3D printing material for root canal preparation, preparation method thereof and preparation rehearsal model

Abstract

The application discloses a 3D printing material for root canal preparation and a preparation method and a preparation simulation model thereof, and belongs to the technical field of tooth branch root canal. The 3D printing material disclosed by the application comprises the following components in parts by weight: a photosensitive resin matrix 40-70 parts; an active diluent 15-35 parts; a rigid filler 5-15 parts; a photoinitiator 0.2-2.0 parts; and a functional auxiliary agent 0.05-1.0 parts. The photosensitive resin matrix is a mixture of a polyol-based aliphatic acrylate and a polyurethane acrylate. The hardness and wear resistance are improved by cooperation of the rigid filler and the resin matrix, the curing precision is optimized by regulating the proportion of the active diluent, the mechanical strength is ensured, the high material transparency is maintained, the mechanical properties are close to those of natural teeth, the complex root canal anatomical network can be restored with high precision, and the internal lumen communication state can be directly observed and the filling effect can be evaluated.

Description

Technical Field

[0001] This invention belongs to the field of dental root canal technology, specifically relating to a 3D printing material for root canal preparation, its preparation method, and a preparation simulation model. Background Technology

[0002] Root canal treatment is currently the most effective and commonly used method for treating pulpitis and periapical periodontitis in clinical practice. However, the internal anatomy of the root canal system is extremely complex, often featuring curved canals, C-shaped canals, and complex lateral canal networks. This requires dental students and clinicians to undergo extensive in vitro simulation training to master root canal preparation and filling techniques. Traditional in vitro teaching and training mainly rely on collecting extracted natural human teeth. However, the source of natural teeth is limited and poses biosafety risks. Using extracted natural teeth faces significant collection difficulties and potential risks of cross-infection. Furthermore, the internal root canal morphology varies greatly, making it impossible to provide standardized anatomical structures. This results in a lack of unified and objective standards for teaching assessment, hindering the achievement of large-scale, homogenized clinical skills evaluation.

[0003] With the rapid development of 3D printing technology in the field of oral medicine, the use of photopolymer 3D printing technologies, including SLA and DLP, to create root canal anatomical models has become a new trend in teaching and training, replacing natural teeth. Currently, there are some 3D printing resin materials on the market for dental education, which are mainly formed by photopolymerization to simulate the morphology of real teeth.

[0004] While current 3D-printed root canal models have alleviated the shortage of teaching teeth to some extent, existing technologies and products still have significant shortcomings. First, existing 3D printing materials have poor optical properties, often appearing opaque or semi-transparent. During complex root canal preparation and filling training, operators cannot directly observe the movement of internal instruments through the model, making it difficult to monitor the connectivity between the main and lateral canals in real time, and impossible to visually assess the density of the 3D filling after completion. This results in delayed and unintuitive teaching feedback. Second, existing 3D printing materials struggle to balance hardness and toughness, resulting in significant differences in mechanical properties compared to real dentin and a distorted cutting feel. Summary of the Invention

[0005] The purpose of this invention is to provide a 3D printing material for root canal preparation, its preparation method, and a preparation training model, in order to solve the technical problems of traditional natural tooth models being unable to be standardized and having infection risks, existing models being unable to intuitively observe internal structures and filling effects, and existing 3D printing materials having distorted cutting feel.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a 3D printing material for root canal preparation, which, by weight, comprises the following components: 40-70 parts of photosensitive resin matrix; 15-35 parts of reactive diluent; 5-15 parts of rigid filler; 0.2-2.0 parts of photoinitiator; 0.05-1.0 parts of functional additives; The photosensitive resin matrix is ​​a mixture of polyol-based aliphatic acrylate and polyurethane acrylate.

[0007] Furthermore, the reactive diluent is an acrylic acid derivative monomer.

[0008] Furthermore, the rigid filler is one or more of nanoscale silica, alumina, and zirconium oxide that have undergone surface modification treatment.

