POLYMERIC MATERIALS

From Big Medical Encyclopedia

POLYMERIC MATERIALS are widely applied in the national economy and medicine; they contain high-molecular compounds (polymers), molecules (macromolecule) to-rykh consist of a large number of the repeating links.

Distinguish natural polymers (biopolymers, napr, animal and phytalbumins, carbohydrates, nucleic acids, natural rubber, etc.) and the synthetic polymers (created artificially), received from low-molecular substances (monomers) by means of polyreactions or polycondensation (e.g., polyethylene, capron, polypropylene, etc.). And the main P. m carry plasts, synthetic resins, rubbers, fibers, varnishes, paints, glue.

Items of m from artificial polymers use for replacement or recovery of functions of fabrics and bodies, for production of bandages for wounds and burns, blood substitutes, medicinal films (see), packagings for medicines, suture materials (see), objects of patient care, details of the medical equipment, etc.

P. m turned into a constant factor of the habitat of the person as are used in the food industry, water supply, construction, at production of furniture and numerous prime necessities. Along with valuable properties P. of m have the harmful properties caused by features of their chemical structure and technology of receiving that can constitute danger to the person. It predetermined emergence and development of the new special section of preventive medicine — hygiene of use of P. of m in the national economy, tasks to-rogo include studying of adverse properties, character and degree inherent in them biol, actions on a human body and development of the actions providing safe conditions of use of P. of m at contact with tissues of a body of the person or in the presence of them in the environment.

The chemists synthesizing P. of m the engineers creating products from them and the doctors using them first of all develop questions biol, compatibility of the applied polymers and possible endurances taking into account a complex of useful properties (mechanical, diffusion, optical, etc.)*.

P.'s most of m at their introduction to an organism contact to fabrics, blood, a lymph, exudate. At the same time two mutually connected processes proceed: destruction of polymers under the influence of biologically active agents (P.'s «fatigue» of m) and interaction of decomposition products of polymers with biol, Wednesdays, i.e. influence of products of their metabolism on life activity of an organism.

P.'s interaction the m with an organism can be presented as follows:

Interaction of polymeric materials with an organism

The most difficult range of application of P. of m is Endoprosthesis replacement (see). It is caused not only difficulty of chemical and technological processes of synthesis of polymers with the set properties, but generally need of a solution biol, m

Biochemistry of polymeric materials

At contact with P.'s organism of m allocate interactions of fabrics of a live organism with P. not only low-molecular own decomposition products, but also residual monomers and additives which are contained in them (plasticizers, stabilizers, dyes, fillers, emulsifiers, etc.). Therefore the main objective biochemical, researches — studying of decomposition products P. of m in an organism, and also processes of metabolism and ways of removal of chemical substances. Primary biochemical, reaction of an organism to P. of m is characterized by decrease in partial pressure of oxygen in fabrics, reduction in them of pH, ion concentration of potassium, sodium, calcium and magnesium, accumulation of physiologically active agents, increase in permeability in a zone of damage. However biochemical, studying of interaction of P. of m with an organism is complicated ryadokhm factors. E.g., at any P.'s implantation the m occurs multistage process of migration of low-molecular substances to limit of the section with biol, Wednesday within several hours or many months. Diffusion rate in P. in m is defined by a chemical structure, structure, structure and technological conditions of its processing. The structure of the migrating connections is not always known; there are no sensitive and selection methods of their definition.

A number P. of m has impurity which are emitted from them and are metabolized in an organism. It is established that in low-molecular substances of a similar structure there is a metabolic transformation of impurity (oxidation, recovery, hydrolysis) to the subsequent conjugation (biochemical, synthesis of the deactivated or toxic connections). E.g., from phenolformaldehyde plastic such toxics as phenol and formaldehyde, from ureaformaldehyde plastic — formaldehyde, from polystyrene and polyacrylates — styrene and acrylates, from polyvinylchloride — plasticizers and residual monomer vinyl chloride are emitted. In the course of metabolism enzymes of an endoplasmic reticulum of cells of a liver and other fabrics, and also enzymes of an intermediate metabolism participate: alcohol dehydrogenase, aldegiddegidrogenaza, xanthineoxidase and esterases.

P.'s transformations study m in an organism standard biochemical, methods on animals, in particular with allocation of metabolites and their conjugates with the subsequent definition of a chemical structure, attracting at the same time a method chromatography (see), spectral analysis (see), autoradiography (see) etc. Investigate local reaction of fabrics to the m entered by P. for definition of biocompatibility with an organism and immunol. indicator of allogeneity of an implant.

