Novel root canal filling composite material and preparation method thereof

Abstract

The invention relates to the technical field of oral cavity materials, and discloses a novel root canal filling composite material and a preparation method thereof.The composite material comprises a solid hard core and a pasty paste material, and the outer surface of the hard core is evenly coated with the paste material; the hard core is prepared from the following raw materials: medical synthetic eucommia ulmoides rubber, liquid rubber, a silane coupling agent, white carbon black, an anti-aging agent, zinc oxide, stearic acid, an accelerant, sulfur and barium sulfate; the paste material comprises medical synthetic eucommia ulmoides rubber, zinc oxide and barium sulfate. The method has excellent operability and enhanced sealing performance, damage to periapical tissues can be reduced, and processing safety and system hardness are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oral materials, and in particular to a novel root canal filling composite material and a preparation method thereof. Background Art

[0002] Root canal therapy is a dental procedure commonly used to treat endodontic and periapical diseases. Its primary purpose is to remove infected pulp tissue and thoroughly disinfect and seal the root canal system to prevent bacterial reinfection and further progression of the disease. Root canal filling is a key step in root canal therapy. Its purpose is to fill the root canal with filling material, sealing all gaps and small channels in the root canal system, thereby preventing microbial invasion and protecting the tooth structure.

[0003] Despite significant advances in root canal treatment technology, the effectiveness of root canal filling is still affected by many factors. Studies have shown that one of the main causes of root canal treatment failure is incomplete root canal filling. The complexity and microstructure of the root canal system make uniform filling and sealing with filling materials particularly important. Incomplete filling or defects in the filling material can lead to micro-penetration of the root canal system, triggering inflammation of the periapical tissues and recurrence of lesions.

[0004] Hot gutta-percha filling technique is one of the most widely used root canal filling methods. Due to its good plasticity and fluidity, hot gutta-percha can form a sealing layer inside the root canal. However, there are still some problems with hot gutta-percha filling technique. For example, hot gutta-percha may shrink in volume during the cooling process, which may cause a small gap between the filling and the root canal wall. In addition, hot gutta-percha may cause thermal damage to the periapical tissue during the heating process, affecting the treatment effect. Due to these problems, the effectiveness and reliability of hot gutta-percha filling technique are still challenged.

[0005] Natural Eucommia ulmoides gum (EUG) is a traditional root canal filling material widely used due to its excellent biocompatibility and filling properties. However, EUG has problems such as poor fluidity, difficulty in handling, high cost, and high impurity content, which limit its widespread use in clinical applications. To overcome these problems, industrially synthesized Eucommia ulmoides gum (TPI) has gradually been introduced as an alternative to EUG. Although TPI has improved in terms of composition stability, it still has problems such as odor and insufficient fluidity.

[0006] Therefore, the current research trend is to develop a new type of root canal filling material to overcome the defects of traditional materials and provide better treatment effects. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a new root canal filling composite material.

[0008] In order to achieve the above-mentioned purpose, the technical solution of the present invention is: a new root canal filling composite material, comprising a solid hard core and a paste-like paste, wherein the paste is evenly coated on the outer surface of the hard core; the hard core comprises the following raw materials in parts by weight: 100 parts of medical synthetic eucommia rubber, 3-20 parts of liquid rubber, 5-10 parts of silane coupling agent, 60-100 parts of white carbon black, 2-6 parts of antioxidant, 20-60 parts of zinc oxide, 3-10 parts of stearic acid, 2-9 parts of accelerator, 8-25 parts of sulfur, and 8-15 parts of barium sulfate; the paste comprises medical synthetic eucommia rubber, zinc oxide and barium sulfate, and the mass ratio of the medical synthetic eucommia rubber, zinc oxide and barium sulfate is 100:(50-80):(8-15).

[0009] Furthermore, the paste has a thickness of 0.2 to 0.4 mm.

[0010] Furthermore, the liquid rubber is selected from one of liquid polyisoprene rubber, liquid high vinyl polybutadiene rubber, hydroxybutadiene rubber, and hydroxybutadiene rubber copolymer.

[0011] Furthermore, the molecular weight of the liquid rubber is 2000 to 60000 g / mol.

[0012] Furthermore, the Mooney viscosity of the synthetic eucommia rubber used in the hard core raw material is 10 to 40.

[0013] Furthermore, the Mooney viscosity of the synthetic eucommia rubber used in the paste raw material is 1 to 10.

