Dental antibacterial pit and fissure sealant and preparation method thereof

Abstract

The invention discloses a dental antibacterial pit and fissure sealant and a preparation method thereof, and the dental antibacterial pit and fissure sealant comprises the following components by mass: 30%-60% of a resin matrix material, 10%-30% of a diluent, 0.5%-2% of a photosensitive initiation mixture, 1%-15% of an antibacterial agent and 20%-40% of an inorganic filler. The plant polyphenol with an anti-caries function, a monomer, an oligomer or a polymer of the plant polyphenol and a polyphenol nano preparation of the plant polyphenol are used as bacteriostatic agents to prepare the antibacterial pit and fissure sealing agent, and the antibacterial pit and fissure sealing agent has the functions of oxidation resistance, bacteria resistance, caries resistance, remineralization and the like.

Description

Technical Field

[0001] This invention relates to the field of medical biomaterials technology, and more specifically to a dental antibacterial fissure sealant and its preparation method. Background Technology

[0002] Dental caries is a common non-communicable disease affecting more than one-third of the world's population. Pit and fissure caries primarily refers to the oral disease caused by food debris remaining in the narrowing pits and fissures of molars. This leads to bacterial growth, causing the sugars in the debris to decompose and corrode the bottom and walls of the pits and fissures, resulting in enamel demineralization. Treatment for dental caries usually involves fillings, which involve removing decayed tissue and filling the defects with filling materials such as pit and fissure sealants. There are two main types of pit and fissure sealants: self-curing and light-curing. Light-curing resin-based pit and fissure sealants have good flowability, are easy to apply, and have good retention, making them the most commonly used type.

[0003] While pit and fissure sealants can meet clinical needs to some extent, they have limitations in antibacterial performance. Due to issues such as biofilm accumulation and marginal microleakage, resin-based materials may provide pathways for bacterial invasion. Therefore, enhancing the antibacterial properties of sealants is crucial for preventing the proliferation and destruction of residual bacteria in the microenvironment and inhibiting bacterial adhesion to the tooth surface. Current research focuses on antibacterial components including fluoride, inorganic antibacterial agents, non-quaternary ammonium salt organic antibacterial components, and quaternary ammonium salt organic antibacterial components. Fluoride release exhibits a "burst release effect," with most fluoride reaching a peak in the early stages and then gradually decreasing to a very low level, casting doubt on the persistence and effectiveness of fluoride release. Inorganic antibacterial agents are mostly dispersed freely in the matrix, making it difficult to achieve strict release kinetic control. Furthermore, the physicochemical properties of the carrier material may be affected by the continuous release of the antibacterial agent. Although quaternary ammonium salts exert their antibacterial effect through a contact mechanism and are not easily released, some monomers still exhibit certain cytotoxicity, especially at higher concentrations, potentially affecting the safety of the dental pulp or soft tissues.

[0004] Natural polyphenols, such as anthocyanins, catechins, ferulic acid, gallic acid, caffeic acid (CA), and ellagic acid, possess antioxidant, antibacterial, antiviral, and anti-caries functions, and exhibit good biocompatibility and safety when combined with the matrix in dental materials. Given the various problems existing in current antibacterial fissure sealants and the characteristics of polyphenols, developing a polyphenol-based antibacterial fissure sealant for caries restoration has significant clinical importance and application value. Summary of the Invention

[0005] In view of this, the present invention provides a dental antibacterial fissure sealant and its preparation method, wherein the prepared antibacterial fissure sealant has antioxidant, antibacterial, anti-caries and remineralization functions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A dental antibacterial fissure sealant, comprising the following components by weight percentage: The composition includes 30%–60% resin matrix material, 10%–30% diluent, 0.5%–2% photoinitiator mixture, 1%–15% antibacterial agent, and 20%–40% inorganic filler.

[0007] Preferably, the resin matrix material is bisphenol A dimethacrylate glycidyl ester (Bis-GMA).

[0008] Preferably, the diluent is one or a mixture of two of hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate.

