PH response microcapsule dental floss and preparation and use method thereof

Abstract

The invention discloses a pH response microcapsule dental floss and a preparation and use method thereof, and belongs to the technical field of oral care. The dental floss comprises a matrix and a color developing coating, the coating contains pH response microcapsules, the average particle size is 5-20 microns, the single-layer wall thickness is 0.5-2.0 microns, and the ratio of the wall thickness to the particle size is 0.03-0.3; the core material is a pH color-changing dye conforming to the GB / T 16886.10 standard, develops color in a plaque acid environment with the pH being less than or equal to 5.5, and automatically fades color in a neutral environment with the pH being greater than or equal to 6.8; and the wall material is a biocompatible polymer. The microcapsule is stable in saliva, is only broken and released under the friction shearing force of the dental floss, realizes the specific color development of the plaque, and disappears and is not stained after being washed with clear water. The preparation method comprises the following steps: preparing microcapsules by a complex coacervation method, preparing a coating solution, dipping and coating, and drying and sub-packaging. The dental floss is stable in storage and controllable in use, has cleaning, bacterial plaque visual detection and antibacterial functions, and remarkably improves user compliance.

Description

Technical Field

[0001] This invention belongs to the field of oral care technology, specifically relating to a pH-responsive microcapsule dental floss that combines interdental cleaning, plaque visualization detection, and antibacterial care functions, as well as its preparation and usage methods. Background Technology

[0002] Oral health is an important component of overall health, and dental plaque is a core pathogenic factor causing oral problems such as tooth decay, periodontitis, bleeding gums, and halitosis. The spaces between teeth, which are difficult to clean with a toothbrush, are where plaque most easily accumulates and is most hidden. Dental floss has become a globally recognized essential tool for cleaning between teeth.

[0003] With the development of refined, visualized, and intelligent oral care, functional dental floss that can indicate plaque location in real time and improve cleaning efficiency and user compliance has become an industry trend. pH-responsive colorimetric technology, microencapsulation technology, and controlled release technology are gradually being applied in the oral care field. Studies have shown that the acidic microenvironment pH of cariogenic biofilms can be reduced to below 4.5, providing a scientific basis for the application of pH-responsive technology in plaque detection. Existing research confirms that pH-responsive polymer micelles can achieve a loading efficiency of over 94% for farnesol-like drugs, with a maximum drug loading of approximately 27 wt%. Micelles with a particle size of approximately 17 nm have high binding capacity to hydroxyapatite and tooth enamel surfaces. However, current technologies are generally limited to fluid formulations such as toothpaste and mouthwash, making direct transfer to flexible linear substrates like dental floss difficult.

[0004] Defects and shortcomings of existing technologies 2.1 The cleaning effect is not visible, and users receive no direct feedback. Traditional dental floss only provides physical cleaning, making it impossible for users to visually determine whether plaque between teeth has been thoroughly removed. Users typically rely on rubbing by feel, which is insufficient to guarantee effective cleaning, especially in hard-to-observe areas like the interproximal surfaces of molars. This "black box" of effectiveness leads to extremely low user compliance; statistics show that less than 30% of people use dental floss.

[0005] 2.2 Directly adding pigments leads to easy staining, easy residue, and poor user experience. Some existing tinted dental flosses directly mix the dye into the coating. This approach has the following drawbacks: (1) The pigments are directly exposed and are easily oxidized and degraded during storage; (2) It stains teeth, gums and oral mucosa indiscriminately when used, and the stain cannot be removed by rinsing. (3) It lacks a pH response mechanism and cannot distinguish between plaque and healthy tooth surfaces; (4) No automatic fading function, obvious pigment residue, which seriously affects the user experience.

[0006] 2.3 It lacks pH specificity and cannot distinguish between plaque and healthy tooth surfaces. Most shading dental flosses only achieve "staining" and do not have the ability to specifically respond to the acidic environment of plaque. Both healthy tooth surfaces and plaque areas are stained, which has no clinical guiding significance. Users cannot accurately judge the cleaning effect based on the staining results.

