A gutta-percha microsphere-containing root canal filling sealant and a preparation method thereof

Abstract

The application discloses a root canal filling sealant containing eucommia ulmoides microspheres and a preparation method thereof. The root canal filling sealant is obtained by mixing component A and component B; the component A comprises eucommia ulmoides microspheres, zirconium oxide, vinyl polydimethylsiloxane and hydrogen-containing silicone oil; and the component B comprises eucommia ulmoides microspheres, zirconium oxide, vinyl polydimethylsiloxane and a platinum catalyst. The interface gap between the root canal filling sealant containing eucommia ulmoides microspheres and the dental cement is obviously smaller than that of other sealants commonly used in the current clinic, the effective combination between the homogenous materials greatly improves the interface bonding force, the interface gap problem is solved, the occurrence of microleakage is reduced, and the root canal sealing effect and the root canal treatment effect are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer composite materials, in particular to a root canal filling and sealing agent containing Eucommia ulmoides gum microspheres and a preparation method thereof. BACKGROUND

[0002] The purpose of root canal filling is to tightly seal the root canal system and prevent reinfection. Studies have found that the failure rate of root canal treatment due to leakage caused by imperfect sealing is as high as 30.4% (see [J Endod 2011 Nov; 37(11): 1516-1519.]). The ideal root canal filling should be a tight three-dimensional seal with no gaps between the filling materials and between the materials and the root canal wall. At present, the main body of root canal filling is dental composite material, supplemented by sealing agent. The main component of dental composite material is trans-1, 4-polyisoprene, and inorganic fillers are added to form a high polymer composite material. However, dental composite material is difficult to adapt to the complex morphology of root canal, and it is difficult to fill the gap between the dental composite material and the root canal wall and the complex structure of the lateral branch root canal, so it is necessary to use auxiliary root canal sealing agent to achieve the purpose of tight filling and sealing.

[0003] The ideal root canal sealing agent has good bonding ability with dental composite material and root canal wall to ensure the root canal sealing effect. The commonly used root canal sealing agents in clinical practice include zinc oxide eugenol sealing agent, calcium hydroxide sealing agent, glass ionomer sealing agent, epoxy resin sealing agent, bioceramic sealing agent, and silicone sealing agent. The interface bonding between epoxy resin sealing agent, bioceramic sealing agent and dental composite material is poor, and the cross-sectional gap can reach 15.65um (see [J Conserv Dent, 2018, 21(1): 90-94.]). The root canal sealing agent of methacrylate ester is difficult to tightly seal because the main component polycaprolactone can be degraded (see [J Endod. 2019 May; 45(5): 507-512.]). The interface gap between the silicone sealing agent and the dental composite material can be reduced to 3.51um (see [Clin Oral Investig. 2018 May; 22(4): 1631-1639.]), but the interaction between the silicone sealing agent and the heterogeneous dental composite material may cause interface gap, which becomes a channel for bacterial leakage and a space for bacterial aggregation, ultimately affecting the long-term efficacy of root canal treatment.

[0004] In summary, there is a need for a new type of root canal sealing agent that can solve the interface gap problem between dental composite material and sealing agent, reduce the occurrence of microleakage, and improve the root canal sealing effect and the efficacy of root canal treatment. SUMMARY

[0005] To address the problems in existing technologies, this invention provides a root canal filling sealant containing Eucommia ulmoides gum microspheres and its preparation method. This invention solves the problem of interfacial gaps between gutta-percha and the sealant by preparing a novel root canal sealant with Eucommia ulmoides gum as the main component, which is homogeneous with the gutta-percha filling material, reducing microleakage and improving the sealing effect and treatment efficacy of root canals.

[0006] One objective of this invention is to provide a root canal filling sealant containing Eucommia ulmoides gum microspheres, wherein the root canal filling sealant is obtained by mixing component A and component B;

[0007] Component A includes Eucommia ulmoides gum microspheres, zirconium oxide, vinyl polydimethylsiloxane, and hydrogen-containing silicone oil;

[0008] Each component is calculated based on 100 parts by weight of Eucommia ulmoides gum microspheres in component A.

[0009] Zirconia: 100-500 parts by weight; preferably 300-400 parts by weight; more preferably 353 parts by weight;

[0010] Vinyl polydimethylsiloxane: 100-400 parts by weight; preferably 250-400 parts by weight; more preferably 280-310 parts by weight; most preferably 294 parts by weight;

[0011] The hydrogen-containing silicone oil is 30-150 parts by weight; preferably 60-120 parts by weight; more preferably 82.35 parts by weight.

[0012] Component B includes Eucommia ulmoides microspheres, zirconium oxide, vinyl polydimethylsiloxane, and a platinum catalyst.

[0013] Each component is calculated based on 100 parts by weight of Eucommia ulmoides gum microspheres in component B.

[0014] Zirconia: 100-500 parts by weight; preferably 300-500 parts by weight; more preferably 400 parts by weight;

[0015] Vinyl polydimethylsiloxane: 100-500 parts by weight; preferably 200-400 parts by weight; more preferably 310-350 parts by weight; most preferably 333.3 parts by weight;

[0016] The platinum catalyst is used in amounts of 0.0015 to 0.30 parts by weight; preferably 0.0015 to 0.03 parts by weight; more preferably 0.006 to 0.024 parts by weight.

