Phantom model of tooth with external root resorption and method for its manufacturing

Abstract

FIELD: dentistry.SUBSTANCE: intended for practicing manual endodontic treatment skills in students to improve the effectiveness of treating diseases of the periapical tissues of teeth. A phantom simulation model of a tooth with external root resorption is used, which includes a 3D-printed model of a tooth with a root canal having a hemispherical expansion at the root apex. In this case, the phantom simulation model of the tooth is made of transparent or radiopaque photopolymer resin, has a length of 30 mm with a red-colored canal system of 15 mm in length. In this case, the transparent model of the affected tooth is intended for the initial level of manual skill, and the opaque radiopaque model of the affected tooth is intended for the process of training in endodontic root canal treatment, where quality control of treatment and filling of root canals is possible only by radiographic method. In this case, the root apex has a size of No. 80 according to ISO, and the hemispherical expansion at the root apex of the tooth model, simulating a chronic lesion of the periapical tissues of the tooth, has a diameter of 8 mm. In this case, using Blue Sky Bio software, a three-dimensional image of the affected tooth is extracted from the patient's cone-beam computed tomography (CBCT) scan in DICOM format, then, using artificial intelligence algorithms in Blender software, the model is corrected, virtually modeling a tooth with a root cyst and external resorption. After this, the model is imported into STL format, 1.9 ml of resin is collected for subsequent slicing and 3D printing, and the walls of the root canal system of the resulting model are painted red with Funtodo photopolymer resin.EFFECT: inventions, by simulating endodontic treatment training conditions that are as close as possible to real conditions, namely, an apical plug in the area of the wide apex of a tooth root during inflammatory external resorption or after apical resection, allow for the practice of existing variations of endodontic treatment, and also minimize the time costs for model production.3 cl, 14 dwg, 1 ex

Description

[0001] The invention relates to medicine, namely to dentistry, and is intended for practicing manual endodontic treatment skills in students to improve the effectiveness of treating diseases of the periapical tissues of teeth, in particular, creating an apical plug during external root resorption.

[0002] One of the pressing problems in modern endodontics is the increasing incidence of inflammatory internal and external resorption (Riccuci D., 2023). Root resorption is the loss of hard dental tissue as a result of the activity of clastic cells (Yanushevich O.O., 2024). Unlike the physiological resorption of deciduous teeth, root resorption of permanent teeth is pathological in nature (A.V. Mitronin, A.Sh. Platonova, S.V. Oleinichenko, A.E. Chebotaev, 2017).

[0003] Currently, two types of pathological resorption are distinguished: internal and external. The latter occurs in response to infection on the root surface, which triggers a normal inflammatory response, including the activation of clastic cells. (I.M. Rabinovich, M.V. Snegirev, Ch.I. Markheev, 2018). During resorption, the hard tissues of the tooth, namely dentin and cementum, are absorbed, leading to the loss of periodontal attachment. However, external root resorption is asymptomatic, and therefore does not cause complaints in patients (Kim H., 2020). The progression of the process initiates pathological tooth mobility.

[0004] Characteristic radiographic signs of root resorption include the presence of an eroded area on the root surface; changing the image projection always changes the position of the defect; and a clear boundary between the tooth structures and the resorption area (D.T. Galieva, 2019). The etiological factors for the development of external resorption may include the presence of a chronic infection in the periapical tissues, orthodontic treatment, or acute or chronic trauma. The likelihood of developing an inflammatory process in the form of external root resorption also increases due to unsuccessful endodontic treatment. The modern triad of successful endodontic treatment includes: an accurate diagnosis; knowledge of the topographic anatomy of the root canals; high-quality chemomechanical preparation of the root canals and their subsequent obturation (A.V. Mitronin, 2024).With the development of external and internal resorption, the apical part of the root canal is often destroyed, and it is extremely difficult to obturate the root canal without apical constriction.

[0005] Currently, the technique of creating an apical plug from mineral trioxide aggregate (MTA) is used to close root resorption areas. The procedure for creating an apical plug is extremely complex and requires advanced manual skills on the part of the dentist. Therefore, the development and production of an endodontic phantom with a clinical picture of apical external root resorption with a wide apex is required to develop practical endodontic skills in students and young dentists.

