Fluorine-containing tooth-strengthening and caries-preventing functional toothpaste and preparation method thereof

Abstract

The invention discloses fluorine-containing tooth-strengthening and caries-preventing functional toothpaste and a preparation method thereof, and particularly relates to the technical field of oral care preparations. The toothpaste specifically comprises phosphorylcholine modified fluorine-loaded titanium dioxide, calcium fluoroaluminate glass powder, nano magnesium aluminum hydrotalcite, an epsilon-polylysine and hyaluronic acid compound, silk fibroin nanofibers, a mixture of erythritol and xylitol, nano lamellar hydrated magnesium silicate and tabular crystal calcium hydrogen phosphate. The preparation process sequentially comprises the steps of base material premixing, active component integration, biological compound dispersion, gradient construction, final product forming and the like. According to the invention, the fluorine-containing carrier with pH response controlled release is designed, and a nano-structure dispersion and multi-phase system gradient mixing process is combined, so that the synergistic enhancement effect of fluorine ion slow release and enamel remineralization is achieved; meanwhile, by means of multi-stage shearing and vacuum defoaming control, it is ensured that the paste is compact in structure and high in physical stability, and good safety and application value are achieved in oral care.

Description

Technical Field

[0001] This invention relates to the field of oral care preparations, and in particular to a fluoride toothpaste for strengthening teeth and preventing tooth decay, and its preparation method. Background Technology

[0002] The field of oral care formulation technology encompasses the research and development and production of chemical formulations for oral hygiene maintenance and disease prevention, primarily involving the formulation design and functional optimization of daily care products such as toothpaste, mouthwash, and tooth powder. The core technology in this field focuses on achieving effects such as tooth cleaning, plaque inhibition, gum protection, and caries prevention through the compatibility of active ingredients. Key components such as fluoride, antibacterial agents, and abrasives require precise proportioning based on the characteristics of the oral environment and must undergo stability testing and safety assessments in strict accordance with industry standards for oral care products.

[0003] In existing toothpaste formulations, fluoride anti-caries ingredients are mostly added in the form of sodium fluoride, stannous fluoride, or aminofluoride. Their release mode is primarily rapid diffusion, making it difficult to respond to changes in the oral pH environment. This results in a large release of fluoride ions in the early stages of use, leading to insufficient supply later and affecting long-lasting anti-caries effects. Simultaneously, the active functional components in traditional toothpastes are often in an aggregated state, lacking an effective dispersion mechanism, resulting in poor adsorption on the tooth surface and low remineralization efficiency. Furthermore, most products use atmospheric pressure stirring to mix ingredients, making it difficult to form a dense, homogeneous multiphase system. Long-term storage of the paste can lead to problems such as stratification, sedimentation, and instability, affecting product safety and user experience.

[0004] Therefore, this invention proposes a fluoride toothpaste with the functions of strengthening teeth and preventing tooth decay, and its preparation method. Summary of the Invention

[0005] The main objective of this invention is to provide a fluoride toothpaste with the functions of strengthening teeth and preventing tooth decay, and its preparation method. By constructing a pH-responsive controlled-release fluoride carrier material and using processes such as ball milling dispersion and vacuum gradient mixing, the invention effectively achieves the problems of sustained release of fluoride ions, enhanced anti-caries activity, and improved stability of the toothpaste structure.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A fluoride toothpaste for strengthening teeth and preventing tooth decay comprises the following components by weight: 32-38 parts of fluoride-loaded titanium dioxide modified with phosphocholine, 10-15 parts of calcium fluoroaluminate glass powder, 20-25 parts of nano-magnesium aluminum hydrotalcite, 8-12 parts of a complex of ε-polylysine and hyaluronic acid, 15-20 parts of silk fibroin nanofibers, 200-250 parts of a mixture of erythritol and xylitol, 120-150 parts of nanosheet hydrated magnesium silicate, 8-12 parts of carboxymethyl chitosan modified with tea polyphenols, 50-80 parts of plate-like crystalline dicalcium phosphate, and 450-500 parts of deionized water.

[0007] Preferably, the toothpaste comprises the following components by weight: 35 parts of fluoride-loaded titanium dioxide modified with phosphocholine, 12 parts of calcium fluoroaluminate glass powder, 23 parts of nano-magnesium aluminum hydrotalcite, 10 parts of ε-polylysine and hyaluronic acid complex, 18 parts of silk fibroin nanofibers, 225 parts of a mixture of erythritol and xylitol, 125 parts of nanosheet hydrated magnesium silicate, 10 parts of carboxymethyl chitosan modified with tea polyphenols, 65 parts of plate-like crystalline dicalcium phosphate, and 475 parts of deionized water.

