Bioactive photocurable material, method for its preparation and use in dental substrate restorative materials

Abstract

The present application relates to the technical field of composite materials, and particularly relates to a bioactive photocuring material, a preparation method thereof and application thereof as a dental substrate repair material. The bioactive photocuring material comprises a polymerizable monomer, an initiator and an inorganic filler, wherein the inorganic filler comprises calcium hydroxide; and further comprises a bioactive photocuring prepolymer, wherein the bioactive photocuring prepolymer is obtained by reacting a bioactive organic acid, a polyol monomer and a monomer containing a carbon-carbon double bond at 120-150 DEG C for 1-72 hours, and then neutralizing the reaction product with a neutralizing agent; and the monomer containing a carbon-carbon double bond is selected from at least one of a diol, a diacid and an anhydride. In the present application, the bioactive photocuring prepolymer is introduced into the calcium hydroxide system, so that the viscosity of the system is increased, the toughness, strength and degradability of the photocuring resin are enhanced, and the regeneration of bone and dentin is promoted by releasing active ingredients, and the bioactive photocuring material can be applied to a base material for caries filling and composite resin filling.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, and in particular to a bioactive photocurable material, its preparation method, and its application as a dental substrate restorative material. Background Technology

[0002] Dental lining restoration (also known as "substituting" or "lining restoration") is a technique used in dental treatment to repair tooth defects. It involves placing a special material on the dentin or floor of the cavity before filling a carious cavity or repairing tooth damage. This material protects the pulp, isolates irritants, and enhances the stability of the restoration. The dental lining material is typically located between the tooth structure (enamel, dentin, etc.) and the restoration (inlay, crown, etc.), and its functions include connecting the tooth and restoration, buffering chewing stress, and preventing microleakage.

[0003] Calcium hydroxide is a commonly used material for dental lining restorations. It was first used for pulp capping in the 1930s and can induce the formation of reparative dentin to some extent, exhibiting good antibacterial properties against various oral bacteria. However, calcium hydroxide also has significant drawbacks: it is more cytotoxic than mineral trioxide aggregates (MTA), readily dissolves in the oral environment, and lacks adhesive properties. While existing light-cured calcium hydroxide dental lining restoration materials can form stable resin materials through light curing and encapsulate calcium hydroxide for continuous release, they still lack good osteogenic and osteoinductive biological activities.

[0004] Citric acid is an important intermediate in the tricarboxylic acid (TCA) cycle. In the human body, 90% of citric acid is concentrated in bone tissue (including teeth and bones) and plays a vital biomechanical and biological role (Bone 2018, 114, 189-197; Proc. Natl Acad. Sci. USA 2014, 111, E1354-E1363.). Citric acid plays a crucial regulatory role in bone mineralization, strongly binding to hydroxyapatite (HA) nanocrystals, controlling their excessive growth and thickening, and acting as an important bridging agent in layered HA and HA / collagen complexes. This is essential for bone stability, strength, and fracture resistance (Proc. Natl Acad. Sci. USA 2014, 111, E1354-E1363; Proc. Natl Acad. Sci. USA 2010, 107, 22425-22429.). Osteoblast secretion and accumulation of citric acid (“citric acidification”) is an essential stage in osteogenic differentiation and mineralization (Open Bone J. 2012, 4, 27-33.). Recent research indicates that during osteogenic differentiation of stem cells, cells can promote the uptake of exogenous citric acid through metabolic regulation to adapt to the high metabolic activity required for stem cell differentiation (Proc. Natl Acad. Sci. USA 2018, 115, E11741-E11750.). However, the presence and important role of citric acid in dental tissues have been overlooked by the dental community for the past 40 years. In fact, craniofacial bones, teeth, and periodontal tissues, especially alveolar bone, dentin, and cementum, also contain high concentrations of citric acid (approximately 0.9 wt%, compared to 0.04 wt% in muscle) (Madridge J. Dent. Oral Surg. 2018, 3, 85-90.). Citric acid plays a similar important role in dental tissues as it does in bone tissues. Therefore, incorporating citric acid into the design of light-cured calcium hydroxide dental substrate restorative materials has significant scientific importance and practical application value.