[0006] An invention is known for training dentists in filling root canals [Patent 2095032 Russian Federation, IPC A61C 19 / 00, A61C 5 / 04. Tooth model for training dentists / Rekhachev V.M., Zbarzh Ya.M., applicant and patent holder Rekhachev Vladimir Mikhailovich - No. 94027341 / 14, declared. 19.07.1994; published. 10.11.1997], according to which the tooth model is a mock-up of a real tooth, fixed in a fixing mass with a gap simulating bone tissue around the tooth. The tooth is provided with a root canal, and the retainer is made of a radiopaque material. This model is made of thermoplastic impression material. To shape the retainer, it is placed in a housing, for example, made from polyethylene tubing from a disposable syringe. This manufacturing method does not allow for precise modeling of a clinical case, nor does it provide the conditions for testing various endodontic treatment methods for lesions of the periapical tissues of the tooth.

[0007] An invention is known in the form of a tooth root model with a removable destroyed crown part or with a washable opaque coating of the tooth roots [Patent 2565132 Russian Federation, IPC G09B 23 / 28. Tooth root model / Vinokurov V. I., Uryaseva E. V., Goman M. V., Zaborovets I. A., applicant and patent holder Vinokurov V. I., Uryaseva E. V., Goman M. V., Zaborovets I. A. - No. 2014106206 / 14, declared 19.02.2014; published 20.10.2015, Bulletin No. 29 - 5 p], intended to improve the efficiency of the educational process of endodontic treatment of single-root and multi-root teeth. The model has slots for fixing it to the jaw model with mounting screws. Quality control of the root canal treatment is possible after removing the opaque crown.This invention has a multi-stage scheme of use, which requires a lot of time, and is suitable for improving manual skills in preparing root canals for the manufacture of pin structures, however, it does not meet the requirements for mastering the skills of treating inflammatory periodontal diseases.

[0008] There is an endodontic phantom for teaching students and dentists various methods of endodontic treatment [Patent 111333 Russian Federation, IPC G09B 23 / 28. Endodontic phantom for performing therapeutic manipulations / Melekhov SV, Morozov I.V., Khromtsova I.V., applicant and patent holder State Educational Institution of Higher Professional Education "Kuban State Medical University" of the Ministry of Health and Social Development of the Russian Federation (GOU HPE KubSMU of the Ministry of Health and Social Development of the Russian Federation), Melekhov SV, Morozov I.V., Khromtsova I.V. - No. 2011117850 / 14, 04.05.2011; published 10.12.2011, Bulletin No. 34 - 1 s], made from a radiopaque self-hardening mass, in the center of which 1-2 artificial or previously removed natural teeth are fixed.A porous, conductive material is located on the removable bottom of the housing on the root side. A groove is machined along the side of the housing and in the self-hardening compound, securing an electrical wire connected to the porous material. The model is designed for practicing all stages of endodontic treatment, including determining working length, performing dental restorations, and treating caries. A drawback of the phantom is that it requires radiovisiography for control, which is unsuitable for beginning practitioners who require visualization during root canal treatment. The model does not simulate the presence of pathological bone loss due to cysts and granulomas, and therefore is unsuitable for practicing apexification techniques and therapeutic treatment of periapical lesions.

[0009] An endodontic phantom is known for developing practical skills in preparing tooth roots [Patent 180218 Russian Federation, IPC G09B 23 / 28. Endodontic phantom / Chirkova N.V., Vecherkina Zh.V., Koretskaya I.V., Kotov M.A., Morozov A.N., applicant and patent holder Federal State Budgetary Educational Institution of Higher Education "Voronezh State Medical University named after N.N. Burdenko" of the Ministry of Health of the Russian Federation - No. 2017127139, 07 / 28 / 2017; published 06 / 06 / 2018 Bulletin No. 16 - 7 p.], made by printing on a 3D printer using plastic. The model is an upper or lower jaw with imitation of the alveolar bone, gums and 16 non-separable teeth with root canals, the walls of which are painted red.The phantom is not disassemblable, which complicates the task of quality control of preparation and filling of root canals, and does not simulate the picture of a periapical focus of inflammation of periodontal tissues, which does not allow students to practice methods of creating an apical plug at the stages of endodontic treatment.