[0009] Furthermore, the photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0010] This invention also discloses a method for preparing the above-mentioned 3D printing material for root canal preparation, comprising the following steps: S1: The rigid filler is placed in a coupling agent solution to carry out a surface modification reaction, and the modified rigid filler is obtained; S2: Mix the photosensitive resin matrix with the reactive diluent to obtain a mixture; S3: Add the modified rigid filler to the mixture and disperse it; then add the photoinitiator and functional additives under light-protected conditions, mix and dissolve, and then perform vacuum degassing to obtain the 3D printing material.

[0011] Further, in S1, the mass ratio of the coupling agent solution to the rigid filler is (0.05~1.0):(5~15).

[0012] Further, in S1, the coupling agent solution is one or more of aminosilane solution, epoxysilane solution, vinylsilane solution and methacryloxysilane solution; The surface modification reaction is carried out at a temperature of 50~70 ℃ and for a reaction time of 30 min~2 h.

[0013] Furthermore, in S2, the temperature at which the photosensitive resin matrix and the reactive diluent are mixed is 30~80 ℃.

[0014] Furthermore, in S3, the dispersion process is performed by ultrasonic dispersion or vacuum stirring dispersion; the dispersion speed is 60~1000 rad, and the time is 30 s~3 min. The vacuum degassing is performed at a vacuum level of -0.1 to -0.09 MPa for a time of 3 to 10 minutes.

[0015] The present invention also discloses a root canal preparation exercise model, which is printed using the above-mentioned 3D printing material for root canal preparation. The model has a main root canal and lateral root canal channel that simulates a natural tooth. A fluid conduction window is provided at the junction of the main root canal and the lateral root canal. The fluid conduction window is set to a size that can be directly observed by the naked eye.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a 3D printing material for root canal preparation. This material comprises 40-70 parts of a photosensitive resin matrix, 15-35 parts of an active diluent, 5-15 parts of a rigid filler, 0.2-2.0 parts of a photoinitiator system, and 0.05-1.0 parts of a functional additive. Compared with existing technologies, due to the synergistic effect of its components, the rigid filler and resin matrix work together to improve hardness and wear resistance, while the proportion of the active diluent optimizes curing precision. Furthermore, it maintains high material transparency while ensuring mechanical strength. It possesses advantages such as mechanical properties close to natural teeth, the ability to accurately reproduce complex root canal anatomy networks, and support for direct observation of internal lumen connectivity and evaluation of filling effects.

[0017] Furthermore, through the synergistic effect of a specific weight ratio of photosensitive resin matrix (40-70 parts), reactive diluent (15-35 parts), rigid filler (5-15 parts), photoinitiator system (0.2-2.0 parts), and functional additives (0.05-1.0 parts), firstly, by utilizing an appropriate amount of rigid filler in combination with the resin matrix, the hardness and wear resistance of the printed root canal model are significantly improved, making it closer to the mechanical properties of natural teeth, thus enabling it to withstand repeated cutting exercises by root canal files; secondly, this component system, by regulating the reactive diluent... The optimized ratio of the material to the photosensitive resin matrix improves its flowability and curing precision, enabling high-resolution 3D printing and accurately reproducing the complex anatomical network of the main and lateral canals. This overcomes the weakness of traditional models in terms of the simulation of fine structures. Furthermore, this formulation helps maintain high material transparency while ensuring mechanical strength. Combined with the fluid conduction window structure at the junction of the main and lateral canals in the subsequent printed model, operators can directly observe the connectivity and filling density of the internal lumen, providing intuitive and quantitative evaluation feedback for clinical teaching. This invention fundamentally solves the shortcomings of existing root canal models, such as poor anatomical reproduction and inability to effectively detect the connectivity of lateral canals, achieving low-cost preparation of highly realistic, highly transparent, and standardized root canal preparation models.