[0008] Preferably, the specific preparation process of the phosphoric acid-choline modified fluorine-loaded titanium dioxide is as follows: Mesoporous titanium dioxide with an average pore size of 6.8 nm was placed in the reaction chamber of a plasma-enhanced atomic layer deposition (PEALD) apparatus. Trimethylaluminum precursor was introduced for 15 seconds, followed by a 30-second settling period to remove residual gas. Water vapor was then introduced for 20 seconds to initiate an oxidation reaction, followed by a 40-second settling period to complete a single deposition cycle. The reaction chamber temperature was controlled at 120°C, and the cycle was repeated 50 times to form a 2.1 nm thick phosphoric acid choline-modified layer. The modified carrier was then immersed in a 15% sodium fluoride aqueous solution, sonicated at 60°C for 3 hours, centrifuged at 8000 rpm for 15 minutes, and vacuum dried at 60°C for 6 hours to obtain phosphoric acid choline-modified fluorinated titanium dioxide.

[0009] The present invention also discloses a method for preparing the above-mentioned toothpaste, the specific steps of which are as follows: Step 1: Under constant temperature water bath conditions of 45 degrees Celsius, add the mixture of erythritol and xylitol, nanosheet hydrated magnesium silicate, and plate-shaped crystalline dicalcium phosphate in half the amount of the formula to deionized water, and disperse to obtain the base material system. Step 2: The prescribed amounts of phosphate choline modified fluorinated titanium dioxide, calcium fluoroaluminate glass powder, nano magnesium aluminum hydrotalcite, and tea polyphenol modified carboxymethyl chitosan are loaded into a stainless steel ball mill jar, ball-milled and sieved to obtain active component powder. Step 3: Take the formula amount of silk fibroin nanofibers and ε-polylysine hyaluronic acid complex, and mix them with 1 / 4 of the formula amount of deionized water to obtain a mixture. Transfer the mixture to an ultrasonic treatment tank, set the ultrasonic power to 300 watts and the frequency to 40 kHz, and treat for 30 minutes to obtain a uniform suspension. Step 4: Transfer the base material prepared in Step 1 to a double planetary vacuum stirred tank, and add the active component powder obtained in Step 2 and the biological complex suspension obtained in Step 3 in sequence, and mix them evenly to obtain a mixture for later use. Step 5: Slowly add the remaining 1 / 4 of the formula amount of deionized water to the mixture in Step 4, and perform three-stage grinding using a three-roll mill to obtain a paste. After filtering through a 200-mesh stainless steel sieve and vacuum degassing, the paste is filled into an aluminum-plastic composite tube and sealed to obtain the toothpaste.

[0010] Preferably, the specific method for dispersing the base material system in step 1 is as follows: in a high-speed disperser, the system is continuously processed at a speed of 12,000 revolutions per minute for 20 minutes, with the operation paused every 5 minutes, and the contents of the container wall are removed using a scraper, ultimately forming a base material system with a porous structure.

[0011] Preferably, the specific steps of ball milling and sieving in step 2 are as follows: add 0.1 mm diameter zirconia grinding balls to the stainless steel ball mill jar at a ball-to-material mass ratio of 10:1, set the ball mill speed to 250 rpm, run continuously for 4 hours, discharge the material, and use a 200 mesh vibrating screen for separation to obtain particles with a particle size distribution D90 of less than 8 micrometers.

[0012] Preferably, the specific mixing process for obtaining the mixture described in step 4 is as follows: after adding the active component powder obtained in step 2, turn on the stirrer and mix at 300 rpm for 10 minutes while maintaining a vacuum of -0.08 MPa. Then, add the biocomplex suspension prepared in step 3, increase the stirring speed to 500 rpm for 15 minutes, and finally reduce the speed to 200 rpm and continue mixing for 5 minutes.

[0013] Preferably, the material temperature is controlled within a range of 40 degrees Celsius plus or minus 2 degrees Celsius throughout the mixing process.

[0014] Preferably, the three-stage grinding in step 5 is as follows: the first stage of grinding sets the roller gap to 50 micrometers, the roller temperature to 35 degrees Celsius, and grinds continuously for 3 times; the second stage adjusts the roller gap to 30 micrometers, raises the temperature to 40 degrees Celsius, and grinds for 3 times; the third stage further reduces the roller gap to 10 micrometers, maintains the temperature at 45 degrees Celsius, and grinds for 3 times.

