An injectable silicophosphocalcic-based dental paste with high osteogenic activity, and a preparation method and application thereof

Abstract

The application discloses an injectable silicon-phosphorus-calcium-based dental paste with high osteogenic activity and a preparation method and application thereof, and belongs to the field of biomedical materials. The dental paste is prepared by mixing a solid-phase powder and a solidification liquid; the solid-phase powder at least contains alpha-tricalcium phosphate; and the solidification liquid at least contains an aqueous solution of hydroxypropyl methylcellulose. The dental paste prepared by the application is easy to inject, can be self-cured in situ, has excellent anti-collapse performance and osteogenic activity, and can induce the deposition of bone-like hydroxyapatite; and the dental paste can be used for preparing a dental filling repair material.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials technology, specifically relating to an injectable silica-phosphorus-calcium-based dental paste with high osteogenic activity, its preparation method, and its application. Background Technology

[0002] Pulp and periapical diseases are common and frequently occurring oral diseases. Depending on the patient's pulp and periapical lesions, clinical endodontic treatment methods mainly include pulp capping, repair of pulp chamber floor and root canal perforations, root canal treatment, apexification, apical barrier surgery, retrograde filling, and revascularization. Many factors determine the effectiveness of endodontic treatment, among which dental filling and restorative materials are the most crucial step. Calcium silicate-based bioceramic pastes are currently one of the best performing materials in the field of endodontics. Mineral trioxide aggregates (MTA) are the first calcium silicate-based bioceramic material to enter clinical application, possessing excellent bioactivity, biocompatibility, bone-like apatite mineralization ability, sealing ability, and certain antibacterial properties.

[0003] Despite these drawbacks, early versions of MTA materials also suffered from poor handling, difficulty in injection, poor anti-collapse properties, insufficient curing performance, and a tendency to cause tooth discoloration. Early MTA formulations had a strong gritty texture, were difficult to prepare, and were challenging to deliver to narrow, winding root canals. Furthermore, MTA slurries were prone to particle disintegration in aqueous environments. For example, in revascularization procedures, MTA slurries are often placed on blood clots to seal root canals and induce pulp mineralization. However, uncured paste will disintegrate upon contact with fresh blood clots, potentially leading to microleakage of free paste particles and potential inflammatory reactions. MTA curing times were long, around 4 hours. Excessive curing time not only extended treatment time and added extra procedures but also increased the risk of slurry disintegration and displacement.

[0004] Researchers primarily accelerate the hydration reaction of calcium silicate-based materials by doping them with inorganic salts (such as calcium chloride and calcium carbonate) to shorten their curing time. Additionally, the use of organic gelling agents such as sodium alginate, chitosan, and gelatin can effectively improve the anti-collapse properties and handling characteristics of calcium silicate-based pastes. The introduction of organic additives forms an organic gel film on the surface of the paste particles, effectively resisting external moisture erosion. Furthermore, these organic materials possess good rheological and gelling properties, enhancing the adhesion and flow properties of the paste particles. However, the organic matter adhering to the surface of the paste particles inevitably hinders the hydration reaction of the calcium silicate-based materials, thus reducing their curing performance. Currently, this field mainly uses organic-inorganic composite strengthening strategies to address the shortcomings of the above methods.

[0005] CN202111263723.7 discloses an anti-collapse calcium silicate-based root canal filling paste, its preparation method, and its application. This root canal filling paste uses a calcium silicate-based compound and calcium formate as the solid phase and konjac gum solution as the liquid phase. The hydration-accelerating effect of calcium formate and the bonding effect of konjac gum effectively improve the anti-collapse performance and curing characteristics of the calcium silicate-based material. However, calcium formate itself lacks gelling properties and cannot self-cur. Furthermore, konjac gum can form a highly viscous liquid phase even at low concentrations, making solid-liquid mixing difficult at slightly higher concentrations.

