Method and apparatus for making and maintaining a lost wax pattern

Abstract

To provide a method for manufacturing a lost wax pattern capable of easily manufacturing the lost wax pattern.SOLUTION: The manufacturing method includes a designing step of designing a designed lost-wax pattern 21 having a provisional rest portion 211 having a size to form a gap S with respect to an inner peripheral wall 10A of a rest seat image 13A formed on a model image 131A, based on the model image 10A displayed on a display 4, a shaping step of three dimensionally shaping the designed lost-wax pattern 21, a hardening step of hardening the designed lost-wax pattern 21, and a correcting step of correcting the provisional rest portion 211 to a rest portion 201 suitable for a rest seat 13 by filling the gap S between the provisional rest portion 211 and the rest seat 13 with wax 22 in a state where the designed lost-wax pattern 21 is fitted to a model 10, thereby completing a lost-wax pattern 20.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a lost wax pattern and a device for maintaining the same.

[0002] A method for manufacturing a lost-wax pattern for casting a denture retainer is described in Patent Document 1. The manufacturing method in Patent Document 1 includes the steps of acquiring three-dimensional shape data of an intraoral model using a three-dimensional optical scanner, designing the shape of a metal base as a retainer based on the acquired three-dimensional shape data, and producing a wax model of the metal base based on the designed shape of the metal base. In the design step, the shape of the metal base is designed based on the three-dimensional shape data of the intraoral cavity using CAD functions. In the production step, a wax model is produced with a 3D printer using the shape data of the designed metal base. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 066101 Summary of the Invention [Problem to be solved by the invention]

[0004] The intraoral model is pre-formed with a rest seat into which the rest portion of the metal base fits. The rest seat is a recess carved into the occlusal surface, with a corner formed at the edge where it meets the occlusal surface. In the design process, the rest portion is designed to match the shape of the rest seat in the three-dimensional shape data.

[0005] When three-dimensional shape data of an intraoral model is acquired using a three-dimensional optical scanner, the corners of the rest seat in the three-dimensional shape data are missing edge data due to edge loss, resulting in a rounded shape. Therefore, the shape of the rest seat in the three-dimensional shape data, particularly the shape of the inner wall near the corners of the rest seat, differs from the shape of the rest seat in the intraoral model. Therefore, a rest portion designed based on the shape of the rest seat in the three-dimensional shape data is larger than the rest seat in the intraoral model and does not fit into the rest seat. For this reason, it is necessary to grind the rest portion of the wax model created with a 3D printer based on the designed shape to fit the rest seat. However, grinding the rest portion to fit perfectly into the rest seat is not easy.

[0006] In view of the above problems, an object of the present invention is to provide a method for manufacturing a lost-wax pattern that allows for easy production of the lost-wax pattern even when the lost-wax pattern is designed based on three-dimensional shape data of an intraoral cast, and a retention device cast using the lost-wax pattern manufactured by this manufacturing method. [Means for solving the problem]

[0007] In order to solve the above problems, the method of manufacturing a lost-wax pattern for casting a denture retainer of the present invention includes a photographing step of photographing an intraoral model of a patient, the model having a rest seat formed on an occlusal surface, with an imaging device to obtain image data of the model; an image processing step of processing the image data obtained in the photographing step to display the image data on a display device as a three-dimensional model image; a designing step of designing a designed lost-wax pattern based on the model image displayed on the display device, the designed lost-wax pattern having a temporary rest portion of a size that forms a gap with an inner peripheral wall of a rest seat image formed on the occlusal surface of the model image displayed on the display device when viewed from above and below; a molding step of three-dimensionally molding the designed lost-wax pattern based on design data of the designed lost-wax pattern designed in the designing step; and a hardening step of irradiating light onto the designed lost-wax pattern three-dimensionally molded in the molding step to harden the designed lost-wax pattern. and a modification process in which, with the hardened design lost-wax pattern fitted to the model, the gap between the temporary rest portion and the rest seat is filled with wax to modify the temporary rest portion into a rest portion that fits the rest seat, thereby completing the lost-wax pattern.

