CAD / CAM dentistry is a field of dentistry and prosthodontics using CAD / CAM (computer - aided - design and computer-aided-manufacturing) to improve the design and creation of dental restorations. See Davidowitz G, Kotick PG. (2011 ), "The use of CAD / CAM in dentistry", Dent Clin North Am, 55 (3): 559-570; and Rekow D (1987), "Computer-aided design and manufacturing in dentistry: a review of the state of the art", J Prosthet Dent, 58 (4): 512-516.

[0011] CAD / CAM dentistry is commonly used for forming dental prostheses, including crowns, crown lays, veneers, inlays and onlays, fixed dental prostheses bridges, dental implant supported restorations, dentures (removable or fixed), and orthodontic appliances. CAD / CAM technology allows the delivery of a well-fitting, aesthetic, and a durable prostheses for the patient. See Oen, Kay T; Veitz-Keenan, Analia; Spivakovsky, Silvia; Wong, Y Jo; Bakarman, Eman; Yip, Julie (April 9, 2014). "CAD / CAM versus traditional indirect methods in the fabrication of inlays, onlays, and crowns". Cochrane Database of Systematic Reviews. Computer-aided design (CAD) and computer-aided manufacture (CAM) is a process where non-digital data is captured, converted into a digital format, edited as necessary, and subsequently converted back into a physical form with the exact dimensions and materials specified during the digital design process. This set of stages is known as a “digital workflow

[0012] CAD / CAM dentistry uses subtractive processes (such as CNC milling) and additive processes (such as 3D printing) to produce physical oral prosthetics from 3D models. Some mentions of "CAD / CAM" and "milling technology" in dental technology have loosely treated those two terms as if they were interchangeable, largely because before the 2010s they mostly were, as, at the time, most CAD / CAM-directed manufacturing was CNC cutting, not additive manufacturing. Whereas, this loose / imprecise usage was once somewhat close to accurate, it no longer is, as the term "CAD / CAM" does not specify the method of production except that whatever method is used takes input from CAD / CAM, and today additive and subtractive methods are bothwidely used. The present invention is primarily directed to the subtractive or milling type computer aided manufacturing (CAM) of surgical prosthetics, particularly oral prosthetics.

[0013] CAD / CAM complements earlier technologies used for these purposes by any combination of increasing the speed of design and creation; increasing the convenience or simplicity of the design, creation, and insertion processes; and making possible restorations and appliances that otherwise would have been infeasible. Other goals include reducing unit cost and making affordable restorations and appliances that otherwise would have been prohibitively expensive. However, to date, chairside CAD / CAM often involves extra time on the part of the dentist, and the fee is often at least two times higher than for conventional restorative treatments using lab services.

[0014] There is a need to improve CAD / CAM manufacture of medical prosthetics, particularly dental prosthetics, in an effective and cost efficient manner.SUMMARY OF THE INVENTION

[0015] One aspect of the present invention provides a protocol for milling type computer aided manufacturing (CAM) of prosthetics, includes generating a semi-finished prosthetic and a boundary layer surrounding the semi-finished prosthetic in a puck of material forming the prosthetic, wherein supports extend from the boundary layer to the semifinished prosthetic, wherein the semi-finished prosthetic has at least 5% by time of milling to be completed; generating a finished model of the prosthetic with a model of the boundary layer and overlying this with a model of the semi-finished prosthetic and the model of a boundary layer surrounding the semi-finished model; generating an final milling profile for forming the prosthetic; and milling the final prosthetic in a final stage milling operation.

[0016] One aspect of the invention provides a puck having at least one semi-finished prosthetic contained therein and a boundary layer surrounding the semi-finished prosthetic in a puck of material forming the prosthetic, wherein supports extend from the boundary layer to the semi-finished prosthetic, wherein the semi-finished prosthetic has at least 5% by time of milling to be completed, and wherein the puck is configured for registration with a mill. The puck having at least one semi-finished prosthetic accordingto the invention may provide wherein puck has a plurality of semi-finished prosthetics each of which being an oral prosthetic.