[0006] Furthermore, CN200710047442.1 discloses an in-situ self-curing bioactive material for filling human bone defects and its preparation method. This material uses calcium phosphate and tricalcium silicate as composite powders to obtain a bone repair material with self-curing properties. Although the solid phase powder of this material involves calcium phosphate, which has self-curing gelling properties, calcium phosphate is a complex system with various curing properties, and the curing mechanism and curing behavior of different component combinations vary greatly. In addition, this material does not address the problem of insufficient anti-collapse performance of calcium silicate-based materials.

[0007] CN103007340A discloses a self-curing composite bone repair material and its application for repairing human hard tissue. The solid phase of this bone repair material contains tricalcium silicate and calcium phosphate bone cement, as well as various inorganic substances such as potassium dihydrogen phosphate and magnesium oxide. The liquid phase contains potassium citrate and chitosan. Although the curing time of this bone repair material is relatively short, its anti-collapse properties, injection properties, and handling properties are poor because it contains multiple gelling systems with curing characteristics, such as calcium silicate, calcium phosphate, and magnesium phosphate, and the organic matter in the liquid phase has insufficient binding properties.

[0008] In treatments such as apexification, apical barrier surgery, and retrograde root canal filling, dental materials with excellent osteogenic induction properties not only help reduce periapical and periodontal ligament inflammation, stimulate cementum deposition in the periapical region, and promote continued root growth and development, but also promote regeneration of bone defects such as alveolar bone. Therefore, for these reasons, there is an urgent need in the field of endodontic treatment to develop a silica-calcium based bioactive paste material with good curing properties, injectability, anti-collapse properties, and high osteogenic activity.

[0009] However, to date, there have been no reports of synergistic application of α-tricalcium phosphate self-curing materials with hydroxypropyl methylcellulose to improve the handling properties, anti-collapse properties, and osteogenic activity of calcium silicate pastes. Summary of the Invention

[0010] Objective of this invention: To address the shortcomings of existing technologies, this invention provides an injectable silica-phosphorus-calcium-based dental paste with high osteogenic activity, its preparation method, and its applications. The dental paste provided by this invention solves the problems of insufficient handling performance and poor anti-collapse properties of existing silica-phosphorus-based materials, and improves their osteoinductive ability.

[0011] Technical solution: The objective of this invention is achieved through the following technical solution:

[0012] This invention provides an injectable silica-phosphorus-calcium-based dental paste with high osteogenic activity, wherein the dental paste is prepared by mixing a solid powder and a curing liquid; the solid powder contains at least α-tricalcium phosphate; and the curing liquid contains at least an aqueous solution of hydroxypropyl methylcellulose.

[0013] This invention is the first to use α-tricalcium phosphate self-curing paste in conjunction with hydroxypropyl methylcellulose to form an organic-inorganic composite reinforcement. The α-tricalcium phosphate self-curing paste improves the hardening kinetics of calcium silicate-based materials and accelerates the curing reaction of the paste. At the same time, the hydroxypropyl methylcellulose enhances the cohesive force between paste particles and improves the handling performance and anti-collapse properties of calcium silicate-based materials.

[0014] In a preferred embodiment of the present invention, the dental paste is prepared by mixing a curing liquid and a solid powder at a ratio of 0.4 to 0.65 g / g.

[0015] Preferably, the solid powder comprises tricalcium silicate and tricalcium α-phosphate.

[0016] More preferably, the tricalcium silicate powder has a particle size of 0.1–10 μm. Within this particle size range, tricalcium silicate exhibits good fineness and favorable mixing and processing characteristics.

[0017] Furthermore, in the solid powder, the weight percentage of tricalcium silicate is 50-90%, the weight percentage of tricalcium α-phosphate is 10-50%, and the sum of the weight percentages of the two is 100%.

[0018] Preferably, the curing solution is an aqueous solution containing disodium hydrogen phosphate and hydroxypropyl methylcellulose.

[0019] Furthermore, in the curing solution, the weight percentage of disodium hydrogen phosphate is 1-5%, and the weight percentage of hydroxypropyl methylcellulose is 0.5-3%.

[0020] The present invention also provides a method for preparing the above-mentioned injectable silica-phosphorus-calcium-based dental paste, comprising the following steps:

[0021] (1) Tricalcium silicate powder and α-tricalcium phosphate powder are mixed evenly to obtain solid powder;

[0022] (2) Hydroxypropyl methylcellulose powder is added to water and fully dissolved to obtain a homogeneous liquid phase. Then, disodium hydrogen phosphate powder is dissolved in the liquid phase to obtain a curing liquid.