[0017] The weight ratio of component A to component B is 0.5 to 2.5, preferably 1.0 to 2.0, more preferably 1.02 to 1.22, and even more preferably 1.05 to 1.15.

[0018] In a preferred embodiment of the present invention,

[0019] The average particle size of the Eucommia ulmoides gum microspheres is 0.5–11 μm, preferably 2–4 μm, more preferably 2–3 μm; and / or, the maximum particle size of the Eucommia ulmoides gum microspheres does not exceed 30 μm, preferably not more than 15 μm, more preferably not more than 6 μm; and / or

[0020] The vinyl polydimethylsiloxane has a vinyl content of 1.06 ± 0.12 wt% and a viscosity of 85–135 mPa·s, preferably RH-Vi321 type vinyl polydimethylsiloxane; and / or,

[0021] The hydrogen-containing silicone oil has a hydrogen content of 0.35% to 0.37% and a viscosity of 10 to 20 mm. 2 / s; and / or,

[0022] The zirconium oxide is nano-zirconia, preferably with a particle size of 100–300 nm; and / or,

[0023] The platinum catalyst is at least one of platinum metal and its salts, Speier catalyst, zero-valent platinum complex catalyst, and supported platinum catalyst. The supported platinum catalyst is preferably at least one of selenide platinum complex catalyst, sulfoplatinum complex catalyst, selenide crown ether platinum complex catalyst, chelated platinum complex catalyst, fullerene and its derivative platinum complex catalyst, allylsiloxane platinum complex catalyst, and methylvinylsiloxane platinum complex catalyst. The methylvinylsiloxane platinum complex catalyst is preferably Zhejiang Jiancheng VM23 type platinum catalyst.

[0024] In a preferred embodiment of the present invention,

[0025] The Eucommia ulmoides gum microspheres are prepared by an emulsion solvent evaporation method; preferably,

[0026] The preparation process of the Eucommia ulmoides gum microspheres includes:

[0027] (1) Eucommia gum solution is prepared by dissolving Eucommia gum in a low-boiling-point organic solvent;

[0028] (2) After centrifuging the Eucommia gum solution to remove impurities, an oil phase is formed;

[0029] (3) Dissolve the water-soluble emulsifier in deionized water to form an aqueous phase;

[0030] (4) Add the oil phase to the water phase under low-speed stirring, and then emulsify at high speed to obtain a gel dispersion;

[0031] (5) Evaporate the adhesive dispersion to remove the organic solvent to obtain the microsphere dispersion;

[0032] (6) The microsphere dispersion is centrifuged, washed, and the residual emulsifier on the microspheres is removed. The microspheres are then dried to obtain the Eucommia ulmoides gum microspheres.

[0033] In a preferred embodiment of the present invention,

[0034] In step (1),

[0035] The eucommia gum is one or a combination of eucommia gum, gutta-po gum, balata gum, and euonymus gum.

[0036] The low-boiling-point organic solvent is dichloromethane;

[0037] The mass ratio of the low-boiling-point organic solvent to eucommia gum is (10-100):1, preferably (15-100):1;

[0038] The dissolution temperature is 25–40℃, and the dissolution time is 4–6 hours.

[0039] In a preferred embodiment of the present invention,

[0040] In step (2),

[0041] After centrifuging to remove impurities, an oil-soluble emulsifier is added to the Eucommia ulmoides gum solution to form an oil phase;

[0042] The oil-soluble emulsifier is one or a combination of polyoxyethylene ether and polyoxyethylene fatty alcohol ether;

[0043] The amount of the oil-soluble emulsifier is 1-5% of the mass of the oil phase, preferably 1%-2%.

[0044] In a preferred embodiment of the present invention,

[0045] In step (3),

[0046] The water-soluble emulsifier is polyvinyl alcohol;

[0047] The amount of polyvinyl alcohol used is 0.5% to 5% of the mass of the aqueous phase, preferably 0.7% to 2%, and more preferably 0.8% to 1%.

[0048] The dissolution temperature is 50–70℃.

[0049] In a preferred embodiment of the present invention,

[0050] In step (3),

[0051] Sodium dodecylbenzenesulfonate or sodium dodecyl sulfonate, preferably sodium dodecylbenzenesulfonate, may also be added to the water-soluble emulsifier, and the pH of the aqueous phase is adjusted to 10-13 with alkaline solution;

[0052] The mass ratio of sodium dodecylbenzenesulfonate or sodium dodecyl sulfonate to polyvinyl alcohol is (0.5-2):1;

[0053] The alkaline solution is one of potassium hydroxide aqueous solution, sodium hydroxide aqueous solution, or ammonia solution, and the mass concentration of the alkaline solution is 10% to 30%.

[0054] In a preferred embodiment of the present invention,

[0055] In step (4),

[0056] The oil-to-water ratio of the oil phase to the water phase is 1:(1-4), preferably 1:(1.5-2);

[0057] The low speed is 2000-4000 r / min, and the high speed is 8000-10000 r / min;

[0058] The emulsification time is 5 to 20 minutes.