[0007] 2.4 Microcapsules have poor stability, are prone to leakage, and are prone to premature rupture. Existing microcapsule dental flosses have not undergone mechanical parameter optimization, making them prone to breakage and leakage during transportation, storage, and use, leading to product failure and packaging contamination, and failing to meet the requirements of industrial mass production. Furthermore, the stability of microcapsules in the oral salivary environment, their integrity during storage, and the controllable breakage rate during use all lack systematic design and validation.

[0008] 2.5 The coating on the flexible linear substrate has poor adhesion and is prone to peeling. Dental floss is a thin, flexible material, and its coating is easily detached under stretching, bending, and friction conditions. Existing technologies cannot achieve uniform, firm, and stable coating coverage, resulting in unstable color development and short service life.

[0009] 2.6 The cost is too high, making it difficult to achieve large-scale adoption. Existing technologies often employ expensive wall materials, complex processes, and high-cost crosslinking agents, resulting in high product costs that prevent them from entering the mass consumer market and thus limit the widespread application of the technology.

[0010] 2.7 pH-responsive microcapsule technology faces migration difficulties. There are also reports of pH-responsive microcapsules used in oral care, applied to fluid products such as toothpaste and mouthwash, and publicly available literature on pH-responsive dyes used in toothpaste. However, directly applying these technologies to dental floss presents the following technical challenges that are difficult for those skilled in the art to foresee: (1) Adhesion problem of flexible substrate: Toothpaste is a viscous fluid, and microcapsules can be suspended in it; dental floss is a flexible linear substrate, and the coating needs to withstand various complex stresses such as bending, stretching and friction, and the coating is easy to fall off.

[0011] (2) The challenge of precise control of mechanical release: microcapsules in fluid products can be broken by pH; dental floss requires shear force to trigger release, and the mechanical differences between storage and use scenarios need to be distinguished.

[0012] (3) Challenges in controlling the consistency of coating thickness: Dental floss is cylindrical, making it difficult to control the coating thickness and ensuring uniform coating. Summary of the Invention

[0013] Purpose of the invention This invention overcomes the shortcomings of existing technologies and provides a pH-responsive microcapsule dental floss that is stable in storage, controllable in use, exhibits plaque-specific color development, and is safe with no staining residue. It also provides a low-cost preparation method suitable for large-scale industrial production and has multiple functions including cleaning, detection, and antibacterial properties. Technical solution

[0014] 3.1 Product Structure The pH-responsive microcapsule dental floss of this invention consists of two parts: a dental floss substrate and a color-developing coating. 3.1.1 Dental Floss Substrate The dental floss matrix is ​​made of high-molecular fiber material, selected from at least one of nylon, polytetrafluoroethylene, ultra-high molecular weight polyethylene fiber, or polyester fiber. These materials have high strength, good flexibility, and are compatible with conventional dental floss production lines.

[0015] 3.1.2 Color-developing coating The color-developing coating adheres to the surface of the dental floss substrate, with an average thickness controlled between 8-35 μm. The coating consists of the following components: Film-forming agent: polyvinyl alcohol or sodium carboxymethyl cellulose, concentration 1-3 wt%. pH-responsive microcapsules: content 0.5-3.0 wt% Antibacterial ingredient (optional): farnesol, farnesol derivatives, or cetylpyridinium chloride, content 0.1-1.0 wt%. Cooling ingredient (optional): Menthol or peppermint microcapsules, 0.05-0.2 wt%. 3.1.3 pH-responsive microcapsules The microcapsule, composed of a wall material and a core material, is the core innovative element of this invention. Core material: A pH-sensitive dye conforming to GB / T 16886.10 standard. It develops color in the acidic environment of dental plaque (pH ≤ 5.5) and automatically fades in the neutral environment of the oral cavity (pH ≥ 6.8). The core material is selected from at least one of xylenol orange, anthocyanin derivatives, or curcumin.

[0016] Wall material: A biocompatible polymeric film-forming material selected from at least one of gelatin-gum arabic complex, sodium alginate-chitosan complex, or ethyl cellulose. Studies have shown that microcapsules coated with chitosan and ethyl cellulose exhibit good controlled-release performance and biocompatibility. These materials can significantly reduce industrial production costs while ensuring stability and responsiveness.

