A premixed calcium silicate-niobium compound composite root canal filling agent, a preparation method and application thereof

Abstract

The present application relates to the technical field of medical materials, in particular to a premixed calcium silicate-niobium compound composite root canal filling agent, a preparation method and application. The composite root canal filling agent comprises: (a) a calcium silicate compound, (b) a phosphate compound, (c) a calcium compound, (d) a niobium compound, (e) a barrier material, (f) a non-aqueous phase solvent miscible with water, and (g) an organic substance, wherein the total amount of components (a), (b), (c), (d), (e) and (g) accounts for 60-95% of the total mass of the filling agent, and the component (f) accounts for 5-40% of the total mass of the filling agent. The filling agent has the advantages of fast solidification, good biological activity, excellent antibacterial performance and easy popularization and application.

Description

Technical Field

[0001] This invention relates to the field of medical materials technology, and in particular to a premixed calcium silicate-niobium compound composite root canal filling agent, its preparation method, and its application. Background Technology

[0002] Root canal diseases mainly encompass two common conditions: pulpitis and periapical periodontitis. Pulpitis often occurs due to bacterial infection or irritation of the dental pulp tissue, and its typical symptoms include localized tooth pain and sensitivity to hot and cold stimuli. Periapical periodontitis, on the other hand, results from untreated or incompletely treated pulpitis, leading to the spread of infection to the tissues surrounding the root apex, subsequently causing local inflammation and bone damage. While current root canal treatments have shown some effectiveness, they still face numerous challenges, such as the complex structure of the root canal system and the multiple difficulties encountered during the treatment process.

[0003] Necrotic dental pulp becomes a breeding ground for microorganisms, which multiply in the form of planktonic cells, aggregates, or biofilms. Enterococcus faecalis is the most common bacterium isolated from the root canals of teeth in patients with persistent periapical periodontitis. Enterococcus faecalis can penetrate dentinal tubules to a depth of 159-1790 μm, survive root canal treatment, and its ability to adapt to constantly changing environments and form monotypic biofilms helps it tolerate the harsh microenvironment encountered in teeth after root canal treatment, resulting in a secondary root canal infection rate of 24%–77%. Studies have shown that if these diseases are not effectively treated, they can lead to tooth loss or severe oral infections.

[0004] Root canal treatment includes physical therapy, chemical therapy, and biological therapy. A key challenge at the physical level is that mechanical instruments cannot completely eradicate infection within the canal, resulting in instruments failing to reach 2.66-79.0% of the canal surface. Secondly, the complex microstructure of the root canal, including its intricate network of channels, collateral pathways, and non-linear contours, not only increases the technical difficulty of root canal treatment but also affects its success rate and prognosis. The complex internal structure of the root canal provides an ideal environment for oral pathogens such as Enterococcus faecalis, which can form biofilms in the pulp chamber and collateral pathways. The presence of biofilms not only enhances the antibiotic resistance and survival ability of the microorganisms but also makes effective irrigation during root canal treatment more difficult and complex. Irrigation-based disinfection plays an indispensable role in purifying microorganisms and their byproducts. Among various irrigating agents, sodium hypochlorite remains the preferred choice due to its antibacterial and pulp-dissolving activities. However, it carries a high risk of tissue damage at high concentrations, easily causing dentin demineralization, and is also cytotoxic. Conversely, at low concentrations, the rinsing effect is very poor.

[0005] Root canal treatment is a highly challenging technical task in modern dentistry, primarily due to the complex structure of the root canal system and the multiple difficulties involved in the treatment process. The microchannels, collateral pathways, and non-linear contours within the root canal system constitute the primary challenges in treatment. Secondly, the treatment process involves more than just simple removal of apical tissue or the apex; more importantly, it requires ensuring the complete sealing of the root canal system to prevent reinfection. In this context, if our root canal filling materials possess effective antibacterial properties and can maintain their antibacterial effect after filling, effectively controlling microbial infection within the root canal and the biofilm outside the apical foramen, it will increase the success rate of root canal treatment and reduce the incidence of refractory periapical periodontitis.