[0005] Patent document CN102580144A discloses a surgical bone cement that can be used in orthopedics, plastic surgery, dentistry, otology, and maxillofacial applications. The cement includes bone cement components, a curing agent, and water; it also contains a biocompatible filler, optionally calcium hydroxide; and a soluble pH adjuster, optionally citric acid. This prior art material still suffers from insufficient tensile strength after curing, affecting its core application effects as a dental lining restorative material in the special environment of the oral cavity, such as its role in connecting the tooth and restoration, buffering stress, and preventing microleakage. Summary of the Invention

[0006] The present invention aims to solve the above problems by providing a bioactive photocurable material that is easy to shape before curing and has suitable tensile strength after curing, as well as its preparation method and its application as a dental substrate restorative material.

[0007] The technical solution to the problem solved by the present invention is, in a first aspect, to provide a bioactive photocurable material, comprising a polymerizable monomer, an initiator, and an inorganic filler, wherein the inorganic filler comprises calcium hydroxide; the bioactive photocurable material further comprises a bioactive photocurable prepolymer, wherein the bioactive photocurable prepolymer is obtained by reacting a bioactive organic acid, a polyol monomer, and a monomer containing a carbon-carbon double bond at 120-150°C for 1-72 hours, and then neutralizing it with a neutralizing agent; wherein the monomer containing a carbon-carbon double bond is selected from at least one of diols, diacids, and acid anhydrides; and wherein the neutralizing agent is selected from at least one of sodium bicarbonate and calcium carbonate.

[0008] In this invention, the inventors discovered through experiments that adding a specific bioactive photocurable prepolymer to a system containing calcium hydroxide and then polymerizing it together can enhance the tensile strength of the final cured resin. The inventors speculate that this may be due to the synergistic effect of calcium hydroxide and the specific prepolymer: the prepolymer of this invention is a relatively flexible chain segment composed of ester bonds, providing basic mechanical properties, while possessing covalently crosslinkable carbon-carbon double bond sites and ionicly crosslinkable carboxylate anions at the ends. When mixed with calcium hydroxide, the calcium ions provided by the calcium hydroxide can form strong ionic bonds with the carboxylate anions on the prepolymer chain, creating an ionic crosslinking network. The alkaline environment provided by the calcium hydroxide induces free radical polymerization of the carbon-carbon double bonds in the prepolymer, thus constructing a very stable covalent crosslinking network on the basis of the ionic crosslinking network. This forms an interpenetrating double crosslinking network, with the covalent crosslinking network providing the basic framework of the material and the ionic crosslinking network forming reinforcement points on the basic framework. At the same time, taking advantage of the fact that ionic bonds are more likely to undergo reversible breakage and recombination than covalent bonds, this process can effectively absorb and dissipate energy, preventing energy from concentrating on a certain covalent main chain and causing it to break, thereby improving the tensile strength of the cured material.

[0009] Bioactive photocurable prepolymers The selection of bioactive organic acids is generally unrestricted; for example, citric acid, tartaric acid, and itaconic acid can be used. However, suitable organic acids can further improve the performance of the material. Preferably, the bioactive organic acid is citric acid. Citric acid is bio-based, safe, and non-toxic; it can bind to calcium ions released from calcium hydroxide, promoting bone and dentin regeneration; it has multiple reaction sites; its molecular chain length is moderate, achieving a balance between rigidity and flexibility; and after heating and dehydration, it can provide additional carbon-carbon double bonds in situ, increasing covalent cross-linking sites and further realizing the aforementioned double cross-linked network.

[0010] The choice of polyol monomer is unrestricted, but bio-based non-toxic materials are preferred. As a preferred embodiment of the present invention, the polyol monomer is selected from at least one of diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 1000, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, and glycerol.

[0011] The choice of monomers containing carbon-carbon double bonds is not limited, but bio-based non-toxic materials are preferred. As a preferred embodiment of the present invention, the monomers containing carbon-carbon double bonds are selected from at least one of compound A having the structure of Formula 1, compound B having the structure of Formula 2, maleic acid, maleic anhydride, fumaric acid, and itaconic acid.