Knowledge biochemical, processes of interaction with an organism and ways of metabolism of products biol, P.'s destructions forms m a basis for development of questions of pharmacology and P.'s toxicology of m, and also a dignity. - a gigabyte. requirements to them.

Hygienic requirements

As as a part of P. of m practically always are in a stand-at-ease low-molecular chemical substances (monomers, plasticizers, hardeners, solvents, dyes, stabilizers, products of destruction, etc.), the danger connected with migration on the Wednesdays contacting to them (tissues of a body of the person, foodstuff, water, air) these substances possessing, as a rule, expressed biol, activity is real toksikol. At P.'s contact m with internal environments of an organism formation of toxic products of biotransformation is possible. P.'s use leads m in bio-destruktiruyushchikh products to formation of products of a catabolism of directly high-molecular basis.

Items of m can oppress in one cases, and in others to activate development of microflora on the surface or in the Wednesdays contacting to them (e.g., in drinking water at production of water pipes from nek-ry types of P. of m).

Because P. of m are dielectrics, at friction on their surface the charges of static electricity (reaching quite often tens of kilovolts) can collect that, in turn, leads to formation of static electric fields, change of ionic structure and conductivity of air. The spark categories arising at the same time can be the reason of explosions and fires if at air of rooms (e.g., at operational, factory workshops) there are vapors of explosive or flammable substances. At the fires there is a danger of formation of highly toxic flying products of thermal-oxidative degradation of P. of m. Spark categories can also cause formation of ozone and nitric oxides in the concentration sometimes exceeding admissible sizes. On a surface of the m electrified by P. perhaps mokhoobrazny accumulation of dust.

Some features of fiziko-hygienic properties P. of the m applied in construction (a high rate of heatassimilation of building constructions with thin layer polymer coatings, finishing P.' water repellency of m, etc.), can be the cause of adverse changes of a microclimate of rooms (considerable temperature drops of air down, big fluctuations of relative humidity of air, etc.).

The direct or mediated influence of the specified adverse factors can be different reason of the frustration arising at the person in the next or remote terms or to affect posterity.

Manifestations of harmful effect of the chemical substances getting to an organism depending on range of application and P.'s appointment of m in various ways — parenteral, percutaneous (transdermal), peroral, inhalation or their combination are extremely various.

At direct contact of P. of m with internal environments of an organism along with all-toxic reactions (from direct cytotoxic effect before frustration at the level of a complete organism) various manifestations to a spa ~ tsifichesky character (allergic reactions, blastomogenic action) are possible. So, danger of emergence of malignant new growths is proved (more often sarcomas, are more rare than a carcinoma, etc.) at animals in places of implantation of materials from synthetic polymers.

Even more difficult are relationships of cause and effect at simultaneous impact on an organism of volumetric, physical and biological factors that takes place at P.'s use of m in construction. So, on-site investigations of residential and public buildings, in construction or registration of an interior to-rykh are applied some P. by m, allowed to reveal at various groups of the population of the complaint to a persistent foreign smell in rooms, tactile and pain at hiting at to the grounded objects, irritability, a bad dream, pains in heart, increased fatigue, overcooling of the lower extremities, etc., and also the changes in the state of health which are shown in growth of the general incidence with changes in its structure: to bigger frequency of radiculitises, went. - kish. diseases, patol. changes of an ear, throat and nose, in decrease nonspecific immunol. reactivity of an organism and so forth.

Pilot studies showed that the olfactory feelings connected with pollution by chemical substances of the environment are quite often accompanied by reflex changes from separate bodies and systems (c. N of page, cardiovascular, etc.), napr, decrease in light sensitivity of eyes, lengthening of the hidden time of motor reaction, change of a tone of a vascular wall and krovenapolneniye of fabrics, etc.

Natural and experimental observations showed that the created P. of m multicomponent chemical pollution of the air environment along with an all-toxic hron, action can cause allergization of the population, and also the cytogenetic effect which is shown in emergence of chromosomal disturbances in somatic and sex cells of experimental animals. Experimental data about P.'s influence the m on various parties of reproductive function of an organism shown in the form of gonadotropic, embriotropny and teratogenic effects are obtained.

At action on an organism of static electricity (see) there can be various changes in an organism, character and degree of manifestation to-rykh depend on level and polarity of static electric fields and the direction of power lines. E.g., static electric fields interfere with penetration of aeroions of the charge of the same name that promotes change of trophic processes in skin, and, therefore, can affect protective and thermoregulatory its functions; reflex changes from functions of nek-ry bodies and systems are possible. Static electric fields at the level of 500 in/cm and more can cause mutagen and embriotropny action.