[0014] Furthermore, the antioxidant is selected from one or more of protective wax, microcrystalline wax, phosphite antioxidant, and phenolic antioxidant. Preferably, the antioxidant is selected from one or a combination of antioxidant 1010 and antioxidant 168.

[0015] Furthermore, the accelerator is selected from one or more of dithiocarbamate accelerators and sulfonamide accelerators; the dithiocarbamate is selected from one or more of zinc dimethyldithiocarbamate (ZDMC), zinc diethyldithiocarbamate (ZDC), zinc dibenzyldithiocarbamate (ZBEC), zinc dibutyldithiocarbamate (BZ), and zinc ethylphenyldithiocarbamate (PX); the sulfonamide accelerator is selected from one or more of N-cyclohexyl-2-benzothiazole sulfenamide (CZ), N-tert-butyl-2-benzothiazole sulfenamide (TBBS), N-oxydiethylene-2-benzothiazole sulfenamide, N,N-dicyclohexyl-2-benzothiazole sulfenamide, and N-oxydiethylenethiocarbamoyl-N'-oxydiethylenesulfenamide.

[0016] Furthermore, the silane coupling agent is selected from one or more of bis-[γ-(triethoxysilyl)propyl]tetrasulfide (silane coupling agent Si69), γ-aminopropyltriethoxysilane, γ-thiopropyltrimethoxysilane, and vinyltriethoxysilane.

[0017] Furthermore, the sulfur is ordinary sulfur or insoluble sulfur (IS).

[0018] Another technical solution of the present invention is: a method for preparing the novel root canal filling composite material, comprising the following steps:

[0019] (1) Preparation of hard core: Weigh liquid rubber, silane coupling agent and white carbon black, mix and heat to disperse, and prepare modified white carbon black masterbatch, and sequentially put modified white carbon black masterbatch, medical synthetic eucommia rubber, antioxidant, zinc oxide, stearic acid and barium sulfate into an internal mixer, mix evenly to obtain a rubber mix, and cool and stand; then roll the rubber mix, accelerator and sulfur on an open mixer, turn the rubber, roll it and make it into triangular packages to make it evenly dispersed, and press it into thin sheets for use; the rubber mix with sulfur and accelerator is molded by an injection vulcanizer to obtain a hard core;

[0020] (2) Preparation of paste: Weigh medical synthetic eucommia rubber, zinc oxide, and barium sulfate and put them into an internal mixer in sequence, mix them evenly, and crush them into small particles after debonding to obtain a paste;

[0021] (3) Place the paste in a container and heat it to 70°C to melt it into a paste. Immerse the hard core in the paste and take it out after 20-30 seconds to obtain the root canal filling composite material.

[0022] Beneficial effects of the present invention:

[0023] (1) Excellent operability: The present invention significantly improves the fluidity and plasticity of the prepared dental cement composite material through the combination of the hard core and the paste, making the filling operation more convenient and accurate. In addition, the eucommia rubber in the hard core and the paste is medically synthesized and has no odor problem.

[0024] (2) Enhanced sealing: The combination of the ultra-high hardness of the hard core material and the excellent fluidity of the paste can effectively fill the complex structures and tiny gaps in the root canal system, forming a long-lasting sealing layer to prevent microbial invasion.

[0025] (3) Reducing damage to periapical tissues: Due to the efficient interface compatibility and improved operating performance, the gutta-percha composite material of the present invention reduces the thermal damage and mechanical pressure on periapical tissues during the filling process to a minimum, thereby improving the safety of treatment.

[0026] (4) Improve processing safety and system hardness: The introduction of liquid high vinyl polybutadiene rubber and liquid polyisoprene rubber in the hard core material improves processing safety, improves the system cross-linking efficiency during the vulcanization process, and can increase the hardness of the hard core system. It is easy to operate and has a better sealing effect when used with the paste. DETAILED DESCRIPTION

[0027] The medical synthetic eucommia rubbers with Mooney viscosities of 40, 20, 10, and 5 in the present invention were all purchased from Qingdao Depai New Materials Co., Ltd.

[0028] The hardness in the present invention is tested using a GT-GS-MB Shore hardness tester (type D) in accordance with the national standard: GB / T531.1.

[0029] Melting point: Scan the sample using a differential scanning calorimeter, heating from 40°C to 80°C; hold for 5 min; cooling from 80°C to -80°C; hold for 5 min; heating from -80°C to 80°C; nitrogen atmosphere, 10°C / min.

[0030] Melt index: tested according to standard ASTM D 1238.

