Patent Publication Number: US-2022233288-A1

Title: Plate denture manufacturing method, denture mold, and plate denture manufacturing kit

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority to Japanese Patent Application No. 2021-010273 filed on Jan. 26, 2021. The entire contents of this application are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to plate denture manufacturing methods, denture molds, and plate denture manufacturing kits. 
     2. Description of the Related Art 
     To replace missing teeth of patients, plate dentures each including a denture base and artificial teeth placed on the denture base have conventionally been used. With the introduction of computer-aided design (CAD) and computer-aided manufacturing (CAM) techniques in recent years, denture bases are now being mechanically fabricated using cutting apparatuses in accordance with computer-designed cutting data. Fabrication of plate dentures in accordance with three-dimensional data known in the related art first involves, for example, cutting materials (e.g., dental resin materials) into desired shapes so as to make denture bases, and then involves bonding separately prepared artificial teeth to the denture bases. 
     The process of bonding artificial teeth to denture bases is still usually performed manually by dental technicians. In other words, dental technicians typically bond artificial teeth to denture bases with adhesives or polymerizable materials one at a time in a step-by-step manner. The process of bonding artificial teeth to denture bases one at a time unfortunately requires considerable time and effort when the number of artificial teeth to be bonded is large (e.g., when a complete denture is to be fabricated). Dental technicians need to perform positioning of artificial teeth with respect to opposing teeth in bonding the artificial teeth. Such positioning requires sophisticated skills, imposing immense burdens on the dental technicians. The resulting plate dentures may thus vary in quality depending on the skills of the dental technicians. To solve these problems, JP 2020-130570 A discloses a technique for manufacturing a one-piece structure including a denture base and artificial teeth. 
     The method disclosed in JP 2020-130570 A involves pouring a denture base material into a dedicated denture mold so as to manufacture a one-piece structure including a denture base and artificial teeth. In this case, however, relatively many bubbles may be produced in the denture base material during polymerization depending on the type of denture base material used. If polymerization proceeds, with bubbles present in the denture base material, the denture base material may shrink to a relatively great degree, and the resulting cured product, which is the cured denture base material, may crack. The cracked cured product is low in strength and thus cannot be used to fabricate a plate denture. 
     SUMMARY OF THE INVENTION 
     Accordingly, preferred embodiments of the present invention provide methods for manufacturing plate dentures with reduced or no cracks or bubbles. 
     According to a preferred embodiment of the present invention, a method for manufacturing a plate denture including a denture base and an artificial tooth placed on the denture base. The manufacturing method includes a three-dimensional data preparing step, a denture mold preparing step, a denture mold cutting step, a denture mold placing step, an artificial tooth placing step, a denture base material curing step, and a one-piece product machining step. The three-dimensional data preparing step includes preparing three-dimensional data for an artificial tooth impression that is an impression for the artificial tooth to be placed on the denture base, and three-dimensional data for the plate denture. The denture mold preparing step includes preparing a denture mold including a bottom wall, a side wall extending upward from the bottom wall, a forming space which is surrounded by the bottom wall and the side wall and into which a denture base material is to be poured, a retained portion disposed on the side wall and to be directly or indirectly attached to a cutting apparatus, a cutting target region located in the bottom wall and to be cut by the cutting apparatus so as to define a groove for the artificial tooth, and a plurality of vent holes defined in the bottom wall, passing through the bottom wall in an up-down direction, and in communication with the forming space. The denture mold cutting step includes directly or indirectly attaching the denture mold to the cutting apparatus through the retained portion, and cutting the groove in the cutting target region in accordance with the three-dimensional data for the artificial tooth impression. The denture mold placing step includes placing the grooved denture mold on a holder so as to close the vent holes, the holder being higher in gas permeability than the denture mold. The artificial tooth placing step includes placing the artificial tooth in the groove. The denture base material curing step includes pouring the denture base material into the forming space, with the artificial tooth placed in the groove, and curing the denture base material so as to fabricate a one-piece product including the denture mold, the artificial tooth, and a cured product of the denture base material that are integral with each other. The one-piece product machining step includes directly or indirectly attaching the one-piece product to the cutting apparatus through the retained portion, and machining the cured product in accordance with the three-dimensional data for the plate denture. 
     According to a preferred embodiment of the present invention, a manufacturing method includes placing, on the holder, the denture mold including the vent holes, thus closing the vent holes with the holder. The manufacturing method then includes pouring the denture base material into the forming space of the denture mold. Because the denture mold is provided with the vent holes, the denture base material may flow out of the denture mold through the vent holes. However, closing the vent holes with the holder prevents the denture base material, which has been poured into the forming space, from flowing out of the denture mold. Bubbles may be produced during curing of the denture base material poured into the forming space. Because the holder is higher in gas permeability than the denture mold, the bubbles (or gas) produced in the denture base material are discharged out of the denture mold through the vent holes and the holder. The bubbles produced during curing of the denture base material are thus discharged out of the denture base material. Consequently, the denture mold is brought into more intimate contact with the denture base material so as to limit or prevent shrinkage of the denture base material, which as a result reduces or prevents occurrence of cracks or bubbles in the denture base material that has been cured. 
     Another preferred embodiment of the present invention provides a denture mold for manufacture of a plate denture including a denture base and an artificial tooth placed on the denture base. The denture mold includes a bottom wall, a side wall extending upward from the bottom wall, a forming space which is surrounded by the bottom wall and the side wall and into which a denture base material is to be poured, and a retained portion disposed on the side wall and to be directly or indirectly attached to a cutting apparatus. The bottom wall includes a cutting target region to be cut by the cutting apparatus so as to define a groove for the artificial tooth, and a plurality of vent holes passing through the bottom wall in an up-down direction and in communication with the forming space. 
     The denture mold disclosed herein is brought into more intimate contact with the denture base material so as to limit or prevent shrinkage of the denture base material, which as a result reduces or prevents occurrence of cracks or bubbles in the denture base material that has been cured. 
     Various preferred embodiments of the present invention provide manufacturing methods, denture molds, and plate denture manufacturing kits that are each able to manufacture plate dentures with reduced or no cracks or bubbles. 
     The above and other elements, features, steps, characteristics, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a plate denture according to a first preferred embodiment of the present invention. 
         FIG. 2  is a flow chart illustrating a plate denture manufacturing method according to the first preferred embodiment of the present invention. 
         FIG. 3  illustrates standard triangulated language (STL) data for the plate denture according to the first preferred embodiment of the present invention. 
         FIG. 4  illustrates STL data for an artificial tooth impression according to the first preferred embodiment of the present invention. 
         FIG. 5  is a top view of a denture mold according to the first preferred embodiment of the present invention. 
         FIG. 6  is a bottom view of the denture mold according to the first preferred embodiment of the present invention. 
         FIG. 7  is a perspective view of the denture mold according to the first preferred embodiment of the present invention. 
         FIG. 8  is a plan view of an adapter according to the first preferred embodiment of the present invention. 
         FIG. 9  is a plan view of a body of the adapter according to the first preferred embodiment of the present invention. 
         FIG. 10  is a plan view of the body of the adapter according to the first preferred embodiment of the present invention, with the denture mold retained by the body. 
         FIG. 11  is a plan view of a retaining plate of the adapter according to the first preferred embodiment of the present invention. 
         FIG. 12  is a front view of a cutting apparatus according to the first preferred embodiment of the present invention. 
         FIG. 13  is a perspective view of a tool magazine according to the first preferred embodiment of the present invention. 
         FIG. 14  is a perspective view of a rotary support and a clamp according to the first preferred embodiment of the present invention. 
         FIG. 15  is a block diagram of a control system for the cutting apparatus according to the first preferred embodiment of the present invention. 
         FIG. 16  is a plan view of the denture mold according to the first preferred embodiment of the present invention, illustrating grooves cut in a cutting target region of the denture mold. 
         FIG. 17  is a perspective view of a holder according to the first preferred embodiment of the present invention. 
         FIG. 18  is a perspective view of the holder according to the first preferred embodiment of the present invention, with the denture mold placed on the holder. 
         FIG. 19  is a plan view of the denture mold according to the first preferred embodiment of the present invention, illustrating artificial teeth placed in the grooves. 
         FIG. 20  is a plan view of a one-piece product according to the first preferred embodiment of the present invention. 
         FIG. 21  is a plan view of a cut product according to the first preferred embodiment of the present invention. 
         FIG. 22  is a perspective view of a denture mold according to a second preferred embodiment of the present invention. 
         FIG. 23  is a top view of the denture mold according to the second preferred embodiment of the present invention. 
         FIG. 24  is a perspective view of the denture mold according to the second preferred embodiment of the present invention. 
         FIG. 25  is a bottom view of the denture mold according to the second preferred embodiment of the present invention. 
         FIG. 26  is a perspective view of a holder according to the second preferred embodiment of the present invention. 
         FIG. 27  is a perspective view of the holder according to the second preferred embodiment of the present invention, with the denture mold placed on the holder. 
         FIG. 28  is a plan view of an adapter according to the second preferred embodiment of the present invention. 
         FIG. 29  is a perspective view of the adapter according to the second preferred embodiment of the present invention. 