[0059] In a preferred embodiment of the present invention,

[0060] In step (5),

[0061] The evaporation method is atmospheric pressure evaporation, and the evaporation temperature is 30-40℃.

[0062] In a preferred embodiment of the present invention,

[0063] In step (6),

[0064] The centrifugation speed is 5000-10000 r / min, preferably 5000-8000 r / min, and the centrifugation time is 10-20 min;

[0065] The drying temperature is 30–55℃, preferably 40–50℃, and the drying time is 18–24 hours.

[0066] Other conventional additives in the art, such as defoamers, color developers, plasticizers, and silicone resins, can be added to components A and B of the root canal filling sealant containing Eucommia ulmoides gum microspheres of the present invention. The dosage is also conventional, and those skilled in the art can add them according to the actual situation.

[0067] A second objective of this invention is to provide a method for preparing a root canal filling sealant containing Eucommia ulmoides gum microspheres, which is one of the objectives of this invention, comprising:

[0068] First, mix components A and B according to their respective dosages. Then, mix components A and B according to the stated dosage ratio to obtain the root canal filling sealant.

[0069] The beneficial effects of this invention are:

[0070] When determining the formulation of the root canal filling sealant containing Eucommia ulmoides microspheres, we initially screened the ratio of vinyl polydimethylsiloxane to hydrogen-containing silicone oil to obtain a high crosslinking density. Based on industry standards for root canal filling sealants, we characterized and refined the sealant's curing time, flowability, X-ray radiolucency, film thickness, working time, and solubility. By studying the effects of hydrogen-containing silicone oil (crosslinking agent) and platinum catalyst on curing time, we determined a curing time ratio similar to commercial sealants. In the new sealant formulation, zirconium oxide was added to utilize its X-ray radiolucency to evaluate the root canal filling effect; by adjusting the zirconium oxide ratio, the radiolucency also met industry standards. We also studied the effect of the filling amount of zirconium oxide or Eucommia ulmoides microspheres on the flowability of the new sealant, and finally determined the optimal ratio based on industry standards for sealant flowability.

[0071] We evaluated the interface between the root canal filling sealant containing Eucommia ulmoides microspheres and gutta-percha of this invention. Whether simulating a 120°C environment during clinical heating or a prolonged 37°C environment within the mouth, the interfacial gap between the root canal filling sealant containing Eucommia ulmoides microspheres and gutta-percha of this invention was significantly smaller than that of commonly used bioceramic and silicone-based sealants in clinical practice, thus solving the problem of interfacial gaps between gutta-percha and sealants.

[0072] The root canal filling sealant containing Eucommia ulmoides gum microspheres of the present invention can achieve a crosslinking density of approximately 1.8 × 10⁻⁶. -4 The concentration is mol / ml, the curing time is 16-35 minutes, the aluminum ladder thickness meets the industry standard requirement of no less than 3 mm, and the flowability is greater than 18 mm, meeting the industry standard requirement of 17 mm. Furthermore, the interfacial gap between the root canal filling sealant containing Eucommia ulmoides microspheres and gutta-percha is significantly smaller than other commonly used sealants in clinical practice. This effective bonding between homogeneous materials greatly improves interfacial adhesion, solves the interfacial gap problem, reduces microleakage, and improves the root canal sealing effect and the efficacy of root canal treatment. Attached Figure Description

[0073] Figure 1 This is a schematic diagram of a clinical scenario during root canal filling. In the diagram, 1 represents the root canal wall, 2 represents the sealant, and 3 represents gutta-percha. Figure 1 It is evident that gutta-percha occupies most of the space within the root canal, while the sealant serves as an auxiliary material to fill the space between the root canal wall and the gutta-percha. Therefore, this system has two interfaces: the interface between gutta-percha and the sealant, and the interface between the sealant and the root canal wall.

[0074] Figure 2 SEM characterization image of Eucommia ulmoides gum microspheres prepared in Example 1;

[0075] Figure 3This is a diagram showing the two-component root canal filling sealant in its ready-to-use state in a syringe before mixing;

[0076] Figure 4 This is a diagram showing the state of the two-component root canal filling sealant before mixing and after it is extruded into a syringe, as shown in Example 1.

[0077] Figure 5 Electron micrographs of the interface between the root canal filling sealant prepared in Example 1 at 37°C and gutta-percha (Dentsply 25# 0.06 taper gutta-percha point). In a1, a1 represents the Dentsply 25# 0.06 taper gutta-percha point at 37°C, and b1 represents the root canal filling sealant prepared in Example 1 at 37°C.

[0078] Figure 6 Electron micrographs of the interface between the root canal filling sealant prepared in Example 1 and gutta-percha (Dentsply 25# 0.06 taper gutta-percha point) after heating at 120°C for 30 seconds and cooling to 37°C are shown. In a2, a2 ​​represents the Dentsply 25# 0.06 taper gutta-percha point after heating at 120°C for 30 seconds and cooling to 37°C, and b2 represents the root canal filling sealant prepared in Example 1 after heating at 120°C for 30 seconds and cooling to 37°C.