[0012] Formula 1: In this context, R is methyl or ethyl; and compound A is an acrylate monomer or a methacrylate monomer with an olefinic end group and multiple hydroxyl groups.

[0013] Formula 2: In this context, R is methyl or ethyl; and compound B is an acrylate or methacrylate-terminated polyether polyol.

[0014] The ratio of bioactive organic acid, polyol monomer, and monomer containing carbon-carbon double bonds is not limited, but an appropriate ratio can further optimize the formation of the double crosslinked network. Preferably, the molar ratio of the bioactive organic acid, polyol monomer, and monomer containing carbon-carbon double bonds is 1:(0.5~2):(0.3~0.5). For example, when the bioactive organic acid is 1 mole, the polyol monomer can be 0.5 moles, 0.6 moles, 0.7 moles, 0.8 moles, 0.9 moles, 1 mole, 1.1 moles, 1.2 moles, 1.3 moles, 1.4 moles, 1.5 moles, 1.6 moles, 1.7 moles, 1.8 moles, 1.9 moles, or 2 moles; the monomer containing carbon-carbon double bonds can be 0.3 moles, 0.35 moles, 0.4 moles, 0.45 moles, or 0.5 moles.

[0015] There is no limit to the amount of neutralizing agent used; an excess can be used. Excess neutralizing agent can be removed by dialysis.

[0016] The bioactive photocurable prepolymer is obtained by reacting bioactive organic acids, polyol monomers, and monomers containing carbon-carbon double bonds at 120-150°C for 1-72 hours, followed by neutralization. The reaction temperature can be, for example, 120°C, 130°C, 140°C, or 150°C; the reaction time is preferably 12-36 hours, for example, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, or 36 hours.

[0017] Inorganic packing Calcium hydroxide must be included. The ratio of calcium hydroxide to the bioactive photocurable prepolymer is generally unrestricted, but a suitable ratio can further optimize the formation of the double crosslinked network. Preferably, the mass ratio of calcium hydroxide to the bioactive photocurable prepolymer is 1:(3~9). For example, the mass ratio can be 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, or 1:9.

[0018] The inorganic filler may also include other inorganic materials. As a preferred embodiment of the present invention, the inorganic filler may also include at least one of hydroxyapatite, β-triphosphate, calcium carbonate, zinc oxide, and magnesium oxide.

[0019] The ratio of calcium hydroxide to other inorganic materials is not limited. Preferably, the mass ratio of calcium hydroxide to other inorganic materials is 1:(0.5~2). For example, the mass ratio can be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, or 1:2.

[0020] In polymerizable monomers The choice of monomer is not limited and can be any commonly used material in the prior art that is combined with calcium hydroxide as a pulp capping agent. As a preferred embodiment of the present invention, the polymerizable monomer is selected from at least one of triethylene dimethacrylate (TEDMA), bisphenol A glycerol dimethacrylate (BisGMA), tetraethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate.

[0021] Initiator Preferably, the photoinitiator is selected from at least one of camphorquinone, benzophenone, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone (I2959) and phenyl-2,4,6-trimethylbenzoyl lithium phosphine (LAP).

[0022] In some embodiments, as a preferred embodiment of the present invention, the bioactive photocurable material further includes an antioxidant to improve the material's service life. Preferably, the material is safe and non-toxic. As a preferred embodiment of the present invention, the antioxidant is selected from at least one of hydroquinone, 1,3-butanediol disalicylate, epigallocatechin gallate (EGCG), and resveratrol.

[0023] Bioactive photocurable materialsThe amount of each of the above components is not limited, but the appropriate amount can better balance the fluidity of the material before curing and the tensile strength after curing. As a preferred embodiment of the present invention, the components include 20-55 parts of polymerizable monomer, 10-60 parts of inorganic filler, 0.5-3 parts of initiator, and 30-70 parts of bioactive photocurable prepolymer by weight.

[0024] In embodiments that include antioxidants, 0.1 to 2 parts of antioxidant are also included.