[0010] The prototype of the invention is a model of an affected tooth [Patent 114299804 People's Republic of China, IPC G09B 9 / 00. A tooth model used to simulate a surgical root canal barrier and its production method and application / Wang Chenglin, Wang Lei, Sun Yiming, Niu Zuoliang Applicant and Patent Holder Sichuan University - No. 202111561880.6, 20.12.2021; Published 08.04.2022 Bulletin No. 17 - 12 p], equipped with a model of the crown part and one root canal with imitation of a cyst in the projection of the root apex in a cube-shaped base. The model of the affected tooth has a transparent structure in which the root canal is clearly visualized; and a base where the tooth is placed during endodontic root canal treatment. The outer root wall of the affected tooth model is threaded for fixation in the base. After endodontic treatment, the tooth can be removed from the base to check the quality of the procedure.The model is fabricated by scanning the tooth in vitro using a 3D scanner and converting it to DICOM format. The size and length of the tooth root with the apical inflammation focus are then adjusted according to the established design and imported into the 3D printing system for rapid prototyping. A drawback of the presented model is the classic anatomy of root canals, with an ISO size of 35 for granuloma in the apical region, as well as the transparency of the root canal walls, which precludes training in the creation of an apical plug or monitoring the quality of infected dentin removal from the root canal walls.

[0011] From the above, it follows that it is necessary to develop a new endodontic phantom tooth with external root resorption due to a chronic inflammation focus at the root apex in order to practice the manual skill of creating an apical plug that would meet all the parameters of the corresponding clinical picture, using a more modern manufacturing technique.

[0012] The objective of the claimed invention is to develop a simulation model of a tooth with root resorption and a bone lesion in the root apex projection using modern 3D modeling and printing technologies. These models are transparent or opaque radiopaque structures with a stained canal system, a large apex, and a hemispherical expansion at the root apex, simulating a chronic lesion in the periapical tissues of the tooth.

[0013] The authors propose a method that is characterized by simplicity, low time costs and high efficiency.

[0014] The technical result of the claimed invention consists in improving the manual skills of students by simulating the conditions of endodontic treatment training, which is as close as possible to real conditions, namely, the creation of an apical plug in the area of ​​​​the wide apex of the tooth root during inflammatory external resorption or after apical resection, which allows practicing existing variations of endodontic treatment, and also minimizes the time costs for the production of the model through the use of modern manufacturing technologies using 3D printing and modeling.

[0015] The technical result is achieved by conducting an X-ray examination of patients, obtaining their cone-beam computed tomography (CBCT) scans. Using the RadiAnt DICOM Viewer application for viewing X-ray scans, and based on the clinical picture of a pathological focus of bone rarefaction with a clear outline in the projection of the root apex, a diagnosis of K04.8 "radicular cyst" according to ICD-10 is made. The X-ray data is converted to DICOM format. Using Blue Sky Bio software, a 3D image of the affected tooth is extracted from the CT scan using the program's artificial intelligence algorithms. Using Blender software, the model is corrected through virtual modeling of the tooth with the CBCT scan. The model is then imported into STL format for subsequent slicing.

[0016] Two types of resin are used for 3D printing the phantom model: 1. https: / / anycubic3d.ru / resione-g217 in a volume of 1.9 ml - transparent resin; 2. It has an opaque radiopaque structure due to the addition of 2.5 grams of white pigment.

[0017] https: / / anycubic3d.ru / cmykw?ysclid=m6hyo0ag4t708182413 per 1 kg of resin and 50 grams of barium sulfate per 1 kg of resin. These two resin types are used to produce two types of models for both beginners and advanced dentists. The root canal walls of the resulting model are colored red with a special coloring pigment for Funtodo photopolymer resin https: / / funtodo.ru / tproduct / 482935591 -386869319321-castable-blend to simulate the root portion of the pulp and control the preparation of infected root walls.

[0018] Transparent models of affected teeth are designed for entry-level manual skills, allowing for understanding the location of canals and monitoring their preparation. To enhance the learning process of endodontic root canal treatment, teeth made of opaque radiopaque resin are used, allowing for radiographic control of the quality of root canal treatment and filling. A hemispherical structure, simulating a cystic formation and located at the root apex, contains a hollow space that can be used to treat periapical inflammation and filled with collagen sponge and bioceramic material.