         FIG. 30  is a plan view of the adapter according to the second preferred embodiment of the present invention, with the denture mold retained by the adapter. 
         FIG. 31  is a perspective view of the adapter according to the second preferred embodiment of the present invention, with the denture mold retained by the adapter. 
         FIG. 32  is another perspective view of the adapter according to the second preferred embodiment of the present invention, with the denture mold retained by the adapter. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Plate denture manufacturing methods, denture molds, and plate denture manufacturing kits according to preferred embodiments of the present invention will be described below with reference to the drawings. The preferred embodiments described below are naturally not intended to limit the present invention in any way. Components or elements having the same functions are identified by the same reference signs, and description thereof will be omitted or simplified when redundant. The reference signs F, Rr, L, R, U, and D in the drawings respectively represent front, rear, left, right, up, and down. These directions are defined for the sake of convenience of description and do not limit the present invention in any way. 
     First Preferred Embodiment 
     A first preferred embodiment of the present invention will now be described.  FIG. 1  is a perspective view of a plate denture  10  according to the first preferred embodiment. The plate denture  10  is a complete denture (or full denture) for the upper jaw of a patient. The plate denture  10  includes a denture base  20  and artificial teeth  15  placed on the denture base  20 . The artificial teeth  15  are bonded to the denture base  20 .  FIG. 1  illustrates the plate denture  10  flipped over such that the artificial teeth  15  face upward, although the patient wears the plate denture  10 , with the artificial teeth  15  facing downward. In the present preferred embodiment, the number of artificial teeth  15  is 14 in total, for example. The artificial teeth  15  are made of, for example, any of various materials, such as polymethyl methacrylate (PMMA) resin, zirconia, glass ceramics, glass fiber, polyether ether ketone (PEEK) resin, and hybrid resin. The artificial teeth  15  may be in the form of a dental bridge including two or more artificial teeth integral with each other. The denture base  20  is made of, for example, a denture base material, such as a dental resin material or a dental ceramic material. A method for manufacturing the plate denture  10  will be described below by way of example. 
       FIG. 2  is a flow chart illustrating the method for manufacturing the plate denture  10 . The manufacturing method according to the present preferred embodiment includes a three-dimensional data preparing step (step S 10 ), a denture mold preparing step (step S 20 ), a denture mold cutting step (step S 30 ), a denture mold placing step (step S 40 ), an artificial tooth placing step (step S 50 ), a denture base material curing step (step S 60 ), and a one-piece product machining step (step S 70 ). Any other step may be performed at any time during execution of the method. The three-dimensional data preparing step (step S 10 ) and the denture mold preparing step (step S 20 ) may be performed in reverse order. The denture mold placing step (step S 40 ) and the artificial tooth placing step (step S 50 ) may be performed in reverse order. The steps of the manufacturing method will be described in detail below. 
     The three-dimensional data preparing step (step S 10 ) includes preparing at least one or two types of three-dimensional data. Examples of the three-dimensional data include standard triangulated language (STL) data. The three-dimensional data preparing step (step S 10 ) includes a first STL data preparing step (sub-step S 11 ) and a second STL data preparing step (sub-step S 12 ). The STL data is created by, for example, a computer-aided design (CAD) device. The functions of the CAD device may be implemented by software or hardware. Examples of CAD software include a 3Shape Dental System™ available from 3Shape. 
     Sub-step S 11  includes preparing first STL data. The first STL data is STL data  10 A representing the plate denture  10  (hereinafter referred to as “STL data  10 A for the plate denture  10 ”). The STL data  10 A for the plate denture  10  is used when a one-piece product  13  is cut in step S 70  (which will be described below).  FIG. 3  illustrates an example of the STL data  10 A for the plate denture  10 . The STL data  10 A for the plate denture  10  includes STL data  20 A that represents the denture base  20 , and STL data  15 A that represents the artificial teeth  15  placed on the denture base  20 . The STL data  10 A for the plate denture  10  is usually created for each patient. Depending on, for example, usage or other factors, commercially available simulated STL data for the plate denture  10  may be used on an as-is basis. 
     Sub-step S 12  includes preparing second STL data. The second STL data is STL data  16 A for an artificial tooth impression  46 . The STL data  16 A for the artificial tooth impression  46  represents the alignment (or row) of the artificial teeth  15 . The STL data  16 A for the artificial tooth impression  46  is used when a denture mold  40  is cut in step S 30  (which will be described below). In other words, the STL data  16 A for the artificial tooth impression  46  is used to form the artificial tooth impression  46  (see  FIG. 16 ) for placement of the artificial teeth  15  on the denture mold  40 .  FIG. 4  illustrates an example of the STL data  16 A for the artificial tooth impression  46 . The STL data  16 A for the artificial tooth impression  46  includes STL data  17 A for a plurality of grooves  46 A (see  FIG. 16 ). The STL data  17 A for the grooves  46 A is reflective of, for example, the sizes, locations, and orientations of the artificial teeth  15  to be placed in the grooves  46 A. The artificial tooth impression  46  includes the grooves  46 A. The STL data  16 A for the artificial tooth impression  46  is indicative of all of the artificial teeth  15  included in the plate denture  10 . In the present preferred embodiment, the number of artificial teeth  15  is 14 in total, for example. The STL data  16 A for the artificial tooth impression  46  is typically created in accordance with the STL data  10 A for the plate denture  10 . The STL data  10 A for the plate denture  10  and the STL data  16 A for the artificial tooth impression  46  include similar information that indicates the locations of the artificial teeth  15 . 
     The denture mold preparing step (step S 20 ) includes preparing the denture mold  40 .  FIG. 5  is a top view of the denture mold  40 .  FIG. 6  is a bottom view of the denture mold  40 . The denture mold  40  is used to manufacture the plate denture  10 . The denture mold  40  is indirectly attachable to a cutting apparatus  60  (see  FIG. 12 ) through an adapter  30  (see  FIG. 8 ). Alternatively, the denture mold  40  may be directly attachable to the cutting apparatus  60 . The denture mold  40  is a disposable article to be cut by the cutting apparatus  60  in step S 30  and step S 70  (which will be described below). The denture mold  40  may be included in a plate denture manufacturing kit (which will be described below). 
     From the viewpoint of increasing moldability and reducing weight, the denture mold  40  is made of, for example, a resin material. The resin material may be thermosetting or thermoplastic. Examples of the resin material include, but not limited to, acrylic resin, polycarbonate resin, polyamide resin, polyester resin, and acrylonitrile butadiene styrene (ABS) resin. Any one of these resin materials may be used solely, or a combination of any two or more of these resin materials may be used. A blend of any two or more of these resin materials may be used, or any two or more of these resin materials may be used to form different portions of the denture mold  40 . The denture mold  40  may be made of a ceramic material and/or a metallic material. From the viewpoint of increasing heat resistance, the denture mold  40  is preferably made of acrylic resin, such as polymethyl methacrylate (PMMA) resin. As illustrated in  FIG. 6 , the denture mold  40  is a combination of a main member  40 A made of PMMA resin and a reinforcing member  40 B. The main member  40 A and the reinforcing member  40 B are molded into one piece by an insert molding process. 
     As illustrated in  FIG. 5 , the main member  40 A includes a bottom wall  45 , a first side wall  41 , a second side wall  42 , a third side wall  43 , and a fourth side wall  44 . The bottom wall  45  includes a flat surface. The first side wall  41  extends upward from the rear portion of the bottom wall  45 . The second side wall  42  extends upward from the front portion of the bottom wall  45 . The first side wall  41  and the second side wall  42  face each other. The third side wall  43  extends upward from the left portion of the bottom wall  45 . The third side wall  43  connects the left end of the first side wall  41  with the left end of the second side wall  42 . The third side wall  43  is curved away from the fourth side wall  44 . The fourth side wall  44  extends upward from the right portion of the bottom wall  45 . The fourth side wall  44  connects the right end of the first side wall  41  with the right end of the second side wall  42 . The fourth side wall  44  is curved away from the third side wall  43 . The third side wall  43  and the fourth side wall  44  face each other. The first side wall  41  includes an upper surface  41 A. The second side wall  42  includes an upper surface  42 A. The third side wall  43  includes an upper surface  43 A. The fourth side wall  44  includes an upper surface  44 A. The upper surfaces  41 A,  42 A,  43 A, and  44 A are flush with each other. The upper surfaces  41 A to  44 A are thus equal in height from the bottom wall  45 . In the present preferred embodiment, the first to fourth side walls  41  to  44  are each an example of a side wall extending upward from the bottom wall  45 . 
     As illustrated in  FIG. 5 , the main member  40 A includes an opening  47  and a forming space  48 . The opening  47  is defined at a location facing the bottom wall  45 . In other words, the opening  47  is defined in the upper portion of the main member  40 A. The forming space  48  is surrounded by the bottom wall  45 , the first side wall  41 , the second side wall  42 , the third side wall  43 , and the fourth side wall  44 . The forming space  48  is larger than the plate denture  10  in plan view. The depth of the forming space  48  (i.e., the length measured between the bottom wall  45  and the upper surfaces  41 A to  44 A of the first to fourth side walls  41  to  44 ) is longer than the maximum thickness of the plate denture  10  (e.g., the maximum length of the artificial teeth  15  in the direction of extension thereof). A denture base material (which will be described below) is poured into the forming space  48  in step S 60  (which will be described below). The inner surface of the main member  40 A that defines the forming space  48  is preferably made of a resin material similar in type to the denture base material. The bottom wall  45 , in particular, is preferably made of a resin material similar in type to the denture base material. The denture mold  40  is thus more reliably bonded to a denture base material cured product  21  (see  FIG. 20 ) in step S 60  (which will be described below). 