For providing safe conditions of use of P. of m for human health they shall answer defined a gigabyte. to the requirements differentiated depending on range of application (medicine, the food industry, water supply, construction), the appointments expected external environment. One of the main requirements to all P. of m — harmlessness in toksikol. relation. They shall not worsen considerably organoleptic properties of this or that environment (e.g., intensity of a smell of drinking water or air is not higher than 2 points), and the created P. of m chemical pollution of liquids and body tissues, foodstuff, water and air of rooms shall not cause reflex and resorptive all-toxic reactions, and also specific action (allergenic, mutagen, etc.) * To prevention of effects of contact with P. of m serves the maximum allowable concentrations approved by M3 of the USSR for many chemical substances migrating in use from P. of m in foodstuff, drinking water and air of rooms. The regulations of content of chemical substances in internal environments of an organism are absent that complicates a gigabyte. P.'s assessment m of medical prescription. The items of m intended to contact to internal environments of an organism, shall not have the pyrogenic properties, stimulate development of microflora on their surface and in the Wednesdays adjoining to them. The items of m used in construction for production of furniture, the equipment, household items shall be fire-resistant and to create static electric fields tension higher than 150 in / sm\finishing P. m shall worsen a microclimate of rooms, and an indicator of heatassimilation of a surface of polymer coatings of a floor — to exceed the normative sizes provided Construction Norms and Regulations 11-3-79 «Construction the heating engineer».

For a gigabyte. P.'s estimates m and solutions of other tasks are chosen the methodical approaches realized in natural and modelirovanny conditions with use of chemical, physical, hematologic, biochemical, physiological, immunological, morphological and other methods of a research. Researches in modelirovanny conditions are of the greatest value, at implementation to-rykh the Wednesday adequate to range of application of P. of m (biol, liquids of an organism, the foodstuff or Wednesdays imitating them water, air), comes into contact with a sample of the studied material with reproduction of the main real conditions of their use exerting impact on process of migration of chemical substances.

Temperature, the relation of the area or P.'s mass of m to the volume of the environment, duration and the mode of contact of P. of m with Wednesday, e.g., belong to the specified conditions (in all cases irrespective of range of application); acidity of the environment, etc. (for P. of the m used in medicine, the food industry and water supply); frequency rate and the mode of air exchange, relative humidity of air, sometimes UF-radiation, etc. (for P. of m of construction appointment and used for production of furniture and various objects). At the same time such qualitative and quantitative characteristics of chemical pollution of the environment which are inherent to natural conditions of operation of material are reached. The Wednesday received thus is exposed, as a rule, to a multi-stage research on a certain methodical scheme, the purpose to-rogo is registration of the m of changes arising under the influence of P. in the Wednesday (character and extent of chemical pollution, influence on development of microorganisms, change of organoleptic properties, electrization, change of heat-protective indicators etc.) contacting to it, and also identification of the disturbances connected with these changes in the state of health of the person or experimental animals. The material solution of the experimental systems used at the same time, installations and devices, and also the list of methodical stages are individual for each case. As the example of the decision of similar researches is given table 1, in a cut the list of nek-ry researches P. of the m intended to use in construction of treatment-and-prophylactic, residential and other buildings and constructions in modelirovanny conditions is given. Odorimetrichesky and kliniko-physiological researches are conducted by observation in public, the others — in an experiment on various animals. At P.'s studying m of construction appointment under natural conditions the list of researches other (e.g., studying of incidence of the population, a wedge, inspection, etc.). For studying in modelirovanny conditions of patterns of education on P.'s surface of m of static electricity and biol, its actions on an organism are offered special pilot units.

For studying of influence of P. of m on life activity of microflora a number of methods is applied: crops of culture of microorganisms in the fluid medium (liquid foodstuff, liquid mediums, etc.) contacting to P. of m; imposing of disks P. of m on previously inseminated surface of solid nutrient medium; planting by microorganisms of a surface of P. of m with the subsequent overseeing by their reproduction; etc.

Professional harm

P. m make methods of prints, washouts and process into products at the enterprises chemical industry (see), mechanical engineering, an avia - and shipbuilding, radio-electronic, easy and other industries.

During the receiving and P.'s processing m working are influenced by production factors, influence of chemical substances is conducting from to-rykh. Safety of working conditions at the same time is defined physical. - chemical and toxic properties of raw materials (a volatility, danger of the used substances and a possibility of their turning into more toxic connections, composition of residual monomers and additional components in polymer), features of technological process (a temperature schedule, existence or lack of manual and heavy works, operability and reliability of communications, tightness of the equipment), rationality of a design and ventilation of rooms.