[0019] List of figures

[0020] Figure 1. Schematic diagram of a phantom tooth model with external root resorption

[0021] 1 - crown part of a phantom tooth with external resorption measuring 7 mm

[0022] 2 - root part of a phantom tooth with external resorption, 15 mm long

[0023] 3 - phantom tooth cyst with external resorption, diameter 8 mm

[0024] Figure 2. 3D images of tooth 2.1 with resected apex, extracted from the patient's CBCT

[0025] Figure 3. 3D model of phantom tooth 2.1 with resected apex and root resorption with periapical lesion

[0026] 1 - Crown part of a phantom tooth model with external resorption measuring 7 mm

[0027] 2 - root part of a phantom tooth model with external resorption, 15 mm long

[0028] 3 - 8mm diameter phantom tooth cyst with external resorption

[0029] 4 - Endodontic access of a phantom tooth model with external resorption

[0030] Figure 4. 3D model of phantom tooth 2.1 with root apex resorption and periapical lesion.

[0031] 1 - Crown part of a phantom tooth model with external resorption measuring 7 mm

[0032] 2 - root part of a phantom tooth model with external resorption, 15 mm long

[0033] 3 - 8mm diameter phantom tooth cyst with external resorption

[0034] 4 - Endodontic access of a phantom tooth model with external resorption

[0035] Figure 5. 3D model of phantom tooth 2.4 with root apex resorption and periapical lesion.

[0036] 1 - Crown part of a phantom tooth model with external resorption measuring 7 mm

[0037] 2 - root part of a phantom tooth model with external resorption, 15 mm long

[0038] 3 - 8mm diameter phantom tooth cyst with external resorption

[0039] 4 - Endodontic access of a phantom tooth model with external resorption

[0040] Figure 6. 3D model of a 2.5 phantom tooth with root apex resorption and periapical lesion.

[0041] 1 - Crown part of a phantom tooth model with external resorption measuring 7 mm

[0042] 2 - root part of a phantom tooth model with external resorption, 15 mm long

[0043] 3 - 8mm diameter phantom tooth cyst with external resorption

[0044] 4 - Endodontic access of a phantom tooth model with external resorption

[0045] Figure 7. Phantom model of tooth 2.1 with resected apex and with root resorption and periapical lesion made of transparent resin

[0046] 1 - Crown part of a phantom tooth model with external resorption measuring 7 mm

[0047] 2 - root part of a phantom tooth model with external resorption, 15 mm long

[0048] 3 - 8mm diameter phantom tooth cyst with external resorption

[0049] 4 - Endodontic access of a phantom tooth model with external resorption

[0050] Figure 8. Phantom model of tooth 2.1 with resected apex and root resorption with periapical lesion made of radiopaque resin

[0051] 1 - Crown part of a phantom tooth model with external resorption measuring 7 mm

[0052] 2 - root part of a phantom tooth model with external resorption, 15 mm long

[0053] 3 - 8mm diameter phantom tooth cyst with external resorption

[0054] 4 - Endodontic access of a phantom tooth model with external resorption

[0055] Figure 9. Phantom model of tooth 2.1 with root apex resorption and periapical lesion made of transparent resin

[0056] 1 - Crown part of a phantom tooth model with external resorption measuring 7 mm

[0057] 2 - root part of a phantom tooth model with external resorption, 15 mm long

[0058] 3 - 8mm diameter phantom tooth cyst with external resorption

[0059] 4 - Endodontic access of a phantom tooth model with external resorption

[0060] Figure 10. Phantom model of tooth 2.1 with root apex resorption and periapical lesion made of radiopaque resin

[0061] 1 - Crown part of a phantom tooth model with external resorption measuring 7 mm

[0062] 2 - root part of a phantom tooth model with external resorption, 15 mm long

[0063] 3 - 8mm diameter phantom tooth cyst with external resorption

[0064] Figure 11. Phantom model of tooth 2.4 with root apex resorption and periapical lesion made of transparent resin

[0065] 1 - Crown part of a phantom tooth model with external resorption measuring 7 mm

[0066] 2 - root part of a phantom tooth model with external resorption, 15 mm long

[0067] 3 - 8mm diameter phantom tooth cyst with external resorption

[0068] 4 - Endodontic access of phantom tooth model with external resorption

[0069] Figure 12. Phantom model of tooth 2.4 with root apex resorption and periapical lesion made of radiopaque resin

[0070] 1 - Crown part of a phantom tooth model with external resorption measuring 7 mm

[0071] 2 - root part of a phantom tooth model with external resorption, 15 mm long

[0072] 3 - 8mm diameter phantom tooth cyst with external resorption

[0073] Figure 13. Phantom model of a 2.5 tooth with root apex resorption and periapical lesion made of transparent resin