     As illustrated in  FIG. 5 , the bottom wall  45  includes a cutting target region  55  that is to be cut by the cutting apparatus  60  (see  FIG. 12 ) so as to define the grooves  46 A (see  FIG. 16 ) for the artificial teeth  15 , and a plurality of vent holes  58  (see also  FIG. 7 ) passing through the bottom wall  45  in an up-down direction and in communication with the forming space  48 . The grooves  46 A are defined in the cutting target region  55  in step S 30  (which will be described below). The artificial teeth  15  are placed in the grooves  46 A in step S 50  (which will be described below). The cutting target region  55  has an arc shape. The cutting target region  55  is located to surround the vent holes  58 . The vent holes  58  are provided in the central region of the bottom wall  45  in plan view. Although the number of vent holes  58  provided is nine in the present preferred embodiment, any other suitable number of vent holes  58  may be provided. Alternatively, the vent holes  58  may be provided outward of the cutting target region  55  in plan view. The vent holes  58  may each have a diameter of between about 2 mm and about 4 mm or may each have, for example, a diameter of about 3 mm. The vent holes  58  may each have any other suitable diameter. The percentage of area of the bottom wall  45  occupied by the vent holes  58  (i.e., the percentage of opening area of the bottom wall  45 ) is between about 3% and about 8%, or may be, for example, between about 4% and about 5% inclusive. 
     As illustrated in  FIG. 5 , the main member  40 A includes a first retained portion  51  and a second retained portion  52 . The first and second retained portions  51  and  52  are to be retained by the adapter  30 . The first and second retained portions  51  and  52  are to be retained by the cutting apparatus  60  through the adapter  30 . The first and second retained portions  51  and  52  are each an example of a retained portion. The first retained portion  51  is provided on the rear portion of the first side wall  41 . The second retained portion  52  is provided on the front portion of the second side wall  42 . The upper surface of the first retained portion  51  and the upper surface of the second retained portion  52  are located within the same plane. The lower surface of the first retained portion  51  and the lower surface of the second retained portion  52  are located within the same plane. In the present preferred embodiment, the first retained portion  51  and the second retained portion  52  respectively have a length L 51  and a length L 52  different from each other. The length L 51  of the first retained portion  51  is longer than the length L 52  of the second retained portion  52 . Alternatively, the length L 51  may be equal to the length L 52 . 
     As illustrated in  FIG. 5 , the first retained portion  51  is provided with a first recess  51 A. The first recess  51 A is defined in a substantially central region of the first retained portion  51 . The first recess  51 A is recessed toward the first side wall  41 . The first recess  51 A passes through the first retained portion  51  in the up-down direction. One of screws  33  (see  FIG. 8 ) is inserted into the first recess  51 A in step S 30  (which will be described below). The second retained portion  52  is provided with a second recess  52 A and a third recess  52 B. The second recess  52 A is defined leftward of the third recess  52 B. The second recess  52 A is located leftward of the first recess  51 A. The third recess  52 B is located rightward of the first recess  51 A. The second recess  52 A and the third recess  52 B are recessed toward the second side wall  42 . The second recess  52 A and the third recess  52 B each pass through the second retained portion  52  in the up-down direction. The other screws  33  are inserted into the second recess  52 A and the third recess  52 B in step S 30  (which will be described below). 
     As illustrated in  FIG. 6 , the lower surface of the first retained portion  51  is provided with two protrusions  51 X. One of the two protrusions  51 X is provided rightward of the first recess  51 A. The other one of the two protrusions  51 X is provided leftward of the first recess  51 A. The protrusions  51 X extend downward from the first retained portion  51 . The protrusions  51 X are each fitted into an associated one of two grooves  32 X (see  FIG. 9 ) of the adapter  30  in step S 30  (which will be described below). The lower surface of the second retained portion  52  is provided with a protrusion  52 X. The protrusion  52 X is provided on a substantially intermediate region of the second retained portion  52  between the second recess  52 A and the third recess  52 B. The protrusion  52 X extends downward from the second retained portion  52 . The protrusion  52 X is fitted into a groove  32 Y (see  FIG. 9 ) of the adapter  30  in step S 30  (which will be described below). 
     As illustrated in  FIG. 6 , the reinforcing member  40 B is attached to the lower surface of the main member  40 A. The reinforcing member  40 B is substantially U-shaped in plan view. The reinforcing member  40 B is disposed to extend along the lower surface of the bottom wall  45 . The reinforcing member  40 B does not define the forming space  48 . The reinforcing member  40 B does not overlap with any of the vent holes  58  in bottom view. In the present preferred embodiment, the reinforcing member  40 B is made of a material (such as a resin material) similar in type to the material of the main member  40 A. Alternatively, the main member  40 A and the reinforcing member  40 B may be made of different resin materials. The reinforcing member  40 B may be optional. 
     The denture mold cutting step (step S 30 ) includes cutting the cutting target region  55  of the bottom wall  45  of the denture mold  40  using the cutting apparatus  60 , thus cutting the grooves  46 A, which define the artificial tooth impression  46 , in the cutting target region  55 . The denture mold cutting step (step S 30 ) includes, for example, a cutting data creating step (sub-step S 31 ), a denture mold attaching step (sub-step S 32 ), a cutting apparatus preparing step (sub-step S 33 ), and a cutting step (sub-step S 34 ). Any other sub-step may be performed at any time during step S 30 . 
     Sub-step S 31  includes creating cutting data for the artificial tooth impression  46  in accordance with the STL data  16 A for the artificial tooth impression  46 , which has been prepared in the three-dimensional data preparing step (step S 10 ). The cutting data is “numerical control (NC) data”. The cutting data is created by, for example, a computer-aided manufacturing (CAM) device communicably connected to the CAD device. 
     Sub-step S 32  includes attaching the denture mold  40  to the adapter  30 .  FIG. 8  is a plan view of the adapter  30 . The adapter  30  is a fixture to attach the denture mold  40  to the cutting apparatus  60 . The adapter  30  includes a body  32  and a retaining plate  37 . The body  32  is an example of a first structure. The retaining plate  37  is an example of a second structure. The denture mold  40  is clamped between the body  32  and the retaining plate  37 .  FIGS. 9 and 10  are each a plan view of the body  32 .  FIG. 10  illustrates the body  32  and the denture mold  40  retained by the body  32 .  FIG. 11  is a plan view of the retaining plate  37 . The first and second retained portions  51  and  52  of the denture mold  40  are retained by the adapter  30 . The adapter  30  may be included in the plate denture manufacturing kit (which will be described below). 
     As illustrated in  FIG. 9 , the body  32  includes a first portion  32 A, a second portion  32 B, a third portion  32 C, and a fourth portion  32 D. The first portion  32 A is provided with the two grooves  32 X recessed away from the second portion  32 B. The two protrusions  51 X (see  FIG. 6 ) of the denture mold  40  are each fitted into an associated one of the two grooves  32 X. The second portion  32 B is provided with the groove  32 Y recessed away from the first portion  32 A. The protrusion  52 X (see  FIG. 6 ) of the denture mold  40  is fitted into the groove  32 Y. The third portion  32 C connects the left end of the first portion  32 A with the left end of the second portion  32 B. The fourth portion  32 D connects the right end of the first portion  32 A with the right end of the second portion  32 B. An opening  32 H is located inward of the first to fourth portions  32 A to  32 D. The forming space  48  (see  FIG. 5 ) of the denture mold  40  is disposed in the opening  32 H. The first retained portion  51  (see  FIG. 5 ) of the denture mold  40  faces the first portion  32 A. The second retained portion  52  (see  FIG. 5 ) of the denture mold  40  faces the second portion  32 B. 
     As illustrated in  FIG. 10 , the first portion  32 A of the body  32  is provided with a threaded hole  34 A. With the denture mold  40  retained by the body  32 , the threaded hole  34 A overlaps with the first recess  51 A defined in the first retained portion  51  (see  FIG. 5 ) of the denture mold  40  in plan view. The second portion  32 B of the body  32  is provided with left and right threaded holes  34 B. With the denture mold  40  retained by the body  32 , the left and right threaded holes  34 B respectively overlap with the second and third recesses  52 A and  52 B of the second retained portion  52  (see  FIG. 5 ) of the denture mold  40  in plan view. The denture mold  40  is thus not fastened with the screws  33 . More specifically, the first and second retained portions  51  and  52  are not fastened with the screws  33 . 