[0025] Preferably, the composition, by weight, includes 20-55 parts of polymerizable monomer, 5-20 parts of calcium hydroxide, 5-40 parts of other inorganic materials, 0.5-3 parts of initiator, 30-70 parts of bioactive photocurable prepolymer, and 0.1-2 parts of antioxidant. For example, the weight percentages of polymerizable monomer can be 30, 40, 50, 60, or 70 parts; the weight percentages of calcium hydroxide can be 5, 10, 15, or 20 parts; the weight percentages of other inorganic materials can be 5, 10, 15, 20, 25, 30, 35, or 40 parts; the weight percentages of initiator can be 0.5, 1, 1.5, 2, 2.5, or 3 parts; the weight percentages of bioactive photocurable prepolymer can be 30, 40, 50, 60, or 70 parts; and the weight percentages of antioxidant can be 0.1, 0.5, 1, 1.5, or 2 parts.

[0026] Secondly, another objective of this invention is to provide a method for preparing the above-mentioned bioactive photocurable material, comprising the following steps: dispersing the bioactive photocurable prepolymer in the polymerizable monomer, then adding the inorganic filler and initiator, and mixing them evenly.

[0027] Thirdly, another objective of this invention is to provide the application of the above-mentioned bioactive photocurable material as a dental substrate restorative material.

[0028] As a preferred embodiment of the present invention, in application, the bioactive light-curing material is coated onto the dentin or the bottom of the cavity, and after adjusting its plasticity, it is light-cured and shaped.

[0029] In this invention, the tensile strength-enhanced material, used as a dental lining restorative material, effectively plays a crucial role in the unique oral environment by acting as a bridge between the tooth and the restoration, buffering stress, and preventing microleakage. Specifically, in the oral environment, the material faces multi-directional forces (including tensile and shear forces) generated by chewing, as well as temperature changes. The high tensile strength material effectively resists these chewing stresses and the thermal expansion and contraction caused by temperature changes, thereby preventing cracks or even debonding between the restoration and the tooth, achieving the effect of bridging the gap and preventing microleakage. Simultaneously, since teeth are typically relatively soft and restorations are typically harder, the high tensile strength material located between them uses elasticity to transfer and disperse forces from the restoration to the tooth, avoiding stress concentration and thus buffering stress.

[0030] The beneficial effects of this invention are:

[0031] 1. This invention provides a bioactive photocurable material that utilizes the synergistic effect of calcium hydroxide and a specific prepolymer containing ester chain segments, carbon-carbon double bond sites, and carboxylate anions to improve the tensile strength of the cured material, making it suitable as a dental substrate restorative material in the special environment of the oral cavity.

[0032] 2. The bioactive light-curing material of the present invention has a suitable viscosity before curing, reduced fluidity, and is more like bone paste, exhibiting better shape plasticity and conformability. This avoids the gravitational influence caused by excessive fluidity, allowing for better filling and shaping before light curing. Especially when used as a dental substrate restorative material in the special environment of the oral cavity, it can perfectly fill irregular tooth defects.

[0033] 3. In some embodiments, the bioactive photocurable material of the present invention uses citric acid as one of the reaction raw materials of the prepolymer. The material has a certain degree of biodegradability and can release active ingredients such as citric acid during the degradation process. Combined with the calcium ions released by calcium hydroxide, it promotes bone and dentin regeneration, allowing the newly formed dentin to fill the degraded sites and better repair the dentin and alveolar bone. At the same time, it can also play a continuous bactericidal role by releasing calcium hydroxide, and the released citric acid can partially neutralize calcium hydroxide, buffer the pH value of the system, and also provide a certain degree of antibacterial properties. Detailed Implementation

[0034] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described, but the present invention is not limited to these embodiments.

[0035] Example 1

[0036] A bioactive photocurable material, by weight, comprises 40 parts polymerizable monomer, 1 part initiator, 18 parts inorganic filler, 40 parts bioactive photocurable prepolymer, and 1 part antioxidant. The polymerizable monomer is TEDMA, the initiator is benzophenone, the antioxidant is hydroquinone, the inorganic filler includes 6 parts calcium hydroxide and 12 parts hydroxyapatite, and the bioactive photocurable prepolymer is obtained by reacting citric acid, polyethylene glycol 600, and maleic anhydride, followed by neutralization with calcium carbonate.