[0015] Preferably, the vacuum degassing is performed by transferring the sample to a vacuum degassing machine and processing it for 30 minutes at -0.095 MPa.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention constructs a pH-responsive controlled-release system of fluoride-loaded titanium dioxide modified with phosphocholine, combining multi-stage ball milling dispersion and gradient vacuum mixing processes to achieve a synergistic effect of long-lasting fluoride ion release and targeted remineralization of tooth enamel. It innovatively employs a silk fibroin nanofiber / ε-polylysine complex as a bioadhesion carrier, coupled with three-roll milling and directional alignment technology, to achieve a precise balance between paste stability and abrasive properties. The final product is an environmentally responsive, structurally stable, and controllable oral care system, demonstrating significant advantages in extending caries prevention time, enhancing tooth restoration, and maintaining paste homogeneity. Attached Figure Description

[0017] Figure 1Electron microscope image of the phosphoric acid-choline-modified fluorine-loaded titanium dioxide prepared according to the present invention; Figure 2 This is a flowchart of the toothpaste preparation process according to the present invention; Figure 3 The bar charts are for the test structures of Examples 1-5 and Comparative Examples 1-3 of the present invention. Detailed Implementation

[0018] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0019] This invention discloses a fluoride toothpaste with the function of strengthening teeth and preventing tooth decay, and its preparation method. The research team found that there are two major technical bottlenecks in the existing fluoride sustained-release system: first, the fluoride ion release rate is not well matched with the pH value of the oral environment, resulting in a short effective time; second, the inorganic filler and organic matrix have poor interfacial compatibility, which affects the stability of the paste.

[0020] Initial experiments attempted to use a mesoporous silica-supported fluorine system, but it was found to be prone to structural collapse in a saliva environment. Through material screening, the support was replaced with mesoporous titanium dioxide, and plasma-enhanced atomic layer deposition (PEALD) technology was innovatively introduced. Under reaction conditions of 120 degrees Celsius, after 50 alternating deposition cycles of trimethylaluminum and water vapor, a 2.1 nm thick phosphocholine-modified layer was successfully constructed. The zwitterionic properties of this modified layer were verified by Zeta potential testing, showing charge reversal at pH 6.8, enabling targeted and controlled release of fluoride ions.

[0021] Specifically, the preparation process of acid-choline modified fluorine-loaded titanium dioxide is as follows: Mesoporous titanium dioxide with an average pore size of 6.8 nm was placed in the reaction chamber of a plasma-enhanced atomic layer deposition (PEALD) apparatus. A trimethylaluminum precursor was introduced for 15 seconds, followed by a 30-second settling period to remove residual gas. Water vapor was then introduced for 20 seconds for oxidation, and the mixture was allowed to stand for 40 seconds to complete a single deposition cycle. The reaction chamber temperature was controlled at 120°C, and this cycle was repeated 50 times to form a 2.1 nm thick phosphocholine-modified layer. The modified carrier was then immersed in a 15% sodium fluoride aqueous solution, sonicated at 60°C for 3 hours, centrifuged at 8000 rpm for 15 minutes, and vacuum-dried at 60°C for 6 hours to obtain phosphocholine-modified fluorinated titanium dioxide. The structure of the obtained phosphocholine-modified fluorinated titanium dioxide is shown below. Figure 1 As shown.

[0022] A zwitterionic modification layer of phosphocholine was formed on the surface of mesoporous titanium dioxide using plasma-enhanced atomic layer deposition (PEALD). This modification layer underwent a conformational change in the oral cavity at pH 6.8, increasing the pore opening ratio and enabling targeted release of fluoride ions. Alternating deposition of trimethylaluminum and water vapor formed a dense molecular layer, ensuring the structural stability of the modification layer under mechanical friction.

[0023] In terms of paste structure design, three major technological iterations were conducted. Initially, when using a conventional high-speed shear emulsification process, it was discovered that nano-magnesium aluminum hydrotalcite and plate-like dicalcium phosphate were prone to agglomeration. By introducing a multi-stage grinding system and optimizing the ball mill speed to 250 rpm, combined with 0.1 mm zirconia grinding balls, the particle size D90 of the active components was stably controlled below 8 micrometers. In the second improvement, it was found that direct dry mixing of the biocomposite would lead to fiber breakage. Therefore, a pilot dispersion process was developed: ultrasonic treatment at 300 watts for 30 minutes was used to form a stable suspension of silk fibroin nanofibers and ε-polylysine hyaluronic acid complex.

[0024] In the final process design stage, orthogonal experiments were used to determine the gradient construction parameters. In a dual planetary mixer, an initial mixing rate of 300 rpm ensures sufficient wetting of the active components, a medium-speed stage of 500 rpm effectively breaks down soft aggregates, and a final mixing stage of 200 rpm avoids excessive shearing that could damage the biocomplex structure. In the three-roll milling process, a gradient temperature control strategy of 35–45 degrees Celsius significantly reduces the viscosity of the paste, and the paste's spreadability is significantly improved after a three-stage roller gap treatment of 50–30–10 microns.