[0023] (3) The obtained curing liquid and solid powder are mixed evenly in proportion to obtain an injectable silicon-phosphorus-calcium-based dental paste with high osteogenic activity.

[0024] This invention also provides the application of the above-mentioned injectable silica-phosphorus-calcium-based dental paste in the preparation of dental filling and restorative materials. The injectable silica-phosphorus-calcium-based dental paste provided by this invention can be applied in endodontic treatments such as apical barrier surgery, apical backfilling, apexification, root canal treatment, and pulp capping.

[0025] Beneficial effects:

[0026] 1. This invention is the first to use α-tricalcium phosphate self-curing paste in conjunction with hydroxypropyl methylcellulose to form an organic-inorganic composite reinforcer. The α-tricalcium phosphate self-curing paste improves the hardening kinetics of calcium silicate-based materials and accelerates the curing reaction of the paste. At the same time, the hydroxypropyl methylcellulose enhances the cohesive force between paste particles, thereby improving the handling performance and anti-collapse properties of calcium silicate-based materials.

[0027] 2. After introducing the α-tricalcium phosphate self-curing system, this invention can effectively enhance the expression of osteogenic genes in calcium-silicon-based materials and improve the biocompatibility and osteogenic capacity of the paste.

[0028] 3. The silicon-phosphorus-calcium-based bioactive paste of this invention possesses excellent bone-like apatite mineralization ability, which can promote the rapid deposition of apatite crystals and form a tight bond with the tooth structure, exhibiting excellent sealing properties. Furthermore, this paste possesses strong alkali-forming ability and antibacterial properties.

[0029] 4. By rationally proportioning solid powder and curing liquid, this invention can produce injectable dental paste materials with adjustable flow properties, which can meet the needs of different clinical applications. Attached Figure Description

[0030] Figure 1 The injection force result diagram of the injectable silica-phosphorus-calcium-based dental paste with high osteogenic activity prepared in the embodiment of the present invention;

[0031] Figure 2 Anti-collapse photographs of the injectable silica-phosphorus-calcium-based dental paste with high osteogenic activity prepared in Comparative Examples 1 and 2 and Examples 1-3 of the present invention;

[0032] Figure 3 These are anti-collapse photographs of the injectable silica-phosphorus-calcium-based dental paste with high osteogenic activity prepared in Examples 4-6 of this invention after vibration.

[0033] Figure 4The curing time results of the injectable silica-phosphorus-calcium-based dental paste with high osteogenic activity prepared in the embodiments of the present invention;

[0034] Figure 5 The results of the alkali-forming ability of the injectable silica-phosphorus-calcium-based dental paste with high osteogenic activity prepared in the embodiments of the present invention;

[0035] Figure 6 Cell activity results of the injectable silica-phosphorus-calcium-based dental paste with high osteogenic activity prepared according to embodiments of the present invention;

[0036] Figure 7 The results of ALP gene expression in osteoblasts by the injectable silica-phosphorus-calcium-based dental paste with high osteogenic activity prepared in the embodiments of the present invention.

[0037] Figure 8 The results of OPN gene expression in osteoblasts on the injectable silica-phosphorus-calcium-based dental paste with high osteogenic activity prepared in the embodiments of the present invention.

[0038] Figure 9 SEM image of the surface of the injectable silica-phosphorus-calcium-based dental paste with high osteogenic activity prepared in Example 1 of this invention after being soaked in SBF. Detailed Implementation

[0039] The technical solution of the present invention will be described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to the embodiments described.

[0040] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0041] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the experimental materials used in the following examples are commercially available products, with tricalcium silicate powder and α-tricalcium phosphate powder purchased from Kunshan Huaqiao Science & Technology New Materials Co., Ltd. The particle size of the tricalcium silicate powder is 0.1–10 μm.