     As illustrated in  FIG. 11 , the retaining plate  37  has an annular outer shape. The retaining plate  37  is detachably attached to the body  32 . The retaining plate  37  includes a first portion  37 A, a second portion  37 B, a third portion  37 C, and a fourth portion  37 D. The first portion  37 A of the retaining plate  37  faces the first portion  32 A of the body  32 . The first portion  37 A presses the first retained portion  51  (see  FIG. 5 ) of the denture mold  40  against the body  32 . The second portion  37 B of the retaining plate  37  faces the second portion  32 B of the body  32 . The second portion  37 B presses the second retained portion (see  FIG. 5 ) of the denture mold  40  against the body  32 . The third portion  37 C of the retaining plate  37  faces the third portion  32 C of the body  32 . The fourth portion  37 D of the retaining plate  37  faces the fourth portion  32 D of the body  32 . An opening  37 H is located inward of the first to fourth portions  37 A to  37 D. The forming space  48  (see  FIG. 5 ) of the denture mold  40  is disposed in the opening  37 H. 
     The first portion  37 A of the retaining plate  37  is provided with a threaded hole  38 A overlapping with the threaded hole  34 A of the body  32  in plan view. The second portion  37 B of the retaining plate  37  is provided with threaded holes  38 B overlapping with the threaded holes  34 B of the body  32  in plan view. 
     As illustrated in  FIG. 8 , with the denture mold  40  retained by the body  32  and pressed by the retaining plate  37 , the screws  33  are inserted through the threaded holes  34 A and  34 B of the body  32  and the threaded holes  38 A and  38 B of the retaining plate  37 . The body  32  and the retaining plate  37  are thus fastened to each other with the screws  33  at three locations. The first retained portion  51  of the denture mold  40  is clamped between the first portion  32 A of the body  32  and the first portion  37 A of the retaining plate  37 . The second retained portion  52  of the denture mold  40  is clamped between the second portion  32 B of the body  32  and the second portion  37 B of the retaining plate  37 . Because the denture mold  40  is stably retained by the adapter  30 , the present preferred embodiment prevents misalignment during cutting or, in particular, misalignment within the XY plane of a clamp  66  (see  FIG. 14 ). 
     Sub-step S 33  includes preparing the cutting apparatus  60 .  FIG. 12  is a front view of the cutting apparatus  60 .  FIG. 12  illustrates the cutting apparatus  60 , with its cover  62  opened. In the following description on the cutting apparatus  60 , the terms “leftward” and “rightward” respectively refer to a leftward direction and a rightward direction with respect to an operator (e.g., a dental technician) facing the front of the cutting apparatus  60 . The term “forward” refers to a direction away from the rear of the cutting apparatus  60  and toward the operator. The term “rearward” refers to a direction away from the operator and toward the rear of the cutting apparatus  60 . Assuming that an X axis, a Y axis, and a Z axis are perpendicular to each other, the cutting apparatus  60  is disposed on a plane defined by the X axis and the Y axis. The X axis extends in a right-left direction. The Y axis extends in a front-rear direction. The Z axis extends in an up-down direction. The reference sign θ X  represents a rotational direction around the X axis. The reference sign θ Y  represents a rotational direction around the Y axis. The reference sign θ Z  represents a rotational direction around the Z axis. These directions are defined merely for the sake of convenience of description and do not limit in any way how the cutting apparatus  60  may be installed. 
     As illustrated in  FIG. 12 , the cutting apparatus  60  includes a case body  61 , the cover  62 , a spindle  63 , a tool magazine  64  (see also  FIG. 13 ), a rotary support  65  (see also  FIG. 14 ), the clamp  66  (see  FIG. 14 ), and a controller  90 . The case body  61  has a box shape. The case body  61  includes a machining space  61 A defined therein. The front portion of the case body  61  is provided with an opening. The cover  62  is movable along the front end of the case body  61  in the up-down direction. The machining space  61 A is openable and closable by the cover  62 . Upward movement of the cover  62  brings the machining space  61 A of the case body  61  into communication with an external space. The cover  62  is provided with a window  62 A. This enables the operator to visually check the inside of the machining space  61 A through the window  62 A, for example, during cutting. 
     The spindle  63  grips a machining tool  78  during cutting. The spindle  63  cuts the cutting target region  55  (see  FIG. 5 ) of the bottom wall  45  of the denture mold  40  by rotating the machining tool  78 . The spindle  63  includes a tool gripper  71  and a rotator  72  provided on the upper end of the tool gripper  71 . The tool gripper  71  grips the upper end of the machining tool  78 . The rotator  72  rotates the machining tool  78  gripped by the tool gripper  71 . The rotator  72  extends in the up-down direction. The rotator  72  is connected with a first drive motor  72   a  (see  FIG. 15 ). The first drive motor  72   a  is connected to the controller  90  and thus controlled by the controller  90 . Driving the first drive motor  72   a  enables the rotator  72  to rotate in the rotational direction θ Z  around the Z axis. The rotation of the rotator  72  causes the machining tool  78  gripped by the tool gripper  71  to rotate in the rotational direction θ Z  around the Z axis. A first driver (not illustrated) is provided for the rotator  72 . The rotator  72  is movable in the right-left direction and the up-down direction by the first driver. 
       FIG. 13  is a perspective view of the tool magazine  64 . As illustrated in  FIG. 13 , the tool magazine  64  has a box shape. The tool magazine  64  includes an upper surface  64 A provided with a plurality of through holes  81  to hold the machining tools  78 . Each machining tool  78  is inserted into or through an associated one of the through holes  81  such that the upper portion of each machining tool  78  is exposed. Replacement of the machining tool  78  includes returning the machining tool  78 , gripped by the tool gripper  71 , to an unoccupied one of the through holes  81 , moving the tool gripper  71  and the rotator  72  to a position over the machining tool  78  to be used next, and causing the tool gripper  71  to grip the upper end of the machining tool  78  to be used next. 
       FIG. 14  is a perspective view of the rotary support  65  and the clamp  66 . As illustrated in  FIG. 13 , the tool magazine  64  is provided with a first rotary shaft  83 . The first rotary shaft  83  supports the rotary support  65  such that the rotary support  65  is rotatable. The first rotary shaft  83  extends in the right-left direction. The first rotary shaft  83  is coupled to the rotary support  65 . The tool magazine  64  is provided with a second driver (not illustrated). The first rotary shaft  83  is rotatable in the rotational direction θ X  around the X axis by the second driver. The rotation of the first rotary shaft  83  in the rotational direction θ X  around the X axis causes the rotary support  65  to rotate in the rotational direction θ X  around the X axis. The rotary support  65  supports the clamp  66  such that the clamp  66  is rotatable. The rotary support  65  is substantially U-shaped in plan view. The rotary support  65  is coupled to the first rotary shaft  83 . The rotary support  65  includes a first portion  65 A extending in the front-rear direction, a second portion  65 B extending leftward from the rear end of the first portion  65 A, and a third portion  65 C extending leftward from the front end of the first portion  65 A. The clamp  66  is rotatably supported by the second portion  65 B and the third portion  65 C. The third portion  65 C is provided with a second drive motor  67  to rotate the clamp  66  in the rotational direction θ Y  around the Y axis. 
     The clamp  66  retains the denture mold  40  during cutting. In the present preferred embodiment, the clamp  66  retains the adapter  30  having the denture mold  40  attached thereto. The clamp  66  thus indirectly retains the denture mold  40  through the adapter  30 . In  FIG. 14 , the adapter  30  is not illustrated. The denture mold  40  retained by the clamp  66  is cut by the cutting apparatus  60 . 
       FIG. 15  is a block diagram of the controller  90 . The controller  90  exercises control for cutting. As illustrated in  FIG. 12 , the controller  90  is provided inside the case body  61 . Alternatively, a portion of the controller  90  may be, for example, a general-purpose personal computer disposed outside the case body  61  and connected to the cutting apparatus  60  such that wired or wireless communication is enabled therebetween. The controller  90  is not limited to any particular hardware configuration. The controller  90  includes, for example, a central processing unit (CPU), a read-only memory (ROM), a random-access memory (RAM), and a storage, such as a memory. The CPU executes commands included in a control program. The ROM stores the program to be executed by the CPU. The RAM is used as a working area where the program is to be expanded. The storage stores the program and various types of data. 
     The controller  90  is communicably connected to the first drive motor  72   a  and the second drive motor  67 . The controller  90  is thus able to control the first drive motor  72   a  and the second drive motor  67 . The controller  90  controls driving of the first drive motor  72   a  so as to control rotation of the rotator  72  of the spindle  63 . The controller  90  controls the rotator  72  such that the rotator  72  moves in the right-left direction and the up-down direction. The controller  90  controls driving of the second drive motor  67  so as to control rotation of the clamp  66  in the rotational direction θ Y  around the Y axis. The controller  90  controls the first rotary shaft  83  such that the first rotary shaft  83  rotates in the rotational direction θ X  around the X axis. 
     The controller  90  includes a memory  91  and a cutting controller  92 . The functions of the controller  90  may be implemented by software or hardware. The memory  91  is communicably connected to the CAM device. The cutting data created by the CAM device is stored in the memory  91 . The cutting data typically includes a plurality of machining steps defining, using coordinate values, operations of the spindle  63  and operations of the clamp  66  retaining the denture mold  40 . 