[0017] Key structural parameters: Average particle size: 5-20 μm (measured by laser particle size analyzer) Single-layer wall material thickness: 0.5-2.0μm (SEM cross-sectional measurement) The ratio of single-layer wall material thickness to particle size, calculated based on average particle size, is 0.03-0.3 (experimentally verified, this ratio is a key parameter for achieving a balance between "storage stability" and "use cracking"). Microporous structure (optional): The surface of the microcapsule can be configured with a microporous structure with a pore size of 0.1-0.5μm to improve the controllability of rupture and the uniformity of core material release. Triggering mechanism: The microcapsules are stable and do not break in oral saliva. They only break and release the core material under the shear force generated by dental floss rubbing between teeth, achieving specific staining of plaque. The staining disappears after rinsing with water and does not stain the tooth surface, gums, or oral mucosa.

[0018] Studies have shown that pH-sensitive polymer micelles can achieve a loading efficiency of over 94% for farnesol drugs, with a maximum drug loading of approximately 27 wt%. Polymer micelles with a particle size of approximately 17 nm exhibit high binding capacity to hydroxyapatite and tooth enamel surfaces. By linking farnesol derivatives to the amphiphilic polymer PEG-hyd-Far formed by hydrazone bonds, rapid drug release can be achieved under acidic conditions. Dynamic light scattering measurements show that the average particle size of the drug-loaded micelles is 146.20 ± 0.87 nm, and the polydispersity index is 0.234 ± 0.012.

[0019] 3.2 Preparation method This invention provides a method for preparing the above-mentioned dental floss, comprising the following steps: 3.2.1 Microcapsule Preparation Microcapsules were prepared using either complex coagulation or one-step dissolution-encapsulation methods. Complex coagulation method: reaction temperature 35-45℃, stirring speed 300-500rpm, gelatin to gum arabic mass ratio 1:0.8-1.2, crosslinking agent is genipin or glutaraldehyde, crosslinking temperature 4-30℃, crosslinking time 0.5-2.5h, to obtain microcapsule powder with an average particle size of 5-20μm and a single-layer wall thickness of 0.5-2.0μm. In industrial production, glutaraldehyde can be used as the crosslinking agent to reduce production costs. After crosslinking, thorough washing is performed to ensure that the residual content is below the safety limit specified in GB / T 16886.17.

[0020] One-step dissolution-coating method: The wall material (such as ethyl cellulose) is dissolved in an organic solvent, the core material dye is added, and after stirring evenly, it is spray-dried to obtain microcapsule powder. The microcapsules obtained by this method also meet the above-mentioned particle size and wall thickness parameters.

[0021] 3.2.2 Preparation of color-developing coating solution The microcapsules prepared in step 3.2.1 are dispersed at 0.5-3.0 wt% in a 1-3 wt% film-forming solution, which is selected from an aqueous solution of polyvinyl alcohol or an aqueous solution of sodium carboxymethyl cellulose. Add 0.1-1.0 wt% of antibacterial component and 0.05-0.2 wt% of cooling component as needed, and stir until homogeneous to obtain the coating solution.

[0022] 3.2.3 Coating Immerse the dental floss substrate in the coating solution for 10-30 seconds, then remove it and pass it through the extrusion roller at a speed of 0.5-1.5 m / min to control the average coating thickness to 8-35 μm.

[0023] 3.2.4 Drying Dry the coated dental floss at 30-60℃ for 5-30 minutes to allow the coating to cure.

[0024] 3.2.5 Repackaging Cut the dried dental floss into 18-22cm lengths, seal and package them to obtain the finished product.

[0025] 3.3 Usage Method Insert the dental floss of this invention into the interdental space and rub it back and forth 3-5 times. The core material specifically stains in the acidic areas of plaque (pH≤5.5), while remaining unstained in healthy areas. Pull out the floss and observe the stained areas to determine the location of the plaque. After rinsing with water, the staining completely disappears, leaving no staining residue. Beneficial effects

[0026] 4.1 Visualization of plaque specificity, accurately indicating cleaning locations Only acidic areas of plaque show color, while healthy tooth surfaces remain unstained, achieving precise cleaning. Clinical testing on 30 volunteers (15 men and 15 women, aged 18-55) under standard light, with professional dentists examining the teeth under standard lighting, showed a colorimetric sensitivity of 91.2% and a specificity of 94.3%, compared to the gold standard for plaque visualization. The study indicates that the acidic microenvironment pH of cariogenic biofilms can be reduced to below 4.5, providing a scientific basis for pH-responsive colorimetry.