[0079] Figure 7 Electron micrographs of the interface between commercially available GuttaFlow2 (Swiss Contec Dental Group) root canal sealant and gutta-percha (Dentsply 25# 0.06 taper gutta-percha point) at 37°C are shown. In a1, a1 represents Dentsply 25# 0.06 taper gutta-percha point at 37°C, and c1 represents commercially available GuttaFlow2 (Swiss Contec Dental Group) root canal sealant at 37°C.

[0080] Figure 8 Electron micrographs of the interface between commercially available GuttaFlow2 (Swiss Contec Dental Group) root canal sealant and gutta-percha (Dentsply 25# 0.06 taper gutta-percha point) after a heated stage at 120°C for 30 seconds and then cooled to 37°C. a2 represents the Dentsply 25# 0.06 taper gutta-percha point after a heated stage at 120°C for 30 seconds and then cooled to 37°C, and c2 represents the commercially available GuttaFlow2 (Swiss Contec Dental Group) root canal sealant after a heated stage at 120°C for 30 seconds and then cooled to 37°C.

[0081] Figure 9Electron micrographs of the interface between commercially available iRoot SP (Innovative BioCreamix, Canada) root canal sealant and gutta-percha (Dentsply 25# 0.06 taper gutta-percha point, USA) at 37°C are shown. In the image, a1 represents the Dentsply 25# 0.06 taper gutta-percha point at 37°C, and d1 represents the commercially available iRoot SP (Innovative BioCreamix, Canada) root canal sealant at 37°C.

[0082] Figure 10 Electron micrographs of the interface between commercially available iRoot SP (Innovative BioCreamix, Canada) root canal sealant and gutta-percha (Dentsply 25# 0.06 taper gutta-percha point, USA) after a heated stage at 120°C for 30 seconds and then cooled to 37°C are shown. a2 represents the Dentsply 25# 0.06 taper gutta-percha point after a heated stage at 120°C for 30 seconds and then cooled to 37°C, and d2 represents the commercially available iRoot SP (Innovative BioCreamix, Canada) root canal sealant after a heated stage at 120°C for 30 seconds and then cooled to 37°C.

[0083] Figure 11 Electron micrographs of the interface between commercially available AH Plus Jet (Dentsply DeTrey, Germany) root canal sealant and gutta-percha (Dentsply DeTrey 25# 0.06 taper gutta-percha point, USA) at 37°C are shown. In the figure, a1 represents Dentsply DeTrey 25# 0.06 taper gutta-percha point at 37°C, and e1 represents commercially available AH Plus Jet (Dentsply DeTrey, Germany) root canal sealant at 37°C.

[0084] Figure 12 Electron micrographs of the interface between commercially available AH Plus Jet (Dentsply DeTrey, Germany) root canal sealant and gutta-percha (Dentsply 25# 0.06 taper gutta-percha point, USA) after a heated stage at 120°C for 30 seconds and then cooled to 37°C. a2 represents the Dentsply 25# 0.06 taper gutta-percha point after a heated stage at 120°C for 30 seconds and then cooled to 37°C, and e2 represents the commercially available AH Plus Jet (Dentsply DeTrey, Germany) root canal sealant after a heated stage at 120°C for 30 seconds and then cooled to 37°C. Detailed Implementation

[0085] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0086] All raw materials used in the examples are commercially available, and some of the raw materials are from the following sources:

[0087] Vinyl polydimethylsiloxane is RH-Vi321 type vinyl polydimethylsiloxane (Ningbo Runhe High-tech Materials Technology Co., Ltd.);

[0088] Hydrogen-containing silicone oil has a hydrogen content of 0.35-0.37% and a viscosity of 10-20 mm. 2 / s(RH-H536, Ningbo Runhe Advanced Materials Technology Co., Ltd.);

[0089] Zirconia is nano-zirconia with an average particle size of 200 nm;

[0090] The platinum catalyst is Zhejiang Jiancheng VM23 type platinum catalyst.

[0091] The SEM images of this invention were obtained using a Hitachi S4800 scanning electron microscope;

[0092] The particle size of the Eucommia ulmoides gum microspheres of the present invention was measured by a ZetaPALS potentiometric and particle size analyzer from Brookhaven Instruments, Inc., USA.

[0093] In this invention, the crosslinking density, curing time, flowability, X-ray radiometric properties, film thickness, and solubility of the root canal filling sealant were tested in accordance with standard ISO 6876:2012.