[0018] Furthermore, this invention specifies that the reactive diluent is an acrylic acid derivative monomer. This type of monomer has low viscosity, high reactivity, and good compatibility, which can significantly reduce the mixing viscosity of the photosensitive resin matrix, thereby improving the resin's leveling properties and curing rate during 3D printing and reducing interlayer defects. Simultaneously, the acrylic acid derivative monomer participates in the photocuring crosslinking network and, unlike non-reactive solvents, does not leave residues that affect material properties, ensuring the uniformity and transparency of the printed part's internal structure, enabling high-fidelity molding of the micro-branch root canal structure in the root canal model.

[0019] Furthermore, the rigid filler is one or more of nano-sized silica, alumina, or zirconium oxide that have undergone surface modification. Surface modification (such as using a silane coupling agent) significantly improves the interfacial bonding force between the inorganic filler and the organic resin matrix, reduces filler agglomeration, and allows the nanoparticles to be uniformly dispersed in the resin. Thus, with an addition amount of 5-15 parts, the material hardness can be increased to near dentin, while avoiding light scattering and decreased transparency caused by agglomeration. The nano-sized particle size (typically 10-100 nm) further ensures the smoothness and detail resolution of the printed layer, allowing the complex network of main and lateral canals to be clearly presented.

[0020] Furthermore, the photoinitiator is specified as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO). Its advantage lies in TPO's highly efficient light absorption properties, especially its high initiation efficiency at the 405 nm wavelength of common DLP / SLA 3D printer light sources, enabling deep curing and ensuring uniform curing both inside and outside large-sized root canal models. Simultaneously, the yellowing index initiated by TPO is significantly lower than that of traditional photoinitiators (such as 819 or 1173). Combined with the use of polyol-based aliphatic acrylates, this ensures high transparency in the printed product, meeting the teaching requirements for direct visual observation of the internal root canal connectivity.

[0021] This invention also discloses a method for preparing the above-mentioned 3D printing material for root canal preparation. The method involves first premixing the photosensitive resin matrix with an active diluent to reduce the viscosity of the system, then introducing rigid fillers for high-speed shearing or ultrasonic dispersion, and finally adding a photoinitiator system and functional additives in the dark and performing vacuum degassing treatment. This method has the advantages of simple and efficient process, uniform filler dispersion and non-agglomeration, and can significantly improve the storage stability of the material and the curing uniformity during the molding process, thus ensuring the high resolution of the printed model.

[0022] Furthermore, limiting the mass ratio of coupling agent solution to rigid filler to (0.05~1.0):(5~15) has the advantage of precisely controlling the amount of coupling agent: too low a ratio (<0.05:15) will result in incomplete coating of the filler surface and weak interfacial bonding; too high a ratio (>1.0:5) may form multiple physical adsorption layers, which will reduce the dispersibility of the filler and introduce impurities. This ratio range has been optimized to achieve monolayer chemical grafting while avoiding excessive coupling agent residue from affecting the photocuring reaction, thus controlling the particle size D90 of the modified filler in the resin to below 200 nm, thereby balancing mechanical reinforcement and transparency.

[0023] Furthermore, limiting the type of coupling agent (one or more of amino, epoxy, vinyl, and methacryloxysilanes) and the reaction conditions (50-70 °C, 30 min-2 h) offers the following advantages: the functional groups at the ends of different silanes can be matched with different resin matrices (e.g., copolymerization of methacryloxysilane with acrylate systems), enhancing interfacial chemical bonding; the reaction temperature of 50-70 °C accelerates the hydrolysis and condensation reactions of silanes without initiating resin thermal polymerization; and the time range of 30 min-2 h ensures complete modification of the filler surface without excessive self-condensation. These conditions are mild and controllable, suitable for large-scale production. After modification, the contact angle of the filler in the resin decreases from >90° to <30°, significantly improving wettability and dispersion uniformity.

[0024] Furthermore, limiting the mixing temperature of the photosensitive resin matrix and reactive diluent in S2 to 30-80 ℃ has the advantage that the viscosity of the resin matrix can be reduced by 20%-70% within this temperature range, thus achieving rapid and uniform mixing without the need for additional solvents and avoiding thermally initiated polymerization caused by local overheating. The gentle heating of 30-80 ℃ is also suitable for conventional glass beakers or reaction flasks, requiring less equipment, and subsequent filler dispersion can be carried out after cooling to room temperature after mixing, resulting in good process adaptability.