[0037] This bioactive photocurable material is obtained through the following steps:

[0038] S1. Bioactive photocurable prepolymer: 15.36 g (0.08 mol) of citric acid and 60 g (0.08 mol) of polyethylene glycol 600 were placed in a 250 mL round-bottom flask equipped with a magnetic stir bar of appropriate size. After melting at 160 °C, the mixture was cooled to 140 °C, and 2.94 g (0.03 mol) of maleic anhydride was added. The reaction mixture was continued to react at 140 °C for more than 12 h until the stir bar stopped rotating at 60 rpm. After cooling, 100 mL of deionized water was added to dissolve the reaction product, and then 25 g of excess calcium carbonate was added. The mixture was stirred at high speed at room temperature for more than 12 h, and then dialyzed using a dialysis bag with a molecular weight cutoff of 1000 Da. Excess calcium carbonate was removed by centrifugation, and the resulting solution was freeze-dried to obtain the bioactive photocurable prepolymer.

[0039] S2. Bioactive photocurable material: Disperse 40 parts of the freeze-dried bioactive photocurable prepolymer obtained in step S1 into 40 parts of TEDMA according to the mass ratio, stir evenly, and then evenly disperse 6 parts of calcium hydroxide, 12 parts of hydroxyapatite, 1 part of benzophenone, and 1 part of hydroquinone into the above mixed monomers to make a paste or bone paste mixture, which can be used as a photocurable calcium hydroxide dental substrate restoration material.

[0040] Viscosity testing before photocuring

[0041] The viscosity of the material obtained above was measured using a rotational viscometer: a sufficient amount of material was placed in the rotating measuring head of the rotational viscometer, and the viscosity was determined by measuring the torque of the liquid at different shear rates. Its viscosity was 5000 mPa·s, indicating suitable fluidity and ease of plasticization.

[0042] Tensile strength test after light curing

[0043] The tensile strength of the material obtained above was measured using a universal tensile testing machine (Instron 34TM-10): the material was light-cured in a dumbbell-shaped mold, and then the sample was stretched using the universal tensile testing machine until it broke. The highest strength before breakage was the tensile strength. Its tensile strength reached 252 MPa.

[0044] Example 2

[0045] This embodiment is basically the same as Embodiment 1, except that the bioactive photocurable prepolymer is obtained by reacting citric acid, polyethylene glycol 600 and maleic acid, and then neutralizing it with calcium carbonate.

[0046] Specifically, in step S1, 15.36 g (0.08 mol) of citric acid and 60 g (0.08 mol) of polyethylene glycol 600 are placed in a 250 mL round-bottom flask equipped with a magnetic stir bar of appropriate size. After melting at 160 °C, the temperature is lowered to 140 °C, and then... 3.48g (0.03 mol) maleic acid The reaction mixture was continued to react at 140°C for more than 12 hours until the stir bar stopped rotating at 60 rpm. After cooling, 100 mL of deionized water was added to dissolve the reaction product, and then 25 g of excess calcium carbonate was added. The mixture was stirred at high speed at room temperature for more than 12 hours, then dialyzed using a dialysis bag with a molecular weight cutoff of 1000 Da and centrifuged to remove excess calcium carbonate. The resulting solution was freeze-dried to obtain the bioactive photocurable prepolymer.

[0047] Example 3

[0048] This embodiment is basically the same as Embodiment 1, except that the bioactive photocurable prepolymer is obtained by reacting citric acid, tetraethylene glycol, and maleic anhydride, and then neutralizing it with calcium carbonate.

[0049] Specifically, in step S1, 15.36 g (0.08 mol) of citric acid and 18.64g (0.08mol) tetraethylene glycol The mixture was placed in a 250 mL round-bottom flask equipped with a magnetic stir bar of appropriate size, melted at 160 °C, cooled to 140 °C, and 2.94 g (0.03 mol) of maleic anhydride was added. The reaction mixture was continued to react at 140 °C for more than 12 h, until the stir bar stopped rotating at 60 rpm. After cooling, 100 mL of deionized water was added to dissolve the reaction product, and then 25 g of excess calcium carbonate was added. The mixture was stirred at high speed at room temperature for more than 12 h, dialyzed through a dialysis bag with a molecular weight cutoff of 1000 Da, and the excess calcium carbonate was removed by centrifugation. The resulting solution was freeze-dried to obtain the bioactive photocurable prepolymer.

