Orthodontic elastomer with flora regulation function and preparation method thereof

Abstract

The present invention provides an oral orthodontic elastomer with a flora regulating function and a preparation method thereof, and belongs to the technical field of elastomer modification. The present invention utilizes a quaternary ammonium salt bioactive agent to modify the orthodontic elastomer, so that the elastomer has an antibacterial function, reduces the proportion of cariogenic bacteria, increases the proportion of non-cariogenic bacteria, and has a good flora regulating effect. At the same time, the self-anti-aging performance can be increased, the attenuation of the self-mechanical properties can be delayed, the correction efficiency can be improved, and the treatment cycle can be shortened. The present invention can directly modify the commercialized orthodontic elastomer, and the preparation method is simple and rapid, with high safety and a wide range of applications.

Description

Technical Field

[0001] The present invention relates to the technical field of elastomer modification, and in particular to an oral orthodontic elastomer with a flora regulating function and a preparation method thereof. Background Art

[0002] During the period of wearing braces, oral hygiene problems are prone to occur, especially after eating. If the mouth is not cleaned in time, various bacteria are easy to breed, increasing the patient's susceptibility to caries. Enamel demineralization around the brackets caused by dental plaque is the main complication of fixed orthodontic treatment, with an incidence rate as high as 50%-80%. Orthodontic elastomers are commonly used accessory materials in orthodontic clinics. They are fixed around orthodontic brackets to assist in correcting teeth. If the elastomer has antibacterial function, it can accurately kill bacteria adhering to the surface of the teeth around the brackets. Through its precise, long-term and continuous antibacterial effect, it has very important clinical significance for preventing enamel demineralization and improving the effectiveness of correction.

[0003] However, sterilization alone cannot completely eliminate dental plaque. Dental plaque is a multi-species biofilm, and the oral environment will affect the ecological balance of the flora. For example, excessive intake of sugar compounds will lead to an increase in the number of cariogenic bacteria in the plaque, and cariogenic bacteria metabolize to produce acid, forming a local high-acid environment that causes calcium and phosphorus ions in the enamel to dissolve, which is the root cause of enamel demineralization. If orthodontic elastomers can effectively regulate the balance of the flora, reduce the number of cariogenic bacteria, and reduce the cariogenicity of dental plaque biofilms, they can permanently prevent the occurrence of enamel demineralization.

[0004] Orthodontic elastomers made of ordinary materials will have their mechanical properties attenuated with the frequency and duration of traction use, as well as the aging of their own base material, which will affect the effectiveness of correction and prolong the treatment cycle. Most quaternary ammonium salt bioactive agents on the market are granular, usually mixed with base materials to prepare antibacterial masterbatches, and then processed into products. Orthodontic elastomers have high safety requirements for bioactive agents because they are in direct contact with the oral cavity. Orthodontic elastomers have many tiny structures. The addition or uneven mixing of bioactive agents often affects the mechanical properties of the base material, making it unable to meet the mechanical performance requirements of tooth correction.

[0005] At present, most of the popular orthodontic elastomers on the market are modified by surface coating method. Since the antibacterial coating is very easy to peel off, it is impossible to maintain a long-term and stable antibacterial effect. There is currently no method of chemical grafting to modify the biological activity of orthodontic elastomers, so that they can obtain stable flora regulation function to effectively prevent enamel demineralization in the long term. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing an oral orthodontic elastomer with a flora regulating function, which overcomes the shortcomings of the prior art and solves the comprehensive problem of maintaining long-term antibacterial, flora regulating and mechanical properties of the orthodontic elastomer, and further effectively prevents the occurrence of complications of enamel demineralization in traditional fixed orthodontics.

[0007] Based on the above purpose, the present invention provides a method for preparing an oral orthodontic elastomer with a flora regulation function, comprising the following steps:

[0008] 1) Pretreatment: clean and dry the substrate;

[0009] 2) preparing a grafting solution: adding MBPBP to anhydrous ethanol to completely dissolve it, and then adding a quaternary ammonium salt biologically active agent thereto to obtain a grafting solution;

[0010] 3) Graft modification: The pretreated substrate is immersed in the grafting liquid for 5 to 15 minutes, then taken out, the liquid is drained, and the substrate is placed on a UV irradiation table. After irradiation for 5 to 15 minutes, the elastomer is turned over, irradiated again for 5 to 15 minutes, and the grafted substrate is taken out;

[0011] 4) Post-treatment: washing and drying the grafted substrate to a constant weight, and finally synthesizing an oral orthodontic elastomer with a flora regulating function containing a quaternary ammonium salt bioactive agent;

[0012] The chemical formula of the MBPBP is as follows:

[0013]

[0014] The chemical formula of the quaternary ammonium salt biologically active agent is as follows:

[0015]

[0016] Preferably, the substrate in step 1) is polyurethane.