[0025] Furthermore, by limiting the dispersion method (ultrasonic or vacuum stirring), rotation speed (60-1000 rad), time (30 s-3 min), and vacuum degassing parameters (vacuum degree -0.1~-0.09 MPa, time 3-10 min), its advantages are as follows: high shear dispersion (600-1000 rad, 30 s-3 min) can quickly depolymerize nanoscale filler agglomerates, while short-time treatment avoids excessive shearing leading to excessive resin temperature rise; ultrasonic dispersion further utilizes the cavitation effect to break up soft agglomerates, which is especially suitable for high-density fillers (such as zirconia); vacuum degassing completely removes dissolved bubbles and dispersed encapsulated bubbles within 3-10 min under negative pressure, ensuring that the material is free of bubble defects during printing, increasing the tensile strength of printed parts by 10-15%, and achieving a surface smoothness of Ra<0.5 μm, thus ensuring the restoration of the fine structure of the root canal inner wall.

[0026] This invention also discloses a root canal preparation practice model printed using the aforementioned 3D printing material for root canal preparation. This model, through high-precision 3D printing materials and processes, accurately recreates the complex anatomical network including the main and branch canals, completely overcoming the shortcomings of traditional models in terms of weak simulation of fine structures and significantly improving the realism of clinical operations. Simultaneously, this invention innovatively optimizes material transparency and, in conjunction with a specific structural design, achieves high transparency and visualization of the internal lumen, enabling teachers and students to intuitively detect the connectivity and filling density of the main and branch canals, providing precise quantitative assessment feedback and addressing the pain point of vague traditional teaching assessments. Furthermore, this technology perfectly replaces rare and potentially infectious natural extracted teeth, enabling large-scale, low-cost, standardized, and safe mass production of teaching models, fully meeting the high standards required for modern clinical dental teaching. Attached Figure Description

[0027] Figure 1 This is a cross-sectional view of the three-dimensional digital model of the root canal preparation simulation model of the present invention; Figure 2 This is a physical image of the 3D-printed root canal preparation simulation model of the present invention; Figure 3 This is a top view of the root canal preparation simulation model obtained in this invention, as observed by an image dimensional measuring instrument. Figure 4 The left view of the root canal preparation simulation model obtained in this invention, as observed by an image size measuring instrument; Figure 5 The rheological test curve of the 3D printing material used for root canal preparation according to the present invention is shown. Figure 6 This is the hardness test curve of the 3D printing material used for root canal preparation in this invention. Detailed Implementation

[0028] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0029] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0030] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0031] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0032] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0033] This invention provides a 3D printing material and preparation method for root canal preparation, aiming to solve the problems of traditional natural tooth models being unstandardized and posing infection risks, existing models not allowing for intuitive observation of internal structures and filling effects, and the distorted cutting feel of existing 3D printing materials. This invention, through high-precision 3D printing materials and processes, aims to accurately reproduce the complex interconnected network containing root canal structures, enhancing the simulation level of the model. This invention aims to optimize material transparency and, in conjunction with specific structural design, enable operators to clearly observe and inspect the connectivity and filling density between root canals.

[0034] The present invention discloses a 3D printing material for root canal preparation, comprising the following components by weight: 40-70 parts of photosensitive resin matrix; 15-35 parts of reactive diluent; 5-15 parts of rigid filler; 0.2-2.0 parts of photoinitiator; 0.05-1.0 parts of functional additives.

[0035] The photosensitive resin matrix is ​​preferably a mixture of polyol-based aliphatic acrylate and polyurethane acrylate.

[0036] The reactive diluent is preferably an acrylic acid derivative monomer.

[0037] Rigid fillers are preferably nano-sized silica, alumina, zirconium oxide, etc., that have undergone surface modification treatment.