[0031] Example 1:

[0032] A method for preparing a novel root canal filling composite material comprises the following steps:

[0033] (1) Preparation of hard core: 10 g of liquid polyisoprene rubber (molecular weight 30,000 g / mol), 6 g of silane coupling agent Si69, and 60 g of white carbon black were weighed and mixed, dispersed in a high-speed stirrer, heated to 110° C., at a speed of 30 Hz, stirred for 120 minutes, and discharged to obtain a modified white carbon black masterbatch;

[0034] Take the modified silica masterbatch prepared above, 100g medical synthetic eucommia rubber (Mooney viscosity 40), 2g antioxidant 1010, 2g antioxidant 168, 20g zinc oxide, 5g stearic acid, and 10g barium sulfate, and put them into an internal mixer in sequence at a speed of 55 rpm and an initial temperature of 80°C to mix them evenly. After heating to 150°C for rubber removal, use an open mill to press the sheets into sheets about 2 mm thick and park them to obtain a rubber mixture; the rubber mixture and 0.8g ZDMC, 6.0g TBBS, and 15g insoluble sulfur are rolled on an open mill in sequence, the rubber is turned over three times, rolled three times, and six triangle packages are made to make it evenly dispersed and smooth. A 2 mm film is then placed for standby use; the rubber mixture with sulfur and accelerator is molded by an injection vulcanizer at a vulcanization temperature of 160°C and a vulcanization time of 10min to prepare a hard core.

[0035] (2) Preparation of paste: Weigh 100 g of medical synthetic eucommia rubber (Mooney viscosity 10), 50 g of zinc oxide, and 10 g of barium sulfate, and put them into an internal mixer in sequence at a speed of 55 rpm and an initial temperature of 80°C to mix them evenly. When the temperature is raised to 120°C, the rubber is discharged and broken into small particles to prepare a paste.

[0036] (3) Place the paste in a container and heat it to 70°C in an oven to melt it into a paste. Immerse the hard core in the paste and take it out after 20 seconds. Make sure that the paste is evenly attached to the outside of the hard core with a thickness of about 0.3 mm. This will give a root canal filling composite material that can be used for root canal treatment.

[0037] The hard core prepared in step (1) has a Shore D hardness of 67 degrees.

[0038] The paste prepared in step (2) has a Shore D hardness of 48 degrees, a melting point of 55° C., and a melt index of 0.266 g / 10 min (160° C., 5 kg).

[0039] Example 2:

[0040] A method for preparing a novel root canal filling composite material comprises the following steps:

[0041] (1) Preparation of hard core: 10 g of liquid polyisoprene rubber (molecular weight 30,000 g / mol), 6 g of silane coupling agent Si69, and 60 g of white carbon black were weighed, mixed, dispersed using a high-speed stirrer, heated to 110° C., at a speed of 30 Hz, and stirred for 120 minutes to prepare the modified white carbon black masterbatch.

[0042] Take the modified silica masterbatch prepared above, 100g medical synthetic eucommia rubber (Mooney viscosity 20), 2g antioxidant 1010, 2g antioxidant 168, 20g zinc oxide, 5g stearic acid, and 10g barium sulfate, and put them into an internal mixer in sequence at a speed of 55 rpm and an initial temperature of 80°C to mix them evenly. After heating to 150°C to discharge the glue, use an open mill to press a sheet about 2 mm thick, and park it to obtain a mixed rubber; the mixed rubber and 0.8g ZDMC, 6.0g TBBS, and 15g sulfur are rolled on an open mill in sequence, the rubber is turned over three times, rolled three times, and six triangle packages are made to make it evenly dispersed and smooth. A 2 mm film is placed for standby use; the mixed rubber with sulfur and accelerator is molded by an injection vulcanizer at a vulcanization temperature of 160°C and a vulcanization time of 10min to prepare a hard core.

[0043] (2) Preparation of paste: Weigh 100 g of medical synthetic eucommia rubber (Mooney viscosity 5), 50 g of zinc oxide, and 10 g of barium sulfate, and put them into an internal mixer in sequence at a speed of 55 rpm and an initial temperature of 80°C to mix them evenly. When the temperature is raised to 120°C, the rubber is discharged, broken into small particles, and allowed to stand to obtain a paste.

[0044] (3) Place the paste in a container and heat it to 70°C in an oven to melt it into a paste. Immerse the hard core in the paste and take it out after 20 seconds. Make sure that the paste is evenly attached to the outside of the hard core with a thickness of about 0.3 mm. This will give a root canal filling composite material that can be used for root canal treatment.