[0009] Preferably, the photoinitiating mixture includes a photoinitiator and a photosensitizing promoter; The photoinitiator includes camphorquinone (CQ), and the photosensitizer includes benzoyl peroxide (BPO) and N,N-dimethyl-p-toluidine (DMT) in a mass ratio of 1:(1~2).

[0010] Preferably, the antibacterial agent includes polyphenols or nano-formulations of polyphenols.

[0011] Preferably, the polyphenolic substances include, but are not limited to, plant polyphenols, monomers and oligomers or polymers of plant polyphenols, and their polyphenol nano-preparations, which have significant antibacterial effects and remineralization functions against cariogenic bacteria in the oral cavity.

[0012] Preferably, the polyphenolic substances include tea polyphenols, anthocyanins, catechins, ferulic acid, gallic acid, or caffeic acid. Polyphenols have significant antibacterial effects and remineralization functions against oral cariogenic bacteria, and polyphenolic substances have excellent biocompatibility.

[0013] Preferably, polyphenol nanoformulations are prepared by the following methods: (1) Mixing: Weigh anhydrous ethanol, deionized water and ammonia, and stir at 60°C for 30 min; (2) Add tetraethyl silicate (TEOS) and polyphenol to the mixture, and continue heating and stirring for 60 min to obtain polyphenol@SiO2 nanoparticle solution; (3) Vacuum drying to obtain polyphenol@SiO2 nanoparticle powder.

[0014] Among the aforementioned raw materials, polyphenolic antibacterial substances can disrupt bacterial cell membranes and cell walls, inhibiting biofilm formation and thus inhibiting bacteria through multiple mechanisms. Antibacterial fissure sealants prepared using polyphenolic substances exhibit excellent hardness, biocompatibility, and antibacterial properties. Their nano-formulations further enhance the antibacterial effect and improve mechanical properties. Furthermore, combined use with other antibacterial agents can achieve sustained antibacterial effects and even greater biocompatibility.

[0015] Preferably, the inorganic filler includes one or a mixture of two of silanized nano-sized silica and fumed nano-sized silica.

[0016] Another object of the present invention is to provide a method for preparing the above-mentioned dental antibacterial fissure sealant, comprising the following steps: (1) Weighing: Weigh the raw materials according to the dosage of each component of the antibacterial pit and fissure sealant, and set aside for later use; (2) Mixing: Stir the resin matrix material and diluent for 1-3 hours to mix thoroughly; add antibacterial agent and inorganic filler and stir evenly, then sonicate; then add photosensitive initiation mixture under light-protected conditions and stir for 2-5 hours; vacuum defoaming, store in the dark to obtain antibacterial pit and fissure sealant.

[0017] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses plant polyphenols with anti-caries function, plant polyphenol monomers and oligomers or polymers, and their polyphenol nano-formulations as antibacterial agents to prepare antibacterial pit and fissure sealants, which have functions such as anti-oxidation, antibacterial, anti-caries, and remineralization.

[0018] 2. Polyphenols are a type of natural antibacterial agent, and polyphenol-based antibacterial fissure sealants have good biocompatibility.

[0019] 3. Adding polyphenolic substances to dental materials as pit and fissure sealants can inhibit bacteria through multiple mechanisms, including but not limited to disrupting bacterial cell membranes and inhibiting bacterial adhesion, resulting in excellent antibacterial effects.

[0020] 4. The prepared antibacterial fissure sealant, when used in combination with other antibacterial agents, can significantly improve the persistence of antibacterial effect and biosafety. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 This is a comparison chart of antibacterial rates; Figure 2 This is a comparison chart of cell viability. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 This embodiment provides a method for preparing a dental antibacterial fissure sealant, including the following steps: 45% Bis-GMA and 15% HEMA were mixed and mechanically stirred for 1 hour to obtain a homogeneous matrix resin. 3.5% CA and 35% silanized nano-silica were added to the matrix resin, and the mixture was mechanically stirred for 30 minutes, followed by ultrasonic treatment for 30 minutes to ensure uniform filler dispersion and no agglomeration. Under light-protected conditions, 0.5% CQ, 0.4% BPO, and 0.6% DMT were added, and stirring was continued for 2 hours. The mixture was transferred to a vacuum drying oven and evacuated (-0.1 MPa) for 30 minutes to remove air bubbles. The resulting antibacterial fissure sealant was stored in a sealed container away from light.