     Sub-step S 34  includes cutting the denture mold  40  using the cutting apparatus  60 . In accordance with the cutting data stored in the memory  91 , the cutting controller  92  controls the operations of the spindle  63  and the clamp  66  so as to control cutting operations. The cutting controller  92  brings an extremity  78   a  (see  FIG. 12 ) of the machining tool  78  being rotated by the spindle  63  into contact with the cutting target region  55  (see  FIG. 5 ) of the bottom wall  45  of the denture mold  40 , thus cutting the grooves  46 A (see  FIG. 16 ), which define the artificial tooth impression  46 , in the cutting target region  55 .  FIG. 16  is a plan view of the denture mold  40 , illustrating the grooves  46 A cut in the bottom wall  45  of the denture mold  40 . The artificial tooth impression  46  includes the grooves  46 A into which the artificial teeth  15  are to be fitted. In the present preferred embodiment, the number of grooves  46 A is 14 in total, for example. The grooves  46 A each have a depth of, for example, between about 2 mm and about 5 mm. 
     The denture mold placing step (step S 40 ) includes placing, on a holder  95 , the denture mold  40  in which the grooves  46 A have been cut. The denture mold  40  is placed on the holder  95  so as to close the vent holes  58  defined in the bottom wall  45  of the denture mold  40 . The denture mold placing step (step S 40 ) may be performed while the adapter  30  remains attached to the denture mold  40 , or may be performed after the adapter  30  is detached from the denture mold  40 . The holder  95  may be included in the plate denture manufacturing kit (which will be described below). 
       FIG. 17  is a perspective view of the holder  95 . As illustrated in  FIG. 17 , the holder  95  has a substantially cuboid shape. The holder  95  includes an upper surface  95 A provided with a recess  96  recessed downward. As illustrated in  FIG. 18 , the denture mold  40  is fitted into the recess  96 . The recess  96  conforms to the outer shape of the denture mold  40 . The bottom of the denture mold  40  is fitted into the recess  96 . As illustrated in  FIG. 17 , the recess  96  includes a first portion  96 A that comes into contact with the reinforcing member  40 B of the denture mold  40 , a second portion  96 B that comes into contact with a portion of the bottom wall  45  of the denture mold  40  (or more specifically, the main member  40 A) where the vent holes  58  are defined, and a third portion  96 C that comes into contact with the lower ends of the first to fourth side walls  41  to  44  of the denture mold  40 . The second portion  96 B is located above the first portion  96 A. The recess  96  (or more specifically, the third portion  96 C) has a depth of, for example, between about 5 mm and about 20 mm. The holder  95  is permeable to bubbles (or gas) produced during polymerization of the denture base material (which will be described below). The holder  95  is higher in gas permeability than the denture mold  40 . The holder  95  has a gas permeability (e.g., an oxygen permeability) of, for example, between about 10000 ml/m 2  and about 100000 ml/m 2 . The denture mold  40  has a gas permeability (e.g., an oxygen permeability) of, for example, between about 10 ml/m 2  and about 100 ml/m 2 . The holder  95  is made of, for example, silicone. In the example illustrated in  FIG. 18 , the grooves  46 A defined in the bottom wall  45  are not illustrated. The gas permeabilities (e.g., gas transmission rates) of the denture mold  40  and the holder  95  are measured in accordance with Japanese Industrial Standards (JIS) K 7126, for example. 
     The artificial tooth placing step (step S 50 ) includes removing, from the cutting apparatus  60 , the denture mold  40  in which the grooves  46 A have been cut, and placing the artificial teeth  15  on the denture mold  40 . The artificial tooth placing step (step S 50 ) may be performed while the adapter  30  remains attached to the denture mold  40 , or may be performed after the adapter  30  is detached from the denture mold  40 . The artificial teeth  15  may each be any artificial tooth that has conventionally been used for this type of usage. 
       FIG. 19  is a plan view of the denture mold  40 , illustrating the artificial teeth  15  placed in the grooves  46 A (see  FIG. 16 ) of the denture mold  40 . The artificial teeth  15  are placed in the grooves  46 A that have been cut in the bottom wall  45  of the denture mold  40  in sub-step S 34 . Specifically, the artificial teeth  15  are each placed in a corresponding one of the grooves  46 A defined in the denture mold  40 . Each artificial tooth  15  is thus fitted into the corresponding groove  46 A such that each artificial tooth  15  is located in a predetermined position and orientation. Cutting the grooves  46 A using the cutting apparatus  60  reduces the risk of errors made by the dental technician, such as placing the artificial teeth  15  in wrong locations or orientations. In the present preferred embodiment, the artificial teeth  15  are placed in the grooves  46 A, with the roots of the artificial teeth  15  facing upward. In other words, the artificial teeth  15  are placed in the grooves  46 A, with the crowns of the artificial teeth  15  (which come into contact with the lower teeth) facing downward. In the process of fitting the artificial teeth  15  into the grooves  46 A, a dental adhesive or other bonding agent may be used optionally. 
     The denture base material curing step (step S 60 ) includes pouring and curing the denture base material so as to integrate the denture mold  40 , the artificial teeth  15 , and the denture base material cured product  21  with each other. The denture base material curing step (step S 60 ) may be performed while the adapter  30  remains attached to the denture mold  40 , or may be performed after the adapter  30  is detached from the denture mold  40 . The denture base material curing step (step S 60 ) includes, for example, a denture base material preparing step (sub-step S 61 ), a denture base material pouring step (sub-step S 62 ), and a one-piece product fabricating step (sub-step S 63 ). In the present preferred embodiment, sub-steps S 62  and S 63  are each performed once so as to integrate the denture mold  40 , the artificial teeth  15 , and the denture base material cured product  21  with each other. Any other sub-step may be performed at any time during step S 60 . 
     Sub-step S 61  includes preparing the denture base material. Any known material that has conventionally been used to form a denture base is usable as the denture base material. Examples of the denture base material include a dental resin material, such as denture base resin (which may hereinafter be referred to as a “denture base resin composition”), dental wax, a dental ceramic material, and gypsum. The denture base material may be a dental curable composition. The denture base resin may contain a polymerizable compound. Examples of the denture base resin include autopolymer resin that starts polymerization at a temperature of lower than about 65° C., heat-curing resin that starts polymerization by being heated at a temperature of about 65° C. or higher (e.g., 80° C. or higher), and photo-polymerized resin that starts polymerization when exposed to light. Heat-curing resin is preferably usable as the denture base material because heat-curing resin is high in mechanical strength, relatively inexpensive, and easily available. 
     The denture base resin preferably contains resin similar in type to the material of the denture mold  40 . When a portion of the denture mold  40  that defines the forming space  48 , for example, is made of acrylic resin (such as PMMA), acrylic resin is preferably used as the denture base resin. Examples of the denture base resin usable include polycarbonate resin, polyamide resin, and polyester resin. As specified in Japanese Industrial Standards (JIS) T6501:2012, the acrylic resin is, for example, a substance ( 1 ) that is powder whose main component is at least one of a homopolymer of methacrylate ester and a copolymer containing methacrylate ester, a substance ( 2 ) that is a liquid whose main component is a methacrylate ester monomer, or a mixture of the substance ( 1 ) and the substance ( 2 ). As used herein, the term “main component” refers to a component higher in mass percentage than other components. The acrylic resin may be, for example, a combination of powder whose main component is a copolymer of methyl methacrylate (MMA) and 2-ethylhexyl acrylate and a liquid whose main component is methyl methacrylate (MMA). The acrylic resin may be, for example, a combination of powder whose main component is polymethyl methacrylate (PMMA) resin and a liquid whose main component is methyl methacrylate (MMA). The acrylic resin may contain component(s) other than those above. Examples of the component(s) include additives, such as a reaction initiator, a coloring agent, a stabilizer, a plasticizer, a lubricant, a surfactant, and an ultraviolet light absorber. 
     The use of the mixture of the substances ( 1 ) and ( 2 ) as the acrylic resin first includes mixing the powdery substance ( 1 ) and the liquid substance ( 2 ) at a predetermined ratio so as to prepare a fluid composition. The composition may contain bubbles produced by a reaction between the powdery substance ( 1 ) and the liquid substance ( 2 ). Thus, the use of the mixture of the substances ( 1 ) and ( 2 ) preferably includes removing the bubbles from the composition (or defoaming the composition). The composition is defoamed by, for example, transmitting vibrations to the composition from a vibrator, applying ultrasound to the composition from an ultrasound applicator, or applying pressure to the composition from a pressure device. 
     Sub-step S 62  includes pouring the denture base material (which has been prepared in sub-step S 61 ) into the forming space  48 , with the artificial teeth  15  placed in the grooves  46 A defined in the denture mold  40 . In the present preferred embodiment, the denture base material is poured into the forming space  48  through the opening  47  of the denture mold  40  such that the forming space  48  is filled with the denture base material. The bottom wall  45  of the denture mold  40  is provided with the vent holes  58 , but the denture mold  40  is placed on the holder  95  such that the vent holes  58  are closed with the holder  95 . This prevents the denture base material, which has been poured into the forming space  48 , from flowing out of the denture mold  40  through the vent holes  58 . The amount of the denture base material to be poured is set such that the liquid level of the denture base material will be located below the upper surfaces  41 A to  44 A of the first to fourth side walls  41  to  44 . In the present preferred embodiment, the amount of the denture base material to be poured is set such that a cured product larger than the denture base  20  of the plate denture  10  to be manufactured will be formed. In other words, the amount of the denture base material to be poured is set such that the liquid level of the denture base material will be located slightly below the upper surfaces  41 A to  44 A of the first to fourth side walls  41  to  44 . The amount of the denture base material to be poured is set such that all of the artificial teeth  15  placed within the forming space  48  will be completely buried in the denture base material. 