[0094] Example 1: Preparation of Eucommia ulmoides gum microspheres

[0095] (1) Preparation of the oil phase: Prepare a 2% Eucommia ulmoides gum solution: Add 13.5g of Eucommia ulmoides gum and 662.5g of dichloromethane (500mL, density 1.325) to a three-necked flask, heat to 40℃ in a water bath, stir at 300r / min, and dissolve for 3h. Centrifuge the dissolved Eucommia ulmoides gum solution at 14000r / min for 30min to remove impurities from the bottom of the centrifuge tube to form the oil phase. (2) Preparation of the aqueous phase: Pour 24g of polyvinyl alcohol (type 1788) into 1.2L of deionized water, stir at 800r / min with a magnetic stirrer at 60℃ until the polyvinyl alcohol is completely dissolved in the water to form the aqueous phase. (3) Emulsification: Adjust the speed of the homogenizer to 4000 r / min. Under the shearing action of the homogenizer, slowly add the oil phase to the water phase. The ratio of oil phase to water phase is 1:2 (450 mL: 900 mL). After the oil phase is completely added, adjust the speed of the homogenizer to 8000 r / min and continue emulsification for 15 min to obtain the gel dispersion. (4) Evaporation: Place the emulsified gel dispersion in a three-necked flask and heat it to 40°C in a water bath. Evaporate the dichloromethane while stirring with a stirrer at a speed of 200 r / min. Use a condenser to recover the dichloromethane. Stop evaporation when the liquid level in the flask no longer drops or there is no more distillate flowing out of the condenser. Obtain the Eucommia ulmoides gum microsphere dispersion. (5) Washing: The Eucommia ulmoides gum microsphere dispersion obtained in the previous step was centrifuged at 2500 r / min for 10 min. The emulsifier aqueous solution at the bottom of the centrifuge tube was removed, deionized water was added, and the mixture was shaken thoroughly and centrifuged again. This process was repeated three times to obtain a high solids content Eucommia ulmoides gum microsphere dispersion without emulsifier residue. (6) Drying: The high solids content Eucommia ulmoides gum microsphere dispersion without emulsifier residue was placed in an oven at 45℃ for 24 h to completely remove water, resulting in Eucommia ulmoides gum microsphere 1. The average particle size of Eucommia ulmoides gum microsphere 1 was 2 μm, and the maximum particle size was 4.5 μm.

[0096] Example 2: Preparation of Eucommia ulmoides gum microspheres

[0097] (1) Preparation of the oil phase: 50g of Eucommia ulmoides gum and 950g of dichloromethane were added to a three-necked flask and heated to 25°C in a water bath. The stirring speed was 400r / min, and the dissolution time was 6h. The dissolved Eucommia ulmoides gum solution was centrifuged at 16000r / min for 40min to remove impurities from the bottom of the centrifuge tube to form the oil phase. (2) Preparation of the aqueous phase: 12g of polyvinyl alcohol (type 1788) and 11.25g of sodium dodecylbenzenesulfonate were poured into 1476.75g of deionized water. The solution was stirred at 800r / min with a magnetic stirrer at 60°C until the polyvinyl alcohol and sodium dodecylbenzenesulfonate were completely dissolved in the water to form the aqueous phase. 20g of sodium hydroxide was dissolved in 80g of water to prepare an alkaline solution. The alkaline solution was added dropwise to the aqueous phase to adjust the pH of the solution to 10. (3) Emulsification: Adjust the speed of the homogenizer to 4000 r / min. Under the shearing action of the homogenizer, slowly add the oil phase to the water phase. The ratio of oil phase to water phase is 1:1.5. After the oil phase is completely added, adjust the speed of the homogenizer to 8000 r / min and continue emulsification for 5 min to obtain the gel dispersion. (4) Evaporation: Place the emulsified gel dispersion in a three-necked flask and heat it to 40°C in a water bath. Evaporate the dichloromethane while stirring with a stirrer at a speed of 300 r / min. Use a condenser to recover the dichloromethane. Stop evaporation when the liquid level in the flask no longer drops or there is no more distillate flowing out of the condenser. Obtain the Eucommia ulmoides gum microsphere dispersion. (5) Washing: The Eucommia ulmoides gum microsphere dispersion obtained in the previous step was centrifuged at 5000 r / min for 10 min. The emulsifier aqueous solution at the bottom of the centrifuge tube was removed, deionized water was added, and the mixture was shaken thoroughly and centrifuged again. This process was repeated three times to obtain a high solids content Eucommia ulmoides gum microsphere dispersion without emulsifier residue. (6) Drying: The high solids content Eucommia ulmoides gum microsphere dispersion without emulsifier residue was placed in an oven at 45℃ for 24 h to completely remove water, resulting in Eucommia ulmoides gum microsphere 2. The average particle size of Eucommia ulmoides gum microsphere 2 was 3.2 μm, and the maximum particle size was 6 μm.

[0098] Example 1

[0099] Component A comprises 85 mg of the aforementioned Eucommia ulmoides microspheres 1, 250 mg of vinyl polydimethylsiloxane, 300 mg of zirconium oxide, and 70 mg of hydrogen-containing silicone oil; Component B comprises 75 mg of the aforementioned Eucommia ulmoides microspheres 1, 250 mg of vinyl polydimethylsiloxane, 300 mg of zirconium oxide, and 0.009 mg of platinum catalyst. Components A and B are mixed separately according to their respective dosages, and then the resulting Components A and B are combined to obtain root canal filling sealant 1 containing Eucommia ulmoides microspheres.

[0100] The crosslinking density of root canal filling sealant 1 containing Eucommia ulmoides gum microspheres is 1.81 × 10⁻⁶. -4The film has a viscosity of mol / mL, a curing time of 34 min (37℃, 100% RH), a flowability of 19.76 mm, an X-ray resistance of 3.52 mm aluminum, meets industry standard requirements (>3 mm aluminum), a film thickness not exceeding 50 μm, and a solubility not exceeding 3 wt%.