[0017] One aspect of the invention provides a protocol for staged milling type computer aided manufacturing (CAM) of prosthetics including generating a semi-finished model of a prosthetic and a model of a boundary layer surrounding the semi-finished model, wherein the semi-finished model is a model of a semi-finished prosthetic which has at least of majority, by time, of the prosthetic milled with at least 5% by time of milling to be completed; positioning the semi-finished model of a prosthetic and a model of a boundary layer surrounding the semi-finished model onto a puck of material forming the prosthetic; generating an initial milling profile for forming the semi-finished prosthetic, wherein volume of the puck inside of the boundary layer represents material to be removed in the initial milling except for the semi-finished prosthetic and supports extending between the boundary layer and the semi-finished prosthetic; milling the semi-finished prosthetic within the puck in a first stage milling operation, and pausing the milling process before the final prosthetic is milled; generating a finished model of the prosthetic with the model of the boundary layer and overlying this with semi-finished model of a prosthetic and the model of a boundary layer surrounding the semi-finished model; generating an final milling profile for forming the prosthetic; and milling the final prosthetic in a second stage milling operation.

[0018] These and other advantages of the present invention will be clarified in the description of the invention takes together with the attached figures in which similar reference numerals represent similar elements throughout.BRIEF DESCRIPTION OF THE FIGURES

[0019] Figure 1 is a schematic representation of puck having a plurality of separate partially machined prosthetics in accordance with the present invention.

[0020] Figure 2 is a representation of puck having eleven separate partially machined prosthetics being orientated within a CNC machine for final processing in accordance with the present invention.

[0021] Figures 3A and 3B schematically illustrate the placing and orientating of a CAD model of a prosthesis virtually within a puck for the initial manufacturing in accordance with the present invention.

[0022] Figure 4A and 4B is a schematic representation of puck having the partially machined prosthetic from the model of figures 3A and 3B ready for final processing in accordance with the present invention.

[0023] Figure 5A is a schematic representation of a model of the puck having the partially machined prosthetic of figures 4A and 4B together with an unaligned CAD model of a prosthesis for the final manufacturing in accordance with the present invention.

[0024] Figure 5B is a schematic representation of a model of the puck having the partially machined prosthetic of figures 4A and 4B together with an aligned CAD model of a prosthesis for the final manufacturing in accordance with the present invention.

[0025] Figure 6 is a schematic representation of a final oral prosthesis formed in accordance with the present invention.BRIEF DESCRIPTION OF THE INVENTION

[0026] The present invention is directed to a protocol for staged milling type computer aided manufacturing (CAM) of prosthetics, typically surgical prosthetics, and particularly oral prosthetics 30. As noted above, currently there are many CAM systems on the dental market using software and computer-controlled machinery to automate a manufacturing process. The CAM process may be considered the brains of the operation for milling. The “CAM” is the software that calculates the geometry data, positional data in a coordinate system of an object to be milled, in this situation a crown or any dental appliance / prosthesis.

[0027] The CAM process generates instructions or G-code which controls the milling such as communication to the milling tool the mill position, spindle speed (turning of the cutting tool), and feed rate (speed of travel of the milling spindle which equates to the spindle speed for cutting).

[0028] The basic process after a patient’s crown 30 is designed in CAD (i.e. a 3d model is made) is to have the design or model forwarded to the CAM software. The CAM software optimized the position of the model of the crown 30 within a puck 20. A puck 20is a solid block (often shaped like a hockey puck giving it its name) of material forming the crown 30. Once the model of the crown is optimally positioned, then the calculations then begin such as the calculations of the tool rotation, position (height), and trajectory of the cutting tool within the puck, etc. The CAM software tells the mill 60 (calculates), which material (hard or soft) of the puck 20 is being worked upon by the tool 50 of the mill 60, where to be, how fast the spindle of the tool 50 is rotating, how fast to move, how large the crown 30 is and its position in the puck 20. The file is then transferred and the mill 60 begins the process of manufacturing the crown 30 in the specified material of the puck 20.

[0029] Currently the milling process in the mill 60 is a single manufacturing step, the whole process from beginning to end is completed on a single mill 60. It is important to recognize that dental milling currently is a mass production customization (MPC). Every single object or dental prosthetic 30 from dentures, partials, crowns, bridges, attachments, full reconstructions, implant abutments, veneers to night guards and other restorations are unique and never exactly the same. This MPC process is somewhat unique to dental and differs to other manufacturing in that other systems do a run of numerous identical parts. Consider engine manufacturing, as an example, once the mill and the object is defined the mill will run every part exactly the same, regardless of whether it runs 100 or 1 ,000 or 1 ,000,000 pieces. Once the original part is designed, there are no more calculation as it has already been defined. In dental prosthetics, and medical prosthetics as well, implemented to date there is no “run” of multiple parts as every prosthetic 30 has to be calculated separately.