[0050] Examples 4-6

[0051] This embodiment is basically the same as Example 1, except that the amount of polyethylene glycol 600 used in preparing the bioactive photocurable prepolymer is different, as shown in Table 1 below.

[0052] Table 1. .

[0053] Examples 7-10

[0054] This embodiment is basically the same as Embodiment 1, except that the amounts of bioactive photocurable prepolymer, calcium hydroxide, and polymer monomers are different when preparing the bioactive photocurable material, as shown in Table 2 below.

[0055] Table 2. .

[0056] Example 11

[0057] A bioactive photocurable material, by weight, comprises 40 parts polymerizable monomer, 1 part initiator, 18 parts inorganic filler, 40 parts bioactive photocurable prepolymer, and 1 part antioxidant. The polymerizable monomer is BisGMA, the initiator is I2959, the antioxidant is EGCG, the inorganic filler includes 6 parts calcium hydroxide and 12 parts calcium carbonate, and the bioactive photocurable prepolymer is obtained by reacting citric acid, 1,8-octanediol, and itaconic acid, followed by neutralization with sodium bicarbonate.

[0058] This bioactive photocurable material is obtained through the following steps:

[0059] S1. Bioactive photocurable prepolymer: 15.36 g (0.08 mol) of citric acid and 11.70 g (0.08 mol) of 1,8-octanediol were placed in a 250 mL round-bottom flask equipped with a magnetic stir bar of appropriate size. After melting at 160 °C, the mixture was cooled to 140 °C, and 3.90 g (0.03 mol) of itaconic acid was added. The reaction mixture was continued to react at 140 °C for more than 12 h until the stir bar stopped rotating at 60 rpm. After cooling, 100 mL of deionized water was added to dissolve the reaction product, and then 25 g of excess sodium bicarbonate was added. The mixture was stirred at high speed at room temperature for more than 12 h, and then dialyzed using a dialysis bag with a molecular weight cutoff of 1000 Da. Excess sodium bicarbonate was removed by centrifugation, and the resulting solution was freeze-dried to obtain the bioactive photocurable prepolymer.

[0060] S2. Bioactive photocurable material: Disperse 40 parts of the freeze-dried bioactive photocurable prepolymer obtained in step S1 into 40 parts of BisGMA according to the mass ratio, stir evenly, and then evenly disperse 6 parts of calcium hydroxide, 12 parts of calcium carbonate, 1 part of I2959 and 1 part of EGCG into the above mixed monomers to make a paste or bone paste mixture, which can be used as a photocurable calcium hydroxide dental substrate repair material.

[0061] Comparative Example 1

[0062] This comparative example is basically the same as Example 1, except that it does not contain bioactive photocurable prepolymer.

[0063] Specifically, the materials in Comparative Example 1, by weight, comprised 80 parts of a polymerizable monomer, 1 part of an initiator, 18 parts of an inorganic filler, and 1 part of an antioxidant. The polymerizable monomer was TEDMA, the initiator was benzophenone, the antioxidant was hydroquinone, and the inorganic filler included 6 parts of calcium hydroxide and 12 parts of hydroxyapatite.

[0064] The mixture is obtained by the following steps: 6 parts by weight of calcium hydroxide, 12 parts by weight of hydroxyapatite, 1 part by weight of benzophenone, and 1 part by weight of hydroquinone are uniformly dispersed into 40 parts by weight of TEDMA to form a mixture.

[0065] Comparative Example 2

[0066] This comparative example is basically the same as Example 1, except that it does not contain calcium hydroxide.