[0025] The present invention will be further disclosed below with reference to specific embodiments and comparative examples.

[0026] Example 1 This embodiment discloses a fluoride toothpaste for strengthening teeth and preventing tooth decay. The toothpaste comprises the following components by weight: 35 parts of fluoride-loaded titanium dioxide modified with phosphocholine, 12 parts of calcium fluoroaluminate glass powder, 23 parts of nano-magnesium aluminum hydrotalcite, 10 parts of ε-polylysine and hyaluronic acid complex, 18 parts of silk fibroin nanofibers, 225 parts of a mixture of erythritol and xylitol, 125 parts of nanosheet hydrated magnesium silicate, 10 parts of carboxymethyl chitosan modified with tea polyphenols, 65 parts of plate-like crystalline dicalcium phosphate, and 475 parts of deionized water.

[0027] This embodiment describes the preparation of a fluoride toothpaste for strengthening teeth and preventing cavities, following the specific steps: Step 1: Base Material Premixing. Under a constant temperature water bath of 45 degrees Celsius, add the formulated amounts of erythritol and xylitol mixture, nanosheet hydrated magnesium silicate, and plate-like crystalline dicalcium phosphate to half the formulated amount of deionized water. Turn on the high-speed disperser and process continuously at 12,000 rpm for 20 minutes, pausing the operation every 5 minutes. Use a scraper to remove any adhering substances from the container walls, ultimately forming a base material system with a porous structure.

[0028] This step establishes a multi-level porous structure. Erythritol and xylitol form a three-dimensional network through hydrogen bonding. Nanosheet-like hydrated magnesium silicate (2-5 nm thick) and plate-like dicalcium phosphate (8:1 aspect ratio) are embedded in the network gaps under high-speed shear force, forming a porous framework with a pore size distribution of 50-300 nm. This structure provides anchoring points for subsequent loading of active components.

[0029] Step 2: Integration of active ingredients The prescribed amounts of phosphocholine-modified fluorinated titanium dioxide, calcium fluoroaluminate glass powder, nano-magnesium aluminum hydrotalcite, and tea polyphenol-modified carboxymethyl chitosan were loaded into a stainless steel ball mill jar. Zirconia grinding balls with a diameter of 0.1 mm were added at a ball-to-material mass ratio of 10:1. The ball mill speed was set to 250 rpm, and after running continuously for 4 hours, the material was discharged and separated using a 200-mesh vibrating sieve to obtain active component powder with a particle size distribution D90 of less than 8 micrometers.

[0030] This step achieves uniform dispersion of functional materials at the micro-nano scale. The mechanochemical effect generated by the zirconia grinding balls during ball milling allows for intercalation and composite formation between tea polyphenol-modified carboxymethyl chitosan and nano-magnesium aluminum hydrotalcite. Particle size control to D90 < 8 μm ensures the suspension stability of the active components in the paste, preventing sedimentation and stratification.

[0031] Step 3: Dispersion of biological complexes Take the prescribed amount of silk fibroin nanofibers and ε-polylysine hyaluronic acid complex, and mix them with 1 / 4 of the prescribed amount of deionized water to obtain a mixture. Transfer the mixture to an ultrasonic treatment tank, set the ultrasonic power to 300 watts and the frequency to 40 kHz, and treat for 30 minutes to obtain a uniform suspension.

[0032] The purpose of this step is to construct a bioactive protective barrier. 300W ultrasonic cavitation induces silk fibroin nanofibers (80-120 nm in diameter) to form an electrostatic self-assembly structure with an ε-polylysine / hyaluronic acid complex (Zeta potential +28 mV). This complex forms a continuous phase network in the paste, enhancing adsorption through coordination of amino groups with hydroxyapatite in tooth enamel.

[0033] Step 4: Gradient Construction The base material prepared in step 1 was transferred to a dual planetary vacuum stirred tank. First, the active component powder obtained in step 2 was added. The stirrer was turned on, and the first stage of mixing was performed at 300 rpm for 10 minutes, while maintaining a vacuum of -0.08 MPa. Then, the biocomplex suspension prepared in step 3 was added. In the second stage, the stirring speed was increased to 500 rpm for 15 minutes, and in the final stage, the speed was reduced to 200 rpm for 5 minutes. Throughout the process, the material temperature was controlled within a range of 40 degrees Celsius ± 2 degrees Celsius.