[0006] Bioceramic root canal filling pastes contain components such as calcium phosphate, calcium silicate, zirconium oxide, and calcium hydroxide, exhibiting a composition similar to white MTA. These materials are recognized for their excellent sealing properties, stability, and antibacterial properties. They are insoluble in tissue fluid, maintain long-term stability, and release hydroxide ions during and after solidification to maintain a high pH, ​​thereby inhibiting bacterial growth. Furthermore, bioceramic root canal filling pastes have good biocompatibility, no toxic side effects, and can be used for apexification and endodontic restoration. However, these bioceramic filling pastes have certain limitations in promoting the removal of immature pulp. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to provide a premixed calcium silicate-niobium compound composite root canal filling agent and its preparation method. To achieve the above objective, the present invention employs the following technical solution:

[0008] A premixed calcium silicate-niobium compound composite root canal filling agent comprising:

[0009] (a) calcium silicate compounds, (b) phosphate compounds, (c) calcium compounds, (d) niobium compounds, (e) radiation-shielding materials, (f) water-miscible non-aqueous solvents, and (g) organic matter, wherein components (a), (b), (c), (d), (e), and (g) together account for 60% to 95% of the total mass of the filler, and component (f) accounts for 5% to 40% of the total mass of the filler.

[0010] This premixed calcium silicate-niobium compound root canal filling agent is a biphase composite self-curing system that combines the advantages of niobium oxide compounds and calcium silicate self-curing materials. It not only significantly shortens the curing time but also has excellent biocompatibility, bioactivity, and antibacterial properties, which can promote the further maturation of immature pulp-removed root canals.

[0011] The component (a) may be selected from one or more of tricalcium silicate, dicalcium silicate, and monocalcium silicate; the general chemical formula of tricalcium silicate is Ca3SiO5, the general chemical formula of dicalcium silicate is Ca2SiO4, and the general chemical formula of monocalcium silicate is CaSiO3.

[0012] The calcium silicate compound is a powder; the particle size of the powder is 10 nm to 200 μm, more preferably 100 μm.

[0013] Two powders selected from tricalcium silicate, dicalcium silicate, and monocalcium silicate in a ratio of 1.8:1 to 2.2:1 are preferred as the main components of the material to provide good sealing and stability.

[0014] Wherein, group (b) may be selected from: calcium phosphate, magnesium phosphate, sodium phosphate, zinc phosphate, ferric phosphate, potassium phosphate, nickel phosphate, zirconium phosphate, phosphoric acid, organometallic phosphates, and mixtures thereof. The phosphates used in the paste may contain water hydrate. More complex (pre-reacted) phosphates may also be used. Further, calcium phosphate includes, but is not limited to, monocalcium phosphate, monocalcium phosphate, tricalcium phosphate, tetracalcium phosphate, and mixtures thereof. Calcium phosphate may contain water hydrate. The present invention does not impose any particular limitation on the source of component (c), and commercially available products well known to those skilled in the art may be used.

[0015] The phosphate compound is a powder; the particle size of the powder is 10 nm to 200 μm, more preferably 100 μm. Choosing a phosphate compound powder helps to enhance the antibacterial properties and bioactivity of the material.

[0016] Component (c) may be selected from calcium hydroxide, calcium carbonate, calcium bicarbonate, and mixtures thereof. Further, calcium phosphate includes, but is not limited to, calcium hydroxide, calcium carbonate, calcium bicarbonate, and mixtures thereof. Calcium hydroxide is more preferred. The present invention does not impose any particular limitation on the source of component (c), and commercially available products well known to those skilled in the art may be used.

[0017] The calcium compound is a powder; the particle size of the powder is 10 nm to 200 μm, more preferably 100 μm.

[0018] The component (d) may be selected from: niobium pentoxide, niobium trioxide, niobium dioxide, niobium monoxide, niobium sulfide, niobium oxalate, niobium carbide (NbC), niobium nitride (NbN), and mixtures thereof. Niobium pentoxide is more preferred. The present invention does not impose any particular limitation on the source of the component (d), and commercially available products well known to those skilled in the art may be used.

[0019] The general chemical formula of niobium pentoxide is Nb₂O₅, the general chemical formula of niobium dioxide is NbO₂, the general chemical formula of niobium trioxide is Nb₂O₃, the general chemical formula of niobium monoxide is NbO, the general chemical formula of niobium sulfide is NbS₂, and the general chemical formula of niobium oxalate is C. 10 H5NbO 20 The general chemical formula of niobium carbide is NbC, and the general chemical formula of niobium nitride is NbN.