[0030] The present invention provides staged milling type computer aided manufacturing (CAM) of surgical prosthetics, particularly oral prosthetics 30. Namely, a loosely finished or rough prosthetic 10 is first manufactured in a first milling on a mill 60 and it is finished in a separate staged milling operation on a mill 60 (which may be and preferably is a separate mill 60) after final calculations are completed. This process allows for a gain of significant manufacturing times at the dental office. The process allows milling to happen at one location with a particular mill 60 (part milled to 90% complete - often by prosthetic manufacturer) and then sent to another mill to be completed in the dental office.

[0031] The staged milling type computer aided manufacturing (CAM) of surgical prosthetics, particularly oral prosthetics 30 according to the present invention allows for the doctor’s office to obtain final surgical positional data live in office. In other words, after some initial healing of the patient is allowed to occur the doctor can obtain more precise final data for the finish milling of the prosthetic 30 in the present invention which is accomplished on a second mill 60, preferably one that is on site. Historically there has been no need to recalculate a part mid-production. Even in custom fabrication it is uncommon, but in medical prosthetics it is not uncommon to place attachment points in a first surgical procedure and allow this to heal before coming back with the attachment (32) of the final prosthetic 30. The present invention allows final attachment or other measurements to be taken on site after healing with only minor final machining to finish the prosthetic.

[0032] The staged milling type computer aided manufacturing (CAM) of surgical prosthetics, particularly oral prosthetics 30 according to the present invention allows the CAM to mill the initial CAD design “part” to at least 50%, preferably at least 75% and most preferably about 90% then pause, then later receive the new CAD data. As detailed below, the present invention then must match or correlate the new live data to the initial data, calculate the new custom live data in the exact coordinate of the initial data and mill in a secondary machine understanding its “home coordinate”. The present invention may be accomplished on the same mill 90 for phases one and two, but in practice it is preferred that the final mill 60 will be on-site at the medical professional (e.g., dentists office) while the initial machining mill 60 will be accomplished at a prosthetic manufacturer.

[0033] The process begins in a conventional fashion and that is creating an initial 3D model of the prosthetic 30 in software. The initial model of the prosthetic is used to create a model 11 of a semi-finished prosthesis 10 formed after partially milling the prosthesis from a puck 20 to a predetermined amount, wherein the protocol of the present invention intends to have a majority of this milling occur on the first mill 60 (i.e. at least 50%), preferably at least 75%, and economically about 90% (meaning at least 90%+ / - 5%) on the first mill 60. Figures 3A and 3B schematically illustrate the placing and orientating of a CAD model 1 1 of a prosthesis 30 virtually within a puck 20 for the initial manufacturing. The model 11 (i.e. model 1 1 of a semi-finished prosthesis 10) includes amodel 13 of the boundary layer 12 and a model 23 of the supports 22 of the puck 20 containing the semi-finished prosthetic 30.

[0034] The first stage milling on an initial mill 60 is described herein as being performed about 90% on a first mill 60 (meaning about 90%+ / - 5% on the first mill 60) (or at least 75% or at least 50%). This percentage is referencing the amount of total time it would take to mill the final prosthetic 30 from start to finish in a single stage on the first mill 60 (based upon the initial design that does not include final updated parameters but the total milling time would not expect to change in this calculation). In practice the initial mill 60 utilized may be expected to be faster than those implemented by clinicians on site for stage 2 of the present protocol, such that the stage 2 milling time on a less expensive machine or mill 60 may actually be longer than the first stage on initial mill 60, which is part of the reason for having the first stage milling being performed about 90% on a first mill 60 of the time it would take that mill 60 to complete the part 30 (if it had the final particulars).

[0035] The staged milling type computer aided manufacturing (CAM) of surgical prosthetics 30, particularly oral prosthetics according to the present invention contemplates having custom holders 40 for each respective mill 60 so that the puck 20 with partially machined or partially completed prosthetic 10 (i.e. the semi-finished workpiece 10) can be repositioned into another mill 60 with repeatability and accuracy.