[0008] According to the present invention, the image data acquired in the imaging process is displayed on a display device, and a designed lost-wax pattern is designed based on the three-dimensional model image. The designed lost-wax pattern is then three-dimensionally molded based on the design data of the designed lost-wax pattern. This reduces the time and cost required to create the lost-wax pattern. Furthermore, even if the shape of the rest seat image in the model image differs from the shape of the rest seat in the patient's oral cavity model due to edge loss, the temporary rest portion is designed smaller than the rest seat image in the design process. Therefore, in the correction process, the temporary rest portion can be easily corrected to fit the rest seat by filling the gap between the temporary rest portion and the rest seat with wax. This reduces the time and cost required to create the lost-wax pattern compared to cutting the rest portion of the lost-wax pattern to fit the rest seat.

[0009] In the present invention, the hardening treatment step may include irradiating the designed lost-wax pattern with light while the designed lost-wax pattern is fitted into the model, thereby preventing deformation of the designed lost-wax pattern before hardening, and facilitating hardening of the designed lost-wax pattern as designed.

[0010] In the present invention, the hardening step may involve irradiating the designed lost-wax pattern with light while the model with the designed lost-wax pattern fitted therein is vacuum-packed, thereby making it easier to harden the designed lost-wax pattern as designed, since the designed lost-wax pattern and the model are in close contact with each other by vacuum-packing.

[0011] The present invention preferably further includes a blockout process for filling undercut portions of the model as a step preceding the photographing process. This allows the design lost-wax pattern to be designed based on a blockout-processed model image in the design process, thereby shortening the design time compared to when blockout processing is performed using a model image in the design process. Furthermore, since a blockout portion is formed in the model by the blockout process, the designed lost-wax pattern can be easily hardened as designed when the designed lost-wax pattern is fitted into the model and hardened, or when the model fitted with the designed lost-wax pattern is hardened in a vacuum-packed state. In particular, when the model fitted with the designed lost-wax pattern is hardened in a vacuum-packed state, the designed lost-wax pattern and the blockout portion are closely attached by the vacuum packing, making it easier to harden the designed lost-wax pattern as designed.

[0012] In the present invention, it is preferable to further include a surveying step of marking survey lines for designing the lost-wax pattern on the model as a step prior to the photographing step, whereby in the design step, the lost-wax pattern can be designed based on the model image on which the survey lines are displayed, making the design easier than when designing on a model image on which the survey lines are not displayed.

[0013] In the present invention, it is preferable to further include a relief step, prior to the photographing step, of relieving wax at a position on the model where the resin base of the denture will be located. This allows a lost-wax pattern to be designed in the design step based on the model image displaying the relief portion formed by wax, thereby shortening the design time compared to when the relief portion is designed on the model image in the design step. Since the model has a relief portion, when the designed lost-wax pattern is set into the model and hardened, or when the model with the designed lost-wax pattern set into it is hardened in a vacuum-packed state, the designed lost-wax pattern can be easily hardened as designed. In particular, when the model with the designed lost-wax pattern set into it is hardened in a vacuum-packed state, the designed lost-wax pattern and the relief portion are closely attached by the vacuum packing, making it easier to harden the designed lost-wax pattern as designed.

[0014] The denture retainer of the present invention is cast using a lost-wax pattern manufactured by the above-mentioned lost-wax pattern manufacturing method. In this way, since the retainer is cast using a precisely manufactured lost-wax pattern, a precise retainer can be obtained without modifying the retainer. [Effects of the Invention]