[0101] Figure 3 , 4 The image shows the two components of the root canal sealant in the syringe before mixing and in their ready state after extrusion, as shown in Example 1. It can be seen that its macroscopic properties are a paste with a certain degree of fluidity, which meets the requirements for the macroscopic properties of root canal sealants in the industry standard.

[0102] Figure 5 Electron micrographs of the interface between the root canal filling sealant and gutta-percha prepared in Example 1 at 37°C are shown. The evaluation method is as follows: (1) Preparation of gutta-percha sheets: A clean glass slide, commercial gutta-percha points (Dentsply 25# 0.06 taper gutta-percha points), and a pre-made polytetrafluoroethylene mold were placed on a 150°C hot table and heated. The softened commercial gutta-percha points were placed on the polytetrafluoroethylene mold and the softened gutta-percha was hot-pressed into 5mm×5mm×1.2mm sheets using a preheated glass slide, ensuring that the surface of the gutta-percha sheet in contact with the glass slide was clean and smooth; (2) At 37°C, the root canal filling sealant prepared in Example 1 was mixed evenly. One gutta-percha sheet was taken and its smooth surface was coated with the root canal filling sealant. The smooth surface of the second gutta-percha sheet was placed on top of the root canal filling sealant, and then the two gutta-percha sheets and the root canal filling sealant in the middle were clamped together with stainless steel clamps. The amount and pressure of the root canal filling sealant were ensured for each sample. After cryo-embedding, sections were prepared, and SEM was used to evaluate the interface between gutta-percha, the root canal filling sealant from Example 1, and the gutta-percha at the sample section. It was observed that the root canal filling sealant in the middle adhered tightly to the upper and lower gutta-percha layers without any gaps, indicating that the root canal filling sealant prepared in this invention has good sealing properties even at room temperature.

[0103] Figure 6After heating the stage at 120°C for 30 seconds, the sample was cooled to 37°C. Electron micrographs of the interface between the root canal filling sealant and gutta-percha prepared in Example 1 were obtained. The evaluation method was as follows: (1) The preparation of the gutta-percha sheet was the same as above; (2) The root canal filling sealant of Example 1 was mixed evenly. One piece of gutta-percha sheet was taken and coated with the root canal filling sealant on its smooth surface. The amount of root canal filling sealant used for each sample was the same. The smooth surface of the second piece of gutta-percha sheet was placed on top of the root canal filling sealant. A glass plate was placed on the stage at 120°C and preheated for 30 seconds. A stainless steel ring with an inner diameter of 10 mm and a thickness of 2 mm was placed in the center of the glass plate (to ensure that the sample thickness was consistent after hot pressing). The two pieces of gutta-percha sheet together with the root canal filling sealant in the middle were placed in the center of the stainless steel ring. Another preheated glass plate was placed on top for hot pressing. Then, stainless steel clamps were used to clamp the two glass plates together with the stainless steel ring and the sample. The sample was cooled to 37°C. After cryo-embedding, sections were prepared, and SEM was used to evaluate the interface between gutta-percha, the root canal filling sealant from Example 1, and the gutta-percha at the sample section. It was observed that the middle root canal filling sealant adhered tightly to the upper and lower gutta-percha sections without gaps. Furthermore, the Eucommia ulmoides microspheres in the root canal filling sealant deformed upon heating and fused with the gutta-percha upon cooling. This indicates that the root canal filling sealant prepared in this invention achieves fusion with the main gutta-percha filling material upon heating and cooling, exhibiting superior sealing properties.

[0104] Figures 7-12 Electron micrographs of the interfaces between three commercially available root canal sealants (GuttaFlow2, iRoot SP, and AH Plus Jet) and gutta-percha are shown. Compared with the root canal filling sealant prepared in Example 1 under the same conditions, it can be seen that regardless of whether the hot stage is 37°C or 120°C for 30 seconds and then cooled to 37°C, the three commercially available root canal sealants (in the middle of the attached figure) and gutta-percha (at the top and bottom of the attached figure) all have gaps of varying degrees, indicating that the sealing properties of the existing root canal sealants are not good.

[0105] Example 2

[0106] Component A consists of 85 mg of the above-mentioned Eucommia ulmoides microspheres 1, 250 mg of vinyl polydimethylsiloxane, 300 mg of zirconium oxide, and 65 mg of hydrogen-containing silicone oil; Component B consists of 75 mg of the above-mentioned Eucommia ulmoides microspheres 1, 250 mg of vinyl polydimethylsiloxane, 300 mg of zirconium oxide, and 0.009 mg of platinum catalyst. Components A and B are mixed separately according to their respective dosages, and then the resulting components A and B are mixed to obtain root canal filling sealant 2 containing Eucommia ulmoides microspheres.

[0107] The crosslinking density of root canal filling sealant 2 containing Eucommia ulmoides gum microspheres is 1.79 × 10⁻⁶. -4mol / mL. Curing time is 35 min (37℃, 100% RH), flowability is 19.82 mm, X-ray radiometric conductivity is 3.53 mm aluminum, meeting industry standard requirements (>3 mm aluminum), film thickness does not exceed 50 μm, and solubility does not exceed 3 wt%.