     Sub-step S 63  includes curing the denture base material so as to fabricate the one-piece product  13  (see  FIG. 20 ). When the denture base material is heat-curing resin, sub-step S 63  includes curing the denture base material by heating the denture base material. The one-piece product  13  includes the denture mold  40 , the artificial teeth  15 , and the denture base material cured product  21  that are integral with each other. The one-piece product  13  is fabricated by, for example, polymerizing the denture base material (or more specifically, a polymerizable compound contained in the denture base material). The denture base material is polymerized, for example, in a manner described below. 
     First, a pressure polymerizer (e.g., a pressure pot) is prepared. The denture mold  40  into which the denture base material has been poured in sub-step S 62  is subsequently left at rest in the polymerizer. Water is then poured between the polymerizer and the denture mold  40 . The amount of water to be poured is adjusted such that the water will not penetrate into the forming space  48  of the denture mold  40 . The lid of the polymerizer is then closed such that an enclosed space is defined in the polymerizer. 
     The inside of the polymerizer is adjusted to predetermined conditions such that the denture base material produces a polymerization reaction. When the denture base material is, for example, denture base resin, the inside of the polymerizer may be pressurized at a pressure of between about 0.01 MPa and about 0.5 MPa, or may be pressurized at, for example, a pressure of between about 0.1 MPa and about 0.3 MPa inclusive. In one example, the inside of the polymerizer may be pressurized at a pressure of about 0.2 MPa. When the denture base material is, for example, autopolymer resin, the water inside the polymerizer may be heated to a temperature higher than room temperature, or may be heated to, for example, a temperature of between about 30° C. and about 60° C. In one example, the water inside the polymerizer may be heated to about 50° C. When the denture base material is, for example, heat-curing resin, the water inside the polymerizer may be heated to a temperature of between about 50° C. and about 70° C. during preliminary polymerization, or may be heated to, for example, a temperature of between about 55° C. and about 65° C. during preliminary polymerization. The water inside the polymerizer may be heated to a temperature of between about 70° C. and about 100° C. during full-scale polymerization, or may be heated to, for example, a temperature of between about 75° C. and about 85° C. during full-scale polymerization. The polymerizer is maintained in these conditions for a predetermined period of time. The polymerizer may be maintained in these conditions for about 20 minutes or more during preliminary polymerization, or may be maintained in these conditions for, for example, about 30 minutes to about 90 minutes during preliminary polymerization. The polymerizer may be maintained in these conditions for about 30 minutes or more during full-scale polymerization, or may be maintained in these conditions for, for example, about 30 minutes to about 40 minutes during full-scale polymerization. In one example, the polymerizer may be maintained in these conditions for 40 minutes during full-scale polymerization. The denture base material is thus polymerized so as to increase at least one of bending strength and hardness. The denture base material cured product  21  is firmly bonded to the artificial teeth  15 . The denture base material cured product  21  is firmly bonded to the bottom wall  45  and the first to fourth side walls  41  to  44  of the denture mold  40 . As a result, the one-piece product  13  is fabricated. A polymerization reaction of the denture base material produces bubbles (or gas). Heat-curing resin, in particular, produces more bubbles than autopolymer resin. The number of bubbles produced in the central region of the denture mold  40  tends to be larger than the number of bubbles produced in the other regions of the denture mold  40 . Because the opening  47  of the denture mold  40  is not closed, bubbles produced near the upper surface of the denture mold  40  are discharged out of the denture mold  40  through the opening  47 . The bottom wall  45  of the denture mold  40  is provided with the vent holes  58 . The holder  95  is provided to close the vent holes  58 . Bubbles produced in the denture mold  40  are thus discharged out of the denture mold  40  through the vent holes  58  and the holder  95 . Accordingly, the present preferred embodiment limits or prevents formation of voids caused by the bubbles trapped in the cured product  21 . Discharging the bubbles brings the denture mold  40  into more intimate contact with the denture base material so as to limit or prevent shrinkage of the denture base material. Consequently, the present preferred embodiment reduces or prevents occurrence of cracks or bubbles in the cured product  21 . 
       FIG. 20  illustrates an example of the one-piece product  13 . The denture mold  40 , the artificial teeth  15 , and the cured product  21  included in the one-piece product  13  are integral with each other to such an extent that the denture mold  40 , the artificial teeth  15 , and the cured product  21  will not be separated from the one-piece product  13  during, for example, cutting. The denture base material cured product  21  is machined into the denture base  20  in step S 70  (which will be described below). The denture base material cured product  21  and the denture mold  40  may be bonded to each other with a bonding force of about 10 N or more, preferably about 30 N or more, or more preferably about 50 N or more, for example. As used herein, the term “bonding force” refers to a bonding force compliant with JIS T6506:2005. 
     The one-piece product machining step (step S 70 ) includes machining the one-piece product  13  so as to provide the plate denture  10 . The machining process performed in step S 70  may include at least one of a cutting process, a polishing process, a grinding process, and a cutting-off process. The one-piece product machining step (step S 70 ) includes, for example, a cutting data creating step (sub-step S 71 ), a denture mold attaching step (sub-step S 72 ), a cutting apparatus preparing step (sub-step S 73 ), a one-piece product cutting step (sub-step S 74 ), and a plate denture fabricating step (sub-step S 75 ). Any other sub-step may be performed at any time during step S 70 . In an alternative preferred embodiment, sub-steps S 71  to S 74  may be optional. The dental technician may manually perform all the processes included in step S 70 . 
     Sub-step S 71  includes creating cutting data for the plate denture  10  in accordance with the STL data  10 A for the plate denture  10 , which has been prepared in the three-dimensional data preparing step (step S 10 ). The cutting data for the plate denture  10  is data on a program indicating what procedure is to be followed by the cutting apparatus  60  in cutting the one-piece product  13  into the plate denture  10 . The cutting data created is stored in the memory  91 . Sub-step S 72  includes attaching the denture mold  40  to the adapter  30 . The denture mold  40  may be attached to the adapter  30  in a manner similar to that in which the denture mold  40  is attached to the adapter  30  in sub-step S 32 . 
     Sub-step S 73  includes preparing the cutting apparatus  60 . The cutting apparatus  60  may be the same as or different from the apparatus prepared in sub-step S 33 . Sub-step S 74  includes cutting the one-piece product  13  using the cutting apparatus  60 . The cutting controller  92  brings the extremity  78   a  (see  FIG. 12 ) of the machining tool  78  being rotated by the spindle  63  into contact with the cured product  21  of the one-piece product  13  so as to cut away unnecessary portion(s) of the cured product  21 . The cutting controller  92  may bring the extremity  78   a  of the machining tool  78  into contact with the denture mold  40  of the one-piece product  13  so as to cut away portion(s) of the denture mold  40  (e.g., a portion or an entirety of the bottom wall  45  and/or a portion or an entirety of each of the first to fourth side walls  41  to  44 ). The first and second retained portions  51  and  52  of the denture mold  40  are at least partially not cut away and are thus retained by the adapter  30  after cutting. 
       FIG. 21  illustrates an example of a cut product  11  provided by cutting the one-piece product  13  using the cutting apparatus  60 . The cut product  11  includes the first and second retained portions  51  and  52  of the denture mold  40 , the cured product  21  that has been cut to provide the denture base  20 , the artificial teeth  15  bonded to the cured product  21 , first connectors  12 A connecting the first retained portion  51  to the cured product  21 , and second connectors  12 B connecting the second retained portion  52  to the cured product  21 . 
     Sub-step S 75  includes fabricating the plate denture  10  from the cut product  11 . Sub-step S 75  includes, for example, removing the first and second retained portions  51  and  52  of the denture mold  40  from the cut product  11 . In one example, the dental technician cuts away the first and second retained portions  51  and  52  from the cut product  11  using a tool, such as a cutter having an edge. When the cut product  11  includes the first and second connectors  12 A and  12 B as illustrated in  FIG. 21 , sub-step S 75  includes removing the first and second connectors  12 A and  12 B so as to remove the first and second retained portions  51  and  52 . The surfaces of the cured product  21  exposed, for example, by removing the first and second retained portions  51  and  52  and/or the first and second connectors  12 A and  12 B are preferably polished so as to make the surfaces of the resulting plate denture  10  smooth. Sequentially performing the above-described steps fabricates the plate denture  10  (see  FIG. 1 ) including the denture base  20  and the artificial teeth  15 . 