[0074] 1 - crown part of phantom tooth model with external resorption, size 7mm 2 - root part of phantom tooth model with external resorption, length 15mm

[0075] 3 - 8mm diameter phantom tooth cyst with external resorption

[0076] 4 - Endodontic access of a phantom tooth model with external resorption

[0077] Figure 14. Phantom model of tooth 2.5 with root apex resorption and periapical lesion made of radiopaque resin

[0078] 1 - Crown part of a phantom tooth model with external resorption measuring 7 mm

[0079] 2 - root part of a phantom tooth model with external resorption, 15 mm long

[0080] 3 - 8mm diameter phantom tooth cyst with external resorption

[0081] 4 - Endodontic access of phantom tooth model with external resorption

[0082] Example #1.

[0083] As a basis for the fabrication of a phantom model, 3D images of tooth 2.1 with a resected apex, tooth 2.1 with external resorption, as well as tooth 2.4 and tooth 2.5, on the roots of which a granulomatous formation is located (Fig. 2) were extracted from patients' CBCT scans using the Blue Sky Bio software. In the Blender software, the future models of tooth 2.1 with a resected apex (Fig. 3), tooth 2.1 (Fig. 4), tooth 2.4 (Fig. 5) and tooth 2.5 (Fig. 6) were modeled with the formation of endodontic access to the root canals, a hollow hemisphere at the apex of the tooth, as well as the root canal size No. 80 according to ISO. After slicing and 3D printing, endodontic models of teeth with a cyst were obtained: 2.1 with a resected apex (Fig. 7, 8), 2.1 (Fig. 9, 10), 2.4 (Fig. 11, 12), 2.5 (Fig. 13, 14) with formed endodontic access. The size of the phantom model is 30 mm (Fig. 1 No. 1), the length of the coronal part is 7 mm (Fig. 1 No. 2), the length of the root canal was 15 mm (Fig.1 No. 3), the size of the apical part of the root canal according to ISO is No. 80, the diameter of the artificial cyst is 8 mm (Fig. 1 No. 4). The simulation model allows for the stage of root canal preparation with the receipt of colored chips from the infected walls, the stage of creating an apical barrier using a collagen sponge and bioceramic cements as one of the methods for preventing the extrusion of endodontic filling material into the periapical tissues. A collagen sponge is installed in the apical part of the root canal using an endodontic probe after preliminary mechanical and medicinal treatment with 3% sodium hypochlorite and 17% EDTA solutions and drying the canals with paper pins. Then, MTA cement is mixed in accordance with the manufacturer's instructions and introduced into the prepared apical part of the root using a suitable carrier. After the cement has set, the root canals are obturated using gutta-percha and sealer.The final clinical stage that can be carried out using a phantom model is the creation of an aesthetic restoration using filling materials.

Claims

1. A phantom simulation model of a tooth with external root resorption for practicing manual endodontic treatment skills in students, including a 3D-printed model of a tooth with a root canal having a hemispherical expansion at the root apex, characterized in that the phantom simulation model of the tooth is made of transparent or opaque radiopaque photopolymer resin, has a length of 30 mm with a red-colored canal system of 15 mm in length, while the transparent model of the affected tooth is intended for the initial level of manual skill, and the opaque radiopaque model of the affected tooth is intended for the process of training in endodontic root canal treatment, where quality control of treatment and filling of root canals is possible only by radiographic method, while the root apex has a size No. 80 according to ISO, and the hemispherical expansion at the apex of the root of the tooth model,simulating a chronic lesion of the periapical tissues of the tooth, diameter 8 mm., 2. A method for producing a phantom model of a tooth with external root resorption according to claim1, made of a transparent or opaque radiopaque structure 30 mm long with a red-colored canal system 15 mm long, an apex size of No. 80 according to ISO and a hemispherical expansion at the root apex with a diameter of 8 mm, simulating a chronic lesion of the periapical tissues of the tooth, consists of 3D modeling and 3D printing, while using Blue Sky Bio software, a three-dimensional image of the affected tooth is extracted from the patient's cone-beam computed tomography in DICOM format, then using artificial intelligence algorithms in Blender software, the model is corrected, virtually modeling a tooth layout with a root cyst and external resorption, after which the model is imported into STL format, resin is selected in a volume of 1.9 ml for subsequent slicing and 3D printing, the walls of the root canal system of the resulting model are painted red with Funtodo photopolymer resin.

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