[0108] Example 3

[0109] Component A consists of 85 mg of the above-mentioned Eucommia ulmoides microspheres 1, 250 mg of vinyl polydimethylsiloxane, 300 mg of zirconium oxide, and 100 mg of hydrogen-containing silicone oil; Component B consists of 75 mg of the above-mentioned Eucommia ulmoides microspheres 2, 250 mg of vinyl polydimethylsiloxane, 300 mg of zirconium oxide, and 0.009 mg of platinum catalyst. Components A and B are mixed separately according to their respective dosages, and then the resulting components A and B are mixed to obtain root canal filling sealant 3 containing Eucommia ulmoides microspheres.

[0110] The crosslinking density of root canal filling sealant 3 containing Eucommia ulmoides gum microspheres is 1.53 × 10⁻⁶. -4 The film has a viscosity of mol / mL, a curing time of 16 min, a flowability of 19.25 mm, and an X-ray resistance of 3.57 mm aluminum, meeting industry standard requirements (>3 mm aluminum). The film thickness does not exceed 50 μm, and the solubility does not exceed 3 wt%.

[0111] Example 4

[0112] Component A consists of 85 mg of the above-mentioned Eucommia ulmoides microspheres 1, 250 mg of vinyl polydimethylsiloxane, 375 mg of zirconium oxide, and 70 mg of hydrogen-containing silicone oil; Component B consists of 75 mg of the above-mentioned Eucommia ulmoides microspheres 2, 250 mg of vinyl polydimethylsiloxane, 150 mg of zirconium oxide, and 0.009 mg of platinum catalyst. Components A and B are mixed separately according to their respective dosages, and then the resulting components A and B are mixed to obtain root canal filling sealant 4 containing Eucommia ulmoides microspheres.

[0113] The crosslinking density of root canal filling sealant 4 containing Eucommia ulmoides gum microspheres is 1.79 × 10⁻⁶. -4 The film has a viscosity of mol / mL, a curing time of 34 min (37℃, 100% RH), a flowability of 18.21 mm, an X-ray radiometric conductivity of 4.48 mm aluminum, a film thickness not exceeding 50 μm, and a solubility not exceeding 3 wt%.

[0114] Example 5

[0115] Component A comprises 85 mg of the aforementioned Eucommia ulmoides microspheres 1, 250 mg of vinyl polydimethylsiloxane, 300 mg of zirconium oxide, and 70 mg of hydrogen-containing silicone oil; Component B comprises 75 mg of the aforementioned Eucommia ulmoides microspheres 1, 250 mg of vinyl polydimethylsiloxane, 300 mg of zirconium oxide, and 0.027 mg of platinum catalyst. Components A and B are mixed separately according to their respective dosages, and then the resulting Components A and B are mixed to obtain the root canal filling sealant 5 containing Eucommia ulmoides microspheres.

[0116] The crosslinking density of root canal filling sealant 5 containing Eucommia ulmoides gum microspheres is 1.77 × 10⁻⁶. -4 The film has a viscosity of mol / mL, a curing time of 25 min (37℃, 100% RH), a flowability of 19.13 mm, an X-ray radiometric conductivity of 3.43 mm aluminum, meets industry standard requirements (>3 mm aluminum), a film thickness not exceeding 50 μm, and a solubility not exceeding 3 wt%.

[0117] Comparative Example 1

[0118] Component A consists of 85 mg of the above-mentioned Eucommia ulmoides microspheres 1, 250 mg of vinyl polydimethylsiloxane, 1000 mg of zirconium oxide, and 70 mg of hydrogen-containing silicone oil; Component B consists of 75 mg of the above-mentioned Eucommia ulmoides microspheres 1, 250 mg of vinyl polydimethylsiloxane, 300 mg of zirconium oxide, and 0.009 mg of platinum catalyst. Components A and B are mixed separately according to their respective dosages, and then the resulting components A and B are mixed to obtain root canal filling sealant 5 containing Eucommia ulmoides microspheres.

[0119] The crosslinking density of root canal filling sealant 5 containing Eucommia ulmoides gum microspheres is 1.79 × 10⁻⁶. -4 mol / mL. Curing time is 32 min (37℃, 100% RH), flowability is only 15.07 mm (not meeting the requirement of >17 mm), X-ray radiometric properties meet industry standards (>3 mm aluminum), film thickness does not exceed 50 μm, and solubility does not exceed 3 wt%.

[0120] From Examples 1-5, Figures 1-12 As can be seen from Comparative Example 1, the crosslinking density of the root canal filling sealant containing Eucommia ulmoides gum microspheres of the present invention can reach approximately 1.8 × 10⁻⁶. -4The concentration is mol / ml, the curing time can reach 16-35 min, the aluminum ladder thickness meets the industry standard requirement of not less than 3 mm, and the fluidity is greater than 18 mm, meeting the industry standard requirement of 17 mm. When the amount of zirconia is too large (as in Comparative Example 1), it will lead to a significant decrease in fluidity and fail to meet the industry standard requirements. Furthermore, the interfacial gap between the root canal filling sealant containing Eucommia ulmoides microspheres and gutta-percha in this invention is significantly smaller than that of other sealants commonly used in clinical practice. The effective bonding between homogeneous materials greatly improves the interfacial bonding force, solves the interfacial gap problem, reduces the occurrence of microleakage, and improves the root canal sealing effect and the efficacy of root canal treatment.