[0042] Example 1

[0043] Weigh out 90% tricalcium silicate powder and 10% α-tricalcium phosphate powder by weight, mix them evenly to obtain a solid phase powder; dissolve 0.6g hydroxypropyl methylcellulose in 18.9g deionized water, and after it is fully dissolved, add 0.5g disodium hydrogen phosphate powder and stir thoroughly to form a homogeneous liquid phase.

[0044] The curing liquid and solid powder are then thoroughly mixed at a ratio of 0.5 g / g to obtain a dental paste material.

[0045] Example 2

[0046] Weigh out 70% tricalcium silicate powder and 30% α-tricalcium phosphate powder by weight, mix them evenly to obtain a solid phase powder; dissolve 0.6g hydroxypropyl methylcellulose in 18.9g deionized water, and after it is fully dissolved, add 0.5g disodium hydrogen phosphate powder and stir thoroughly to form a homogeneous liquid phase.

[0047] The curing liquid and solid powder are then thoroughly mixed at a ratio of 0.5 g / g to obtain a dental paste material.

[0048] Example 3

[0049] Weigh out 50% tricalcium silicate powder and 50% α-tricalcium phosphate powder by weight, mix them evenly to obtain a solid phase powder; dissolve 0.6g hydroxypropyl methylcellulose in 18.9g deionized water, and after it is fully dissolved, add 0.5g disodium hydrogen phosphate powder and stir thoroughly to form a homogeneous liquid phase.

[0050] The curing liquid and solid powder are then thoroughly mixed at a ratio of 0.5 g / g to obtain a dental paste material.

[0051] Example 4

[0052] Weigh out 70% tricalcium silicate powder and 30% α-tricalcium phosphate powder by weight, mix them evenly to obtain a solid phase powder; dissolve 0.05g hydroxypropyl methylcellulose in 9.45g deionized water, and after it is fully dissolved, add 0.5g disodium hydrogen phosphate powder and stir thoroughly to form a homogeneous liquid phase.

[0053] The curing liquid and solid powder are then thoroughly mixed at a ratio of 0.4 g / g to obtain a dental paste material.

[0054] Example 5

[0055] Weigh out 90% tricalcium silicate powder and 10% α-tricalcium phosphate powder by weight, mix them evenly to obtain a solid phase powder; dissolve 0.3g hydroxypropyl methylcellulose in 9.6g deionized water, and after it is fully dissolved, add 0.1g disodium hydrogen phosphate powder and stir thoroughly to form a homogeneous liquid phase.

[0056] The curing liquid and solid powder are then thoroughly mixed at a ratio of 0.65 g / g to obtain a dental paste material.

[0057] Example 6

[0058] Weigh out 70% tricalcium silicate powder and 30% α-tricalcium phosphate powder by weight, mix them evenly to obtain a solid phase powder; dissolve 0.15g hydroxypropyl methylcellulose in 9.75g deionized water, and after it is fully dissolved, add 0.1g disodium hydrogen phosphate powder and stir thoroughly to form a homogeneous liquid phase.

[0059] The curing liquid and solid powder are then thoroughly mixed at a ratio of 0.5 g / g to obtain a dental paste material.

[0060] Comparative Example 1

[0061] Using tricalcium silicate powder as the solid phase powder and deionized water as the curing liquid;

[0062] The curing liquid and solid powder are then thoroughly mixed at a ratio of 0.5 g / g to obtain a dental paste material.

[0063] Comparative Example 2

[0064] Tricalcium silicate powder was used as the solid phase powder, and deionized water was used as the curing liquid. 0.6g of hydroxypropyl methylcellulose was dissolved in 18.9g of deionized water. After it was fully dissolved, 0.5g of disodium hydrogen phosphate powder was added and stirred thoroughly to form a homogeneous liquid phase.

[0065] The curing liquid and solid powder are then thoroughly mixed at a ratio of 0.5 g / g to obtain a dental paste material.

[0066] The performance of each embodiment and comparative example is characterized below:

[0067] Injectability test: The prepared paste material is loaded into a syringe and then placed in a universal testing machine to measure the changes in injection force and displacement. Injectability is expressed by measuring the weight of the paste before and after injection. Injectability is expressed as the percentage of the weight of the injected paste to the total weight of the original paste.