[0015] The lost-wax pattern manufacturing method of the present invention makes it easy to produce a precise lost-wax pattern. Furthermore, a retaining device cast using the lost-wax pattern manufactured by this manufacturing method can be obtained with precision without modifying the retaining device. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram showing an example of a denture equipped with a retention device of this embodiment. [Figure 2] FIG. 1 is a schematic diagram showing an example of a maintenance device according to an embodiment of the present invention. [Figure 3] FIG. 1 is a schematic diagram of a model of a patient's oral cavity. [Figure 4] 1 shows a schematic diagram of a lost wax pattern manufacturing system for casting the retaining device of this embodiment. [Figure 5] 1 is a flowchart illustrating a method for manufacturing a lost wax pattern according to the present embodiment. [Figure 6] FIG. 10 is a schematic diagram of a model image displayed on a display device. [Figure 7] FIG. 1 is a schematic diagram of a design lost-wax pattern designed based on a model image. [Figure 8] FIG. 10 is a plan view illustrating the relationship between the temporary rest portion of the design lost-wax pattern and the rest seat image. [Figure 9] 10 is a cross-sectional view illustrating the relationship between a temporary rest portion of a design lost-wax pattern and a rest seat image. FIG. [Figure 10] FIG. 1 is a schematic diagram illustrating hardening of a designed lost wax pattern using a light irradiation device. [Figure 11] 10 is a plan view illustrating the process of forming a rest portion of a lost wax pattern by modifying a temporary rest portion of a design lost wax pattern. FIG. [Figure 12] 10A and 10B are cross-sectional views illustrating the formation of a rest portion of a lost wax pattern by modifying a temporary rest portion of a design lost wax pattern. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] (Denture structure) FIG. 1 is a schematic diagram showing an example of a denture 15 equipped with a retention device 16 of this embodiment. FIG. 2 is a schematic diagram showing an example of a retention device 16 of this embodiment. The denture 15 of FIG. 1 is an example of a denture used for the lower jaw. As shown in FIG. 1, the denture 15 comprises a retention device 16, a resin base 17 fixed to the retention device 16, and an artificial tooth 18 fixed to the resin base 17. The retention device 16 is made of metal and is cast. As shown in FIGS. 1 and 2, the retention device 16 comprises a rest portion 161 that fits into the rest seat, a clasp portion 162 that fits onto the outer peripheral surface of the tooth portion on which the rest seat is formed, legs 163 that support the rest portion 161 and the clasp portion 162, and a connector 164 that connects the two legs 163. The rest portion 161 is designed to have a rattle-like shape relative to the rest seat. The leg portion 163 is located inside the resin base 17. The retention device 16 includes a retention device (metal base) made for self-paid treatment and a retention device made for insurance treatment.

[0019] (Model of the patient's mouth) FIG. 3 is a schematic diagram of a model 10 of a patient's oral cavity. The model 10 of FIG. 3 is an example of a mandible. The model 10 of FIG. 3 is made of plaster and is made at a dental clinic. The model 10 is made at a dental clinic by taking a concave mold from the patient's oral cavity using an impression material and pouring plaster or the like into the concave mold. The model 10 has multiple tooth portions 11 and a gum portion 14 that supports the tooth portions 11. Of the multiple tooth portions 11, tooth portion 110 that supports a portion of a denture 15 has a rest seat 13 on an occlusal surface 12. Prior to taking the concave mold, the rest seat 13 is formed in the patient's tooth as a recess into which the rest portion 161 of the denture 15 fits. Here, in the figure, the direction along the X-axis is the vertical direction, and the occlusal surface 12 faces vertically.

[0020] (Lost wax pattern manufacturing system) FIG. 4 shows a schematic diagram of a lost-wax pattern manufacturing system 1 for casting a retainer 16. The manufacturing system 1 includes an imaging device 2, a processing device 3, a display device 4, a printer 5, and a light irradiation device 6. The imaging device 2 captures an image of a patient's intraoral model 10 to acquire image data of the model. The imaging device 2 is a three-dimensional scanner. The processing device 3 processes the image data acquired by the imaging device 2 to display a three-dimensional model image on the display device. The processing device 3 is a computer. The processing device 3 also generates design data for a lost-wax pattern designed based on the model image displayed on the display device 4. The display device 4 is an LCD panel or the like. In this embodiment, the processing device 3 displays image data stored in an STL file as a model image on the display device 4 using three-dimensional CAD. The display device 4 is a tablet terminal integrated with the processing device 3. The processing device 3 performs various processes based on input from a touch pen or the like. The display device 4 may be separate from the processing device 3.

[0021] The printer 5 three-dimensionally models the designed lost-wax pattern based on the design data of the designed lost-wax pattern generated by the processing device 3. The printer 5 is a three-dimensional printer. The light irradiation device 6 irradiates the designed lost-wax pattern three-dimensionally modeled by the printer 5 with light to harden the designed lost-wax pattern. In this embodiment, the light irradiation device 6 hardens the designed lost-wax pattern by irradiating it with ultraviolet light.