[0045] The hard core prepared in step (1) has a Shore D hardness of 65 degrees.

[0046] The paste prepared in step (2) has a Shore D hardness of 46 degrees, a melting point of 55° C., and a melt index of 0.312 g / 10 min (160° C., 5 kg).

[0047] Example 3:

[0048] A method for preparing a novel root canal filling composite material comprises the following steps:

[0049] (1) Preparation of hard core: 10 g of liquid high vinyl polybutadiene rubber (molecular weight 8000 g / mol), 6 g of silane coupling agent Si69, and 60 g of white carbon black were weighed and mixed, dispersed in a high-speed stirrer, heated to 110° C., at a speed of 30 Hz, stirred for 120 minutes, and discharged to obtain a modified white carbon black masterbatch;

[0050] Take the modified silica masterbatch prepared above, 100g medical synthetic eucommia rubber (Mooney viscosity 20), 2g antioxidant 1010, 2g antioxidant 168, 20g zinc oxide, 5g stearic acid, and 10g barium sulfate, and put them into an internal mixer in sequence at a speed of 55 rpm and an initial temperature of 80°C to mix them evenly. After heating to 150°C to discharge the glue, use an open mill to press a sheet about 2 mm thick, and park it to obtain a mixed rubber; the mixed rubber and 0.8g ZDMC, 8.0g TBBS, and 20g sulfur are rolled on an open mill in sequence, the rubber is turned over three times, rolled three times, and six triangle packages are made to make it evenly dispersed and smooth, and a 2 mm film is placed for standby use; the mixed rubber with sulfur and accelerator is molded by an injection vulcanizer, the vulcanization temperature is 160°C, and the vulcanization time is 10min to prepare a hard core.

[0051] (2) Preparation of paste: Weigh 100 g of medical synthetic eucommia rubber (Mooney viscosity 5), 50 g of zinc oxide, and 10 g of barium sulfate, and put them into an internal mixer in sequence at a speed of 55 rpm and an initial temperature of 80°C to mix them evenly. When the temperature is raised to 120°C, the rubber is discharged and broken into small particles to prepare a paste.

[0052] (3) Place the paste material in a container and heat it to 70°C in an oven to melt it into a paste. Immerse the hard core in the paste and take it out after 20 seconds. Make sure that the paste is evenly attached to the outside of the hard core with a thickness of about 0.3 mm. This will give a root canal filling composite material that can be used for root canal treatment.

[0053] The hard core prepared in step (1) has a Shore D hardness of 70 degrees.

[0054] The paste prepared in step (2) has a Shore D hardness of 46 degrees, a melting point of 55° C., and a melt index of 0.312 g / 10 min (160° C., 5 kg).

[0055] Comparative Example 1:

[0056] A tooth glue composite material comprises the following components in parts by weight: 22 parts of medical synthetic eucommia rubber (Mooney viscosity 40), 10102 parts of antioxidant, 1682 parts of antioxidant, 70 parts of zinc oxide, and 10 parts of barium sulfate.

[0057] A method for preparing a gutta-percha composite material comprises weighing 22g of medical synthetic eucommia rubber (Mooney viscosity 40), 2g of antioxidant 1010, 2g of antioxidant 168, 70g of zinc oxide, and 10g of barium sulfate, sequentially placing the mixture into an internal mixer at a speed of 55 rpm and an initial temperature of 80°C for uniform mixing. The mixture is then heated to 150°C for rubber removal, pressed into a sheet approximately 2 mm thick using an open mixer, and allowed to stand to obtain a mixed rubber. The mixed rubber is then molded using an injection vulcanizer at a vulcanization temperature of 160°C for 10 minutes to produce a gutta-percha composite material. The gutta-percha composite material can be directly used in root canal treatment.

[0058] The dental cement composite material has a Shore D hardness of 49 degrees, a melting point of 62° C., and a melt index of 0.025 g / 10 min (160° C., 5 kg).

[0059] The hard core prepared in Example 1 has high hardness and good formability, and can be made into fine, tapered gutta-percha tips. The paste has a lower melting point and a higher melt index than the commercially available gutta-percha comparison sample (the gutta-percha composite material prepared in Comparative Example 1), indicating that the gutta-percha composite material prepared in Example 1 has excellent filling and leakage resistance, facilitating doctor operation while improving the cure rate.