[0038] The photoinitiator is preferably 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO).

[0039] The functional additives are selected from one or more of the following: silane coupling agent KH-570, p-hydroxyanisole, polyether-modified polydimethylsiloxane, and fluorescent whitening agent OB.

[0040] This invention also discloses a method for preparing the above-mentioned 3D printing material for root canal preparation, comprising the following steps: Step S1: Pretreatment of the filler. The rigid filler is placed in a coupling agent solution for surface modification and then dried for later use.

[0041] Step S2: The matrix and reactive diluent are blended. The photosensitive resin matrix and reactive diluent are mixed evenly at a specific temperature.

[0042] Step S3, packing dispersion: The modified packing from step S1 is added to the mixture from step S2 and subjected to high-shear dispersion treatment.

[0043] Step S4: Degassing is initiated by adding a photoinitiator and functional additives under light-protected conditions, mixing and dissolving them, and then performing vacuum degassing to obtain the 3D printing material.

[0044] The silane coupling agent used in step S1 is one or more types, including aminosilane, epoxysilane, vinylsilane, and methacryloxysilane. The reaction time in step S1 is between 30 min and 2 h, and the reaction temperature is between 50 °C and 70 °C.

[0045] The blending temperature in step S2 is between 30 ℃ and 80 ℃, which effectively reduces the flow resistance of high viscosity resin.

[0046] Step S3 involves using ultrasonic dispersion or a planetary vacuum mixer at a speed between 600 and 1000 rpm for a dispersion time between 30 seconds and 3 minutes to achieve a homogeneous suspension of the nanofiller. The vacuum level is between -0.1 and -0.09 MPa, and the degassing time is between 3 and 10 minutes.

[0047] A root canal preparation simulation model printed using the aforementioned material, the model having root canal channels that simulate natural teeth inside.

[0048] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0049] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0050] Example 1 A method for preparing a 3D printing material for root canal preparation includes the following steps: In this embodiment, the composition of the 3D printing material for root canal preparation is as follows: The photosensitive resin matrix is ​​a mixture of polyol-based aliphatic acrylate and polyurethane acrylate, 40 parts; the reactive diluent is an acrylic derivative monomer, 15 parts; the rigid filler is nano-sized silica, 5 parts; the photoinitiator is TPO, 0.2 parts; the functional additive is 0.05 parts; the functional additive is polyether-modified polydimethylsiloxane. The preparation process includes the following steps: Step S1: Place 5 parts of nano-sized silica in a solution containing methacryloxysilane coupling agent for surface modification, react at 50 °C for 30 min, and dry for later use. Step S2: Add 40 parts of photosensitive resin matrix and 15 parts of reactive diluent to a sealed reaction flask and mix them evenly at 30 °C. Step S3: Add the dried modified filler from step S1 to the mixture from step S2, and use a planetary vacuum stirrer to perform high shear dispersion at 600 rpm for 30 s to keep the nanofiller in a homogeneous suspension state. Step S4: Under light-protected conditions, add 0.2 parts of photoinitiator TPO and 0.05 parts of functional additive to the above homogeneous mixture. After mixing and dissolving, perform vacuum degassing for 3 minutes at a vacuum degree of -0.09 MPa to obtain the 3D printing material.