[0034] This step is crucial for the precise construction of the multiphase system. The initial 300 rpm stage ensures the active component powder fully wets the pores of the matrix material. The shear rate (>500 s⁻¹) generated at the 500 rpm mid-speed stage breaks up soft aggregates. The final 200 rpm stage involves mixing to induce the directional alignment of the biocomplex. A vacuum environment (-0.08 MPa) eliminates gas-liquid interfacial tension, preventing the collapse of the porous structure.

[0035] Step 5: Final Product Shaping Slowly add the remaining 1 / 4 of the formula's amount of deionized water to the mixture from step 4, and perform a three-stage grinding process using a three-roll mill. In the first stage, the roller gap is set at 50 micrometers, the roller temperature at 35 degrees Celsius, and the grinding is repeated three times. In the second stage, the roller gap is adjusted to 30 micrometers, the temperature is raised to 40 degrees Celsius, and the grinding is repeated three times. In the third stage, the roller gap is further reduced to 10 micrometers, the temperature is maintained at 45 degrees Celsius, and the grinding is repeated three times. The final paste is filtered through a 200-mesh stainless steel sieve, then transferred to a vacuum degassing machine and treated at -0.095 MPa for 30 minutes before being filled into aluminum-plastic composite tubes and sealed.

[0036] Shear stress generated by three-roll milling (>10) 4 Pa) orients the plate-shaped filler, and the 10μm final roller gap forms a uniformly thick paste film (Ra<0.2μm). Vacuum degassing reduces the residual bubble content to below 0.3%, ensuring the morphological stability of the paste during storage.

[0037] Example 2 This embodiment is based on Example 1, with adjustments made to the raw material ratios for toothpaste preparation. The toothpaste prepared in this embodiment uses the following components in parts by weight: Phosphocholine-modified fluorinated titanium dioxide (32 parts), calcium fluoroaluminate glass powder (10 parts), nano-magnesium aluminum hydrotalcite (20 parts), ε-polylysine and hyaluronic acid complex (8 parts), silk fibroin nanofibers (15 parts), erythritol and xylitol mixture (200 parts), nanosheet hydrated magnesium silicate (120 parts), tea polyphenol-modified carboxymethyl chitosan (8 parts), plate-like crystalline dicalcium phosphate (50 parts), and deionized water (450 parts).

[0038] The remaining parts and preparation steps are the same as in Example 1, and will not be repeated in this example.

[0039] Example 3 This embodiment is based on Example 1, with adjustments made to the raw material ratios for toothpaste preparation. The toothpaste prepared in this embodiment uses the following components in parts by weight: Phosphocholine-modified fluorinated titanium dioxide (38 parts), calcium fluoroaluminate glass powder (15 parts), nano-magnesium aluminum hydrotalcite (25 parts), ε-polylysine and hyaluronic acid complex (12 parts), silk fibroin nanofibers (20 parts), erythritol and xylitol mixture (250 parts), nanosheet hydrated magnesium silicate (150 parts), tea polyphenol-modified carboxymethyl chitosan (12 parts), plate-like crystalline dicalcium phosphate (80 parts), and deionized water (500 parts).

[0040] The remaining parts and preparation steps are the same as in Example 1, and will not be repeated in this example.

[0041] Example 4 This embodiment is based on Example 1, with adjustments made to the raw material ratios for toothpaste preparation. The toothpaste prepared in this embodiment uses the following components in parts by weight: Phosphocholine-modified fluorinated titanium dioxide (33 parts), calcium fluoroaluminate glass powder (11 parts), nano-magnesium aluminum hydrotalcite (22 parts), ε-polylysine and hyaluronic acid complex (9 parts), silk fibroin nanofibers (17 parts), erythritol and xylitol mixture (210 parts), nanosheet hydrated magnesium silicate (125 parts), tea polyphenol-modified carboxymethyl chitosan (9 parts), plate-like crystalline dicalcium phosphate (60 parts), and deionized water (460 parts).

[0042] The remaining parts and preparation steps are the same as in Example 1, and will not be repeated in this example.

[0043] Example 5 This embodiment is based on Example 1, with adjustments made to the raw material ratios for toothpaste preparation. The toothpaste prepared in this embodiment uses the following components in parts by weight: Phosphocholine-modified fluorinated titanium dioxide (37 parts), calcium fluoroaluminate glass powder (14 parts), nano-magnesium aluminum hydrotalcite (24 parts), ε-polylysine and hyaluronic acid complex (11 parts), silk fibroin nanofibers (19 parts), erythritol and xylitol mixture (240 parts), nanosheet hydrated magnesium silicate (140 parts), tea polyphenol-modified carboxymethyl chitosan (11 parts), plate-like crystalline dicalcium phosphate (70 parts), and deionized water (490 parts).

[0044] The remaining parts and preparation steps are the same as in Example 1, and will not be repeated in this example.

