RU2414882C1 - Antibacterial material for bases of removable teeth prostheses - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to field of medicine, namely to orthopedic dentistry, and deals with material for manufacturing plastic bases of removable tooth prostheses, which have antibacterial properties. Claimed is material for teeth prosthesis basis, which consists of acrylic polymers, containing 0.0005-0.03 wt % of nanosilver, evenly distributed in entire polymer volume. Introduction in plastic composition of nanodispersive silver in said quantities excludes reduction of esthetic properties of tooth prosthesis and ensures creation of prolonged antimicrobial effect both on entire surface of product and in its volume.

EFFECT: invention elongates term of tooth prosthesis service and ensures long antibacterial effect.

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Description

The invention relates to medicine, in particular to orthopedic dentistry, and relates to a material for the manufacture of polymer (plastic) bases of removable dentures with antibacterial properties.

More than 12 million people in Russia use dentures containing elements made of polymers. At the same time, for about 60 years, the most widely used polymers (according to the price-quality criterion) are acrylic. Any prosthetics to one degree or another (depending on the type of prosthetic materials) changes the balance of the microflora of the oral cavity. This is due to the response of the body to the introduction of foreign materials into the established balance between useful and conditionally pathogenic flora.

Under the basis of the prosthesis, a thermostat is created with a constant temperature, humidity, impaired self-cleaning of the mucous membrane, food residues, which contributes to the rapid development of the microbial film. So, in the work "Injection thermoplastics of medical purity - the road to dental orthopedics", E. Ya. Vares, V.A. Nagorny et al., “Dentistry”, 2004, No. 6, pp. 53-54, it is noted that after fixing prostheses made of acrylic plastics in the mouth, the number of E. coli increases from 10 to 63%, yeast-like mushrooms - from 10 to 34%, pathogenic staphylococcus - from 10 to 22%. The content of enterococcus also increases up to 22%, which is not normally observed. The bacterial infection of acrylic plastics and the oral cavity is aggravated by the use of dentures. The reason for this, in addition to thermostatic properties, is a constant increase in the plastic's open microporosity, which is a kind of depot for pathogenic microflora. The depth of the infected plastic layer can reach 2.0-2.5 mm. Due to trauma to the soft tissues adjacent to the prosthetic bed, bacterial and fungal infection leads to candidiasis and other diseases. Acrylic polymers are also colonized by periodontopathogenic bacteria such as A.naeslundii, Prev.melaninogenica, K.nucleatum and S.intermedius. Therefore, with spilled periodontitis, prosthetics using plastics do not contribute to the normalization of the microflora of the oral cavity. In general, dentures made from domestic acrylic polymers (plastics) must be changed after three years, imported ones every five years, in particular, due to colonization by microorganisms.

The situation with bacterial and fungal infection of acrylic plastics, with the level of infection, unfortunately, is not well known. Therefore, disinfection of plastic dentures by special means is carried out only by an insignificant number of citizens and is practically not carried out in rural areas. Given the small size of the formed micropores and their large depth, as well as plaque having good adhesion, it is virtually unrealistic to sanitize plastic dentures without using additional medication or ultrasound. And this makes the prevention and fight against infection of acrylic plastics and, accordingly, the health of the body even more relevant for Russians.

The bactericidal properties of silver and its compounds have been known for centuries. During this time, not a single case of addiction to it of pathogenic flora was revealed. It was found that silver in nanometric dimensions is more active than chlorine, bleach, sodium hypochlorite and other strong oxidizing agents, 1750 times stronger than carbolic acid and 3.5 times stronger than mercuric chloride (in the same concentration). It destroys more than 650 species of bacteria, viruses and fungi [Kulsky L.A. Silver water. 9th ed., K.: Science. Dumka, 1987, 134 pp.].

One of the methods for preventing prosthetic stomatitis is described in RF patent 2287980, A61K 6/08, publ. November 27, 2006, where propolis was introduced into the composition for fixing removable dentures, which has antibacterial and immunotropic effects. The disadvantage of this technical solution is limited in terms of time and in terms of the spectrum of bactericidal action, a positive effect.

The spectrum of antimicrobial action of silver is much wider than that of many antibiotics and sulfanilamides, and the bactericidal effect is manifested with minimal (oligodynamic) doses of silver. It is important to note that there is a large difference in the toxicity of silver for pathogenic flora and for higher organisms. It reaches five to six orders of magnitude. Therefore, silver concentrations causing the death of bacteria, viruses and fungi are absolutely harmless to humans and animals. Some scientists believe that silver is a trace element necessary for the normal functioning of many internal organs, because it stimulates the activity of the immune system.