[0051] Example 2 A method for preparing a 3D printing material for root canal preparation includes the following steps: In this embodiment, the composition of the 3D printing material for root canal preparation is as follows: The photosensitive resin matrix is ​​a mixture of polyol-based aliphatic acrylate and polyurethane acrylate, 70 parts; the reactive diluent is an acrylic derivative monomer, 35 parts; the rigid filler is a mixture of nano-alumina and zirconium oxide, 15 parts; the photoinitiator is TPO, 2.0 parts; the functional additive is 1.0 part; the functional additive is a mixture of silane coupling agent KH-570 and p-hydroxyanisole. The preparation process includes the following steps: Step S1: 15 parts of rigid filler were placed in a solution containing a mixed coupling agent of aminosilane and epoxysilane for surface modification, reacted at 70 °C for 2 h, and then dried for later use. Step S2: Add 70 parts of photosensitive resin matrix and 35 parts of reactive diluent to a sealed reaction flask and mix them evenly at 80 °C. Step S3: Add the modified filler from step S1 to the mixture from step S2, and use an ultrasonic dispersion device to perform high shear dispersion treatment at a speed of 1000 rpm for 3 min, so that the nanofiller is in a homogeneous suspension state. Step S4: Add 2.0 parts of photoinitiator TPO and 1.0 parts of functional additive under light-protected conditions. After mixing and dissolving, perform vacuum degassing for 10 minutes at a vacuum degree of -0.1 MPa to obtain the 3D printing material.

[0052] Example 3 A method for preparing a 3D printing material for root canal preparation includes the following steps: In this embodiment, the composition of the 3D printing material for root canal preparation is as follows: The photosensitive resin matrix is ​​a mixture of polyol-based aliphatic acrylate and polyurethane acrylate, 55 parts; the reactive diluent is an acrylic derivative monomer, 25 parts; the rigid filler is nano-sized silica, 10 parts; the photoinitiator is TPO, 1.0 part; the functional additive is 0.5 parts; the functional additive is fluorescent whitening agent OB. The preparation process includes the following steps: Step S1: Place 10 parts of nano-sized silica in a solution containing vinyl silane coupling agent for surface modification, react at 60 °C for 1 h, and dry for later use. Step S2: Mix 55 parts of photosensitive resin matrix with 25 parts of reactive diluent and blend evenly at 50 °C. Step S3: Add the modified filler from step S1 to the mixture from step S2, and disperse it for 2 minutes at 800 rpm using a planetary vacuum mixer to achieve homogeneous suspension of the filler. In step S4, 1.0 part of TPO and 0.5 parts of functional additives are added in the dark. After mixing and dissolving, the mixture is degassed for 6 minutes under a vacuum of -0.095MPa to obtain the 3D printing material.

[0053] Example 4 A method for preparing a 3D printing material for root canal preparation includes the following steps: In this embodiment, the composition of the 3D printing material for root canal preparation is as follows: The photosensitive resin matrix is ​​a mixture of polyol-based aliphatic acrylate and polyurethane acrylate, 40 parts; the reactive diluent is an acrylic derivative monomer, 35 parts; the rigid filler is nano-sized zirconium oxide, 15 parts; the photoinitiator is TPO, 2.0 parts; the functional additive is p-hydroxyanisole; The preparation process includes the following steps: Step S1: 15 parts of nano-sized zirconium oxide were placed in a solution containing methacryloxysilane coupling agent for surface modification, reacted at 65 °C for 1.5 h, and then dried for later use. Step S2: Mix 40 parts of photosensitive resin matrix with 35 parts of reactive diluent and blend evenly at 60 °C. Step S3: Add the modified filler from step S1 to the mixture. Due to the high density of zirconia, ultrasonic dispersion is used with a rotation speed of 900 rpm for 1.5 min. In step S4, 2.0 parts of TPO and 0.05 parts of functional additives are added in the dark. After dissolving, the mixture is degassed under vacuum at -0.1 MPa for 8 minutes to obtain the 3D printing material.

[0054] Application Example 1 The three-dimensional digital model of the root canal preparation simulation model was printed using the 3D printing material prepared in Example 1. The 3D printing parameters used were as follows: A DLP photopolymer 3D printer was used with a printing light source wavelength of 405 nm, a printing layer thickness of 40 μm, a bottom layer exposure time of 3 s, and a normal layer exposure time of 1~1.5 s. After printing, the model was ultrasonically cleaned in isopropanol solvent for 5 minutes to remove any uncured resin residue on the surface, and then placed in a UV curing chamber for a second curing treatment of 15 minutes.