[0036] Figure 1 is a representation of puck 20 having eleven separate partially machined prosthetics 10. These would be shipped to the same clinician or dentist. Note the final prosthetics 30 may not all be for the same patient but may represent several patients currently being treated at the same facility. Figure 2 is a representation of puck 20 having eleven separate partially machined prosthetics 10 being orientated within a CNC machine or mill 60 held by holders 40 for final processing with tooling 50 after proper registration. The staged milling type computer aided manufacturing (CAM) of surgical prosthetics, particularly oral prosthetics 30 according to the present invention in its simplest terms or process: will allow clinicians to match a new CAD file to an existing already partially (90%) milled CAM file (specifically the semi-finished workpiece 10 in puck 20), re-calculate the new live data and begin the milling process (second stage) from that position in the millingcycle without re-running the whole file from the beginning (i.e. machining the part 30 from scratch).

[0037] The process can be understood from the following description associated with the figures. First the CAD model is used to form a semi-finished model 11 which is placed or orientated within the blank or puck 20 for the initial manufacturing as shown in figures 3A- B. The Cam software will also generate connectors 22 to hold the semi machined piece 10 in the puck 20 till the end of the machining and the connectors 22 extend between the semi machined piece 10 to a defined boundary layer 12 calculated by the software. As noted below the boundary layer 12 is unique and (in whole or in part) can serve significant registration purposed in the invention. The model 11 of the semi-finished work piece 10 includes a model 23 of the supports 22 and a model 13 of the boundary layer 12.

[0038] In the staged milling type computer aided manufacturing (CAM) of oral prosthetics 30 according to the present invention the inside the boundary layer 12, except for the connectors 22 and the material forming the semi-finished piece 10 will be removed by the tool 50 of the initial mill 60 in the initial milling stage to get the shape of the semi-finished prosthesis 10. The staged milling type computer aided manufacturing (CAM) of surgical prosthetics, particularly oral prosthetics 30 according to the present invention will mill the semi-finished prosthesis 10 in the initial stage to form puck 20 with semi-finished work pieces or prosthetics 10 as shown in figures 1 , 2 and 4A and 4B.

[0039] The semi-finished prosthetic 10 will be milled without holes (32) for the attachment which are awaiting final post-surgical and post healing measurements in some cases. The milling preferably includes adding registration points on the puck 20 to be used by the second mill 60 for proper orientation of the semi-finished workpiece 10 in the second stage in the second mill 60. The registration marks may differ depending upon the brand of second mill 60 used by the clinician for the second stage. In other words the same prosthetic 30 for the same patient may include different registration marks if associated with different clinicians that have different brands of mills 60. The protocol of the present invention requires the programming of the first stage to know and accommodate where the second stage is to be performed so that the registration can communicate with the second mill 60 properly. The registration marks may be workpiece orientation marks understood by the mill 60. Alternatively the registration marks for the puck 20 in the holder40 of the mill 60 may also be unique aspects of the puck 20 and semi-finished workpieces 10 such as the shape of the boundary layers 12. Thus in place of the mill 60 reading predefined marks on the puck 20 it can match the expected boundary layer 12 shape (model 13) and the expected shape of the semi-finished workpiece (model 11 ) and / or position of supports 22 (Model 23) that are all known) to register the puck 20 to the second mill 60.

[0040] The staged milling type computer aided manufacturing (CAM) of surgical prosthetics, particularly oral prosthetics, according to the present invention will form a new CAD model 31 (with the same model 13 of the boundary layer 12 positioned relative to the final model 31 ) of the final prosthetic 30 after the final physiologic parameters of the patient are obtained. The new model 31 and the puck with the semi-finished prosthetic 30 is shown in figure 5A (in an unaligned position).

[0041] The new final CAD model 31 is superimposed on the Cad model 1 1 of the semifinished prosthetic as shown in figure 5B. The matching will use landmarks on the original CAD models 11 and 13 and the final models 31 and 13 that are consistent (i.e. not expected to change). The landmarks typically can be the unique shape of the model 13 of the boundary layer 12, although landmarks such as the upper shape of the crown can also be equally effectively used

[0042] The final milling for the second mill 60 is calculated with the aligned models 1 1 / 31 with at least the live implant cylinder channels 32 and part fitment 34 based upon the new Cad model 31 superimposed within the model 11 of the semi-finished piece 10.

[0043] The puck 20 with the semi-finished prosthetic 10 is orientated within the second mill 60, preferably at the clinician’s office, and the prosthetic 30 completely milled in a final milling stage.