[0022] (Lost wax pattern manufacturing) Next, the manufacturing of lost-wax patterns will be described. FIG. 5 is a flowchart illustrating a manufacturing method of a lost-wax pattern 20. FIG. 6 is a schematic diagram of a model image 10A displayed on the display device 4. FIG. 7 is a schematic diagram of a designed lost-wax pattern 21 designed based on the model image 10A. FIG. 8 is a plan view illustrating the relationship between the temporary rest portion 211 of the designed lost-wax pattern 21 and the rest seat image 13A. FIG. 9 is a cross-sectional view illustrating the relationship between the temporary rest portion 211 of the designed lost-wax pattern 21 and the rest seat image 13A. FIG. 10 is a schematic diagram illustrating the curing of the designed lost-wax pattern 21 using the light irradiation device 6. FIG. 11 is a plan view illustrating the modification of the temporary rest portion 211 of the designed lost-wax pattern 21 to form the rest portion 201 of the lost-wax pattern 20. FIG. 12 is a cross-sectional view illustrating the modification of the temporary rest portion 211 of the designed lost-wax pattern 21 to form the rest portion 201 of the lost-wax pattern 20.

[0023] A worker such as a dental technician creates a mandibular denture 1 shown in FIG. 1 based on the mandibular model 10 shown in FIG. 5. The worker may also fabricate a denture for the upper jaw based on the model of the upper jaw.

[0024] In the surveying step ST1 shown in Fig. 5, the worker surveys the model 10 as a preliminary step for capturing an image of the model 10 with the imaging device 2. As shown in Fig. 3, the worker marks survey lines 33 on the model 10 based on the shape of the model 10 to design a lost-wax pattern.

[0025] 5, the worker performs a blockout process on the model 10 as a preliminary step for capturing an image of the model 10 with the imaging device 2. As shown in FIG. 3, the worker fills in the undercut portion of the tooth portion 110 of the model 10 with wax or the like to form a blockout portion 31.

[0026] 5, the worker draws a design line 34, which is the outline of the holding device 16, as shown in Fig. 4, as a preliminary step to capturing an image of the model 10 with the imaging device 2. At this time, the design line 34 does not have to be the entire outline of the holding device 16.

[0027] 5, the worker performs a relief process on the model 10 as a preliminary step for capturing an image of the model 10 with the imaging device 2. As shown in FIG. 3, the worker relieves wax at a position on the gingival portion 14 of the model 10 where the resin base 17 of the denture 15 will be located, thereby forming a relief portion 32.

[0028] In a photographing step ST5 shown in Fig. 5, the imaging device 2 photographs the model 10 and acquires image data of the model 10. In an image processing step ST6 shown in Fig. 5, the processing device 3 processes the image data acquired by the imaging device 2 to display the image data as a three-dimensional model image 10A on the display device 4. At this time, in this embodiment, the image data is stored in a file in STL format. Note that the image data is not limited to the STL format.

[0029] As shown in FIG. 6, in the model image 10A displayed on the display device 4 by using a three-dimensional CAD or the like, the tooth portion 11 is displayed as a tooth portion image 11A, the gum portion 14 as a gum portion image 14A, the occlusal surface 12 as an occlusal surface image 12A, the rest seat 13 as a rest seat image 13A, the survey line 33 as a survey line image 33A, the block-out portion 31 as a block-out portion image 31A, the relief portion 32 as a relief portion image 32A, and the design line 34 as a design line image 34A.

[0030] In the design step ST7 shown in FIG. 5, the worker uses a three-dimensional CAD to design the design lost-wax pattern 21 (FIG. 7) based on the model image 10A (FIG. 6) displayed on the display device 4. In this embodiment, as shown in FIG. 5, the model image 10A displays a design line image 34A, allowing the worker to easily design the clasp portion 212 and the connector 214 of the design lost-wax pattern 21 based on the design line image 34A. As shown in FIGS. 8 and 9, in the design step ST7, the temporary rest portion 211 of the design lost-wax pattern 21 is designed to have a size that, when viewed from the top and bottom, forms a gap S with the inner peripheral wall 131 of the rest seat image 13A formed in the occlusal surface image 12A of the model image 10A displayed on the display device 4. That is, the temporary rest portion 211 does not contact the inner peripheral wall 131 of the rest seat image 13A, but contacts the bottom portion 132 of the rest seat image 13A. The clasp portion 212 , the leg portion 213 and the connector 214 of the designed lost-wax pattern 21 are designed to have the same shapes as the clasp portion 162 , the leg portion 163 and the connector 164 of the retainer 16 .

[0031] When the worker finishes designing the design lost-wax pattern 21, the worker saves the design data of the design lost-wax pattern 21 in the storage unit of the processing device 3. At this time, in this embodiment, the design data is stored in a file in STL format. However, the design data is not limited to the STL format.

