Work model for prosthetic restoration of dental stump and method for manufacturing a work model

Abstract

The invention relates to a working model for dental restoration of a dental stump, comprising a model mandible (1) with teeth made of resin by 3D printing and a detachable model dental stump (4). The model dental stump (4) comprises a body (5) made of resin by 3D printing and a rigid insert (6) introduced into a housing formed in the body (5). First fixing means (8a, 8b) comprised in the rigid insert (6) cooperate with second fixing means (9a, 9b) passing through through-holes (10a, 10b) made in the model mandible (1) with teeth for integrally attaching the model dental stump (4) to the model mandible (1) with teeth in a detachable manner.

Description

Technical Field

[0001] This invention includes the field of denture restoration.

[0002] More specifically, the present invention relates to a working model for prosthetic restoration of tooth roots, the type of which includes:

[0003] - A model mandible with teeth, made of resin by 3D printing, including at least one toothless space corresponding to a missing tooth in the model mandible with teeth, and at least one cavity facing the toothless space.

[0004] - A model tooth remnant placed in the toothless space, the model tooth remnant being detachably connected to the model mandible having teeth, the model tooth remnant comprising a first end detachably introduced into the cavity and a second end extending from the first end and in the form of a tooth remnant.

[0005] The present invention also relates to a method for manufacturing a working model. Background Technology

[0006] The working models of the type described above involved in this invention are particularly suitable for prosthetic restorations, such as crowns, to be placed on tooth remnants previously operated on in a patient's mouth. The tooth remnant is a natural tooth in the patient's mouth that has been mechanically shaped (usually with a dental drill) to remove the upper portion of the tooth, leaving only the portion protruding from the gum line. This portion is appropriately shaped to receive the prosthesis, thereby restoring the shape of the original tooth. The prosthesis is typically a custom-made ceramic piece in the laboratory such that when the prosthesis is fitted and cemented to the tooth remnant, it fits perfectly with the remaining teeth in the patient's mandible. For prosthetic restorations to be performed in the laboratory, a physical working model is used that precisely replicates the shape of a patient's mandible, or a portion thereof, with all teeth, including the tooth remnant to which the prosthesis will be placed. This working model comprises at least two parts: a mandibular model with teeth, having a dentitionless space corresponding to a tooth remnant; and a model tooth remnant detachably connected to the mandibular model, occupying the dentitionless space, such that these two interconnected parts accurately replicate the patient's mandible. As a result of this two-part configuration, technicians performing prosthesis restorations in the laboratory can remove the model tooth remnant and place it in another support for more comfortable prosthesis placement on the model tooth remnant, without obstruction from the teeth of the adjacent mandibular model. Therefore, technicians can repeatedly move the model tooth remnant between this other support and the mandibular model for testing purposes.

[0007] This two-part working model could be made from plaster based on a physical impression taken from the patient's mandible. However, current technology allows the working model to be made from resin via 3D printing. For this purpose, the patient's mandible is scanned, for example, using an intraoral scan with a specific camera, to obtain a dataset that precisely defines the geometry of the patient's mandible. This appropriately processed dataset is then used to manufacture the two parts of the working model from resin via 3D printing.

[0008] This invention relates to the latter technique, namely, 3D printing of working models made of resin.

[0009] One challenge arising from using this 3D printing technology is achieving a precise connection between the two parts—the model mandible with teeth and the model tooth remnants—so that when joined, they accurately replicate the geometry of the patient's actual mandible. Achieving this precision is crucial because it determines whether the lab-made prosthesis, once placed on the patient's actual tooth remnants, will fit perfectly with the patient's real mandible. An imprecise connection between the two parts hinders accurate replication of the geometry, even though that geometry is correctly defined in the dataset.

[0010] Known solutions involve 3D printing corresponding shapes, such as guides and bevels, into the joining area of ​​the two parts of a working model made of resin, which helps improve the joining accuracy between the two parts. EP2538869B1 and WO2019202110A1 disclose various solutions of this type.

[0011] US2013216980A1 discloses a solution in which a serpentine member is formed as an integral part of a cavity in a model mandible. When the first end of a model tooth root remnant is introduced into the cavity, the serpentine member is deflected, generating interfacial forces that laterally push the first end against the corresponding shape of the cavity to ensure the correct positioning of the model tooth root remnant. The model tooth root remnant is then secured to the model mandible by screws passing through a through-hole in the mandible.