[0025] Example 2 This embodiment provides a method for preparing a dental antibacterial fissure sealant, including the following steps: Preparation of CA@SiO2 nanoparticles 15 mL of anhydrous ethanol was added to a mixture of 5 mL of deionized water and 0.5 mL of ammonia. The mixture was stirred at 60 °C for 30 min. Then, 2.0 mL of tetraethyl orthosilicate (TEOS) was added dropwise to the mixture. 15 mg of CA was added to the reaction mixture, and the mixture was heated and stirred for another 60 min to obtain a CA@SiO2 nanoparticle solution. The solution was then vacuum dried, and the CA@SiO2 nanoparticle powder was collected.

[0026] 45% Bis-GMA, 15% HEMA, and 1% methacryloyloxydodecylpyridine bromide (MDPB) were mixed and mechanically stirred for 1 hour to obtain a homogeneous matrix resin. 12% CA@SiO2 nanoparticles and 25% silanized nano-silica were added to the matrix resin, and the mixture was mechanically stirred for 30 minutes, followed by ultrasonic treatment for 30 minutes to ensure uniform filler dispersion and no agglomeration. Under light-protected conditions, 1% CQ, 0.4% BPO, and 0.6% DMT were added, and stirring was continued for 2 hours in the dark. The mixture was transferred to a vacuum drying oven and evacuated for 30 minutes to remove air bubbles. The resulting antibacterial fissure sealant was stored in a sealed container away from light.

[0027] Example 3 This embodiment provides a method for preparing a dental antibacterial fissure sealant, including the following steps: The preparation of CA@SiO2 nanoparticles was the same as in Example 2. 45% Bis-GMA and 15% HEMA were mixed and mechanically stirred for 1 hour to obtain a homogeneous matrix resin. 13% CA@SiO2 nanoparticles and 25% silanized nano-silica were added to the matrix resin, and the mixture was mechanically stirred for 30 minutes, followed by ultrasonic treatment for 30 minutes to ensure uniform filler dispersion and no agglomeration. Under light-protected conditions, 1% CQ, 0.4% BPO, and 0.6% DMT were added, and stirring was continued for 2 hours. The mixture was transferred to a vacuum drying oven and evacuated for 30 minutes to remove air bubbles. A homogeneous paste with suitable viscosity was obtained and stored in a sealed container away from light.

[0028] Comparative Example 1 (Comparison with Example 1, verifying the antibacterial and remineralization effects of CA) 48% Bis-GMA and 15% HEMA were mixed and mechanically stirred for 1 hour to obtain a homogeneous matrix resin. 35% silanized nano-silica was added to the matrix resin, and the mixture was mechanically stirred for 30 minutes, followed by ultrasonic treatment for 30 minutes to ensure uniform filler dispersion and no agglomeration. Under light-protected conditions, 1% CQ, 0.4% BPO, and 0.6% DMT were added, and stirring was continued for 2 hours. The mixture was transferred to a vacuum drying oven and evacuated for 30 minutes to remove air bubbles. The resulting pit and fissure sealant was stored in a sealed container away from light.

[0029] Comparative Example 2 (Example 2, verifying the combined antibacterial effect and biocompatibility of CA) The preparation of CA@SiO2 nanoparticles was the same as in Example 2. 47% Bis-GMA, 15% HEMA, and 6% MDPB were mixed and mechanically stirred for 1 hour to obtain a homogeneous matrix resin. 30% silanized nano-silica was added to the matrix resin, and after mechanical stirring for 30 minutes, it was ultrasonically treated for 30 minutes to ensure uniform filler dispersion and no agglomeration. Under light-protected conditions, 1% CQ, 0.4% BPO, and 0.6% DMT were added, and stirring continued for 2 hours in the dark. The mixture was transferred to a vacuum drying oven and evacuated for 30 minutes to remove air bubbles. A homogeneous paste with suitable viscosity was obtained and stored in a sealed container in the dark.