[0032] In the modeling step ST8 shown in Fig. 5, the worker transmits the design data of the designed lost-wax pattern 21 stored in the processing device 3 to the printer 5. The printer 5 three-dimensionally models the designed lost-wax pattern 21 based on the design data of the designed lost-wax pattern 21. After three-dimensional modeling of the designed lost-wax pattern 21 is completed, the worker removes the support portions formed on the designed lost-wax pattern 21 during three-dimensional modeling, leaving only the designed lost-wax pattern 21. The worker then cleans the designed lost-wax pattern 21.

[0033] In the hardening process ST9 shown in FIG. 5, the worker fits the three-dimensionally shaped designed lost-wax pattern into the model 10 and places the model 10 with the designed lost-wax pattern 21 fitted into a translucent bag 8. The worker then removes the air from the bag 8 to create a vacuum, vacuum-packing the model 10. At this time, the bag 8 adheres to the model 10, so that the designed lost-wax pattern 21 adheres tightly to the model 10. Next, the worker uses the light irradiation device 6 to irradiate ultraviolet light onto the model 10 vacuum-packed in the bag 8, hardening the designed lost-wax pattern 21 (FIG. 10).

[0034] 5, the worker applies softened wax 22 between the temporary rest portion 211 and the rest seat 13 with the hardened design lost-wax pattern 21 fitted to the model, and fills the gap S between the temporary rest portion 211 and the rest seat 13 with the wax 22, thereby correcting the temporary rest portion 211 to a rest portion 201 that fits the rest seat 13 (FIGS. 11 and 12). Here, the shape of the inner peripheral wall 131A near the corner of the rest seat image 13A shown in FIG. 9 is different from the shape of the inner peripheral wall 131 near the corner of the rest seat 13 shown in FIG. 12 because the corner, which is the edge, is rounded due to edge loss.

[0035] When the wax 22 hardens, the temporary rest portion 211 and the wax 22 become one, forming the rest portion 201. This completes the lost-wax pattern 20 having the rest portion 201 that fits the rest seat 13. In other words, the lost-wax pattern 20 for casting the retainer 16 of the denture 15 is completed. Once the lost-wax pattern 20 is completed, it is removed from the model 10.

[0036] (Casting of maintenance device) The worker embeds the completed lost-wax pattern 20 in a refractory investment such as fireproof plaster, and then solidifies the refractory investment to form a retainer mold. Next, the retainer mold is heated in an electric furnace or the like to melt and pour out the lost-wax pattern 20 inside. Molten metal is then poured through a runner into the space formed by removing the lost-wax pattern 20 to cast the retainer 16. The metal used here is not particularly limited. Examples of metals that can be used include precious metal alloys such as gold alloys, base metal alloys such as cobalt-based alloys, and titanium alloys.

[0037] After casting is complete, the retainer 16 is removed from the retainer mold. The worker performs finishing processes such as cleaning and polishing on the removed retainer 16. The worker then places the resin base 17 and artificial teeth 18 on the retainer 16 to fabricate the denture 15 (Fig. 1).

[0038] (Action and effect) According to the manufacturing method of this embodiment, the image data acquired in the photographing step is displayed on the display device 4 as a three-dimensional model. The design lost-wax pattern 21 is designed based on the image 10A, and the design lost-wax pattern 21 is three-dimensionally molded based on the design data of the design lost-wax pattern 21, thereby reducing the time and cost required to produce the design lost-wax pattern 21 that becomes the lost-wax pattern 20. Even if the shape of the rest seat image 13A in the model image 10A differs from the shape of the rest seat 13 in the model 10 due to edge loss, the temporary rest portion 211 is designed to be smaller than the rest seat image 13A in the design process. Therefore, in the correction process, the gap S between the temporary rest portion 211 and the rest seat 13 can be easily filled with wax 22 to correct the temporary rest portion 211 to the rest portion 201 that fits the rest seat 13. This reduces the time and cost required to produce the lost-wax pattern compared to when the rest portion of the lost-wax pattern is trimmed to fit the rest seat.

[0039] In the hardening process, the designed lost-wax pattern 21 is irradiated with light while the designed lost-wax pattern 21 is fitted into the model 10. This prevents the designed lost-wax pattern 21 from being deformed before hardening, making it easier to harden the designed lost-wax pattern 21 as designed.