[0067] Specifically, the materials in Comparative Example 2, by weight, comprised 40 parts polymerizable monomer, 1 part initiator, 18 parts inorganic filler, 40 parts bioactive photocurable prepolymer, and 1 part antioxidant. The polymerizable monomer was TEDMA, the initiator was benzophenone, the antioxidant was hydroquinone, the inorganic filler included 6 parts β-triphosphate and 12 parts hydroxyapatite, and the bioactive photocurable prepolymer was obtained by reacting citric acid, polyethylene glycol 600, and maleic anhydride, followed by neutralization with calcium carbonate.

[0068] The following steps were performed to obtain the mixture: 40 parts by weight of the freeze-dried bioactive photocurable prepolymer obtained in step S1 of Example 1 were dispersed into 40 parts of TEDMA and stirred evenly. Then, 6 parts of β-triphosphate, 12 parts of hydroxyapatite, 1 part of benzophenone, and 1 part of hydroquinone were evenly dispersed into the above mixed monomers to form a mixture.

[0069] Comparative Example 3

[0070] This comparative example is basically the same as Example 1, except that maleic anhydride (maleic acid) is replaced with succinic acid when preparing the bioactive photocurable prepolymer, so that the bioactive photocurable prepolymer does not contain carbon-carbon double bonds.

[0071] Specifically, in step S1, 15.36 g (0.08 mol) of citric acid and 60 g (0.08 mol) of polyethylene glycol 600 are placed in a 250 mL round-bottom flask equipped with a magnetic stir bar of appropriate size. After melting at 160 °C, the temperature is lowered to 140 °C, and then... 3.54g (0.03mol) succinic acidThe reaction mixture was continued to react at 140°C for more than 12 hours until the stir bar stopped rotating at 60 rpm. After cooling, 100 mL of deionized water was added to dissolve the reaction product, and then 25 g of excess calcium carbonate was added. The mixture was stirred at high speed at room temperature for more than 12 hours, then dialyzed using a dialysis bag with a molecular weight cutoff of 1000 Da and centrifuged to remove excess calcium carbonate. The resulting solution was freeze-dried to obtain the bioactive photocurable prepolymer.

[0072] Comparative Example 4

[0073] This comparative example is basically the same as Example 1, except that: when preparing the bioactive photocurable prepolymer, there is no excess of citric acid and polyethylene glycol 400, so that the bioactive photocurable prepolymer does not contain end carboxylic acid anions.

[0074] Specifically in step S1, take 120g (0.16mol) polyethylene glycol 600 The mixture was placed in a 250 mL round-bottom flask equipped with a magnetic stir bar of appropriate size, melted at 160 °C, cooled to 140 °C, and 2.94 g (0.03 mol) of maleic anhydride was added. The reaction mixture was continued to react at 140 °C for more than 12 h, until the stir bar stopped rotating at 60 rpm. After cooling, 100 mL of deionized water was added to dissolve the reaction product, and then 25 g of excess calcium carbonate was added. The mixture was stirred at high speed at room temperature for more than 12 h, dialyzed through a dialysis bag with a molecular weight cutoff of 1000 Da, and the excess calcium carbonate was removed by centrifugation. The resulting solution was freeze-dried to obtain the bioactive photocurable prepolymer.

[0075] Tensile strength test after light curing

[0076] The tensile strength of the materials obtained in the examples and comparative examples was measured using a universal tensile testing machine (Instron 34TM-10): the materials were light-cured in a dumbbell-shaped mold, and then the samples were stretched with the universal tensile testing machine until they broke. The highest strength before breakage was the tensile strength. The test results are shown in Table 3 below.

[0077] Table 3. experimental group Tensile strength (MPa) Example 1 252 Example 2 240 Example 3 233 Example 4 241 Example 5 216 Example 6 227 Example 7 240 Example 8 249 Example 9 220 Example 10 227 Example 11 243 Comparative Example 1 185 Comparative Example 2 191 Comparative Example 3 196 Comparative Example 4 200