[0012] Specific difficulties include the shrinkage of the resins used for 3D printing (especially photosensitive resins), which results in slight deviations in the geometry of the manufactured part compared to the theoretical geometry defined in the dataset. This shrinkage occurs after the workpiece is manufactured via 3D printing and is difficult to predict because it depends on many factors, such as exposure time, light intensity, the density of the cured resin, the type of post-processing applied to the resin, the characteristics of the 3D printer used, and the typical properties of the resin. Despite the known solutions discussed above, this shrinkage still occurs and negatively impacts the accuracy of the joins between parts. Summary of the Invention

[0013] The purpose of this invention is to provide a working model for prosthetic restoration of the aforementioned type of tooth remnant, wherein the connection between the mandible with teeth and the tooth remnant is more precise, thereby ensuring more accurate positioning of the tooth remnant, and all of this does not significantly complicate the work of technicians in the laboratory.

[0014] This objective is achieved through a working model for prosthetic restoration of the aforementioned type of tooth remnant; wherein the model tooth remnant includes at least a first fixation device that cooperates with a complementary second fixation device for detachably attaching the model tooth remnant integrally to a toothed model mandible when the first end is introduced into a cavity; the toothed model mandible includes at least one through-hole aligned with the first fixation device; and the second fixation device passes through the through-hole to cooperate with the first fixation device;

[0015] The model tooth remnant is characterized by comprising a body made of resin by 3D printing and a rigid insert including at least a first fixing device. The body includes a first end and a second end of the model tooth remnant. The rigid insert is introduced into a shell formed at the first end in the body, and the rigid insert is integrally attached to the body.

[0016] Unlike the resin used for 3D printing, the rigid insert is a component that does not undergo the typical shrinkage of the resin. This shrinkage occurs only in the two parts made of resin by 3D printing, namely, the mandible model with teeth and the body of the model tooth remnant, and not in the rigid insert that maintains its geometry. The model tooth remnant with the rigid insert is detachably attached integrally to the mandible model with teeth via the rigid insert, whose shape remains unchanged. Therefore, the change in the relative position of the model tooth remnant attached to the mandible model with teeth due to resin shrinkage is significantly reduced, resulting in better attachment accuracy. Furthermore, under the action of the first and second fixing devices that cooperate with each other, the model tooth remnant remains integrally attached to the mandible model with teeth, and therefore it cannot withstand accidental changes in its position, for example, due to accidental impacts during laboratory technician work. Unlike the known solutions described above, the solution according to the invention prevents the positioning of the model tooth remnant from being based solely on the matching of the geometries formed in the two parts made of resin by 3D printing, a matching that can lead to misalignment due to resin shrinkage. Furthermore, laboratory technicians can freely attach and detach the two parts as a whole by applying force to the fixing device.

[0017] Although it is conceivable that the rigid insert is made of different materials so that it does not undergo significant geometric changes, in a preferred embodiment, the rigid insert is metallic, preferably made of an iron alloy, such as steel.

[0018] Preferably, the rigid insert includes two of the first fixation devices, and the mandibular model with teeth includes two of the through-holes, each through-hole aligned with one of the first fixation devices in the rigid insert, and the through-holes in the mandibular model with teeth are arranged such that the axis of the first through-hole is in the crown direction, and the axis of the second through-hole is in a direction other than the crown direction. More preferably, the axis of the second through-hole in the mandibular model with teeth is in the vestibular-lingual direction. This configuration allows for particularly precise positioning of the mandibular model tooth remnants when they are integrally attached to the mandibular model with teeth by means of fixation devices. Furthermore, the crown direction provides easy access from the lower region of the mandibular model with teeth, and the vestibular-lingual direction similarly provides easy access from the anterior region.

[0019] Different mechanical solutions for manufacturing the fixation device can be envisioned. For example, a fixation device based on a quick-closing system can be envisioned, which acts on a rod that pulls a rigid insert. In a preferred embodiment, the first fixation device is a threaded hole in the rigid insert, and the second fixation device is a screw, preferably a metal screw, passing through a through-hole in the mandible of the toothed model and screwed into the threaded hole in the rigid insert. The advantage of this solution is that it does not require the complex shape of the mandible model with teeth. Providing a support for the head of the screw is sufficient.