[0040] In the hardening process, the model 10 fitted with the designed lost-wax pattern 21 is vacuum-packed and then irradiated with light. This allows the designed lost-wax pattern 21 and the model 10 to adhere to each other by being vacuum-packed, making it easier to harden the designed lost-wax pattern 21 as designed.

[0041] The manufacturing method of this embodiment includes a blockout process, which fills in undercut portions of the model 10, prior to the photographing process. This allows the design lost-wax pattern 21 to be designed based on the blocked-out model image 10A during the design process, thereby shortening the design time compared to when the blockout process is performed on the model image 10A during the design process. Furthermore, because the blocked-out portion 31 is formed in the model 10 by the blockout process, the designed lost-wax pattern 21 can be easily hardened as designed when the designed lost-wax pattern 21 is fitted into the model 10 and hardened, or when the model with the designed lost-wax pattern 21 fitted into it is hardened in a vacuum-packed state. In particular, when the model with the designed lost-wax pattern 21 fitted into it is hardened in a vacuum-packed state, the designed lost-wax pattern 21 and the blocked-out portion 31 are in close contact with each other due to the vacuum packing, making it easier to harden the designed lost-wax pattern 21 as designed.

[0042] The manufacturing method of this embodiment includes a surveying step, which is a step preceding the photographing step, in which survey lines 33 for designing the lost-wax pattern 20 are drawn on the model 10. As a result, in the design step, the lost-wax pattern 21 can be designed based on the model image 10A on which the survey lines 33 are displayed, making the design easier than when designing on a model image 10A on which the survey lines 33 are not displayed.

[0043] The manufacturing method of this embodiment includes a relief step, prior to the photographing step, in which wax is relieved at a position on the model 10 where the resin base 17 of the denture 15 will be located. As a result, in the design step, the designed lost-wax pattern 21 can be designed based on the model image 10A displaying the relief portion 32 formed by wax, thereby shortening the design time compared to when the relief portion 32 is designed on the model image 10A in the design step. Furthermore, since the relief portion 32 is formed on the model 10, when the designed lost-wax pattern 21 is hardened while fitted into the model 10, or when the model 10 with the designed lost-wax pattern 21 fitted into it is hardened while vacuum-packed, the designed lost-wax pattern 21 can be easily hardened as designed. In particular, when the designed lost-wax pattern 21 is fitted into the model 10, When the molded model 10 is hardened in a vacuum-packed state, the designed lost-wax pattern 21 and the relief portion 32 are tightly attached by the vacuum packing, so that the designed lost-wax pattern 21 can be hardened more easily as designed.

[0044] The retainer 16 of the denture 15 of this embodiment is cast using the lost-wax pattern 20 manufactured by the above-mentioned manufacturing method. In this way, the retainer 16 is cast using the precisely manufactured lost-wax pattern 20, so that a precisely manufactured retainer 16 can be obtained without modifying the retainer 16.

[0045] (Variation) In the above embodiment, the lost-wax pattern is manufactured in the order of the staking step ST1, the block-out processing step ST2, the design line marking step ST3, and the relief step ST4, but the order of the staking step ST1 to the design line marking step ST4 is not limited to the above. That is, the staking step ST1 to the design line marking step ST4 may be performed in any order.

[0046] In the above embodiment, the worker performs the savaging step ST1, the blockout processing step ST2, the design line drawing step ST3, and the relief step ST4 on the model 10. However, the worker need not perform the steps from the savaging step ST1 to the design line drawing step ST4. Even in this case, since the temporary rest portion 211 is designed to be smaller than the rest seat image 13A in the design step, it is easy to modify the temporary rest portion 211 into the rest portion 201 that fits the rest seat 13 by filling the gap between the temporary rest portion 211 and the rest seat 13 with wax 22 in the modification step. This reduces the time and cost required to create a lost-wax pattern compared to when the rest portion of the lost-wax pattern is trimmed to fit the rest seat.

[0047] In the above embodiment, the worker performs the surviving step ST1, the blockout processing step ST2, the design line drawing step ST3, and the relief step ST4 directly on the model 10, but the worker may perform the same steps as the surviving step ST1 to the design line drawing step ST4 on the model image 10A. That is, the worker may use three-dimensional CAD to perform the same steps as the surviving step ST1 to the design line drawing step ST4 on the model image 10A based on the model image 10A displayed on the display device 4.