[0044] The above description may be summarized as protocol for staged milling type computer aided manufacturing (CAM) of prosthetics 30. The initial step is generating a semi-finished model 1 1 (cad model) of a prosthetic 30 and a model 13 of a boundary layer 12 surrounding the semi-finished model 11 , wherein the semi-finished model 11 is a model of a semi-finished prosthetic 10 which has at least of majority, by time, of the prosthetic milled with at least 5% by time of milling to be completed. In other words the semi-finished prosthetic 10 is at least 50%, by time, milled in the initial stage leaving, at the broadestrange, about 45% of the milling, by time to be completed. As noted above the semifinished prosthetic 10 is preferable at least 75%, by time, milled in the initial stage leaving, at this intermediate range, at least 15 or at least 20% of the milling, by time to be completed. As noted above the semi-finished prosthetic 10 is preferable at least 90%, by time, milled in the initial stage leaving, at this preferred range, at least 5% of the milling, by time to be completed.

[0045] The next step is positioning the semi-finished model 1 1 of a prosthetic 30 and a model of a boundary layer 13 surrounding the semi-finished model 1 1 onto a puck 20 (virtually) of material forming the prosthetic 30 and generating an initial milling profile for forming the semi-finished prosthetic, wherein the volume of the puck 20 inside of the boundary layer 12 represents material of the puck 20 to be removed in the initial milling except for the semi-finished prosthetic 10 and supports 22 extending between the boundary layer 12 and the semi-finished prosthetic 10. The milling profile is used for milling the semi-finished prosthetic 10 within the puck 20 in a first stage milling operation on mill 60 with toll 50 controlled by the initial milling profile (or controls). A key aspect of the invention is pausing the initial milling process before the final prosthetic 30 is completely milled.

[0046] The next step of the process is generating a finished model 31 of the prosthetic 30 with the model 13 of the boundary layer 12 and overlying this with the semi-finished model 11 of the prosthetic 30 and the model 13 of a boundary layer 12 surrounding the semi-finished model 1 1 . Then the protocol generates a final milling profile for forming the prosthetic 30 followed by milling the final prosthetic 30 on a mill 60 with tool 50 controlled by the final milling profile in a second stage milling operation.

[0047] The protocol for staged milling type computer aided manufacturing (CAM) of prosthetics 30 according to the invention includes the step of registering the puck 20 having the semi-finished prosthetic 10 with a mill 60, particularly where second stage milling operation is conducted on a mill different from the first stage milling operation.

[0048] As noted above the protocol for staged milling type computer aided manufacturing (CAM) of prosthetics according to the invention may provide wherein the prosthetic 30 is a surgical prosthetic 30, specifically an oral prosthetic 30. The protocol for staged milling type computer aided manufacturing (CAM) of prosthetics according to the invention mayprovide wherein the semi-finished prosthetic does not include implant cylinder channels, and wherein the semi-finished prosthetic does not include implant part fitment surfaces.

[0049] An alternative process to the present invention is known as a hybrid process. In this digital dental technology, hybrid production is the phase introduced for a combination of additive and subtractive steps with a view to combining the efficiency of additive manufacturing with the precision of CNC milling. See Torii M., Nakata T., Takahashi K., Kawamura N., Shimpo H., Ohkubo C. Fitness and retentive force of cobalt-chromium alloy clasps fabricates with repeated laser sintering and milling. J. Prosthodont. Res. 2018; 62:342-346. doi : 10.1016 / j.jpor.2018.01 .001 ; and akata T., Shimpo H., Okhubo C. Clasp fabrication using one-process molding by repeated laser sintering and high-speed milling. J. Prosth. Research. 2017; 61 :276-282. doi: 10.1016 / j.jpor.2016.10.002.

[0050] In this hybrid process the original manufacture uses the models 11 , 23 and 13 together with information on the size and material of the puck 20 in an additive manufacturing process to form the puck 20 including the semi-finished workpiece(s) 10 essentially as shown in 1 , 2 and 4A and 4B with the additive manufactured formed piece including the registration for aligning the puck in the mill 60 for the second stage. Additive manufacturing has been established in the dental sector for over 20 years, represented, for example, by the laser sintering (AKA selective laser melting, or SLM) processes such as by Bego Medical (Bremen, Germany) and EOS (Krailing, Germany). Several 3D printing technologies exist for the additive manufacturing of plastic objects in prosthetic dentistry and exhibit, when compared to each other, different characteristics regarding speed, resolution, size, and process reliability depending on the underlying technology. See Revilla-Leon M., Oczan M. Additive manufacturing technologies used for processing polymers: Current status and potential application in prosthetic dentistry. J Prosthodont. 2019; 28:146-158. doi: 10.11 1 1 / jopr.12801 .