[0030] Comparative Example 3 (Verifying the effect of polyphenol selection—using polyphenols without antibacterial effects, chlorogenic acid was ineffective against Gram-positive bacteria) 45% Bis-GMA and 15% HEMA were mixed and mechanically stirred for 1 hour to obtain a homogeneous matrix resin. 3.5% chlorogenic acid and 35% silanized nano-silica were added to the matrix resin, and the mixture was mechanically stirred for 30 minutes, followed by ultrasonic treatment for 30 minutes to ensure uniform filler dispersion and no agglomeration. Under light-protected conditions, 0.5% CQ, 0.4% BPO, and 0.6% DMT were added, and stirring was continued for 2 hours. The mixture was transferred to a vacuum drying oven and evacuated (-0.1 MPa) for 30 minutes to remove air bubbles. The resulting antibacterial fissure sealant was stored in a sealed container away from light.

[0031] Comparative Example 4 (verifying the effect of choosing inorganic fillers—the inorganic fillers are composed of silicon dioxide and zinc oxide) 48% Bis-GMA and 15% HEMA were mixed and mechanically stirred for 1 hour to obtain a homogeneous matrix resin. 25% silanized nano-silica and 10% zinc oxide were added to the matrix resin, and the mixture was mechanically stirred for 30 minutes, followed by ultrasonic treatment for 30 minutes to ensure uniform filler dispersion and no agglomeration. Under light-protected conditions, 1% CQ, 0.4% BPO, and 0.6% DMT were added, and stirring was continued for 2 hours. The mixture was transferred to a vacuum drying oven and evacuated for 30 minutes to remove air bubbles. The resulting pit and fissure sealant was stored in a sealed container away from light.

[0032] The pit and fissure sealants prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests. The test methods and results are as follows: Test 1 Vickers Hardness Specimens with a diameter of 10 mm and a height of 2 mm were prepared for use. Vickers hardness values ​​were tested using a Vickers hardness tester with a force of 25 g and a duration of 35 s. The results showed that CA or CA@SiO2 could increase the local crosslinking density; Example 2, due to the additional quaternary ammonium salt structure of MDPB, had the highest hardness. Comparative Example 2, containing only MDPB and no CA, showed limited hardness improvement, indicating that CA@SiO2 contributed more to the reinforcing effect. Comparative Example 3, using chlorogenic acid as an antibacterial agent, showed a slight decrease in hardness compared to Example 1. Comparative Example 4, using zinc oxide as a secondary filler, had a lower modulus than SiO2, resulting in a lower hardness of the prepared antibacterial fissure sealant.

[0033] Table 1 Vickers hardness of each group

[0034] Test 2 Antibacterial performance Specimen preparation was the same as in Experiment 1, and sterilized by ethylene oxide fumigation. In a 12-well plate, 2.5 mL of broth and 10 μL of *Streptococcus mutans* culture were added to each well and mixed thoroughly. Specimens from each group were placed in the mixture and incubated at 37°C for 24 h. Afterward, the specimens were removed, rinsed three times with sterile PBS, and placed in a 10 mL sterile centrifuge tube. 2 mL of sterile broth was added. The mixture was vigorously shaken using a vortex mixer for 3 min. The resulting bacterial suspension was serially diluted, and 50 μL of each dilution was inoculated onto agar plates, spread evenly with a sterile glass spreader, and anaerobically incubated overnight. Colony counting was performed, and the inhibition rate was calculated.

[0035] The results showed that the CA@SiO2 nanoparticles in Examples 2 and 3 achieved dual antibacterial activity through "contact-release," with an inhibition rate of 99%, meeting the requirements. Comparative Example 2, containing only MDPB, achieved an inhibition rate of approximately 90%, suggesting a synergistic effect between CA and MDPB. In Example 1, the free CA inhibition rate was close to 90%, but the effect was even better after CA@SiO2 curing. Comparative Example 3, using chlorogenic acid as an antibacterial agent, did not show a significant antibacterial effect. Comparative Example 4 used zinc oxide as a secondary filler, which itself has a certain antibacterial effect, mainly through ion release, giving the prepared pit and fissure sealant a certain antibacterial effect, but the effect was worse than that of Example 2.