[0055] The final model features root canal channels that mimic those of a natural tooth. These channels accurately replicate the complex anatomy of the pulp chamber, including the main root canal and apical foramen with specific curvature. Thanks to the excellent molding precision and mechanical properties of the material used in this embodiment, the inner walls of the root canals are smooth and less prone to interlaminar fracture under high-speed cutting, resulting in a highly realistic cutting feel.

[0056] Figure 1 This is a cross-sectional view of the three-dimensional digital model of the root canal preparation training model of the present invention. As can be seen from the figure, the complex three-dimensional anatomical morphology of the natural pulp cavity is highly accurately reproduced inside the model.

[0057] Specifically, such as Figure 2 As shown in the figure, the root canal model prepared using the material of this invention exhibits excellent overall transparency. Without the aid of a special light source, the complex three-dimensional root canal network structure can be clearly seen with the naked eye. After simulating clinical root canal preparation and filling operations, the direction and distribution of the filling material inside the root canal, as well as the filling density, can be clearly monitored through the transparent outer wall of the model, achieving real-time, comprehensive visual monitoring of the entire root canal treatment process.

[0058] Figure 3 This is a top view of the root canal preparation simulation model obtained by the present invention, observed by an image sizing measuring instrument. As can be seen from the figure, the external contour curve of the model, as well as the geometry and dimensions of the root canal orifice, highly match the original three-dimensional digital model. This indicates that the resin system of the present invention exhibits extremely low volume shrinkage during the photocuring crosslinking reaction, effectively avoiding warping deformation of the printed part in the XY plane and ensuring absolute accuracy in the positioning of the root canal orifice.

[0059] Figure 4 This is a left view of the root canal preparation simulation model obtained in this invention, observed using an image sizing measuring instrument. As can be seen from the image, the subtle morphology at the root apex is perfectly replicated. Combined with... Figure 3 and Figure 4 The measurement data further verified that the material of the present invention has excellent overall dimensional stability and can meet the strict requirements of standardized and homogenized clinical skills teaching and assessment.

[0060] Figure 5 The rheological test curves of the 3D printing material for root canal preparation according to this invention are shown in the figure. As can be seen from the figure, the resin system of this invention exhibits excellent shear thinning properties in its uncured liquid state. This indicates that the scientifically proportioned nano-zirconia and functional additives did not cause excessive thickening or agglomeration of the liquid. This rheological property ensures that the resin liquid can achieve rapid leveling and backfilling during the layer-by-layer reciprocating motion of the 3D printing platform, effectively avoiding pull-out defects during the molding process and providing a physical guarantee for the successful molding of high-precision lateral root canals.

[0061] Figure 6 The figure shows the hardness test curve of the 3D printing material used for root canal preparation in this invention. As can be seen from the figure, the cured material exhibits excellent mechanical properties. This enables the model to provide realistic and continuous clinical cutting resistance and a "feel of air" when prepared with instruments such as nickel-titanium files, effectively avoiding the problem of distorted cutting feel caused by existing materials.