[0020] Preferably, when the rigid insert is introduced into the housing, the first fixing device of the rigid insert is positioned inside the housing of the main body, and the main body includes at least one straight through-hole aligned with the through-hole of the mandible model with teeth and the first fixing device in the rigid insert, such that a second fixing device passes through the through-hole of the mandible model with teeth and through the through-hole of the main body to engage with the first fixing device in the rigid insert. Manufacturing a main body with this configuration by 3D printing is not difficult. This configuration facilitates the integral attachment of the rigid insert to the main body.

[0021] Preferably, the rigid insert is fully incorporated into the housing of the body, such that the rigid insert does not protrude from the housing. This configuration prevents interference between the rigid insert and the cavity in the mandible of the toothed model, which simplifies the shape of the cavity.

[0022] In a preferred embodiment, the housing is a hollow portion formed in the body, such that when the first end is introduced into the cavity of the mandible of the model tooth with teeth, the rigid insert is introduced into the housing from the first end of the model tooth remnant root by translation in a direction corresponding to the crown direction. This configuration facilitates the fabrication of the housing within the body and also results in the rigid insert and housing being protected when the model tooth remnant root is attached to the model mandible with teeth.

[0023] Preferably, the rigid insert has a shape complementary to the shape of the housing in the body, such that the rigid insert is inserted snugly into the housing, and the complementary shape prevents the rigid insert from rotating relative to the housing. This facilitates the assembly of the rigid insert in the housing and prevents positioning errors. More preferably, the rigid insert has a cylindrical shape with planar sides, and the housing has a cylindrical shape with planar sides that is complementary to the shape of the rigid insert.

[0024] Different solutions for integrally attaching the rigid insert to the body are conceivable. For example, the rigid insert can be introduced into the housing under high pressure. In a preferred embodiment, the rigid insert is introduced into the housing of the body and integrally attached to the body by an adhesive (e.g., a contact adhesive in the form of a liquid or gel).

[0025] The present invention also relates to a method for manufacturing the above-mentioned working model, comprising the following steps:

[0026] - Scan all or part of the patient's mandible with teeth, said all or part including at least one tooth root remnant, and as a result of said scan, obtain at least one raw dataset that defines the geometry of said all or part of the mandible with teeth.

[0027] - Create a first processing dataset and a second processing dataset from the at least one original dataset, the first processing dataset defining the geometry of a model mandible with teeth, including a toothless space, a cavity, and at least one through hole, and the second processing dataset defining the geometry of the body of a model tooth root, including a shell and, where appropriate, a through hole; such that when a first end is introduced into the cavity, the assembly formed by the model mandible with teeth and the body of the model tooth root has a geometry corresponding to the geometry of the mandible with teeth, which is all or part of the teeth, as defined in the at least one original dataset;

[0028] -The mandible with teeth is manufactured from resin by 3D printing based on the first processed dataset;

[0029] -The main body is manufactured from resin by 3D printing based on the second processed dataset;

[0030] - Provide a rigid insert that is introduced into the housing of the body and integrally attached to the body;

[0031] - Provide at least a second fixing device.

[0032] The main body of the mandible model with teeth and the model tooth remnants can be made of the same resin or different resins. Preferably, they are made of the same resin and preferably using the same 3D printer.

[0033] The present invention also includes other detailed features shown in the following detailed description and accompanying drawings of embodiments of the invention. Attached Figure Description

[0034] The advantages and features of the invention will be apparent from the following description, in which preferred embodiments of the invention are described in a non-limiting manner with reference to the accompanying drawings, relative to the scope of the main claims.

[0035] Figure 1 It is an exploded perspective view showing a model mandible with teeth, model tooth remnants, and a second fixation device in the form of screws.

[0036] Figure 2 It is similar to Figure 1 A perspective view, but the parts are assembled together.

[0037] Figure 3 It is a partial cross-sectional side view of a mandible model with teeth.

[0038] Figure 4 It is similar to Figure 3 The view shows the model tooth remnant connected to the model mandible with teeth, and integrally attached to the model mandible via first and second fixation devices in the form of threaded holes and screws.