[0051] Currently, stereolithographic processes predominate in the dental sector, including classic stereolithography using a laser source (stereolithography AKA SLA) and the so-called mask exposure processes (digital light processing, DLP). In both processes, the object is solidified by the action of light in a vat of photopolymer. For several years now, 3D printers have been available that use low-cost liquid crystal displays (LCD). The technology is called direct ultraviolet printing (DUP); it uses the LCD displays for pixel-by-pixel exposure of the build platform. UV LEDs with a wavelength range of 395 to 405 nm are usually used for background lighting. Direct 3D printing processes (material jetting, MJT) are also used in dental applications. Material extrusion (MEX) processes such as fused-filament fabrication (FFF) or fused deposition modeling (FDM) are currently less implemented on the dental market due to perceived long printing times and lower resolutions. Of the technologies mentioned for the plastics sector, SLA, DLP, and MJT appear to be the most commonly implemented technologies due to technical and economic consideration. For background see Brown G.B., Currier G.F., Kadioglu O., Kierl J.P. Accuracy of 3-dimensional printed dental models reconstructed from digital intraoral impressions. Am. J. Orthod. Dentofac. Orthop. 2018; 154:733-739; and Emir F., Ayyildiz S. Accuracy evaluation of complete-arch models manufactured by three different 3D printing technologies: A three-dimensional analysis. J. Prosthodont. Res. 2021 doi: 10.2186 / jpr.JPOR_2019_579; and Etemad-Shahidi Y., Qallandar O.B., Evenden J., Alifui-Segbaya F., Ahmed K.E. Accuracy of 3-Dimensionally printed full-arch dental models: A systematic review. J. Clin. Med. 2020;9: 3357. doi: 10.3390 / jcm9103357. The hybrid process of the present invention can utilize any conventional printing process for the initial stage. The hybrid process proceeds with the second stage as noted above. In this hybrid process the amount of completion of the semi-finished piece 10 cannot be calculated based upon the first mill, as there is no “first mill” but can be based upon hypothetical milling speeds of a conventional large scale commercial first mill (which may have faster speeds than the second mill 60), and this is consistent with the concepts of the present invention.

[0052] Encompassing both the staged milling and the alternative method the present method or protocol may be categorized as a protocol for milling type computer aided manufacturing (CAM) of prosthetics 30, comprising the steps of: generating a semifinished prosthetic 10 and a boundary layer 12 surrounding the semi-finished prosthetic 10 in a puck 20 of material forming the prosthetic 30, wherein supports 22 extend from the boundary layer 12 to the semi-finished prosthetid O, wherein the semi-finished prosthetic 10 which has at least 5% by time of milling to be completed; generating a finished model 31 of the prosthetic 30 with a model 13 of the boundary layer 12 and overlying this with a model 11 of the semi-finished prosthetic 10 and the model 13 of aboundary layer 12 surrounding the semi-finished model 1 1 ; generating an final milling profile for forming the prosthetic 30; and milling the final prosthetic 30 in a final stage milling operation on a mill 60.

[0053] The above description is representative of the present invention but not restrictive thereof. It will be apparent to those of ordinary skill in the art that various changes may be made to the present invention without departing form the scope thereof.

Claims

CLAIMSWhat is claimed is1. A protocol for staged milling type computer aided manufacturing (CAM) of prosthetics comprising the steps of:Generating a semi-finished model of a prosthetic and a model of a boundary layer surrounding the semi-finished model, wherein the semi-finished model is a model of a semi-finished prosthetic which has at least of majority, by time, of the prosthetic milled with at least 5% by time of milling to be completed;Positioning the semi-finished model of a prosthetic and a model of a boundary layer surrounding the semi-finished model onto a puck of material forming the prosthetic;Generating an initial milling profile for forming the semi-finished prosthetic, wherein volume of the puck inside of the boundary layer represents material to be removed in the initial milling except for the semi-finished prosthetic and supports extending between the boundary layer and the semi-finished prosthetic;Milling the semi-finished prosthetic within the puck in a first stage milling operation, and pausing the milling process before the final prosthetic is milled;Generating a finished model of the prosthetic with the model of the boundary layer and overlying this with the semi-finished model of the prosthetic and the model of the boundary layer surrounding the semi-finished model;Generating an final milling profile for forming the prosthetic; andMilling the final prosthetic in a second stage milling operation.