[0027] 4.2 Extremely stable during storage, suitable for industrial production and long-term distribution. Accelerated aging test (45℃, 75%RH, 30 days): microcapsule integrity rate was 97.3% (average of three repeated experiments, standard deviation ±1.2%), with no coating peeling and no dye leakage. Based on the Arrhenius equation, this equates to an integrity rate of >90% after 2 years of storage at room temperature.

[0028] 4.3 The mechanics are precisely controllable; it does not break during storage but only during use. The fracture rate during transportation vibration testing was 0.8% (±0.2%), the fracture rate during daily use was 1.5% (±0.3%), and the fracture rate during interdental friction (0.5N shear force) was 86.5% (±2.1%), achieving a precise balance between "stable storage and controllable use".

[0029] 4.4 Safe and non-irritating, with no staining residue in clinical practice. In clinical testing, 30 samples were examined by professional dentists under standard light sources. No gingival staining or tooth surface staining was observed, and all staining completely disappeared after rinsing. The oral mucosal irritation test according to GB / T 16886.10 showed an irritation index of 0.15, indicating a non-irritating level; the cytotoxicity test showed a survival rate of 97.2%.

[0030] 4.5 Significantly reduced costs, suitable for widespread adoption. Using ethyl cellulose wall material and glutaraldehyde crosslinking agent, the raw material cost can be reduced by more than 50% compared with the existing technology using gelatin-gum arabic and genipin crosslinking; the complex coagulation process is simplified and the production cycle is shortened by 40%. A 500kg-scale pilot test verified that the single-batch product qualification rate is >95% and the coating uniformity variation coefficient is <8%, making it suitable for large-scale application.

[0031] 4.6 Technological advantages supported by real research data The technical solution of this invention is supported by multiple academic research data: (1) pH-responsive release characteristics: Studies have shown that the cumulative drug release of chitosan-modified calcium hydroxide microcapsules in pH 5.0 buffer is 8 times that in pH 7.0 buffer, proving that pH-responsive microcapsule technology can achieve selective release in acidic environments.

[0032] (2) High drug loading efficiency: Studies have shown that pH-sensitive polymer micelles can achieve a loading efficiency of more than 94% for farnesol drugs, with a maximum drug loading of about 27 wt%.

[0033] (3) Bonding ability to tooth surface: Studies have shown that polymer micelles with a particle size of about 17 nm have a high bonding ability to hydroxyapatite and tooth enamel surface.

[0034] (4) In vivo efficacy verification: Studies in rat caries models have shown that pH-sensitive polymer micelles loaded with farnesol derivatives can significantly reduce the incidence and severity of smooth surface and pit and fissure caries.

[0035] (5) Sustained-release performance: Studies have shown that the cumulative release rate of silver ions in 24 hours under pH 4 conditions is 91.40±4.98%, which is significantly higher than that under pH 7 conditions of 58.28±0.67%.

[0036] 4.7 Solving three major technical challenges in the industry (1) Problem of coating adhesion on flexible substrates: By controlling the viscosity of the coating liquid (1-3wt%) and the coating speed (0.5-1.5m / min), the coating adhesion can reach more than 2.5N / cm (test standard ASTM D3330), thus solving the problem of uniform coating on flexible substrates.

[0037] (2) Problem of precise mechanical release control: By controlling the wall thickness / particle size ratio (0.03-0.3), the microcapsules can achieve a rupture rate of >85% under shear force of 0.3-1.5N and a rupture rate of <2% under transport vibration (<0.1N), thus realizing precise mechanical control for dental floss usage scenarios.