[0020] The niobium compound is a powder; the particle size of the powder is 10 nm to 300 nm, more preferably 200 nm. This significantly improves the biocompatibility and antibacterial properties of the material.

[0021] Component (e) may be selected from zirconium oxide, barium sulfate, tantalum oxide, bismuth oxide, and mixtures thereof. More preferably, it is an oxide of zirconium. The present invention does not impose any particular limitation on the source of component (e), and commercially available products well known to those skilled in the art may be used.

[0022] The radiation-shielding material is a powder; the particle size of the powder is 10nm to 300nm, more preferably 200nm.

[0023] Component (f) may be selected from: glycerol, propylene glycol, polyethylene glycol, ethylene glycol, ethanol, silicone oil, eugenol, polyethylene glycol, animal oil, vegetable oil, and mixtures thereof. Component (f) is an anhydrous liquid component that can act as a solvent to promote uniform mixing of the components and form a stable paste.

[0024] The component (g) may be selected from one or more of cellulose and its derivatives, such as carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose. The components (g) can interweave to form a network structure, hindering the flow of various components and achieving a thickening effect. This invention does not impose any special restrictions on the source of the component (g); commercially available products well-known to those skilled in the art can be used.

[0025] The component (g) is crystalline with a particle size of 10 nm to 300 nm, more preferably 200 nm.

[0026] The components (a), (b), (c), (d), (e), and (g) together constitute 60% to 95% of the total mass of the filler, preferably 70% to 85%. The component (f) constitutes 5% to 40% of the total mass of the filler, preferably 15% to 30%.

[0027] Specifically, it could be:

[0028] a: 45.5%, b: 1%, c: 3%, d: 2.5%, e: 19.5%, f: 28%, g: 0.5%.

[0029] Alternatively, the percentages could be: a: 45.5%, b: 1%, c: 3%, d: 5%, e: 17%, f: 28%, g: 0.5%.

[0030] The premixed calcium silicate-niobium compound composite root canal filling agent provided by the present invention is prepared by a method comprising the following steps:

[0031] Powders of calcium silicate compounds, phosphate compounds, calcium compounds, niobium oxide compounds, and radiopaque materials are uniformly mixed with a water-miscible non-aqueous solvent using a ball mill. The resulting paste is then transferred to a medical syringe, packaged, and sterilized to obtain a premixed calcium silicate-niobium compound composite root canal filling agent. This agent can be directly injected in clinical applications and is considered an ideal filling agent for endodontic treatment.

[0032] In the preparation method of the present invention, the medical syringe is preferably a medical syringe equipped with an injection tube needle, the diameter of which is preferably 0.2 mm to 0.5 mm, more preferably 0.25 mm.

[0033] The application of the above-mentioned premixed calcium silicate-niobium compound composite root canal filling agent in the preparation of root canal filling materials for treating pulpitis is also within the scope of protection of this invention.

[0034] Compared to traditional calcium silicate dental fillings, the premixed calcium silicate-niobium compound composite root canal filling agent of the present invention has the following advantages:

[0035] (1) It solidifies very quickly, which is conducive to achieving rapid and high-quality pulpitis treatment;

[0036] (2) The paste with added niobium has better bioactivity than the paste without added niobium and is more likely to form osteogenic hydroxyapatite precipitate.

[0037] (3) The antibacterial properties of the paste were further improved after the addition of niobium compared to before the addition;

[0038] (4) The addition of niobium to the paste can promote the further maturation of immature pulp-de-embedded root canals;

[0039] (5) No mixing is required before use, and it has good clinical operation performance.

[0040] Meanwhile, the preparation method provided by this invention is simple and mild, showing great application potential. Attached Figure Description

[0041] Figure 1Photograph of the composite root canal filling agent in Example 1;

[0042] Figure 2 These are the results of the curing time test;

[0043] Figure 3 SEM images of immersion detection for promoting hydroxyapatite precipitation;

[0044] Figure 4 The results show the distribution of hydroxyapatite precipitation.