[0068] Injection performance tests were conducted on Comparative Examples 1-2 and 1-6. The results showed that the paste in Comparative Example 1 had a gritty texture, low interparticle viscosity, was difficult to inject, and exhibited severe pressure filtration. In contrast, the paste in Comparative Example 2 achieved an injectability of 93%, demonstrating excellent injectability. These results indicate that introducing hydroxypropyl methylcellulose into the paste slurry can improve injectability. Figure 1 It can be seen that, compared with Comparative Example 2, the injection force required for the pastes in Examples 1-3 is significantly reduced, meaning these pastes are easier to inject and have better injection performance. This result indicates that the introduction of α-tricalcium phosphate self-curing material into the paste can enhance injection capability. Furthermore, the pastes in Examples 4, 5, and 6 are easy to inject and exhibit excellent injection performance.

[0069] Anti-collapse performance test: The prepared paste material is loaded into a syringe and injected into a water-containing glass dish. After being placed in a vibrator and vibrated for 10 minutes, the free collapse of the paste particles is observed.

[0070] Anti-collapse performance tests were conducted on comparative examples 1-2 and 1-6, and the results are as follows: Figure 2 As shown, in Comparative Example 1, the paste exhibited particle detachment upon contact with water, and after 10 minutes of vibration, the paste collapsed and disintegrated, with particles scattered across the entire liquid surface. In contrast, in Comparative Example 2, no particle detachment occurred before or after vibration, demonstrating excellent anti-collapse properties. Similarly, the pastes in Examples 1-3 maintained their initial slurry shape after vibration without particle collapse. These results indicate that hydroxypropyl methylcellulose and tricalcium α-phosphate effectively improve the anti-collapse ability of the paste material. Furthermore, from... Figure 3 It can be seen that the pastes in Examples 4-6 can maintain their initial injection shape after vibration, and the particles in the slurry do not collapse or leak, exhibiting excellent anti-collapse properties.

[0071] Curing time determination: The freshly prepared paste material is poured into a mold and then placed in an environment of 37°C for curing. The curing time of the paste is then determined using a Vicat apparatus.

[0072] Examples 1 and 3, as well as Comparative Example 2, were tested, and the results are as follows: Figure 4 As shown, the initial and final setting times of the paste in Comparative Example 2 were 79 and 190 minutes, respectively, while those in Example 1 were 64 and 182 minutes, respectively. The curing time of the paste was shortened. This result indicates that introducing 10% α-tricalcium phosphate into the paste can accelerate the hardening of the paste, while when the content of α-tricalcium phosphate is further increased to 50%, the curing time of the paste is prolonged.

[0073] Alkalinity-forming ability test: The freshly prepared paste material was poured into a mold and cured at 37°C. The sample was then immersed in a Tris-HCl solution (pH = 7.4, 37°C), with the sample surface area to Tris-HCl solution volume ratio being 0.1 cm². 2 / mL. After soaking for different times, the pH value of the solution after soaking was measured using a pH meter.

[0074] Examples 1-3 were tested, and the results are as follows: Figure 5 As shown, after soaking the samples for 1 day, the Tris-HCl solution became alkaline, with a maximum pH of 8.97. When the soaking time was greater than 5 days, the pH of the Tris-HCl solution after soaking all samples exceeded 10, showing a strong alkalinity-forming ability. It can also exhibit a certain bactericidal effect in an environment with a pH greater than 9.

[0075] Cell viability and osteogenic gene expression assays: The cured paste sample was ground into a fine powder, then the powder was added to DMEM (Hyclone, USA) cell culture medium for extraction. The supernatant was collected by centrifugation to obtain the sample extract for subsequent tests. Osteoblasts (ATCC) were used as experimental cells. Cell viability of different pastes was evaluated using a cell counting kit (Counting Kit-8, CCK-8, Beyotime, China). First, osteoblasts were cultured in DMEM medium containing the prepared dental paste extract, then CCK-8 reagent was added, and the mixture was incubated at 37°C in the dark. The OD value at 450 nm was then measured using a microplate reader.