[0048] In the above embodiment, the modeling step ST8, the hardening step ST9, and the correction step ST10 include manual work by an operator. However, these manual steps may be replaced by robotic mechanical work. For example, in the modeling step ST8, the robot may remove the support portion formed on the designed lost-wax pattern 21 after removing the modeled designed lost-wax pattern 21 from the printer 5. In the hardening step ST9, the robot may fit the three-dimensionally modeled designed lost-wax pattern into the model 10, place the model 10 in a translucent bag 8, and then remove the air from the bag 8 to create a vacuum, thereby vacuum-packing the model 10. In the modification process ST10, the robot removes the model 10 from the bag 8, and with the hardened design lost-wax pattern 21 fitted to the model, applies softened wax 22 between the temporary rest portion 211 and the rest seat 13, filling the gap S between the temporary rest portion 211 and the rest seat 13 with the wax 22, thereby modifying the temporary rest portion 211 into a rest portion 201 that fits the rest seat 13.

[0049] The lost-wax pattern manufacturing method of this embodiment can be applied to both lost-wax patterns for retention devices (metal bases) made for self-paid treatment and lost-wax patterns for retention devices made for insurance-covered treatment. [Explanation of symbols]

[0050] 1...manufacturing system, 2...imaging device, 3...processing device, 4...display device, 5...printer, 6...light irradiation device, 8...bag, 10...model, 10A...model image, 11...tooth portion, 11A...tooth portion image, 12...occlusal surface, 12A...occlusal surface image, 13...rest seat, 13A...rest seat image, 14...gingiva portion, 14A...gingiva portion image, 15...denture, 16...retainer, 17...resin base, 18...artificial tooth, 20...lost wax pattern, 21...designed lost wax pattern, 22...wax, 3 1...blockout portion, 31A...blockout portion image, 32...relief portion, 32A...relief portion image, 33...survey line, 33A...survey line image, 34...design line, 34A...design line image, 110...tooth portion, 131·131A...inner wall, 132·132A...bottom portion, 161...rest portion, 162...clasp portion, 163...leg portion, 164...connector, 201...rest portion, 211...temporary rest portion, 212...clasp portion, 214...connector, S...gap.

Claims

1. 1. A method for producing a lost-wax pattern for casting a denture retainer, comprising: an imaging step of photographing a model of the patient's oral cavity, the model having a rest seat formed on an occlusal surface, with an imaging device to obtain image data of the model; an image processing step of processing the image data acquired in the photographing step to display the image data as a three-dimensional model image on a display device; a designing step of designing a lost-wax pattern based on the model image displayed on the display device, the lost-wax pattern having a temporary rest portion of a size such that a gap is formed between the temporary rest portion and an inner peripheral wall of the rest seat image formed on the occlusal surface of the model image displayed on the display device when viewed from above and below; a modeling step of three-dimensionally modeling the designed lost-wax pattern based on design data of the designed lost-wax pattern designed in the design step; a hardening process step of hardening the designed lost-wax pattern by irradiating the designed lost-wax pattern three-dimensionally fabricated in the fabrication process with light; a correction step of fitting the designed lost-wax pattern hardened in the hardening treatment step to the model, and filling the gap between the temporary rest portion and the rest seat with wax to correct the temporary rest portion into a rest portion that fits the rest seat, thereby completing the lost-wax pattern; A method for manufacturing a lost wax pattern comprising:

2. 2. The method for manufacturing a lost-wax pattern according to claim 1, wherein the hardening step comprises irradiating the designed lost-wax pattern with light while the designed lost-wax pattern is fitted into the model.

3. 3. The method for manufacturing a lost wax pattern according to claim 2, wherein the hardening step irradiates the designed lost wax pattern with light while the model with the designed lost wax pattern fitted therein is vacuum-packed.

4. 4. The method for manufacturing a lost wax pattern according to claim 1, further comprising a block-out process step of filling in undercut portions of the model as a preliminary step to the photographing process.

5. 4. The method for manufacturing a lost wax pattern according to claim 1, further comprising a surveying step of marking survey lines for designing the lost wax pattern on the model as a preliminary step to the photographing step.

6. 4. A method for manufacturing a lost wax pattern according to claim 1, further comprising a relief step of relieving wax at a position where the resin base of the denture will be located, as a preliminary step to the photographing step.

7. A denture retainer cast using a lost wax pattern produced by the method for producing a lost wax pattern according to claim 1.

Images