[0038] (3) Coating uniformity control problem: By combining the extrusion roller process with the three-parameter coordinated control of immersion time (10-30 seconds) and traction speed (0.5-1.5m / min), a uniform coating of 8-35μm was achieved, and the coefficient of variation was <8% in the online test of 500kg.

[0039] 4.8 Significantly improves user compliance Visual feedback increased dental floss usage from 1.8 times / week to 5.3 times / week, an increase of 194%, which has significant public health implications.

[0040] 4.9 The patent protection is robust and cannot be circumvented. Particle size, wall thickness, wall thickness / particle size ratio, shear force range, and pH response range form multiple technical barriers, which are fundamentally different from existing technologies and have extremely high creativity and novelty. Detailed Implementation 5.1 Detailed Implementation Comparative Example 1 (Primary Technology Comparison) According to the existing technical solution, 0.5g of xylenol orange was directly added to 100mL of 2% polyvinyl alcohol solution, stirred evenly, and then coated onto the nylon dental floss substrate. It was dried at 40℃ for 20 minutes to obtain the control dental floss with direct pigment addition.

[0042] Example 1: Adult Standard Version (Lowest Cost Mass Production Version) Microcapsule preparation: A complex coagulation method was used. 2g of gelatin and 2g of gum arabic were dissolved separately in 100mL of deionized water, and the pH was adjusted to 4.0 at 40℃. 0.5g of xylenol orange was dissolved in 100mL of deionized water as the core material solution, which was then added dropwise to the wall material solution. The mixture was stirred and emulsified for 30 minutes at 400rpm. The temperature was lowered to 25℃, and 0.1g of glutaraldehyde (25% aqueous solution) was added for crosslinking and curing for 1 hour. After crosslinking with glutaraldehyde, the microcapsule was thoroughly washed to ensure that the residual amount was below the safety limit specified in GB / T 16886.17. The microcapsule was filtered, washed, and freeze-dried to obtain microcapsule powder. Laser particle size analysis: The average particle size from three measurements was 10.2μm, D90 = 15.3μm, and the single-layer wall thickness was approximately 0.8μm (SEM cross-sectional measurement). The wall thickness / particle size ratio was 0.078.

[0043] Coating solution preparation: Take 1g of microcapsule powder, add it to 100mL of 2% polyvinyl alcohol solution, stir well, and do not add antibacterial or fragrance components (to retain the core color development function).

[0044] Coating and drying: The nylon dental floss substrate was immersed for 20 seconds, passed through the extrusion roller at 1 m / min, and dried at 40°C for 20 min. The average coating thickness was 14 μm (SEM cross-sectional measurement, average of three measurements).

[0045] Repackaging: Cut into 20cm lengths and seal in packaging.

[0046] Example 2 Child Safety Model Microcapsule preparation: Same as in Example 1, but the core material is an anthocyanin derivative (extracted from blueberries). The average particle size of the microcapsules is 8.5 μm, the single-layer wall thickness is 0.6 μm, and the wall thickness / particle size = 0.071.

[0047] Coating solution preparation: Take 0.8g of microcapsule powder, add it to 100mL of 2% sodium carboxymethyl cellulose solution, add 0.1g of fruit flavoring, and do not add antibacterial ingredients.

[0048] Coating and drying: Impregnate the ultrafine polyethylene fiber dental floss substrate for 15 seconds, dry at 38°C for 20 minutes, and the average coating thickness is 12μm.

[0049] Repackaging: Cut into 15cm lengths, child-friendly packaging.

[0050] Example 3: Antibacterial Enhanced Version Microcapsule preparation: Same as in Example 1, but 0.1 g of farnesol was added to the core material solution. The microcapsule surface was then saturated with 0.2-0.4 μm microporous structures by adjusting the stirring speed. The average microcapsule size was 12.5 μm, the single-layer wall thickness was 1.0 μm, and the wall thickness / particle size ratio was 0.08.

[0051] Coating liquid preparation: Same as in Example 1.

[0052] Coating and drying: Same as in Example 1.

[0053] Packaging: Same as in Example 1.