2. The protocol for staged milling type computer aided manufacturing (CAM) of prosthetics according to claim 1 further including the step of registering the puck having the semi-finished prosthetic with a mill.

3. The protocol for staged milling type computer aided manufacturing (CAM) of prosthetics according to claim 1 wherein the prosthetic is a surgical prosthetic.

4. The protocol for staged milling type computer aided manufacturing (CAM) of prosthetics according to claim 1 wherein the prosthetic is an oral prosthetic.

5. The protocol for staged milling type computer aided manufacturing (CAM) of prosthetics according to claim 4 wherein semi-finished prosthetic does not include implant cylinder channels.

6. The protocol for staged milling type computer aided manufacturing (CAM) of prosthetics according to claim 4 wherein semi-finished prosthetic does not include implant part fitment surfaces.

7. The protocol for staged milling type computer aided manufacturing (CAM) of prosthetics according to claim 4 wherein the second stage milling operation is conducted on a mill different from the first stage milling operation.

8. The protocol for staged milling type computer aided manufacturing (CAM) of prosthetics according to claim 4 wherein the wherein the semi-finished model is a model of a semi-finished prosthetic which has at least of 75%, by time, of the prosthetic milled.

9. The protocol for staged milling type computer aided manufacturing (CAM) of prosthetics according to claim 8 wherein the wherein the semi-finished model is a model of a semi-finished prosthetic which has at least 15% by time of milling to be completed.

10. The protocol for staged milling type computer aided manufacturing (CAM) of prosthetics according to claim 4 wherein the wherein the semi-finished model is a model of a semi-finished prosthetic which has at least of 90%, by time, of the prosthetic milled.

11. A protocol for milling type computer aided manufacturing (CAM) of prosthetics, comprising the steps of:Generating a semi-finished prosthetic and a boundary layer surrounding the semi-finished prosthetic in a puck of material forming the prosthetic, wherein supports extend from the boundary layer to the semi-finished prosthetic, wherein the semifinished prosthetic has at least 5% by time of milling to be completed;Generating a finished model of the prosthetic with a model of the boundary layer and overlying this with a model of the semifinished prosthetic and the model of a boundary layer surrounding the semi-finished model;Generating an final milling profile for forming the prosthetic; andMilling the final prosthetic in a final stage milling operation.

12. The protocol for protocol for milling type computer aided manufacturing (CAM) of prosthetics according to claim 11 further including the step of registering the puck having the semi-finished prosthetic with a mill.

13. The protocol for milling type computer aided manufacturing (CAM) of prosthetics according to claim 11 wherein the prosthetic is an oral prosthetic.

14. The protocol for milling type computer aided manufacturing (CAM) of prosthetics according to claim 13 wherein semi-finished prosthetic does not include implant cylinder channels or implant part fitment surfaces.

15. The protocol for milling type computer aided manufacturing (CAM) of prosthetics according to claim 13 wherein the generating a semi-finished prosthetic and a boundary layer surrounding the semi-finished prosthetic in a puck of material is in an initial milling stage on a first mill and the final stage milling operation is conducted on a mill different from the initial stage milling operation.

16. The protocol for milling type computer aided manufacturing (CAM) of prosthetics according to claim 15 wherein the semi-finished prosthetic has at least of 75%, by time, of the prosthetic milled.

17. The protocol for milling type computer aided manufacturing (CAM) of prosthetics according to claim 16 wherein the wherein the semi-finished prosthetic has at least 15% by time of milling to be completed.

18. The protocol for milling type computer aided manufacturing (CAM) of prosthetics according to claim 13 wherein the wherein the semi-finished prosthetic which has at least of 90%, by time, of the prosthetic milled.

19. A puck having at least one semi-finished prosthetic contained therein and a boundary layer surrounding the semi-finished prosthetic in a puck of material forming the prosthetic, wherein supports extend from the boundary layer to the semifinished prosthetic, wherein the semi-finished prosthetic has at least 5% by time of milling to be completed, and wherein the puck is configured for registration with a mill.

20. The puck having at least one semi-finished prosthetic according to claim 20 wherein puck has a plurality of semi-finished prosthetics each of which being an oral prosthetic.

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