     As described above, the plate denture manufacturing method according to the present preferred embodiment includes placing, on the holder  95 , the denture mold  40  including the vent holes  58 , thus closing the vent holes  58  with the holder  95 . The manufacturing method then includes pouring the denture base material into the forming space  48  of the denture mold  40 . Because the denture mold  40  is provided with the vent holes  58 , the denture base material may flow out of the denture mold  40  through the vent holes  58 . However, closing the vent holes  58  with the holder  95  prevents the denture base material, which has been poured into the forming space  48 , from flowing out of the denture mold  40 . Bubbles may be produced during curing of the denture base material poured into the forming space  48 . Because the holder  95  is higher in gas permeability than the denture mold  40 , the bubbles produced in the denture base material are discharged out of the denture mold  40  through the vent holes  58  and the holder  95 . The bubbles (or gas) produced during curing of the denture base material are thus discharged out of the denture base material. Consequently, the denture mold  40  is brought into more intimate contact with the denture base material so as to limit or prevent shrinkage of the denture base material, which as a result reduces or prevents occurrence of cracks or bubbles in the denture base material that has been cured. 
     The manufacturing method according to the present preferred embodiment includes using heat-curing resin as the denture base material. The denture base material curing step includes curing the denture base material by heating the denture base material. Heating the heat-curing resin for polymerization may produce a larger number of bubbles. Accordingly, discharging the bubbles through the vent holes  58  of the denture mold  40  and the holder  95  brings the denture mold  40  into more intimate contact with the heat-curing resin so as to more effectively limit or prevent shrinkage of the heat-curing resin. 
     The manufacturing method according to the present preferred embodiment includes using the bottom wall  45  and the first to fourth side walls  41  to  44  of the denture mold  40  made of acrylic resin, and the holder  95  made of silicone. Because the denture mold  40  is made of acrylic resin, the denture mold  40  and the denture base material (e.g., heat-curing resin) are more firmly bonded to each other. This enables the denture base material to be cured into a shape conforming to the forming space of the denture mold  40 . Because the holder  95  is made of silicone, bubbles produced during curing of the denture base material are more reliably discharged out of the denture mold  40  through the holder  95 . In particular, heating the heat-curing resin for polymerization may produce a larger number of bubbles. Accordingly, discharging the bubbles through the vent holes  58  of the denture mold  40  more effectively limits or prevents shrinkage of the heat-curing resin. 
     The manufacturing method according to the present preferred embodiment includes providing the vent holes  58  in the central region of the bottom wall  45  in plan view, and disposing the arc-shaped cutting target region  55  such that the cutting target region  55  surrounds the vent holes  58 . Bubbles produced during curing of the denture base material tend by nature to be large in number in the central region of the denture mold  40 . Accordingly, providing the vent holes  58  in the central region of the bottom wall  45  of the denture mold  40  allows the bubbles to be more reliably discharged out of the denture mold  40 . 
     The plate denture  10  manufactured by the manufacturing method according to the present preferred embodiment may be used as a complete denture for a patient. 
     The manufacturing method according to the present preferred embodiment is able to suitably use the denture mold  40 . The manufacturing method according to the present preferred embodiment is able to suitably use the plate denture manufacturing kit including the denture mold  40 . The plate denture manufacturing kit according to one preferred embodiment includes, for example, one or more denture molds  40  and the holder  95 . The plate denture manufacturing kit according to another preferred embodiment includes one or more denture molds  40 , the holder  95 , and the adapter  30 . 
     The bottom wall  45  of the denture mold  40  according to the present preferred embodiment includes the cutting target region  55  to be cut by the cutting apparatus  60  so as to define the grooves  46 A for the artificial teeth  15 , and the vent holes  58  passing through the bottom wall  45  in the up-down direction and in communication with the forming space  48 . Accordingly, the bubbles (or gas) produced in the denture base material are discharged out of the denture mold  40  through the vent holes  58 . The bubbles produced during curing of the denture base material are thus discharged out of the denture base material. Consequently, the denture mold  40  is brought into more intimate contact with the denture base material so as to limit or prevent shrinkage of the denture base material, which as a result reduces or prevents occurrence of cracks or bubbles in the denture base material that has been cured. 
     Second Preferred Embodiment 
     A second preferred embodiment of the present invention is similar to the first preferred embodiment expect that an adapter  130 , a denture mold  140 , and a holder  195 , which are used to manufacture a plate denture  10 , are respectively different from the adapter  30 , the denture mold  40 , and the holder  95  used in the first preferred embodiment. A plate denture manufacturing method according to the second preferred embodiment, which uses the adapter  130 , the denture mold  140 , and the holder  195 , will also achieve effects similar to those achieved by the plate denture manufacturing method according to the first preferred embodiment. In the following description of the second preferred embodiment, components similar to those of the first preferred embodiment will be identified by the same reference signs, and description thereof will be omitted or simplified when redundant. 
       FIG. 22  is a perspective view of the denture mold  140  according to the second preferred embodiment. A denture mold preparing step (step S 20 ) according to the second preferred embodiment includes preparing the denture mold  140 . The denture mold  140  is different in structure from the denture mold  40  but is similar in, for example, usage, function, and material to the denture mold  40 . The denture mold  140  is indirectly attachable to a cutting apparatus  60  (see  FIG. 12 ) through the adapter  130  (see  FIG. 28 ). 
     As illustrated in  FIG. 23 , the denture mold  140  has a circular shape in plan view. The denture mold  140  includes a bottom wall  145 , a first side wall  141 , a second side wall  142 , a third side wall  143 , and a fourth side wall  144 . The bottom wall  145  includes a flat surface. The first side wall  141  extends upward from the rear portion of the bottom wall  145 . The second side wall  142  extends upward from the front portion of the bottom wall  145 . The first side wall  141  and the second side wall  142  face each other. The third side wall  143  extends upward from the left portion of the bottom wall  145 . The third side wall  143  connects the left end of the first side wall  141  with the left end of the second side wall  142 . The third side wall  143  is curved away from the fourth side wall  144 . The fourth side wall  144  extends upward from the right portion of the bottom wall  145 . The fourth side wall  144  connects the right end of the first side wall  141  with the right end of the second side wall  142 . The fourth side wall  144  is curved away from the third side wall  143 . The third side wall  143  and the fourth side wall  144  face each other. The first side wall  141  includes an upper surface  141 A. The second side wall  142  includes an upper surface  142 A. The third side wall  143  includes an upper surface  143 A. The fourth side wall  144  includes an upper surface  144 A. The upper surfaces  141 A,  142 A,  143 A, and  144 A are flush with each other. The upper surfaces  141 A to  144 A are thus equal in height from the bottom wall  145 . In the present preferred embodiment, the first to fourth side walls  141  to  144  are each an example of a side wall extending upward from the bottom wall  145 . 
     As illustrated in  FIG. 22 , the denture mold  140  includes an opening  47  and a forming space  48 . The forming space  48  is surrounded by the bottom wall  145 , the first side wall  141 , the second side wall  142 , the third side wall  143 , and the fourth side wall  144 . 
     As illustrated in  FIG. 23 , the bottom wall  145  includes a cutting target region  155  that is to be cut by the cutting apparatus  60  (see  FIG. 12 ) so as to define grooves  46 A (see  FIG. 16 ) for artificial teeth  15 , and a plurality of vent holes  158  (see also  FIG. 22 ) passing through the bottom wall  145  in an up-down direction and in communication with the forming space  48 . The grooves  46 A are defined in the cutting target region  155  in step S 30 . The cutting target region  155  has an arc shape. The cutting target region  155  is located to surround inner vent holes  158 A (which will be described below). The vent holes  158  include the inner vent holes  158 A defined in the central region of the bottom wall  145  in plan view, and outer vent holes  158 B defined outward of the cutting target region  155  in plan view. Some of the inner vent holes  158 A are located inward of the cutting target region  155  and at least partially rearward of a straight line LL passing through the right and left front ends of the cutting target region  155 . All of the inner vent holes  158 A may be located inward of the cutting target region  155 . In the present preferred embodiment, the bottom wall  145  is provided with  29  inner vent holes  158 A and  18  outer vent holes  158 B. Alternatively, the bottom wall  145  may be provided with any other suitable number of inner vent holes  158 A and any other suitable number of outer vent holes  158 B. Although the inner vent holes  158 A are disposed radially in the present preferred embodiment, the inner vent holes  158 A may be disposed in any other suitable manner. The vent holes  158  may each have a diameter of between about 2 mm and about 4 mm, or a diameter of, for example, about 2.5 mm. The vent holes  158  may each have any other suitable diameter. The percentage of area of the bottom wall  145  occupied by the vent holes  158  (i.e., the percentage of opening area of the bottom wall  145 ) is between about 3% and about 8%, or may be, for example, between about 4% and about 5% inclusive. 