[0039] Figure 5 It is an exploded perspective view of the model tooth root formed by the main body and rigid inserts.

[0040] Figure 6 It is a frontal perspective view of the bottom of a model mandible with teeth.

[0041] Figure 7 , 8 9 and 9 are perspective, side view, and partial cross-sectional side view of the model tooth root formed by the main body and the rigid insert introduced into the shell, respectively.

[0042] Figure 10 , 11 12 and 13 are the side view, front view, and bottom view of the main body, respectively.

[0043] Figure 13 , 14 15 and 16 are the side view, cross-sectional side view, perspective view, and bottom view of the rigid insert, respectively. Detailed Implementation

[0044] The working model depicted in the attached figures was used in the laboratory for prosthetic restoration of tooth remnants and partially replicated the patient's mandible, including teeth and tooth remnants. The working model consists of two main parts: a model mandible 1 with teeth and a model tooth remnant 4 detachably connected to the model mandible 1 with teeth. Figure 2 The two parts, 1 and 4, are shown to be interconnected.

[0045] like Figure 1-3 As shown in Figure 6, the mandibular model 1 with teeth includes teeth, a toothless space 2 corresponding to the absence of teeth in the mandibular model 1, and a cavity 3 facing the toothless space 2. A straight through-hole 10a is formed on the lower surface of the mandibular model 1 with teeth, the through-hole 10a leading to the cavity 3 and its axis being in the crown direction Z. Another straight through-hole 10b is formed on the anterior surface of the mandibular model 1 with teeth, the through-hole 10b leading to the cavity 3 and its axis being in the vestibular-lingual direction Y. The two through-holes 10a, 10b have a first outer segment, followed by a second inner segment with a diameter smaller than the first outer segment. The diameter difference between the two segments forms a support shoulder for the screw heads constituting the second fixing devices 9a, 9b, which will be described below. The mandibular model 1 with teeth is a monolithic resin part manufactured by 3D printing. For example, for 3D printing, a 3D printer with SLA (stereolithography) technology is used, and the resin is a photosensitive resin that hardens when exposed to ultraviolet light.

[0046] from Figure 5 and 7 As can be seen in -9, the model tooth root 4 is formed by a body 5 and a rigid insert 6 introduced into a shell 7 formed in the body 5.

[0047] The main body 5 is a monolithic resin part manufactured by 3D printing. Preferably, the main body 5 is manufactured using the same 3D printer and the same resin as the mandibular model 1 with teeth. The main body 5 forms a first end 4a of the model tooth root 4 and a second end 4b extending from the first end 4a and in the form of a tooth root. The first end is detachably inserted into the cavity 3 of the mandibular model 1 with teeth, and the second end corresponds to a real tooth root in the patient's mandible. The first end 4a has an external shape corresponding to the internal shape of the cavity 3, such that the first end fits snugly within the cavity. Figure 10-12As shown, the shell 7 in the main body 5 is hollow, formed at the first end 4a and opening to the lower surface of the first end 4a opposite to the second end 4b. The shell 7 has a cylindrical shape with flat sides 13. When the first end 4a is introduced into the cavity 3, the central axis of the cylindrical shape has a direction corresponding to the crown direction Z. The main body 5 also includes a straight through hole 11b in the front wall, which leads to the shell 7, and when the first end 4a is introduced into the cavity 3, the through hole 11b is aligned with the through hole 10b of the mandible 1 of the model with teeth.

[0048] The rigid insert 6 is a single piece, preferably made of metal. For example, the rigid insert 6 is made of steel. Figure 13-16 As can be seen, the rigid insert 6 has a cylindrical shape with flat walls 12. The shape of the rigid insert 6 is complementary to the shape of the housing 7 in the body 5, such that the rigid insert 6 is inserted into the housing 7 by translation along the axial direction of the cylindrical shape of the housing 7. The complementary planes 12 and 13 prevent the rigid insert 6 from rotating relative to the housing 7. In this embodiment, the rigid insert 6 includes two first fixing devices 8a and 8b, each being a threaded hole. The first fixing device 8a is a threaded hole opening on the lower surface of the rigid insert 6, coaxial with the axis of the cylindrical shape of the insert. The other first fixing device 8b is a threaded hole opening on the side cylindrical surface of the rigid insert 6, with its axis perpendicular to the axis of the cylindrical shape of the insert.