[0045] Figure 5 This is one of the results of the antibacterial test;

[0046] Figure 6 This is the second result of the antibacterial test;

[0047] Figure 7 These are results from animal experiments. Detailed Implementation

[0048] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0049] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0050] Example 1: Preparation of a premixed calcium silicate-niobium compound composite root canal filling agent

[0051] 1. Raw material preparation:

[0052] The calcium silicate compounds selected were tricalcium silicate powder and dicalcium silicate powder, with a particle size of 100 μm.

[0053] The phosphate compound selected was calcium phosphate powder with a particle size of 100 μm.

[0054] The calcium compound selected was calcium hydroxide powder with a particle size of 100 μm.

[0055] The niobium oxide compound selected was niobium pentoxide powder with a particle size of 200 nm.

[0056] For non-aqueous phase solvents that are miscible with water, polyethylene glycol-400 is selected.

[0057] The radiation shielding material is zirconium oxide powder with a particle size of 200 nm.

[0058] The organic material selected is hydroxypropyl methylcellulose, which is crystalline and has a particle size of 200 nm.

[0059] 2. Preparation of composite paste:

[0060] Weigh out 1.5g dicalcium silicate, 3.05g tricalcium silicate, 0.1g calcium phosphate, 0.3g calcium hydroxide, 0.25g niobium pentoxide, 1.95g zirconium oxide, 2.8ml polyethylene glycol-400, and 0.05g hydroxypropyl methylcellulose. During the mixing process, maintain a temperature of 25±5℃ and a humidity of <30%, and mix for 30 minutes at a speed of 200-300 rpm. After thorough mixing for 10 minutes, transfer the mixture to a medical syringe equipped with an injection cannula and needle to obtain the premixed calcium silicate-niobium compound composite root canal filling agent.

[0061] The resulting premixed calcium silicate-niobium compound composite root canal filling agent was prepared as a white paste (see...). Figure 1 It has very good liquidity.

[0062] Example 2: Preparation of a premixed calcium silicate-niobium compound composite root canal filling agent

[0063] 1. Raw material preparation:

[0064] The calcium silicate compounds selected were tricalcium silicate powder and dicalcium silicate powder, with a particle size of 100 μm.

[0065] The phosphate compound selected was calcium phosphate powder with a particle size of 100 μm.

[0066] The calcium compound selected was calcium hydroxide powder with a particle size of 100 μm.

[0067] The niobium oxide compound selected was niobium pentoxide powder with a particle size of 200 nm.

[0068] For non-aqueous phase solvents that are miscible with water, polyethylene glycol-400 is selected.

[0069] The radiation shielding material is zirconium oxide powder with a particle size of 200 nm.

[0070] The organic material selected is hydroxypropyl methylcellulose, which is crystalline and has a particle size of 200 nm.

[0071] 2. Preparation of composite paste:

[0072] Weigh out 1.5g of dicalcium silicate, 3.05g of tricalcium silicate, 0.1g of calcium phosphate, 0.3g of calcium hydroxide, 0.5g of niobium pentoxide, 1.7g of zirconium oxide, 2.8ml of polyethylene glycol-400, and 0.05g of hydroxypropyl methylcellulose. Place them in a glass container and mechanically mix using a stainless steel stirring rod for 10 minutes until all components are evenly distributed. After visually inspecting and sampling to check the uniformity of the mixture, transfer it to a medical syringe equipped with a 0.25mm diameter injection cannula needle to obtain the premixed calcium silicate-niobium compound composite root canal filling agent.

[0073] The resulting premixed calcium silicate-niobium compound composite root canal filling agent was prepared as a white paste.

[0074] Test case

[0075] Paste preparation:

[0076] Experimental group: The premixed calcium silicate-niobium compound composite root canal filling agent prepared in Example 1 (2.5wt% Nb) and Example 2 (5wt% Nb) was used.

[0077] Control group (Bio SP): 0.15g dicalcium silicate, 0.305g tricalcium silicate, 0.1g calcium phosphate, 0.3g calcium hydroxide, 22g zirconium oxide, 2.8ml polyethylene glycol-400, and 0.05g hydroxypropyl methylcellulose were weighed and placed in a glass container. The mixture was mechanically mixed with a stainless steel stirring rod for 10 minutes. The mixture was then transferred to a medical syringe equipped with an injection tube and needle to obtain the premixed calcium silicate-niobium compound composite root canal filling material. The source and quality of the raw materials were the same as in Examples 1 and 2.