[0017] Preferably, the substrate has a strip-shaped body, one end of the strip-shaped body is provided with a finger ring sleeve, and two sides of the strip-shaped body are evenly distributed with a plurality of elastic rings.

[0018] Preferably, the pretreatment in step 1) is to immerse the substrate in an acetone solution for 30 minutes to remove surface impurities, then wash it with deionized water for 3-5 times, and dry it in a vacuum oven at room temperature to constant weight; the concentration of the acetone solution is 13-14 mol / L.

[0019] Preferably, after adding the quaternary ammonium salt bioactive agent in step 2), magnetic stirring is performed for 10 to 15 minutes to obtain the grafting solution.

[0020] Preferably, in step 2), the amount of MBPBP used is 0.5-1.5% of the mass of the substrate, and the amount of the quaternary ammonium salt bioactive agent used is 2% of the mass of the substrate.

[0021] Preferably, the cleaning in step 4) is as follows: firstly rinse the grafted substrate with deionized water, then ultrasonically clean it in anhydrous ethanol for 10 to 12 minutes, take it out and then clean it with deionized water for 2 to 3 times, dry it at room temperature to constant weight, and finally synthesize an oral orthodontic elastomer with flora regulation function containing quaternary ammonium salt bioactive agents.

[0022] Another object of the present invention is to provide an oral orthodontic elastomer with flora regulation function prepared by the above method, wherein the elastomer comprises a substrate and a bioactive layer, and the bioactive layer is formed by grafting a quaternary ammonium salt bioactive agent on the surface of the substrate.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention uses quaternary ammonium salt bioactive agents to modify polyurethane orthodontic elastomers. The prepared elastomer not only has antibacterial properties, but can also accurately kill bacteria adhering to the tooth surface around the bracket; it also has a flora regulation function, which can effectively regulate the bacterial composition in the plaque biofilm, reduce the proportion of cariogenic bacteria, and increase the proportion of non-cariogenic bacteria. In addition, the elastomer can be replaced regularly during the correction process, and can exert its biological activity for a long time. At the same time, it can also increase its own anti-aging properties, delay the attenuation of its own mechanical properties, improve the correction efficiency, and shorten the treatment cycle;

[0025] 2. The present invention can directly modify commercial orthodontic elastomers, has a simple preparation method, uses MBPBP as a photoinitiator, can react quickly, has high safety, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The structure of the base material in the oral orthodontic elastomer of the present invention;

[0027] Figure 2 The water contact angle test results of the orthodontic elastomer in Example 1 and the comparative example;

[0028] Figure 3 The stress relaxation test results of the orthodontic elastomer in Example 1 and the comparative example;

[0029] Figure 4 The antibacterial performance test results of the orthodontic elastomers in Example 1 and the comparative example;

[0030] Figure 5 The test results of the flora regulation function of the oral orthodontic elastomer in Example 1 and the comparative example;

[0031] Figure 1 1 is the strip body, 2 is the finger ring sleeve, and 3 is the elastic ring. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the embodiments.

[0033] Example 1

[0034] A method for preparing an oral orthodontic elastomer with a flora regulation function, comprising the following steps:

[0035] 1) Pretreatment: Soak the polyurethane substrate in acetone solution for 30 minutes to remove impurities on its surface, then wash it with deionized water for 3 times, and dry it in a vacuum oven at room temperature to constant weight;

[0036] The polyurethane substrate comprises a strip-shaped body (1), one end of the strip-shaped body (1) is provided with a finger ring sleeve (2), and both sides of the strip-shaped body (1) are evenly distributed with a plurality of elastic rings (3). The specific structure is as follows: Figure 1 .

[0037] 2) preparing a grafting solution: adding MBPBP to anhydrous ethanol to completely dissolve it in an amount of 1% of the mass of the substrate, and then adding a quaternary ammonium salt bioactive agent to it in an amount of 2% of the mass of the substrate, and magnetically stirring for 10 minutes to obtain a grafting solution;

[0038] The quaternary ammonium salt biologically active agent is of formula (II):

[0039]

[0040] 3) Graft modification: The pretreated polyurethane was immersed in the grafting solution for 10 minutes, then taken out, the liquid was drained, and placed on a UV irradiation table. After irradiation for 10 minutes, the polyurethane was turned over and irradiated again for 10 minutes, and then the grafted polyurethane substrate was obtained;

[0041] 4) Post-treatment: The grafted polyurethane substrate is first rinsed with deionized water, then ultrasonically cleaned in anhydrous ethanol for 10 to 12 minutes, taken out and then cleaned with deionized water for 3 times, and dried at room temperature to constant weight to obtain an oral orthodontic elastomer with flora regulation function containing quaternary ammonium salt bioactive agents.