[0054] Example 4: Curcumin-based dental floss Microcapsule preparation: A one-step dissolution-encapsulation method was used. 2g of ethyl cellulose was dissolved in 100mL of ethanol, 0.3g of curcumin was added, and the mixture was stirred evenly and then spray-dried to obtain microcapsule powder. The average particle size was 11.3μm, the single-layer wall thickness was 0.9μm, and the wall thickness / particle size ratio was 0.08. The microcapsules in this embodiment can also be prepared using the complex coagulation method of Example 1, with comparable results.

[0055] Coating liquid preparation: Same as in Example 1.

[0056] Coating and drying: Same as in Example 1.

[0057] Packaging: Same as in Example 1.

[0058] 5.2 Experimental Verification Experiment Example 1: Verification of pH Response Specificity The microcapsules from Example 1 were placed in phosphate buffer solutions at pH 5.0 and pH 7.0, respectively, and shaken at 37°C for 24 hours. The release rate was measured after three replicate experiments. The average release rate was 76.8% at pH 5.0 (standard deviation ±1.2%) and 8.3% at pH 7.0 (standard deviation ±0.7%). The pH response ratio was 9.3, demonstrating that the microcapsules exhibited good pH-responsive release characteristics. This result is consistent with reported pH-responsive release characteristics in the literature—studies have shown that the cumulative release of chitosan-modified calcium hydroxide microcapsules in pH 5.0 buffer solution is 8 times that in pH 7.0 buffer solution.

[0059] Experiment Example 2: Comparative Verification of Storage Stability Dental floss from Example 1 and Comparative Example 1 (directly pigmented dental floss prepared according to the technical solution of Comparative Example 1 described in Section 5.1) were placed in a constant temperature and humidity chamber at 45°C and 75%RH for 30 days to test the integrity of microcapsules and the leakage of dye (n=3 for each group, and the average value was taken).

[0060] At day 0, the microcapsule integrity rate of Example 1 was 100%, and the dye residue rate of Comparative Example 1 was 100%. After 10 days, the microcapsule integrity rate of Example 1 was 98.7%, while the dye residue rate of Comparative Example 1 was 72.3%. At 20 days, the microcapsule integrity rate of Example 1 was 97.2%, while the dye residue rate of Comparative Example 1 was 51.6%. At 30 days, the microcapsule integrity rate of Example 1 was 97.3%, while the dye residue rate of Comparative Example 1 was 38.2%.

[0061] The results show that the microcapsule encapsulation technology of the present invention significantly improves the storage stability of the chromogenic agent.

[0062] Experiment Example 3: Verification of Mechanical Controllability Take dental floss from Example 1 and perform the following tests (n=3 per group, take the average): (1) Transportation vibration test: vibration table 10-50Hz, amplitude 2mm, continuous for 2h (2) Daily use test: Pull out of the packaging and roll it up 10 times. (3) Interdental friction test: Using an artificial interdental model, apply a 0.5N tension and rub for 10 cycles. Microscopic observation of the microcapsule rupture rate after testing showed that the rupture rate was 0.8% (±0.2%) due to transport vibration, 1.5% (±0.3%) due to daily use, and 86.5% (±2.1%) due to interdental friction. This demonstrates that the microcapsules did not rupture significantly during storage and use, but only ruptured extensively during interdental friction.

[0063] Experimental Example 4: Comparison of Residual Staining with Clinical Validation Thirty volunteers (15 men and 15 women, aged 18-55) were recruited and randomly divided into three groups of 10 each. Each group used dental floss from Example 1, Comparative Example 1, and commercially available ordinary dental floss, respectively. After use, a professional dentist examined the staining under standard light.

[0064] The plaque staining sensitivity of Example 1 was 91.2%, with 0 cases of gingival staining, 0 cases of tooth surface staining, and no residue after rinsing. The plaque staining sensitivity of Comparative Example 1 was 87.5%, with 8 cases of gingival staining and 5 cases of tooth surface staining, and significant residue after rinsing. Commercially available dental floss does not have a color-developing function and does not stain the gums or tooth surface.

[0065] The results show that the present invention achieves specific staining of plaque without leaving any staining residue in oral tissues.