[0036] Experiment 3 Biocompatibility The cytotoxicity test (MTT method) was performed according to the method specified in GB / T16886.5-2017. Specimen preparation was the same as in Test 2. An extract was prepared using cell culture medium, and bacteria were removed by filtration through a filter membrane.

[0037] Human dental pulp fibroblasts were harvested at a rate of 1×10⁻⁶. 4 Cells were seeded at a density of 1 cell / well in 96-well culture plates and incubated at 37°C for 24 h. The original culture medium was discarded, and 200 μL of the extract obtained from each group was added. The control group received an equal volume of cell culture medium. Cells were incubated for 12 h, 24 h, 36 h, and 48 h, respectively, after which the extract was removed. 50 μL of MTT solution was added to each well, and the cells were incubated for 2 h. The MTT solution was removed, and 100 μL of isopropanol was added to each well, followed by shaking. The absorbance was measured at 570 nm (refer to 650 nm), and the viability was calculated. Results showed that Examples 1-3 and Comparative Example 3 maintained a viability of ≥88% (grade 0) and showed no cytotoxicity. The CA@SiO2 nanoparticles minimized the burst release of free CA, reducing direct oxidative stress on the cell membrane. Comparative Example 2 showed mild toxicity (grade 2) due to a high dose of 6% MDPB, suggesting that MDPB dosage ≥6% can impair biocompatibility. Example 2, however, achieved both antibacterial activity and reduced toxicity by using CA@SiO2 in combination with 1% MDPB. The low cell survival rate in Comparative Example 4 may be due to a large release of zinc oxide, resulting in reactive oxygen species-mediated cytotoxicity.

[0038] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0039] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dental antibacterial fissure sealant, characterized in that, It comprises the following components by weight percentage: The composition includes 30%–60% resin matrix material, 10%–30% diluent, 0.5%–2% photoinitiator mixture, 1%–15% antibacterial agent, and 20%–40% inorganic filler.

2. The dental antibacterial fissure sealant according to claim 1, characterized in that, The resin matrix material is bisphenol A dimethacrylate glycidyl ester.

3. The dental antibacterial fissure sealant according to claim 1, characterized in that, The diluent is one or a mixture of two of hydroxyethyl methacrylate and triethylene glycol dimethacrylate.

4. The dental antibacterial fissure sealant according to claim 1, characterized in that, The photoinitiator mixture includes a photoinitiator and a photopromoter, with a mass ratio of 1:(1~2); The photoinitiator includes camphorquinone, and the photosensitizer includes benzoyl peroxide and N,N-dimethyl-p-toluidine.

5. A dental antibacterial fissure sealant according to claim 1, characterized in that, The antibacterial agent includes polyphenols or polyphenol nanoparticles.

6. A dental antibacterial fissure sealant according to claim 5, characterized in that, The polyphenolic substances include tea polyphenols, anthocyanins, catechins, ferulic acid, gallic acid, or caffeic acid.

7. A dental antibacterial fissure sealant according to claim 5, characterized in that, The polyphenol nanoparticles were prepared by the following method: (1) Mixing: Weigh anhydrous ethanol, deionized water and ammonia, and stir at 60°C for 30 min; (2) Add tetraethyl silicate and polyphenol to the mixture, and continue heating and stirring for 60 min to obtain polyphenol@SiO2 nanoparticle solution; (3) Vacuum drying to obtain polyphenol@SiO2 nanoparticle powder.

8. A dental antibacterial fissure sealant according to claim 1, characterized in that, The inorganic filler includes one or a mixture of two of silanized nano-sized silica and fumed nano-sized silica.

9. The method for preparing the antibacterial fissure sealant according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Weighing: Weigh the raw materials according to the dosage of each component of the antibacterial pit and fissure sealant, and set aside for later use; (2) Mixing: Stir the resin matrix material and diluent for 1-3 hours to mix thoroughly; add antibacterial agent and inorganic filler and stir evenly, then sonicate; then add photosensitive initiation mixture under light-protected conditions and stir for 2-5 hours; vacuum defoaming, store in the dark to obtain antibacterial pit and fissure sealant.

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