[0042] Using an untreated polyurethane substrate as a comparative example, the following experiment was conducted on the oral orthodontic elastomer with flora regulation function of the present invention:

[0043] 1. Water contact angle test

[0044] The orthodontic elastomers prepared in Example 1 and the comparative example were tested using a contact angle / surface tension tester (Dataphysics OCA20, Germany). The results are as follows: Figure 2 .from Figure 2 It can be seen that the surface of the orthodontic elastomer after grafting the quaternary ammonium salt bioactive agent in Example 1 has changed from hydrophobic to hydrophilic, proving the successful grafting of the quaternary ammonium salt bioactive agent.

[0045] 2. Mechanical properties test

[0046] By comparing the stress relaxation ratio (i.e., the ratio of the 24-hour residual stress to the initial stress) of the orthodontic elastomer grafted with a quaternary ammonium salt bioactive agent in Example 1 with that of the ungrafted polyurethane in the comparative example, the mechanical properties of the oral orthodontic elastomer with flora regulation function were evaluated.

[0047] 2.1. Initial stress

[0048] Ten elastomer specimens were randomly selected from each group. The specimens were placed on the test device. The specimens were stretched to 4 times the test length (the inner diameter of the elastomer) at a speed of 100 mm / min and held for 5 seconds. Then, they were retracted to 3 times the test length at a speed of 100 mm / min. The force value when the specimen was held at 3 times the test length (30±2) seconds was measured and expressed in N.

[0049] 2.2.24-hour residual stress

[0050] The orthodontic elastomers without grafting and grafting quaternary ammonium salt bioactive agents were immersed in artificial saliva at 37℃ for 24 hours, then taken out and drained. Ten samples were randomly selected from each group, and the specimens were placed on the test device. The samples were stretched to 4 times the test length (the inner diameter length of the elastomer) at a speed of 100mm / min and held for 5s, then retracted to 3 times the test length at a speed of 100mm / min, and the force value when holding 3 times the test length (30±2)s was measured, expressed in N.

[0051] 2.3. Stress relaxation

[0052] The ratio of the residual stress to the initial stress of the orthodontic elastomers after adding different mass fractions of quaternary ammonium salt bioactive agents was calculated, that is, the stress relaxation ratio of the orthodontic elastomers in each group. SPSS software (26.0, IBM, USA) was used for statistical analysis and the results were expressed as mean ± standard deviation. Figure 3 In one-way ANOVA, “*”, “**” and “***” indicate no statistical difference (P>0.05), statistical difference (P<0.05), significant difference (P<0.01) and significant difference (P<0.001), respectively.

[0053] Depend on Figure 3 It can be seen that there is no statistical difference in 24-hour stress relaxation between the orthodontic elastomer grafted with quaternary ammonium salt bioactive agents and the original orthodontic elastomer (P<0.05); this indicates that after grafting with quaternary ammonium salt bioactive agents, the original mechanical properties of the orthodontic elastomer will not be damaged, and it may even help improve the mechanical properties of the elastomer and delay the attenuation of the mechanical properties.

[0054] 3. Antibacterial performance testing - biofilm metabolic activity

[0055] After the orthodontic elastomer grafted with quaternary ammonium salt bioactive agents in Example 1 and the ungrafted polyurethane in the comparative example were co-cultured with Streptococcus mutans (initial concentration 1×109 CFU / mL) for 48 hours, their biofilm metabolic activity was detected. The 3-(4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) method was used. The measurement principle is that the yellow tetrazole MTT of metabolically active bacteria is reduced to a purple formazan precipitate by enzyme catalysis. The absorbance was measured at 540nm using a fully automatic quantitative mapping microplate reader. The higher the absorbance, the higher the formazan concentration, indicating that the biofilm metabolic activity on the surface of the specimen is higher and the antibacterial property is weaker. Finally, the biofilm metabolic activity value (A540 / cm2) was calculated as absorbance / surface area of ​​the specimen. The results were statistically analyzed using SPSS software (26.0, IBM, USA). The differences between different groups were analyzed using one-way ANOVA (P < 0.05). Figure 4 The results are expressed as mean ± standard deviation; "*", "**" and "***" indicate no statistical difference (P>0.05), statistical difference (P<0.05), significant difference (P<0.01) and significant difference (P<0.001), respectively.

[0056] Depend on Figure 4 It can be seen that the biofilm metabolic activity of the orthodontic elastomer grafted with quaternary ammonium salt bioactive agents is significantly lower than that of the ungrafted group, indicating that after grafting with quaternary ammonium salt bioactive agents, the orthodontic elastomer has corresponding antibacterial properties.