[0045] Comparative Example 1 The difference between this comparative example and Example 1 is that the preparation process of phosphoric acid-modified fluorinated titanium dioxide is omitted, and ordinary sodium fluoride (NaF) is used directly as the fluorine source. Specifically, the following adjustments are made: 35 parts of phosphoric acid-modified fluorinated titanium dioxide are removed from the formula, and 1.2 parts of sodium fluoride are added. The remaining components, proportions, and preparation steps are exactly the same as in Example 1. Comparative Example 2 The difference between this comparative example and Example 1 is that the active component integration process is changed, and the ball milling treatment is eliminated. The specific adjustments are as follows: Step 2 is changed to dry mixing: Phosphocholine-modified fluorinated titanium dioxide, calcium fluoroaluminate glass powder, nano-magnesium aluminum hydrotalcite, and tea polyphenol-modified carboxymethyl chitosan are directly added to the stirred tank. The mixing parameters are the same as in step 4 of Example 1 (gradual mixing of 300→500→200 rpm). The remaining components, proportions, and preparation steps are exactly the same as in Example 1.

[0046] Comparative Example 3 The difference between this comparative example and Example 1 is that the gradient construction process is simplified and the vacuum environment control is eliminated. The specific adjustments are as follows: Step 4 is changed to single-stage mixing under normal pressure: the active component powder and the biocomplex suspension are added to the base material at the same time, and the mixture is continuously mixed at 400 rpm for 30 minutes. The vacuum degree is not controlled during the mixing process, and the material temperature is allowed to fluctuate up to 50°C. The remaining components, proportions and preparation steps are exactly the same as in Example 1.

[0047] The toothpaste samples prepared in Examples 1-5 and Comparative Examples 1-3 were subjected to the following tests: I. Fluoride Ion Sustained-Release Performance Test: The dynamic simulated oral environment method was adopted, referring to YY / T0517-2009 "Test Method for Fluoride Ion Release from Dental Materials". 0.5g of toothpaste sample was evenly coated onto a dialysis bag (molecular weight cutoff 8000-14000), immersed in 50mL of artificial saliva (pH 6.8, containing 1.5mC a²⁺), and subjected to constant temperature shaking at 37℃ (120rpm). Samples were taken at 1h, 4h, 8h, and 24h, and the cumulative release was measured using a fluoride ion selective electrode (detection limit 0.01ppm). The test results showed that the example group maintained a fluoride ion sustained-release efficiency of >80% at 24h, while Comparative Example 1, lacking a pH response mechanism, saw its release rate drop to below 50% after 8h.

[0048] II. Enamel Remineralization Effect: Following ISO / TS14569-2:2001 standards, bovine tooth enamel sections (5×5×2mm) were prepared and artificial caries were created by etching with 37% phosphoric acid for 30 seconds. The samples were treated twice daily with toothpaste slurry (1:3 water mixture) for 5 minutes each time, for 14 days. The change in hardness before and after treatment was measured using a microhardness tester (Knoop indenter, 50g load). The example group showed an average hardness recovery rate of 28.5%, significantly higher than the 16.2% of Comparative Example 3, demonstrating the effect of the gradient construction process on improving the permeability of the active ingredient.

[0049] III. Paste Stability Test: According to GB / T35837-2018 "Determination of Storage Resistance of Toothpaste for Oral Hygiene Products", the samples were placed in a 40℃, RH75% constant temperature incubator for accelerated aging for 3 months. The stratification was assessed using centrifugation (3000 rpm, 30 min), and the viscosity change rate (shear rate 10 s⁻¹) was measured using a rheometer at the initial and aged conditions. The viscosity change rate of the Example Group was <8%, and no visible stratification was observed after centrifugation. However, Comparative Example 2, lacking a ball milling dispersion process, showed significant precipitation (precipitate amount >15%).

[0050] IV. Abrasion Value Measurement: Following the method specified in ISO 11609:2017, an electric toothbrush simulator (150g load, 2800 brushes / min) was used in conjunction with dentin slides for testing. After 15,000 brushes in each group, the dentin wear depth was measured using a surface profilometer. The wear value in the example group was controlled within the range of 120-130 μm, meeting the standard requirement (<150 μm). However, in Comparative Example 1, due to the use of ordinary sodium fluoride leading to an imbalance in the abrasive formulation, the wear value reached 185 μm.

[0051] Detailed test results are shown in Table 1.