Claims

1. A root canal filling sealant containing Eucommia ulmoides gum microspheres, wherein the root canal filling sealant is obtained by mixing component A and component B; Component A includes Eucommia ulmoides gum microspheres, zirconium oxide, vinyl polydimethylsiloxane, and hydrogen-containing silicone oil; Each component is calculated based on 100 parts by weight of Eucommia ulmoides gum microspheres in component A. Zirconia 100-500 parts by weight; 100-400 parts by weight of vinyl polydimethylsiloxane; 30-150 parts by weight of hydrogen-containing silicone oil; Component B includes Eucommia ulmoides microspheres, zirconium oxide, vinyl polydimethylsiloxane, and a platinum catalyst. Each component is calculated based on 100 parts by weight of Eucommia ulmoides gum microspheres in component B. Zirconia 100-500 parts by weight; 100-500 parts by weight of vinyl polydimethylsiloxane; Platinum catalyst: 0.0015–0.30 parts by weight; The weight ratio of component A to component B is 1.0 to 2.0; The Eucommia ulmoides gum microspheres are prepared by an emulsion solvent evaporation method; the preparation process of the Eucommia ulmoides gum microspheres includes: (1) Eucommia gum solution is prepared by dissolving Eucommia gum in a low-boiling-point organic solvent; (2) After centrifuging the Eucommia ulmoides gum solution to remove impurities, an oil phase is formed; (3) Dissolve the water-soluble emulsifier in deionized water to form an aqueous phase; (4) Add the oil phase to the aqueous phase under low-speed stirring, and then emulsify at high speed to obtain a gel dispersion; (5) Evaporate the adhesive dispersion to remove the organic solvent to obtain a microsphere dispersion; (6) The microsphere dispersion is centrifuged, washed, and the residual emulsifier on the microspheres is removed. The microspheres are then dried to obtain the Eucommia ulmoides gum microspheres.

2. The root canal filling sealant as described in claim 1, characterized in that: Each component in component A is calculated as 100 parts by weight of Eucommia ulmoides gum microspheres in component A. 300-400 parts by weight of zirconium oxide; 250-400 parts by weight of vinyl polydimethylsiloxane; 60-120 parts by weight of hydrogen-containing silicone oil.

3. The root canal filling sealant as described in claim 1, characterized in that: Each component in component B is calculated based on 100 parts by weight of Eucommia ulmoides gum microspheres in component B. 300-500 parts by weight of zirconium oxide; 200-400 parts by weight of vinyl polydimethylsiloxane; Platinum catalyst: 0.0015 to 0.03 parts by weight.

4. The root canal filling sealant as described in claim 1, characterized in that: The average particle size of the Eucommia ulmoides gum microspheres is 0.5–11 μm; and / or, the maximum particle size of the Eucommia ulmoides gum microspheres does not exceed 30 μm; and / or, The hydrogen-containing silicone oil has a hydrogen content of 0.35-0.37% and a viscosity of 10-20 mm. 2 / s; and / or, The zirconium oxide is nano-zirconium dioxide; and / or, The platinum catalyst is at least one of platinum metal and its salts, zero-valent platinum complex catalysts, and supported platinum catalysts.

5. The root canal filling sealant as described in claim 4, characterized in that: The average particle size of the Eucommia ulmoides gum microspheres is 2–4 μm; and / or, the maximum particle size of the Eucommia ulmoides gum microspheres does not exceed 15 μm; and / or The average particle size of the nano-zirconia is 100–300 nm; and / or, The supported platinum catalyst is at least one of the following: selenium ether platinum complex catalyst, sulfoplatinum complex catalyst, selenium crown ether platinum complex catalyst, chelated platinum complex catalyst, fullerene and its derivative platinum complex catalyst, allylsiloxane platinum complex catalyst, and methylvinylsiloxane platinum complex catalyst.

6. The root canal filling sealant as described in claim 5, characterized in that: The maximum particle size of the Eucommia ulmoides gum microspheres does not exceed 6 μm.

7. The root canal filling sealant as described in claim 1, characterized in that: In step (1), the low-boiling-point organic solvent is dichloromethane; and / or, the mass ratio of the low-boiling-point organic solvent to eucommia gum is (10~100):

1.

8. The root canal filling sealant as described in claim 1, characterized in that: In step (3), the water-soluble emulsifier is polyvinyl alcohol; and / or, the amount of polyvinyl alcohol used is 0.5% to 5% of the mass of the aqueous phase.

9. The root canal filling sealant as described in claim 1, characterized in that: In step (4), the oil-water ratio of the oil phase to the water phase is 1:(1~4); and / or, the low speed is 2000~4000 r / min and the high speed is 8000~10000 r / min; and / or, the emulsification time is 5~20 min.

10. A method for preparing a root canal filling sealant as described in any one of claims 1-9, comprising: First, mix components A and B according to their respective dosages. Then, mix components A and B according to the stated dosage ratio to obtain the root canal filling sealant.

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