[0078] As can be seen from Table 3, the material in the embodiments of this application has high tensile strength after curing and is suitable as a dental substrate restoration material to play a key role in the special oral environment, such as connecting the tooth and restoration, buffering stress, and preventing microleakage. Specifically, compared to Example 1 and Comparative Example 1, this invention incorporates a bioactive light-cured prepolymer into the traditional calcium hydroxide pulp capping system. This increases the material viscosity, reduces fluidity, and makes it more like bone paste, resulting in better shape plasticity and conformability. This avoids the gravitational effects caused by excessive fluidity, allowing for better filling of tooth defects before light curing and maintaining better toughness and strength after light curing. Furthermore, the material exhibits a degree of biodegradability and releases active ingredients such as citric acid during degradation. These, combined with calcium ions released from calcium hydroxide, promote bone and dentin regeneration, allowing new dentin to fill the degraded areas and better repair dentin and alveolar bone. Compared to the traditional calcium hydroxide pulp capping system, which only provides continuous bactericidal effects through the release of calcium hydroxide but easily leads to localized high pH, ​​the light-cured calcium hydroxide dental substrate material incorporating the bioactive light-cured prepolymer releases citric acid, which partially neutralizes calcium hydroxide, buffers the system's pH, and also provides some antibacterial properties.

[0079] Regarding tensile strength, the improvement in tensile strength of the material in this embodiment is related to the synergistic effect of calcium hydroxide and a specific prepolymer containing ester chain segments, carbon-carbon double bond sites, and carboxylate anions: Compared with Comparative Example 1 and Comparative Examples 2, 3, and 4, Comparative Example 2 does not contain calcium hydroxide and cannot release a high concentration of OH. - (Hydroxyapatite has extremely low solubility and high inertness), making it difficult to effectively promote the formation of covalent cross-linked networks. In Comparative Example 3, which does not contain carbon-carbon double bonds, it is also difficult to form a covalent cross-linked network. In Comparative Example 4, which does not contain end carboxylate anions, it is difficult to form an ionic cross-linked network. These comparative examples all have the problem of difficulty in forming double cross-linked networks, which affects the mechanism by which double cross-linked networks improve tensile strength, resulting in insufficient tensile strength.

[0080] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A bioactive photocurable material, comprising a polymerizable monomer, an initiator, and an inorganic filler, characterized in that: The inorganic filler includes calcium hydroxide; The bioactive photocurable material also includes a bioactive photocurable prepolymer, which is obtained by reacting bioactive organic acids, polyol monomers, and monomers containing carbon-carbon double bonds at 120~150℃ for 1~72h and then neutralizing with a neutralizing agent. The monomer containing a carbon-carbon double bond is selected from at least one of diols, diacids, and acid anhydrides; The neutralizing agent is selected from at least one of sodium bicarbonate and calcium carbonate.

2. The bioactive photocurable material according to claim 1, characterized in that: The bioactive organic acid is selected from citric acid.

3. The bioactive photocurable material according to claim 1, characterized in that: The polyol monomer is selected from at least one of diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 1000, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, and glycerol.

4. The bioactive photocurable material according to claim 1, characterized in that: The monomer containing a carbon-carbon double bond is selected from at least one of compound A having the structure of Formula 1, compound B having the structure of Formula 2, maleic acid, maleic anhydride, fumaric acid, and itaconic acid. Formula 1: Where R is methyl or ethyl; Formula 2: , where R is methyl or ethyl.

5. The bioactive photocurable material according to claim 1, characterized in that: The molar ratio of the bioactive organic acid, polyol monomer, and monomer containing a carbon-carbon double bond is 1:(0.5~2):(0.3~0.5).

6. The bioactive photocurable material according to claim 1, characterized in that: The mass ratio of calcium hydroxide to the bioactive photocurable prepolymer is 1:(3~9).

7. A bioactive photocurable material according to claim 1 or 6, characterized in that: According to the mass fraction, it includes 20-55 parts of polymeric monomer, 10-60 parts of inorganic filler, 0.5-3 parts of initiator, and 30-70 parts of bioactive photocurable prepolymer.

8. The bioactive photocurable material according to claim 1, characterized in that: It also includes antioxidants.

9. A method for preparing a bioactive photocurable material as described in any one of claims 1 to 8, characterized in that: The process includes the following steps: dispersing the bioactive photocurable prepolymer in the polymerizable monomer, then adding the inorganic filler and initiator, and mixing them evenly.

10. The application of a bioactive photocurable material as described in any one of claims 1 to 8 as a dental substrate restorative material.

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