Considering the healing properties of silver, it is fundamentally important to consider its state of aggregation. According to the degree of increase in bacteriostatic activity, silver preparations (as well as other metals) can be ranked in the following order: massive, ionic, nanocrystalline. In nanocrystalline sizes (less than 100 nm), substances abruptly change their physical and chemical properties. Therefore, the most real and well-known examples of commercialization in the field of nanotechnology are considered targets in the field of human life. Bactericidal paints have been developed to provide long-term surface protection against bacterial infection. In this case, it should be noted the extremely low concentration of nanodispersed silver in the paint (1.6-6.5 × 10 ^-4 % in terms of elemental silver), which provides a biocidal effect [E.M. Egorova, A.A. Revina and others. Germicidal and catalytic properties of stable metal nanoparticles in reverse micelles. Vestn. Mosk. Univ., Ser. 2. Chemistry, 2001, v. 42, No. 5, p. 323-338].

Silver-based preparations are widely used in dentistry. For example, in the patent of the Russian Federation 2243775, A61K 33/38, publ. 01/10/2005, silver nitrate is used to treat tooth decay and sterilize the root canal. During the chemical reduction of silver nitrate, finely dispersed silver is formed, which provides a disinfecting, therapeutic effect. The disadvantage limiting the application of this method is the aesthetic factor - finely divided silver is black.

Described [US Pat. RF 2354668, C08J 5/16, publ. 05/10/2009] a method of manufacturing polymer parts of sliding friction for artificial endoprostheses, consisting of high molecular weight polyethylene with uniformly introduced nanoparticles of gold or gold and silver in an amount of 0.15-0.5 wt.%. The disadvantage of this method is that silver in such quantities gives an unaesthetic appearance to prostheses. In addition, polyethylene has its drawbacks when it is used in prosthetics.

In the composition of the hardening paste for filling the channels "SEALITE REGULAR, ULTRA" of the company "Pierre Roland" silver is also used in large quantities - up to 24%. This solution cannot be used for plastic dentures due to the low aesthetic properties of the material and the low bactericidal activity of coarse silver powders [Kuzmina LN, Zvidencova NS, Kolesnikov LV Obtaining silver nanoparticles by chemical reduction. Materials of the International Conference "Physicochemical Processes in Inorganic Materials" (ФХП-10) Kemerovo: Kuzbassvuzizdat. 2007.V.2. S.321-324].

Known material [Courland V.Yu., Yashchenko P.M. et al. Actual issues of orthopedic dentistry. M., 1968, p.140] of plastic prostheses having an antibacterial effect, obtained by chemical silvering of the inner surface of the plastic. The effect of such an application is also described [L.D. Gozhaya, Ya.T. Nazarov and others. The entry of silver into saliva in individuals using metallized plastic prostheses. Dentistry, 1980, No. 1, pp. 41-43]. Chemical silvering of the surface of a plastic prosthesis is carried out by chemical reduction of silver from its compounds. For the reaction, silver nitrate or its ammonia complex salt is usually used. After chemical silvering of the inner surface of the acrylic prosthesis, discomfort in the mouth disappears, and the affected oral mucosa heals. As a result of applying such a solution, the required technical result is achieved — antimicrobial action in the oral cavity.

The disadvantage of this material is a short-term therapeutic effect in chronic diseases of the oral cavity and pharynx. This is due to the fact that silver deposited on the inner surface of the plastic prosthesis is washed out from it within 2-3 weeks. In this case, the greatest amount of silver enters the human body in the first 3 days. The leaching of silver occurs as a result of both its “mechanical” leaching and dissolution. To prolong the therapeutic effect of the silver coating, it is required every three days to carry out a new metallization of the palatal surface of acrylate prostheses [http: //www.stomatology 24.ru. Orthopedic dentistry. - Part 3. Treatment and prognosis. Part 3]. The second disadvantage of such a material is the inability to prevent bacterial infection of plastic on the outer surfaces of the prostheses (on which silver is not applied for aesthetic reasons) and inside the mass of the material. In addition, the relatively low bactericidal activity of silver monolithic coatings in comparison with nanodispersed silver should be taken into account.

The objective of the present invention is to develop an antibacterial material for bases of removable dentures, providing long-term surface and bulk antibacterial action.

The problem is solved by introducing nanodispersed silver into plastics for denture bases in quantities that do not reduce the aesthetic properties of dentures and at the same time ensure the creation of an antibacterial effect in denture bases. Nanodispersed silver is introduced into the initial micropowders of acrylate polymers by any physical or chemical methods.