[0057] 4. Detection of bacterial flora regulation function—Taqman PCR

[0058] There is interaction between bacterial species in dental plaque biofilm, and a single bacterial species cannot fully play its role in mixed bacterial species dental plaque biofilm. Streptococcus mutans (S. mutans) can produce acid and is acid-resistant and is considered to be the main cariogenic bacteria in the oral cavity. Streptococcus sanguinis (S. sanguinis) and Streptococcus gordonii (S. gordonii) are known non-mutans streptococci, and are competing species with Streptococcus mutans. Streptococcus sanguinis can produce hydrogen peroxide to inhibit Streptococcus mutans. It is an alkali-producing bacterium that can neutralize the acid produced by Streptococcus mutans. Streptococcus gordonii is an early colonizer of biofilm. There are a series of adhesins on the cell surface, which can participate in mediating the adhesion and colonization of other oral bacteria. It can also produce hydrogen peroxide to inhibit the growth of Streptococcus mutans. Clinical investigations have shown that the proportion of Streptococcus sanguinis and Streptococcus gordonii in plaque is high, which is conducive to the construction of a healthy environment on the tooth surface. On the contrary, a high proportion of Streptococcus mutans in plaque is more cariogenic.

[0059] Therefore, a multi-species plaque biofilm model was established using Streptococcus mutans, Streptococcus sanguis, and Streptococcus gestate. After the orthodontic elastomer grafted with quaternary ammonium salt bioactive agents and the original ungrafted group were co-cultured in the multi-species biofilm model for 24 hours, 48 ​​hours, and 72 hours, Taqman PCR was used to absolutely quantify the Streptococcus mutans, Streptococcus sanguis, and Streptococcus gestate in the multi-species plaque biofilm model to verify the flora regulation function of the modified orthodontic elastomer. The results are shown in Figure 2. Figure 5 .

[0060] Depend on Figure 5 It can be seen that the orthodontic elastomer modified with quaternary ammonium salt bioactive agents has the flora regulating function of relatively reducing cariogenic bacteria (Streptococcus mutans) and relatively increasing non-cariogenic bacteria in multi-species biofilms compared to the unmodified group, and the flora regulating function of the orthodontic elastomer with a 2% mass fraction addition is better than that with a 1% mass fraction addition.

[0061] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing an oral orthodontic elastomer with a flora regulation function, characterized in that: The following steps are involved: 1) Pretreatment: cleaning and drying the substrate, wherein the substrate is polyurethane; 2) preparing a grafting solution: adding MBPBP to anhydrous ethanol to completely dissolve it, and then adding a quaternary ammonium salt biologically active agent thereto to obtain a grafting solution; 3) Graft modification: The pretreated substrate is immersed in the grafting liquid for 5 to 15 minutes, then taken out, the liquid is drained, and the substrate is placed on a UV irradiation table. After irradiation for 5 to 15 minutes, the elastomer is turned over, irradiated again for 5 to 15 minutes, and the grafted substrate is taken out; 4) Post-treatment: The grafted substrate is cleaned and dried to a constant weight, and finally an oral orthodontic elastomer with a flora regulating function containing a quaternary ammonium salt bioactive agent is synthesized; the chemical formula of the quaternary ammonium salt bioactive agent is as follows: (II) Wherein: in step 2), the dosage of the MBPBP is 0.5-1.5% of the mass of the substrate, and the dosage of the quaternary ammonium salt bioactive agent is 2% of the mass of the substrate.

2. The method for preparing an oral orthodontic elastomer with a flora regulating function according to claim 1, characterized in that: The substrate has a strip-shaped body, one end of the strip-shaped body is provided with a finger ring sleeve, and two sides of the strip-shaped body are evenly distributed with a plurality of elastic rings.

3. The method for preparing an oral orthodontic elastomer with a flora regulating function according to claim 1, characterized in that: The pretreatment described in step 1) is to immerse the substrate in an acetone solution for 30 minutes to remove impurities on its surface, then wash it with deionized water for 3-5 times, and dry it in a vacuum oven at room temperature to constant weight; the concentration of the acetone solution is 13-14 mol / L.

4. The method for preparing an oral orthodontic elastomer with a flora regulation function according to claim 3, characterized in that: Step 2) After adding the quaternary ammonium salt bioactive agent, magnetic stirring is performed for 5 to 15 minutes to obtain the grafting solution.

5. The method for preparing an oral orthodontic elastomer with a flora regulating function according to claim 3, characterized in that: Step 4) The cleaning is as follows: first rinse the grafted substrate with deionized water, then ultrasonically clean it in anhydrous ethanol for 10 to 12 minutes, take it out and then clean it with deionized water for 2 to 3 times, dry it at room temperature to constant weight, and finally synthesize an oral orthodontic elastomer with flora regulation function containing quaternary ammonium salt bioactive agents.

6. An orthodontic elastomer with flora regulation function, characterized in that: The elastomer is prepared by the preparation method according to any one of claims 1 to 5, wherein the elastomer comprises a substrate and a bioactive layer, and the bioactive layer is formed by grafting a quaternary ammonium salt bioactive agent on the surface of the substrate.

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