[0078] Test Example 1: Curing Time Test

[0079] This study followed the test methods specified in industry standard YY0717-2009. First, the prepared paste was filled into a hydrated plaster mold. Then, the mold was placed in a constant temperature and humidity chamber maintained at 37°C and 95% relative humidity. During curing, the curing state was assessed using a penetration meter, and the curing time was recorded at 25°C / 50% humidity. The penetration meter was equipped with a flat-faced indenter with a mass of 100g ± 0.5g and a diameter of 2mm ± 0.1mm, with a cylindrical tip length of at least 5mm. Timing began after mixing and continued until no indentation was visually visible; this time was recorded as the curing time and plotted as a statistical graph (see [link to graph]). Figure 2 ).

[0080] The results showed that the filler containing niobium pentoxide had a shorter curing time.

[0081] Test Example 2: Immersion test of cured composite paste to promote hydroxyapatite precipitation:

[0082] The prepared premixed calcium silicate-niobium compound composite root canal filling agent was mixed evenly with deionized water at a solid-liquid ratio of 0.5 mL / g and then placed in the solution. Cylindrical samples were prepared using a cylindrical stainless steel mold and placed in a cell culture incubator at 37°C for 7 days. After dehydration with ethanol and drying, the samples were immersed in SBF solution with a surface area to SBF volume ratio of 10:1. Every 48 hours, 25 vol% SBF was aspirated and replenished with an equal amount of fresh SBF. The concentrations of calcium, silicon, niobium, and copper ions in the SBF solution were measured by ICP at 1, 3, 7, 14, 21, and 28 days of immersion. The surface properties of the samples after 1, 3, and 7 days of immersion were analyzed by SEM and energy dispersive spectroscopy (EDX). The amount of phosphate deposition on the surface was analyzed by Raman spectroscopy.

[0083] The results showed that fillers containing niobium pentoxide had a better ability to promote surface phosphate precipitation (see...). Figures 3-4 ).

[0084] Test Example 3: Antibacterial Test

[0085] Remove cryovials containing *Escherichia coli*, *Staphylococcus aureus*, and *Enterococcus faecalis* from the -80°C freezer and immediately place them in a 37°C water bath. Once the bacterial culture in the cryovials has completely thawed, use aseptic techniques to inoculate the culture into an appropriate amount of BHI liquid medium. Incubate the medium at 37°C for 18-24 hours to ensure the bacteria are fully recovered and growing well, restoring their normal physiological state and metabolic activity. Simultaneously, prepare and cool-solidify agar plates before the experiment, ensuring they are at a suitable temperature and condition for subsequent bacterial culture spreading.

[0086] The experimental samples were divided into three groups: a blank control group without any samples, Example 1 group, and Example 2 group.

[0087] Weigh 0.5g of each sample and place them in an autoclave. Treat the samples at 120℃ for 30 minutes to ensure they are sterile. Then place the sterilized samples in a pre-prepared 48-well plate.

[0088] Take the revived bacterial culture and perform appropriate serial dilutions using PBS buffer. Adjust the bacterial concentration precisely to 10⁻⁶ using a turbidimetric method. 6 Approximately CFU / ml, ensuring the accuracy and consistency of bacterial concentration.

[0089] Using a sterile pipette, add 1 ml of the adjusted bacterial solution to each of the three sets of 48-well plates, ensuring that the bacterial solution is evenly distributed in each well. Gently shake the plate to ensure that the bacterial solution is in full contact with the sample.

[0090] Place the 48-well plate containing the bacterial suspension in a suitable incubation environment and incubate for 5 hours to allow sufficient interaction between the bacteria and the sample. After incubation, carefully aspirate 20 μl of bacterial suspension from each well using a sterile pipette and drop it onto a pre-prepared sterile agar plate. Use a sterile glass bead rolling method to evenly spread the bacterial suspension on the agar plate surface, ensuring uniform distribution of bacteria. Place the plate in a 37°C incubator and invert it for 24 hours to promote sufficient bacterial growth and development, while preventing condensation dripping from the plate lid from affecting colony growth.