The essence of the invention lies in the fact that the proposed material with an antibacterial effect for bases of dentures, characterized in that it consists of acrylic polymers containing 0.0005-0.03 wt.% Nanosilver distributed throughout the polymer.

The developed material contains nanosilver uniformly distributed throughout the polymer. This is achieved by applying nanosilver to acrylate micropowders by any physical means (anodic silver dissolution, vapor deposition, mixing with a ready-made sedimentation-stable suspension of nanosilver) or by chemical methods (chemical, biochemical, radiation-chemical reduction of silver compounds) with their subsequent mixing liquid monomer. The monomer dissolves acrylate powders and, due to the small particle size, nanosilver is evenly distributed in the powders, and then throughout the entire volume of the finished plastic dough. During the operation of prostheses made according to the proposed solution, there is a constant micro-dissolution of plastic in saliva (the formation of microporosity). At the same time, more and more active silver nanoparticles are exposed in the depth of micropores, preventing the colonization of pathogenic flora. This ensures a prolonged and reliable antibacterial effect of the denture base material without the use of special hygiene measures, prolonging the life of prostheses and a general healing effect on the human body.

The use of silver in nanometric sizes (nanosilver) and its uniform distribution in the polymer volume allows one to obtain a reliable prolonged antibacterial effect at significantly lower silver concentrations compared to its other forms and at the same time maintain the aesthetic qualities of the prostheses.

To assess the feasibility of implementing the claimed invention with the implementation of the tasks for applying nanosilver to acrylate powders (as a particular example), the powder of the industrially produced preparation "Poviargol" containing 8 wt.% Nanosilver was used.

It is known from the general theory of surface modification of any micropowders that with a decrease in the amount of added additive to fractions of a percent, it cannot be distributed evenly in the main powder only by mixing or co-milling, when both components are in powder form. One of the solutions is the use of microadditives in the form of a solution of a low modifier concentration [Cherepanov A.M., Tresvyatsky SG Highly refractory materials and products from oxides. M., Metallurgy, 1964. - 400 s]. With this in mind, Poviargol powder was dissolved in water up to 1% solution under ultrasonic exposure at an operating frequency of 22 kHz. In an aqueous solution of Poviargol, the average size of the primary cluster particles of silver is 5-10 nanometers.

After that, the solution of “Poviargol”, in calculated amounts, was poured into the powder of acrylate plastic “Ftoraks”. Evenly moistened with a modifying solution, the powder was dried to an air-dry state with constant stirring. At the same time, nanosilver was uniformly fixed (deposited) on the surface of Ftoraks micropowders. The molding material was prepared by mixing a modified acrylate powder with a monomer. After dissolving these powders in the monomer, discs with a diameter of 20 mm were formed to conduct microbiological studies and evaluate color. When these modified acrylate powders are mixed with a liquid of acrylate monomer (solvent and hardener of acrylates), nanosilver is evenly distributed throughout the entire molding mass. During the operation of prostheses made from the material of this invention, the usual destruction of plastic by the oral fluid and constant alternating loads (microporosity, cracking) and constant exposure of silver nanoparticles in the pores of the plastic occur. This ensures a prolonged and reliable antibacterial effect even without the use of special hygiene measures, prolonging the life of prostheses and a general healing effect on the human body.

The claimed amount of nanosilver is determined by two parameters: an aesthetic parameter and an antibacterial effect. It turned out that when the nanosilver content is more than 0.03 wt.%, The color of the plastic acquires a brown tint, which does not satisfy the aesthetic requirements for removable dentures. In particular, a material having such a color cannot be used in the anterior part of the dentition. Thus, the upper limit of the content of nanosilver for the manufacture of denture bases is limited to 0.03 wt.%. When the silver content is less than 0.0005 wt.%, The effect of silver is insufficient to provide a noticeable antibacterial effect.

As a control, discs were prepared from the molding material without the addition of nanosilver. The antibacterial activity of the disks was evaluated by the in vitro plate-suspension method in accordance with the method described in MP No. 2003/17 of March 19, 2004, “Cup Method for Evaluating the Effectiveness of Disinfectants and Antiseptics”. The test strain S. aureus 6538 with a microbial load of 10 ³ CFU / ml was used as a test culture. The exposure was 24 hours.

EXAMPLES OF IMPLEMENTATION

Example 1

A material is prepared with a nanosilver content of 0.0005 wt.%.