[0049] from Figure 4 and 9 As can be seen, the rigid insert 6 is fully introduced into the housing 7, so that the rigid insert does not protrude from the housing 7. The first fixing device 8b (in this case, a threaded hole) is aligned with the through hole 11b of the first body 5. The rigid insert 6 introduced into the housing 7 is integrally attached to the body 5 by an adhesive disposed in the gap space between the outer wall of the rigid insert 6 and the wall of the housing 7. For example, a contact adhesive in liquid or gel form can be used.

[0050] like Figure 4 As shown, when the first end 4a of the model tooth root 4 is introduced into the cavity 3, each of the two first fixing devices 8a, 8b (in this case, threaded holes) of the rigid insert 6 is aligned with one of the through holes 10a, 10b of the model mandible 1 with the tooth. Furthermore, the first fixing device 8b and the through hole 10b are aligned with the through hole 11b of the body 5.

[0051] Two second fixation devices 9a and 9b, respectively cooperating with the two first fixation devices 8a and 8b, are used to detachably attach the model tooth root 4 integrally to the model mandible 1 with teeth when the first end 4a is introduced into the cavity 3. In the example shown, the two second fixation devices 9a and 9b are screws screwed into the threaded holes of the rigid inserts 6 constituting the first fixation devices 8a and 8b. Each second fixation device 9a and 9b in screw form is introduced from the outside of the model mandible 1 with teeth and passes through one of the through holes 10a and 10b of the model. The second fixation device 9b in screw form also passes through the through hole 11b of the body 5.

[0052] The described working model is obtained through the method described below. A scan of the entire or partial mandible of a patient with teeth including at least one tooth root remnant is performed. This yields a raw dataset defining the geometry of the mandible with the teeth, either fully or partially. For example, this dataset is a file in STL (Standard Trigonometric Language) format. The data file can be any format other than STL, which can be read and interpreted by a 3D printer. From this raw dataset, a first processed dataset is created defining the geometry of the mandible 1 with teeth, including a toothless space 2, a cavity 3, and through-holes 10a and 10b. A second processed dataset is also created, defining the geometry of the body 5 of the model tooth root remnant 4, including a shell 7 and through-hole 11b. These two processing datasets are STL files, for example, STL files created using a 3D shape editing program. The program edits the original data STL file so that the mandible with teeth is cut and divided into two parts: a model mandible with teeth 1 and a body 5. All the necessary geometry for joining these two parts is created, namely the cavity 3, the first end 4a, the through holes 10a, 10b, and 11b, and the shell 7. In these processing data STL files, when the first end 4a is introduced into the cavity 3, the assembly formed by the model mandible with teeth 1 and the body 5 of the model tooth remnant 4 has a geometry corresponding to the geometry of the mandible with teeth defined in the original data STL file. The model mandible with teeth 1 and the body 5 are respectively manufactured from these first and second processing data STL files by 3D printing using resin. A rigid insert 6 is introduced into the shell 7 of the body 5 and integrally attached to the body by adhesive. Finally, screws constituting the second fixing devices 9a and 9b are provided.

Claims

1. A working model for dental restoration of tooth root remnants, the working model comprising: - A model mandible (1) with teeth, made of resin by 3D printing, includes at least one toothless space (2) and at least one cavity (3), the toothless space (2) corresponding to a missing tooth in the model mandible (1) with teeth, and the at least one cavity (3) facing the toothless space (2). - A model tooth root (4) is placed in the toothless space (2) and detachably connected to the model mandible (1) with teeth. The model tooth root (4) includes a first end (4a) detachably introduced into the cavity (3) and a second end (4b) extending from the first end (4a) and in the form of a tooth root. The model tooth root remnant (4) includes at least a first fixation device (8a, 8b) that cooperates with a complementary second fixation device (9a, 9b) for detachably attaching the model tooth root remnant (4) integrally to the toothed model mandible (1) when the first end (4a) is introduced into the cavity (3); the toothed model mandible (1) includes at least one through hole (10a, 10b) aligned with the first fixation device (8a, 8b); and the second fixation device (9a, 9b) passes through the through hole (10a, 10b) to cooperate with the first fixation device (8a, 8b); The model tooth root remnant (4) is characterized in that it comprises a body (5) and a rigid insert (6), the body (5) being made of resin by 3D printing and comprising a first end (4a) and a second end (4b), the rigid insert (6) comprising the at least first fixing device (8a, 8b), the rigid insert (6) being introduced into a housing (7) formed at the first end (4a) in the body (5), and the rigid insert (6) being integrally attached to the body (5). Furthermore, the rigid insert (6) includes two of the first fixing devices (8a, 8b), and the mandible (1) with teeth includes two of the through holes (10a, 10b), each through hole being aligned with one of the first fixing devices (8a, 8b) in the rigid insert (6). The through holes (10a, 10b) in the mandible (1) with teeth are arranged such that the axis of the first through hole (10a) is in the crown direction (Z), and the axis of the second through hole (10b) is in a direction different from the crown direction (Z).