[0060] In Example 2, the Mooney viscosity of the medical synthetic eucommia rubber in the hard core and paste was reduced, while the prepared hard core still maintained a relatively high hardness, meaning that smaller and more tapered gutta-percha tips could be produced. The paste had a lower melting point than a commercially available gutta-percha comparison sample (the gutta-percha composite material prepared in Comparative Example 1) and a higher melt index at a higher Mooney viscosity (the paste prepared in Example 1), indicating that the material had superior filling and leakage resistance.

[0061] Example 3 uses liquid high vinyl polybutadiene and increases the amount of sulfur and accelerator TBBS in the hard core material, which can increase the hardness of the hard core material, meaning that a smaller and more tapered gutta-percha tip can be produced, making it easier for doctors to operate while improving the cure rate.

[0062] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A new root canal filling composite material, characterized by: The invention comprises a solid hard core and a paste, wherein the paste is evenly coated on the outer surface of the hard core; the hard core comprises the following raw materials in parts by weight: 100 parts of medical synthetic eucommia rubber, 3-20 parts of liquid rubber, 5-10 parts of silane coupling agent, 60-100 parts of white carbon black, 2-6 parts of antioxidant, 20-60 parts of zinc oxide, 3-10 parts of stearic acid, 2-9 parts of accelerator, 8-25 parts of sulfur, and 8-15 parts of barium sulfate; the paste comprises medical synthetic eucommia rubber, zinc oxide, and barium sulfate, and the mass ratio of the medical synthetic eucommia rubber, zinc oxide, and barium sulfate is 100:(50-80):(8-15).

2. The novel root canal filling composite material according to claim 1, characterized in that: The liquid rubber is selected from one of liquid polyisoprene rubber, liquid high vinyl polybutadiene rubber, hydroxybutadiene rubber, and hydroxybutadiene rubber copolymer.

3. The novel root canal filling composite material according to claim 2, characterized in that: The molecular weight of the liquid rubber is 2000 to 60000 g / mol.

4. The novel root canal filling composite material according to claim 2, characterized in that: The Mooney viscosity of the synthetic eucommia ulmoides rubber used in the hard core raw material is 10-40.

5. The novel root canal filling composite material according to claim 2, characterized in that: The Mooney viscosity of the synthetic eucommia ulmoides rubber in the paste raw material is 1-10.

6. The novel root canal filling composite material according to claim 2, characterized in that: The antioxidant is selected from one or more of protective wax, microcrystalline wax, phosphite antioxidant, and phenol antioxidant.

7. The novel root canal filling composite material according to claim 2, characterized in that: The accelerator is selected from one or more of dithiocarbamate accelerators and sulfenamide accelerators; the dithiocarbamate is selected from one or more of zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibenzyldithiocarbamate, zinc dibutyldithiocarbamate, and zinc ethylphenyldithiocarbamate; the sulfenamide accelerator is selected from one or more of N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, N,N-dicyclohexyl-2-benzothiazole sulfenamide, and N-oxydiethylenethiocarbamoyl-N'-oxydiethylenesulfenamide.

8. The novel root canal filling composite material according to claim 2, characterized in that: The silane coupling agent is selected from one or more of bis-[γ-(triethoxysilyl)propyl]tetrasulfide, γ-aminopropyltriethoxysilane, γ-thiopropyltrimethoxysilane, and vinyltriethoxysilane.

9. The novel root canal filling composite material according to claim 2, characterized in that: The sulfur is common sulfur or insoluble sulfur.

10. A method for preparing the novel root canal filling composite material according to claim 2, characterized in that: The following steps are involved: (1) Preparation of hard core: Weigh liquid rubber, silane coupling agent and white carbon black, mix and heat to disperse, and prepare modified white carbon black masterbatch, and sequentially put modified white carbon black masterbatch, medical synthetic eucommia rubber, antioxidant, zinc oxide, stearic acid and barium sulfate into an internal mixer, mix evenly to obtain a rubber mix, and cool and stand; then roll the rubber mix, accelerator and sulfur on an open mixer, turn the rubber, roll it and make it into triangular packages to make it evenly dispersed, and press it into thin sheets for use; the rubber mix with sulfur and accelerator is molded by an injection vulcanizer to obtain a hard core; (2) Preparation of paste: Weigh medical synthetic eucommia rubber, zinc oxide, and barium sulfate and put them into an internal mixer in sequence, mix them evenly, and crush them into small particles after debonding to obtain a paste; (3) Place the paste in a container and heat it to 70°C to melt it into a paste. Immerse the hard core in the paste and take it out after 20-30 seconds to obtain the root canal filling composite material.