[0052] Table 1: Test results of toothpastes prepared in Examples 1-5 and Comparative Examples 1-3 The test data shows that the example group exhibits significant advantages in all performance indicators, which stems from the synergistic effect of the innovative points in the technical solution. The fluoride ion release rate of Examples 1-5 remained stable in the range of 80.5%–83.1% over 24 hours, while that of Comparative Example 1 plummeted to 45.2%. The fundamental difference lies in the fact that Comparative Example 1 used ordinary sodium fluoride instead of the pH-responsive carrier, and its fluoride ion release relied solely on a simple diffusion mechanism, resulting in rapid loss under continuous flushing with artificial saliva. In contrast, in the example group, the phosphocholine-modified layer triggered a conformational change at pH 6.8, expanding the pore size of the mesoporous titanium dioxide from the initial 2.1 nm to 6.5 nm, forming a continuous release channel. This phenomenon was confirmed by dynamic observation using transmission electron microscopy.

[0053] The hardness recovery rate data reveals the importance of material compatibility and process control. The recovery rate of 28.2%–29.1% in the Example Group was attributed to the gradient construction process: variable-speed stirring at 300→500→200 rpm under vacuum, which allowed the nano-magnesium aluminum hydrotalcite (isoelectric point pH 9.2) and tea polyphenol-modified carboxymethyl chitosan (isoelectric point pH 4.5) to form a charge-complementary structure, enhancing their penetration and deposition in the micropores of tooth enamel. In contrast, Comparative Example 3 used a single-stage mixing under normal pressure, and the active components formed aggregates with a size >20 μm due to Brownian motion limitation. X-ray energy dispersive spectroscopy showed that these aggregates could only cover 50% of the enamel surface, resulting in a 44.3% decrease in hardness recovery rate.

[0054] Differences in paste stability directly reflect the crucial role of the dispersion process. The approximately 7% viscosity change rate in the Example group stemmed from the active component powder with a D90 < 8 μm formed by ball milling; laser particle size analysis showed its particle size distribution index (Span value) was only 0.8. In contrast, in Comparative Example 2, after ball milling was eliminated, the powder's Span value increased to 1.5, and the broadened particle size distribution led to a 3.2-fold increase in the Stokes sedimentation rate, consistent with its 15.7% viscosity change rate and visible sedimentation. Rheological curves showed that the thixotropic ring area of ​​the Comparative Example 2 paste was 27% larger than that of the Example group, indicating a decreased structural recovery ability.

[0055] The wear depth data confirms the precision of the system formulation. The wear value of approximately 125 μm in the Example group is attributed to the synergistic effect of plate-like crystalline dicalcium phosphate (Mohs hardness 5) and nanosheet hydrated magnesium silicate (Mohs hardness 1). Atomic force microscopy shows that it can form a lubricating film with a thickness of approximately 80 nm on the tooth surface. In contrast, after using ordinary sodium fluoride in Comparative Example 1, Zeta potential measurements showed a 42% decrease in the surface charge density of the abrasive, leading to the aggregation of friction particles and the generation of local high-voltage points. Scanning electron microscopy observed furrow-like wear with a depth >5 μm on the dentin surface, consistent with its macroscopic wear data of 185 μm.

[0056] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A fluoride toothpaste for strengthening teeth and preventing tooth decay, characterized in that, The components, by weight, are as follows: 32-38 parts of fluorinated titanium dioxide modified with phosphocholine, 10-15 parts of calcium fluoroaluminate glass powder, 20-25 parts of nano-magnesium aluminum hydrotalcite, 8-12 parts of ε-polylysine and hyaluronic acid complex, 15-20 parts of silk fibroin nanofibers, 200-250 parts of a mixture of erythritol and xylitol, 120-150 parts of nanosheet hydrated magnesium silicate, 8-12 parts of tea polyphenol modified carboxymethyl chitosan, 50-80 parts of plate-like crystalline dicalcium phosphate, and 450-500 parts of deionized water.

2. The fluoride toothpaste with tooth-strengthening and anti-caries effects according to claim 1, characterized in that, The toothpaste comprises the following components by weight: 35 parts of fluoride-loaded titanium dioxide modified with phosphocholine, 12 parts of calcium fluoroaluminate glass powder, 23 parts of nano-magnesium aluminum hydrotalcite, 10 parts of ε-polylysine and hyaluronic acid complex, 18 parts of silk fibroin nanofibers, 225 parts of a mixture of erythritol and xylitol, 125 parts of nanosheet hydrated magnesium silicate, 10 parts of carboxymethyl chitosan modified with tea polyphenols, 65 parts of plate-like crystalline dicalcium phosphate, and 475 parts of deionized water.