2. The working model according to claim 1, characterized in that, The rigid insert (6) is made of metal.

3. The working model according to claim 1 or 2, characterized in that, The axis of the second through-hole (10b) in the mandible (1) of the model with teeth is in the vestibular-lingual direction (Y).

4. The working model according to claim 1, characterized in that, The first fixing device (8a, 8b) is a threaded hole in the rigid insert (6), and the second fixing device (9a, 9b) is a screw that passes through the through hole (10a, 10b) of the mandible (1) with teeth and is screwed into the threaded hole of the rigid insert (6).

5. The working model according to claim 1, characterized in that, When the rigid insert (6) is introduced into the housing (7), the first fixing device (8b) of the rigid insert (6) is positioned inside the housing (7), and the body (5) includes at least one straight through hole (11b) that is aligned with the through hole (10b) of the mandible (1) with teeth and the first fixing device (8b) in the rigid insert (6), such that the second fixing device (9b) passes through the through hole (10b) of the mandible (1) with teeth and through the through hole (11b) of the body (5) to engage with the first fixing device (8b) in the rigid insert (6).

6. The working model according to claim 5, characterized in that, The rigid insert (6) is fully inserted into the housing (7) such that the rigid insert (6) does not protrude from the housing (7).

7. The working model according to claim 1, characterized in that, The housing (7) is a hollow portion formed in the body (5) such that when the first end (4a) of the model tooth root (4) is introduced into the cavity (3), the rigid insert (6) is introduced into the housing from the first end (4a) by translation in a direction corresponding to the crown direction (Z).

8. The working model according to claim 1, characterized in that, The rigid insert (6) has a shape complementary to the shape of the housing (7) in the body (5), such that the rigid insert (6) is inserted into the housing (7) in close contact, and the complementary shape prevents the rigid insert (6) from rotating relative to the housing (7).

9. The working model according to claim 1, characterized in that, The rigid insert (6) has a cylindrical shape with planar sides, and the housing (7) has a cylindrical shape with planar sides that is complementary to the shape of the rigid insert (6).

10. The working model according to claim 1, characterized in that, The rigid insert (6) is integrally attached to the body (5) by an adhesive.

11. A method for manufacturing a working model according to any one of claims 1 to 10, comprising the following steps: - Scan all or part of the patient's mandible with teeth, said all or part including at least one tooth root remnant, and as a result of said scan, obtain at least one raw dataset that defines the geometry of said mandible with teeth, said all or part. - Create a first processing dataset and a second processing dataset from the at least one original dataset, the first processing dataset defining the geometry of the toothed model mandible (1), including the toothless space (2), the cavity (3) and the two through holes (10a, 10b), and the second processing dataset defining the geometry of the body (5) of the model tooth root (4), including the shell (7) and the through hole (11b) where appropriate; such that when the first end (4a) is introduced into the cavity (3), the assembly formed by the toothed model mandible (1) and the body (5) of the model tooth root (4) has a geometry corresponding to all or part of the geometry of the toothed mandible defined in the at least one original dataset; -The mandible with teeth was manufactured by 3D printing from resin according to the first processed dataset (1). -The main body (5) is manufactured by 3D printing from resin according to the second processed dataset; - Provide the rigid insert (6), introduce the rigid insert (6) into the housing (7) of the body (5), and attach the rigid insert (6) integrally to the body (5); - Provide the at least second fixing device (9a, 9b).

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