[0062] In summary, the 3D printing material for root canal preparation disclosed in this invention is composed of a photosensitive resin matrix (40-70 parts), an active diluent (15-35 parts), a rigid filler (5-15 parts), a photoinitiator system (0.2-2.0 parts), and functional additives (0.05-1.0 parts). Through the synergistic effect of each component, the hardness and wear resistance of the printed part are improved while optimizing the curing precision and maintaining high transparency. This makes the mechanical properties close to those of natural teeth, and it can accurately reproduce the complex anatomical network composed of the main root canal and branch root canals. It also supports direct observation of the internal lumen connectivity and filling effect with the naked eye. The reactive diluent uses acrylic acid derivative monomers, which can reduce viscosity, improve leveling and curing rate, and reduce interlayer defects. The rigid filler is made of nano-silica, alumina, or zirconium oxide (particle size 10~100 nm) modified with silane coupling agent, which significantly enhances the inorganic-organic interface bonding force, avoids agglomeration, and balances hardness and light transmittance at an addition amount of 5~15 parts. The photoinitiator is preferably TPO, which has efficient initiation and deep curing ability at a wavelength of 405 nm, and has a low yellowing index, ensuring the transparency of the finished product. The preparation method includes: first, premixing the photosensitive resin matrix and reactive diluent at 30~80 ℃ to reduce viscosity, then adding the rigid filler and dispersing it by high-speed shearing or ultrasonic dispersion (speed 60~1000 rad, time 30 s~3 min), and finally adding the photoinitiator and additives in the dark, and degassing at a vacuum degree of -0.1~-0.09 MPa for 3~10 min. This method is simple and efficient, produces uniformly dispersed fillers, exhibits good storage stability, and increases the tensile strength of printed parts by 10-15%, with a surface roughness Ra < 0.5 μm. Root canal preparation models printed from this material accurately reproduce complex root canal networks, overcoming the shortcomings of traditional models in terms of weak simulation of fine structures. Combined with high transparency and fluid flow window design, it allows teachers and students to intuitively inspect the connectivity and filling density of main and branch canals, providing quantitative assessment feedback. Furthermore, it replaces natural extracted teeth that pose an infection risk, enabling large-scale, low-cost, standardized, and safe mass production of teaching models, fully meeting the high standards required for modern clinical dental teaching.

[0063] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A 3D printing material for root canal preparation, characterized in that, The 3D printing material comprises the following components by weight: 40-70 parts of photosensitive resin matrix; 15-35 parts of reactive diluent; 5-15 parts of rigid filler; 0.2-2.0 parts of photoinitiator; 0.05-1.0 parts of functional additives; The photosensitive resin matrix is ​​a mixture of polyol-based aliphatic acrylate and polyurethane acrylate.

2. The 3D printing material for root canal preparation according to claim 1, characterized in that, The reactive diluent is an acrylic acid derivative monomer.

3. The 3D printing material for root canal preparation according to claim 1, characterized in that, The rigid filler is one or more of nanoscale silica, alumina, and zirconium oxide that have undergone surface modification.

4. The 3D printing material for root canal preparation according to claim 1, characterized in that, The photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

5. A method for preparing a 3D printing material for root canal preparation as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1: The rigid filler is placed in a coupling agent solution to carry out a surface modification reaction, and the modified rigid filler is obtained; S2: Mix the photosensitive resin matrix with the reactive diluent to obtain a mixture; S3: Add the modified rigid filler to the mixture and disperse it; then add the photoinitiator and functional additives under light-protected conditions, mix and dissolve, and then perform vacuum degassing to obtain the 3D printing material.

6. A method for preparing a 3D printing material for root canal preparation according to claim 5, characterized in that, In S1, the mass ratio of the coupling agent solution to the rigid filler is (0.05~1.0):(5~15).

7. A method for preparing a 3D printing material for root canal preparation according to claim 5, characterized in that, In S1, the coupling agent solution is one or more of aminosilane solution, epoxysilane solution, vinylsilane solution and methacryloxysilane solution; The surface modification reaction is carried out at a temperature of 50~70 ℃ and for a reaction time of 30 min~2 h.

8. A method for preparing a 3D printing material for root canal preparation according to claim 5, characterized in that, In S2, the temperature at which the photosensitive resin matrix and the reactive diluent are mixed is 30~80 ℃.

9. A method for preparing a 3D printing material for root canal preparation according to claim 5, characterized in that, In S3, the dispersion process is performed by ultrasonic dispersion or vacuum stirring dispersion; the dispersion speed is 60~1000 rad and the time is 30 s~3 min. The vacuum degassing is performed at a vacuum level of -0.1 to -0.09 MPa for a time of 3 to 10 minutes.

10. A root canal preparation simulation model, characterized in that, The model is printed using the 3D printing material for root canal preparation as described in any one of claims 1 to 4. The model has a main root canal and lateral root canal channel that simulates a natural tooth. A fluid conduction window is provided at the junction of the main root canal and the lateral root canal. The fluid conduction window is set to a size that can be directly observed by the naked eye.

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