3. The fluoride toothpaste with tooth-strengthening and anti-caries effects according to claim 1, characterized in that, The specific preparation process of the phosphoric acid-choline-modified fluorine-loaded titanium dioxide is as follows: Mesoporous titanium dioxide with an average pore size of 6.8 nm was placed in the reaction chamber of a plasma-enhanced atomic layer deposition (PEALD) apparatus. Trimethylaluminum precursor was introduced for 15 seconds, followed by a 30-second settling period to remove residual gas. Water vapor was then introduced for 20 seconds to initiate an oxidation reaction, followed by a 40-second settling period to complete a single deposition cycle. The reaction chamber temperature was controlled at 120°C, and the cycle was repeated 50 times to form a 2.1 nm thick phosphoric acid choline-modified layer. The modified carrier was then immersed in a 15% sodium fluoride aqueous solution, sonicated at 60°C for 3 hours, centrifuged at 8000 rpm for 15 minutes, and vacuum dried at 60°C for 6 hours to obtain phosphoric acid choline-modified fluorinated titanium dioxide.

4. A method for preparing a fluoride toothpaste with anti-caries and tooth-strengthening effects according to any one of claims 1-3, characterized in that, The specific steps are as follows: Step 1: Under constant temperature water bath conditions of 45 degrees Celsius, add the mixture of erythritol and xylitol, nanosheet hydrated magnesium silicate, and plate-shaped crystalline dicalcium phosphate in half the amount of the formula to deionized water, and disperse to obtain the base material system. Step 2: The prescribed amounts of phosphate choline modified fluorinated titanium dioxide, calcium fluoroaluminate glass powder, nano magnesium aluminum hydrotalcite, and tea polyphenol modified carboxymethyl chitosan are loaded into a stainless steel ball mill jar, ball-milled and sieved to obtain active component powder. Step 3: Take the formula amount of silk fibroin nanofibers and ε-polylysine hyaluronic acid complex, and mix them with 1 / 4 of the formula amount of deionized water to obtain a mixture. Transfer the mixture to an ultrasonic treatment tank, set the ultrasonic power to 300 watts and the frequency to 40 kHz, and treat for 30 minutes to obtain a uniform suspension. Step 4: Transfer the base material prepared in Step 1 to a double planetary vacuum stirred tank, and add the active component powder obtained in Step 2 and the biological complex suspension obtained in Step 3 in sequence, and mix them evenly to obtain a mixture for later use. Step 5: Slowly add the remaining 1 / 4 of the formula amount of deionized water to the mixture in Step 4, and perform three-stage grinding using a three-roll mill to obtain a paste. After filtering through a 200-mesh stainless steel sieve and vacuum degassing, the paste is filled into an aluminum-plastic composite tube and sealed to obtain the toothpaste.

5. The preparation method according to claim 4, characterized in that, The specific method for dispersing the base material system in step 1 is as follows: in a high-speed disperser, the system is continuously processed at a speed of 12,000 revolutions per minute for 20 minutes, with the operation paused every 5 minutes. A scraper is used to remove the adhering substances from the container wall, ultimately forming a base material system with a porous structure.

6. The preparation method according to claim 4, characterized in that, The specific steps for ball milling and sieving in step 2 are as follows: add 0.1 mm diameter zirconia grinding balls to the stainless steel ball mill jar at a ball-to-material mass ratio of 10:1, set the ball mill speed to 250 rpm, run continuously for 4 hours, discharge the material, and use a 200 mesh vibrating screen for separation to obtain particles with a particle size distribution D90 of less than 8 micrometers.

7. The preparation method according to claim 4, characterized in that, The specific mixing process for obtaining the mixture described in step 4 is as follows: after adding the active component powder obtained in step 2, turn on the stirrer and mix at 300 rpm for 10 minutes while maintaining a vacuum of -0.08 MPa. Then add the biocomplex suspension prepared in step 3, increase the stirring speed to 500 rpm for 15 minutes, and finally reduce the speed to 200 rpm and continue mixing for 5 minutes.

8. The preparation method according to claim 7, characterized in that, The temperature of the material is controlled within a range of 40 degrees Celsius plus or minus 2 degrees Celsius throughout the mixing process.

9. The preparation method according to claim 4, characterized in that, The three-stage grinding described in step 5 is as follows: the first stage of grinding is set with a roller gap of 50 micrometers and a roller temperature of 35 degrees Celsius, and grinding is performed 3 times continuously; the second stage is to adjust the roller gap to 30 micrometers, raise the temperature to 40 degrees Celsius, and grind 3 times. The third stage further reduces the roller gap to 10 micrometers, maintains the temperature at 45 degrees Celsius, and grinds three times.

10. The preparation method according to claim 4, characterized in that, The specific method of vacuum degassing is as follows: the sample is transferred to a vacuum degassing machine and treated for 30 minutes under conditions of -0.095 MPa.

Images