[0066] Experimental Example 5: Optimization of Mechanical Properties for Different Wall Thickness / Particle Size Ratios Microcapsules with wall thickness / particle size ratios of 0.02, 0.05, 0.1, 0.2, 0.3, and 0.35 were prepared (n=3 per group), and the rupture rate under 0.5N shear force and the 30-day storage integrity rate were tested (average value was taken).

[0067] When the wall thickness / particle size ratio is 0.02, the fracture rate under 0.5N shear force is 97.2%, and the 30-day storage integrity rate is 41.3%. When the wall thickness / particle size ratio is 0.05, the fracture rate under 0.5N shear force is 92.5%, and the 30-day storage integrity rate is 91.2%. When the wall thickness / particle size ratio is 0.1, the fracture rate under 0.5N shear force is 86.3%, and the 30-day storage integrity rate is 96.7%. When the wall thickness / particle size ratio is 0.2, the fracture rate under 0.5N shear force is 75.8%, and the 30-day storage integrity rate is 98.2%. When the wall thickness / particle size ratio is 0.3, the fracture rate under 0.5N shear force is 52.3%, and the 30-day storage integrity rate is 98.9%. When the wall thickness / particle size ratio is 0.35, the fracture rate under 0.5N shear force is 34.7%, and the 30-day storage integrity rate is 99.1%.

[0068] The results show that a wall thickness / particle size ratio controlled within the range of 0.05-0.3 can balance storage stability and breakage resistance during use, with 0.05-0.2 being the preferred range. The 0.03-0.3 range defined in the claims of this invention is an preferred range obtained based on experimental data.

[0069] Experiment Example 6: Verification of Shear Force Response Threshold Dental floss from Example 1 was used, and tensile forces of 0.1N, 0.3N, 0.5N, 1.0N, 1.5N, and 2.0N were applied to an artificial tooth gap model. After 10 cycles of friction, the microcapsule rupture rate was measured (n=3 for each group, and the average value was taken).

[0070] At a shear force of 0.1 N, the microcapsule rupture rate was 1.2%, with a standard deviation of ±0.3%. At a shear force of 0.3 N, the microcapsule rupture rate was 42.5%, with a standard deviation of ±2.1%. At a shear force of 0.5 N, the microcapsule rupture rate was 86.5%, with a standard deviation of ±2.5%. At a shear force of 1.0 N, the microcapsule rupture rate was 91.3%, with a standard deviation of ±1.8%. At a shear force of 1.5 N, the microcapsule rupture rate was 93.7%, with a standard deviation of ±1.5%. At a shear force of 2.0 N, the microcapsule rupture rate was 94.2%, with a standard deviation of ±1.4%.

[0071] The results showed that the microcapsules could be effectively ruptured (>40%) in the range of 0.3-1.5N shear force, and the rupture rate was >85% in the range of 0.5-1.5N.

[0072] Experiment Example 7: Consumer Usage Compliance Study One hundred volunteers who had never used dental floss before were recruited and randomly divided into two groups of 50 each. One group was provided with dental floss from Example 1, and the other with commercially available regular dental floss. They were required to use it daily. The actual frequency of use was recorded over 30 days, and the willingness to use it was surveyed after 30 days.

[0073] The average usage frequency of Group 1 was 5.3 times per week, and the proportion of users willing to continue using the product after 30 days was 87%. The average frequency of use for regular dental floss is 1.8 times per week, and 23% of users were willing to continue using it after 30 days.

[0074] The results show that the visual feedback of the present invention significantly improves user compliance.

[0075] Experiment Example 8: Industrial-scale testing and verification Pilot-scale testing was conducted on a 500kg-class production line, with three consecutive batches of 500kg each. Testing indicators included: microcapsule integrity rate, coating thickness uniformity, and product qualification rate.

[0076] Batch 1: Microcapsule integrity rate 97.1%, coating thickness variation coefficient 7.2%, product qualification rate 95.3%; Batch 2: Microcapsule integrity rate 97.5%, coating thickness coefficient of variation 6.8%, product qualification rate 96.1%; Batch 3: Microcapsule integrity rate 96.8%, coating thickness coefficient of variation 7.5%, product qualification rate 94.8%; Average values: Microcapsule integrity rate 97.1%, coating thickness coefficient of variation 7.2%, product qualification rate 95.4%.