[0091] After the culture is completed, the culture dishes are removed from the incubator. Under good light conditions, the growth of colonies in each group of culture dishes is carefully observed. A colony counter is used to accurately count the colonies in each group of culture dishes, and the inhibition rate of the material against bacteria is calculated based on the counting results.

[0092] The results showed that fillers containing niobium pentoxide had better antibacterial properties (see...). Figures 5-6 ).

[0093] Test Example 4, Animal Experiment

[0094] To verify the effectiveness of this invention in root canal filling treatment, animal experiments were conducted to verify the prepared premixed calcium silicate-niobium compound composite root canal filling agent.

[0095] Male beagle dogs with good growth and development and complete permanent dentition were selected. All animals were under general anesthesia, and their mouths were cleaned and disinfected with 2% iodine tincture and then deiodinated with 75% alcohol under strict aseptic conditions. The mandibular third premolar was selected as the experimental tooth. The pulp chamber was opened on the occlusal surface, the pulp chamber roof was removed, and the pulp was completely extracted. The working length was determined with a #15 K file, and the canal was enlarged to #40 with an H file. After each file change, the root canal was irrigated with physiological saline and 2.5% sodium hypochlorite and dried. The filling materials prepared in Examples 1-2 were used to fill the root canals with gutta-percha points, forming two experimental groups. The Bio SP group (0wt% Nb) in the paste preparation stage served as the paste group without added Nb for animal experiments, while the Controll group consisted of gutta-percha points without paste. The occlusal cavity was lined with glass cement and the pulp was indirectly capped with 8th generation 3M light-cured resin.

[0096] Animals should be fed a soft diet for one week post-surgery and receive antibiotics for one week. Observe the animal for any abnormalities in daily activity and feeding. Regularly observe the animal's mental state, feces, and oral tissue condition. The animal should be euthanized three months after root canal treatment for tissue collection.

[0097] Imaging studies showed that the experimental group had significantly better results than the control group in terms of root canal length growth and root canal wall thickness increase in the two left and right third premolars (L and R, respectively) (see [link]). Figure 7 ).

[0098] The above experiments demonstrate that by adding Nb compounds, the calcium silicate and niobium oxide compounds in the filling agent can construct a biphasic composite self-curing system, accelerating the curing time. Simultaneously, the introduction of Nb improves bioactivity and promotes the precipitation of osteogenic hydroxyapatite; furthermore, its antibacterial properties are enhanced. Therefore, when ultimately applied to pulp filling, it can promote the further maturation of immature, pulp-exposed root canals, significantly improving treatment outcomes. Moreover, the filling agent of this invention, through optimized formulation, requires no mixing before use and exhibits good clinical operability.

[0099] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A premixed calcium silicate-niobium compound composite root canal filling agent, characterized in that: include: (a) calcium silicate compounds, (b) phosphate compounds, (c) calcium compounds, (d) niobium compounds, (e) radiation-shielding materials, (f) water-miscible non-aqueous solvents, and (g) organic matter, wherein components (a), (b), (c), (d), (e), and (g) together account for 60% to 95% of the total mass of the filler, and component (f) accounts for 5% to 40% of the total mass of the filler; The component (a) is selected from tricalcium silicate powder and dicalcium silicate powder, with a particle size of 100 μm; The component (b) is selected from calcium phosphate powder with a particle size of 100 μm; The component (c) is selected from calcium hydroxide powder with a particle size of 100 μm; The component (d) is selected from niobium pentoxide powder with a particle size of 200 nm; The component (e) is selected from zirconium oxide powder with a particle size of 200 nm; The component (f) is selected from polyethylene glycol-400; The component (g) is selected from hydroxypropyl methylcellulose, which is a crystalline powder with a particle size of 200 nm.

2. The composite root canal filling agent according to claim 1, characterized in that, The mass ratio of tricalcium silicate powder to dicalcium silicate powder is 2:

1.

3. The method for preparing the composite root canal filling agent as described in claim 1 or 2, characterized in that, The process includes the following steps: uniformly mixing components (a), (b), (c), (d), (e), (f), and (g) using a ball mill; then transferring the mixed paste into a medical syringe; and finally packaging and sterilizing it to obtain the composite root canal filling agent.

4. The use of the composite root canal filling agent as described in claim 1 or 2 in the preparation of root canal filling materials for the treatment of pulpitis.

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