[0076] Cell viability (%) = Corrected OD value of sample group / Corrected OD value of control group × 100%.

[0077] The effects of different samples on the expression of osteogenic-related genes ALP and OPN in cells were detected using RT-PCR. Osteoblasts were cultured in a medium containing sample extracts, and total RNA was extracted using an RNA kit (Omega, China). The obtained RNA was then converted into cDNA using a reverse transcription kit (Takara, Japan). Finally, the expression of ALP and OPN osteogenic-related genes was detected by real-time quantitative reverse transcription polymerase chain reaction (PCR instrument, Bio-Rad, USA). Using GAPDH as a reference, the synthesized primer gene sequences are shown in Table 1.

[0078] PCR reaction procedure: A 10 μL reaction mixture containing 5 μL of PSYBR Premix Ex Taq II (2×), 0.4 μL each of forward and reverse primers, 1 μL of RT reaction solution (cDNA solution), and 4.2 μL of dH2O (sterile distilled water) was added to an eight-tube set. The samples were analyzed using quantitative real-time PCR using the Bio-Rad CFX Manager system. The program settings were as follows: 95℃, 30 s, for 45 cycles, with each cycle consisting of 95℃, 5 s, 60℃, and 30 s. GAPDH was used as an internal control, and the experimental results were analyzed using BioRad CFX Manager software.

[0079] Table 1 shows the synthesized primer gene sequences.

[0080]

[0081] Examples 1 and 3, as well as Comparative Example 2, were tested, and the cell viability results are as follows: Figure 6 As shown, cell activity increased to 171% in Example 1, exhibiting the highest cell activity, and Examples 1-3 were all higher than Comparative Example 2. This result indicates that α-tricalcium phosphate can enhance the activity of the paste on osteoblasts. ALP and OPN gene expression are shown below. Figure 7 and 8 As shown, the paste extracts in Examples 1-3 can effectively upregulate the expression of ALP and OPN genes, demonstrating excellent osteogenic ability.

[0082] Induced apatite mineralization test: After the paste is cured, the disc sample is immersed in simulated body fluid (SBF), and the formation of apatite on the sample surface is observed by scanning electron microscopy (SEM).

[0083] The SEM image of the surface after soaking SBF in paste in Example 1 of this invention is obtained from... Figure 9 As shown, after soaking in SBF, dense spherical bone-like apatite forms on the surface of the hardened paste, indicating that the paste has excellent ability to induce the formation of bone-like apatite.

[0084] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. An injectable silica-phosphorus-calcium-based dental paste with high osteogenic activity, characterized in that, The dental paste is prepared by mixing a curing liquid and a solid powder at a ratio of 0.4–0.65 g / g; the solid powder comprises tricalcium silicate and α-tricalcium phosphate; the weight percentage of tricalcium silicate is 50–90%, the weight percentage of α-tricalcium phosphate is 10–50%, and the sum of the weight percentages of the two is 100%; the curing liquid is an aqueous solution containing disodium hydrogen phosphate and hydroxypropyl methylcellulose; in the curing liquid, the weight percentage of disodium hydrogen phosphate is 1–5%, and the weight percentage of hydroxypropyl methylcellulose is 0.5–3%.

2. The injectable silica-phosphorus-calcium-based dental paste according to claim 1, characterized in that, The tricalcium silicate powder has a particle size of 0.1–10 μm.

3. The method for preparing the injectable silica-phosphorus-calcium-based dental paste according to claim 1 or 2, characterized in that, Includes the following steps: (1) Tricalcium silicate powder and α-tricalcium phosphate powder are mixed evenly to obtain solid powder; (2) Hydroxypropyl methylcellulose powder is added to water and dissolved completely to obtain a homogeneous liquid phase. Then, disodium hydrogen phosphate powder is dissolved in the liquid phase to obtain a curing liquid. (3) Mix the obtained curing liquid and solid powder in proportion to obtain an injectable silicon-phosphorus-calcium-based dental paste with high osteogenic activity.

4. The use of the injectable silica-phosphorus-calcium-based dental paste according to claim 1 or 2 in the preparation of dental filling and restorative materials.

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