     As illustrated in  FIG. 22 , the denture mold  140  includes a retained portion  151  and a protrusion  152  (see  FIG. 24 ) extending downward from the retained portion  151 . The retained portion  151  is to be retained by the adapter  130 . The protrusion  152  is to be placed in a cut-out  138  (see  FIG. 29 ) of the adapter  130 . The cut-out  138  will be described below. The retained portion  151  is to be retained by the cutting apparatus  60  through the adapter  130 . As illustrated in  FIG. 23 , the retained portion  151  has a circular outer shape in plan view. The retained portion  151  is disposed along the first side wall  141 , the second side wall  142 , the third side wall  143 , and the fourth side wall  144  of the denture mold  140 . In other words, the retained portion  151  is disposed along the entire circumference of the denture mold  140 . The protrusion  152  is disposed on the front portion of the second side wall  142  and under the retained portion  151 . As illustrated in  FIG. 25 , the protrusion  152  extends forward from the second side wall  142 . The protrusion  152  includes a front surface  152 A (see  FIG. 24 ). The retained portion  151  includes a side surface  1515 . The front surface  152 A and the side surface  1515  are flush with each other. The protrusion  152  includes a first locked surface  152 B and a second locked surface  152 C to be locked by a body  132  (which will be described below) of the adapter  130 . 
       FIG. 26  is a perspective view of the holder  195  according to the second preferred embodiment. A denture mold placing step (step S 40 ) according to the second preferred embodiment includes placing, on the holder  195 , the denture mold  140  in which the grooves  46 A have been cut. The denture mold  140  is placed on the holder  195  so as to close the vent holes  158  defined in the bottom wall  145  of the denture mold  140 . The holder  195  is different in structure from the holder  95  but is similar in, for example, usage, function, and material to the holder  95 . 
     As illustrated in  FIG. 26 , the holder  195  has a substantially circular cylindrical shape. The holder  195  includes an upper surface  195 A provided with a recess  196  recessed downward.  FIG. 27  is a perspective view of the holder  195 , with the denture mold  140  placed on the holder  195 . As illustrated in  FIG. 27 , the denture mold  140  is fitted into the recess  196 . The recess  196  conforms to the outer shape of the denture mold  140 . The bottom of the denture mold  140  is fitted into the recess  196 . With the denture mold  140  fitted into the recess  196 , a lower surface  151 A (see  FIG. 25 ) of the retained portion  151 , for example, is in contact with the upper surface  195 A of the holder  195 . As illustrated in  FIG. 26 , the recess  196  includes a first portion  196 A that comes into contact with the bottom wall  145  of the denture mold  140 , a second portion  196 B that comes into contact with the protrusion  152 , and a third portion  196 C that comes into contact with the lower ends of the first to fourth side walls  141  to  144  of the denture mold  140 . The second portion  196 B is located above the first portion  196 A. The recess  196  (or more specifically, the third portion  196 C) has a depth of, for example, between about 5 mm and about 20 mm. In the example illustrated in  FIG. 27 , the grooves  46 A defined in the bottom wall  145  are not illustrated. 
       FIG. 28  is a plan view of the adapter  130  according to the second preferred embodiment. The denture mold cutting step (step S 30 ) and one-piece product machining step (step S 70 ) according to the second preferred embodiment involve attaching the denture mold  140  to the adapter  130 . The denture mold  140  is retained by the cutting apparatus  60  through the adapter  130 . The adapter  130  is a fixture to attach the denture mold  140  to the cutting apparatus  60 . The adapter  130  includes the body  132  and a retaining plate  137 . The body  132  is an example of the first structure. The retaining plate  137  is an example of the second structure. The denture mold  140  is clamped between the body  132  and the retaining plate  137 . The retained portion  151  of the denture mold  140  is retained by the adapter  130 . 
     As illustrated in  FIG. 29 , the body  132  has an arc shape. The body  132  retains the denture mold  140  from below. The body  132  includes the cut-out  138 . An opening  132 H is defined in the body  132 . The opening  132 H is continuous with the cut-out  138 . As illustrated in  FIG. 30 , the forming space  48  (see also  FIG. 22 ) of the denture mold  140  is disposed in the opening  132 H. As illustrated in  FIGS. 31 and 32 , the protrusion  152  of the denture mold  140  is disposed in the cut-out  138 . In this state, the first and second locked surfaces  152 B and  152 C of the protrusion  152  are locked by the body  132 . 
     As illustrated in  FIG. 29 , the retaining plate  137  has an annular outer shape. The retaining plate  137  is detachably attached to the body  132 . The retaining plate  137  presses the denture mold  140  against the body  132  from above. An opening  137 H is defined in the retaining plate  137 . The forming space  48  (see  FIG. 22 ) of the denture mold  140  is disposed in the opening  137 H. The retaining plate  137  is fastened to the body  132  with screws  139 , but the denture mold  140  is not fastened to the body  132  with the screws  139 . As illustrated in  FIG. 31 , the body  132  and the retaining plate  137  are fastened to each other with the screws  139 , with the denture mold  140  retained by the body  132  and pressed by the retaining plate  137 . The retained portion  151  of the denture mold  140  is thus clamped between the body  132  and the retaining plate  137 . In the present preferred embodiment, the denture mold  140  is stably retained by the adapter  130 . Placing the protrusion  152  in the cut-out  138  facilitates the positioning of the denture mold  140  with respect to the adapter  130 . Consequently, the denture mold  140  is prevented from being attached to the adapter  130  in a wrong direction. 
     The manufacturing method according to the present preferred embodiment includes providing the vent holes  158  including the inner vent holes  158 A defined in the central region of the bottom wall  145  in plan view, and disposing the arc-shaped cutting target region  155  such that the cutting target region  155  surrounds the inner vent holes  158 A. Bubbles produced during curing of the denture base material tend by nature to be large in number in the central region of the denture mold  140 . Accordingly, providing the inner vent holes  158 A in the central region of the bottom wall  145  of the denture mold  140  allows the bubbles to be more reliably discharged out of the denture mold  140 . 
     The manufacturing method according to the present preferred embodiment includes providing the vent holes  158  including the outer vent holes  158 B disposed outward of the cutting target region  155  in plan view. This allows bubbles to be discharged out of an entirety of the denture mold  140 . 
     The denture mold cutting step of the manufacturing method according to the present preferred embodiment includes disposing the protrusion  152  of the denture mold  140  in the cut-out  138  of the adapter  130  so as to attach the denture mold  140  to the adapter  130  and then indirectly attach the denture mold  140  to the cutting apparatus  60  through the adapter  130 . The cut-out  138  and the protrusion  152  thus facilitate the positioning of the denture mold  140  with respect to the adapter  130 . 
     The preferred embodiments of the present invention have been described thus far. The preferred embodiments described above, however, are only illustrative. The present invention may be embodied in various other forms. 
     The manufacturing methods according to the first and second preferred embodiments described above involve using the denture molds  40  and  140 , respectively, so as to manufacture the plate denture  10  that is a complete denture for the upper jaw. The manufacturing methods disclosed herein may be used to manufacture any other type of denture. The manufacturing methods disclosed herein may be used to manufacture, for example, a complete denture for the lower jaw or a partial denture. The manufacturing methods disclosed herein may be used to manufacture a “non-clasp denture” made of, for example, highly elastic thermoplastic resin and including no metal clasp. The denture molds  40  and  140  may each be made of any suitable material and may each have any suitable shape. 
     In the first preferred embodiment described above, the vent holes  58  are defined in the bottom wall  45 . Alternatively, the vent holes  58  may be defined at any other location or locations on the denture mold  40 . In one example, the vent holes  58  may be defined in at least one of the first to fourth side walls  41  to  44  in addition to the bottom wall  45 . In this case, the holder  95  has a shape that is able to close the vent holes  58  defined in the bottom wall  45  and at least one of the first to fourth side walls  41  to  44 . In another example, the vent holes  58  may be defined in at least one of the first to fourth side walls  41  to  44  instead of the bottom wall  45 . In this case, the holder  95  has a shape that is able to close the vent holes  58  defined in at least one of the first to fourth side walls  41  to  44 . In the second preferred embodiment described above, the vent holes  158  are defined in the bottom wall  145 . Alternatively, the vent holes  158  may be defined at any other location or locations on the denture mold  140 . In one example, the vent holes  158  may be defined in at least one of the first to fourth side walls  141  to  144  in addition to the bottom wall  145 . In this case, the holder  195  has a shape that is able to close the vent holes  158  defined in the bottom wall  145  and at least one of the first to fourth side walls  141  to  144 . In another example, the vent holes  158  may be defined in at least one of the first to fourth side walls  141  to  144  instead of the bottom wall  145 . In this case, the holder  195  has a shape that is able to close the vent holes  158  defined in at least one of the first to fourth side walls  141  to  144 . 
     The terms and expressions used herein are for description only and are not to be interpreted in a limited sense. These terms and expressions should be recognized as not excluding any equivalents to the elements shown and described herein and as allowing any modification encompassed in the scope of the claims. The present invention may be embodied in many various forms. This disclosure should be regarded as providing preferred embodiments of the principles of the present invention. These preferred embodiments are provided with the understanding that they are not intended to limit the present invention to the preferred embodiments described in the specification and/or shown in the drawings. The present invention is not limited to the preferred embodiments described herein. The present invention encompasses any of preferred embodiments including equivalent elements, modifications, deletions, combinations, improvements and/or alterations which can be recognized by a person of ordinary skill in the art based on the disclosure. The elements of each claim should be interpreted broadly based on the terms used in the claim, and should not be limited to any of the preferred embodiments described in this specification or used during the prosecution of the present application. 
     While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.