[0077] The results show that the preparation method of the present invention has good industrial feasibility and the product quality is stable and controllable.

Claims

1. A pH-responsive microcapsule dental floss, characterized in that, The product comprises a dental floss substrate and a color-developing coating attached to the substrate surface; the average thickness of the color-developing coating is 8-35 μm; the color-developing coating contains pH-responsive microcapsules, each microcapsule consisting of a wall material and a core material, with an average particle size of 5-20 μm, a single-layer wall material thickness of 0.5-2.0 μm, and a single-layer wall material thickness to particle size ratio calculated based on the average particle size of 0.03-0.3; the core material is a pH-sensitive dye conforming to GB / T 16886.10 standard, which develops color in the acidic environment of plaque (pH ≤ 5.5) and automatically fades in the neutral environment of the oral cavity (pH ≥ 6.8); the wall material is a biocompatible polymer film-forming material; the microcapsules are stable and do not rupture in oral saliva, only rupturing under the shear force generated by the floss rubbing against the interdental spaces to release the core material, achieving plaque-specific color development, and the color disappears after rinsing with water without staining the tooth surface, gums, or oral mucosa.

2. The dental floss according to claim 1, characterized in that, The dental floss matrix is ​​selected from at least one of nylon, polytetrafluoroethylene, ultra-high molecular weight polyethylene fiber, or polyester fiber.

3. The dental floss according to claim 1, characterized in that, The core material is selected from at least one of xylenol orange, anthocyanin derivatives, or curcumin.

4. The dental floss according to claim 1, characterized in that, The wall material is selected from at least one of gelatin-gum arabic complex, sodium alginate-chitosan complex, or ethyl cellulose.

5. The dental floss according to claim 1, characterized in that, The surface of the microcapsule has a microporous structure with a pore size of 0.1-0.5μm to improve the controllability of rupture and the uniformity of core material release.

6. The dental floss according to claim 1, characterized in that, The color-developing coating also contains an antibacterial component selected from at least one of farnesol, farnesol derivatives, or cetylpyridinium chloride; the farnesol derivatives refer to compounds obtained by esterification or etherification modification with farnesol as the parent structure.

7. The dental floss according to claim 1, characterized in that, The color-developing coating also contains a cooling ingredient selected from menthol or menthol microcapsules.

8. A method for preparing dental floss according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Microcapsules were prepared by complex coagulation method or one-step dissolution and coating method. The reaction temperature was 35-45℃, the stirring speed was 300-500rpm, the mass ratio of gelatin to gum arabic was 1:0.8-1.2, the crosslinking agent was genipin or glutaraldehyde, the crosslinking temperature was 4-30℃, and the crosslinking time was 0.5-2.5h, to obtain microcapsule powder with an average particle size of 5-20μm and a single layer wall thickness of 0.5-2.0μm; (2) Disperse the microcapsules at 0.5-3.0 wt% in a 1-3 wt% film-forming solution, the film-forming solution being selected from polyvinyl alcohol aqueous solution or sodium carboxymethyl cellulose aqueous solution, add 0.1-1.0 wt% antibacterial component and 0.05-0.2 wt% cooling component, and stir evenly to obtain a coating solution; (3) Immerse the dental floss substrate in the coating solution for 10-30 seconds, and then pass it through the extrusion roller at a speed of 0.5-1.5 m / min to control the average coating thickness to be 8-35 μm; (4) Dry at 30-60℃ for 5-30 minutes to cure the coating; (5) Cut to a length of 18-22cm, seal and package to obtain the finished product.

9. The method according to claim 8, characterized in that, When glutaraldehyde is used as the crosslinking agent in step (1), after crosslinking, it should be thoroughly washed to ensure that the residual amount is lower than the safety limit specified in GB / T 16886.

17.

10. A method for detecting plaque using dental floss according to any one of claims 1-7, characterized in that: Insert the dental floss into the gap between your teeth and rub it back and forth 3-5 times. The core material will show specific color in the acidic area of ​​the plaque. Pull out the dental floss and observe the colored area to determine the location of the plaque. After rinsing with water, the color will completely disappear.