To do this, prepare a 1% solution of "Poviargol" in distilled water under ultrasonic treatment with an operating frequency of 22 kHz, dilute it with distilled water 10 times. 1.9 ml of the obtained Poviargol solution is dissolved in 2 ml of distilled water (to ensure complete wetting of the acrylate powder) and 20 g of Fluoroax acrylate powder are poured into the sample. The amount of nanosilver introduced into the acrylate powder is equal to 0.15 mg. The mass is dried with constant stirring in a porcelain mortar to an air-dry state. The molding material is prepared by mixing silver-modified powder with a liquid monomer. The ratio of powder: monomer is 2 wt.h. powder per 1 parts by weight monomer. After the dissolution of the fluoroX powders in the monomer, the formation of disks with a diameter of 20 mm is carried out for microbiological studies.

The color of the plastic has a pink tint, which satisfies aesthetic requirements.

Example 2

Prepare a material with a nanosilver content of 0.01 wt.% (Working composition).

To do this, prepare a 1% solution of “Poviargol” in distilled water under ultrasonic treatment with a working frequency of 22 kHz, and 3.8 ml of the obtained Poviargol solution is poured into a weighed portion of 20 g of acrylic powder “Ftorax”. The amount of nanosilver introduced into the acrylate powder is 3 mg.

The mass is dried with constant stirring in a porcelain mortar to an air-dry state. The molding material is prepared by mixing the powder with a liquid monomer. The ratio of powder: monomer is 2 wt.h. powder per 1 parts by weight monomer. After dissolving the fluoroX powder in the monomer, discs with a diameter of 20 mm are formed to conduct microbiological studies.

The color of the plastic has a pink tint, which satisfies aesthetic requirements.

Example 3

A material with a nanosilver content of 0.0001 wt.% (Below the minimum) is prepared according to the procedure described in Example 1, but the amount of Poviargol solution is 0.38 ml. The amount of introduced nanosilver in this case is 0.03 mg.

Microbiological tests showed the absence of an antibacterial (bacteriostatic) effect.

The color of the plastic has a pink tint, which satisfies aesthetic requirements.

Example 4

A material is prepared with a nanosilver content of 0.04 wt.% (Above the maximum concentration).

To do this, prepare a 3% solution of “Poviargol” in distilled water under ultrasonic treatment with an operating frequency of 22 kHz and 3.8 ml of the obtained Poviargol solution are poured into a weighed portion of 20 g of acrylic powder “Ftorax”. The amount of nanosilver introduced into the acrylate powder is 12 mg.

The mass is dried with constant stirring in a porcelain mortar to an air-dry state. The molding material is prepared by mixing the powder with a liquid monomer. The ratio of powder: monomer is 2 wt.h. powder per 1 parts by weight monomer. After dissolving the fluoroX powder in the monomer, discs with a diameter of 20 mm are formed to conduct microbiological studies.

Microbiological tests showed a strong bactericidal effect.

The color of the plastic has a brown tint and does not satisfy the aesthetic requirements for the material for the bases of removable dentures.

Microbiological tests showed that 0.0001 wt.% Nanosilver did not have an antibacterial effect against Staphylococcus aureus; 0.0005 wt.% Nanosilver reduce the level of the microbial population by 100 times; 0.01 wt.% Nanosilver - 150 times; 0.03 wt.% Nanosilver - 1000 times; 0.04 wt.% Nanosilver reduce the level of the microbial population by more than 1000 times.

Moreover, studies have shown that nanosilver disks have a pronounced prolonged antibacterial effect. Hoods from the same disk were received every 2 weeks, they were thermostated according to the method of “accelerated aging” (I-42-2-82. “Temporary instructions for work to determine the shelf life of drugs based on the method of“ accelerated aging ”with elevated temperature "), followed by seeding according to the above methodology on cups seeded with staphylococcus test culture.

As shown in the table, extracts from disks with a nanosilver content of from 0.0005 to 0.03 wt.% Exhibit an antibacterial effect that lasts for 250 days.

The content of nanosilver, wt.% Color Antibacterial effect 0.0001 Pink tint Lack of antibacterial effect 0,0005 Pink tint The effect of 250 days 0.01 Pink tint The effect of 250 days 0,03 Pink tint The effect of 250 days 0.04% Brown tint The effect of 250 days

Thus, the material according to the invention has a pronounced prolonged antibacterial effect both over the entire surface of the product and in its volume. This extends the life of dentures and provides a long-lasting antibacterial effect.

The present invention differs from the known ones in that a material for denture bases based on acrylic polymers is developed, containing silver nanodispersed distributed in its entire mass, having an aesthetic appearance, having a pronounced prolonged antibacterial effect.

Claims (1)

An antibacterial material for bases of removable dentures based on acrylic polymers, characterized in that it contains 0.0005-0.03 wt.% Nanosilver uniformly distributed in the polymer.