The m of chemical substance which are allocated in a process of manufacture of various P. — styrene (see), phenols (see), formaldehyde (see. Aldehydes ), vinyl chloride (see. Polyvinylchloride ), solvents (see), residual monomers, additives and products of thermodestruction of P. of m can lead to development acute and hron, poisonings (see), diseases of skin — eczemas (see), dermatosis (see) and such diseases, as angiotrofonevroza (see), polyneurites (see), bronchial asthma (see), etc. An adverse effect on the state of health can be made excess heat release from the equipment, noise (see) and vibration (see). On a number of sites pollution of the air environment dust of polymer, fillers, stabilizers and other additives is possible (see. Dust ).

Preventive actions for improvement of working conditions shall be directed to a gigabyte. the standardization of prescription mixes and raw materials assuming restriction of contents in them harmful impurity on replacement of highly toxic components with less toxic and less volatile compounds, improvement of technological processes and the equipment. The rational design of workshops and placement of the equipment according to a gigabyte are important. requirements, isolation adverse in a gigabyte. the relation of sites (with a considerable gazo-and a pylevydeleniye, with a high level of noise etc.), sealing of the equipment and processes of selection of technological tests, restriction of use of the equipment with big open surfaces, especially at thermal processes (heating).

For fight against dust and an exception of manual operations it is necessary to use more widely pneumotransport and conveyor transportation of raw materials, delivery to the enterprises of raw materials in the granulated, bricketed, tableted look, and also use of small packaging of the dyes, stabilizers and other additives counted on standard loadings.

The maximum restriction of contact working, especially hands and open parts of a body, with harmful substances, use of protective clothes is necessary (see. Clothes special ), footwear (see), protective pastes (see. Pastes protective ), and in nek-ry cases — gas masks (see) or respirators (see), providing working a gigabyte. a shower upon termination of change, introduction of a rational work-rest schedule.

Heat insulation of the heated equipment and communications, the correct device and operation of ventilating installations, especially local have a certain value ventilation (see).

Workers at revenues to work shall have preliminary examination and further periodic medical examination (see). Contraindications to employment and frequency of medical examinations depend on a type of the m produced by P. Training of the rules working to observance is important accident prevention (see) and personal hygiene (see) during the work with chemical connections.

Occupational health and prevention of occupational diseases by P.'s production of m — see also in articles chemical fibers , Rubber production , Varnishes , Rubber production , synthetic resins etc.

Use of polymeric materials in medicine

Fig. 1. Microdrug of soft tissues in 1,5 years after implantation of wattled thread from polycaproamid (capron): 1 — the remains of kapron thread, 2 — the connective tissue capsule around thread; coloring hematoxylin-eosine; h80.

Morphological changes in an organism at P.'s introduction in m are characterized by development of aseptic inflammatory reaction as a result of the directed movement of cells (neutrophils, monocytes, basophiles, macrophages, etc.) in a zone of an arrangement of polymer that is caused by influence of an operational injury and chemical irritants (see. Inflammation ). Chemical irritants are as physiologically active agents produced by the damaged cells and fabrics and the substances emitted to P. by m (products of destruction, the remains of catalysts, stabilizers, fillers etc.). Degree of manifestation of this reaction is defined by chemical and physical properties of the implanted polymer. A favorable outcome of an inflammation is formation of the connective tissue capsule (fig. 1), in a cut there is a continuous updating of the elements making it. For germination of porous prostheses connecting fabric an indispensable condition is full fitting of an implant tissues of the recipient. If the prosthesis adjoins to fabrics of a live organism only on the one hand, and other surface is turned into a gleam of hollow body, full encapsulation of a prosthesis does not happen, connecting fabric covers a prosthesis only from the outer side. Therefore all attempts of recovery of a continuity of a gullet, ureters, bilious channels, a bladder by means of P. in m came to an end with failure.

Fig. 2. Samples of products from polymeric materials: and — a prosthesis of a small egg — a prosthesis of an auricle, in — a prosthesis of a nasal partition — a prosthesis of a ridge of the nose, d — mylar grids for plastics of soft tissues, e — cylinders for endovascular occlusion — blood clots for endovascular occlusion.

Implantation in an organism of animals (rats, mice, Guinea pigs) of biocompatible P.' number of the m which are not possessing all-toxic action can lead to malignant regeneration of the connecting fabric which is formed around polymer. Polymers from polyethylene, a ftoroplast, polyamides, organosilicic rubbers, etc. have blastomogenic effect. Attempts to find any bonds between blastomogenic activity of polymers and their chemical nature were not crowned with success. At the same time dependence of blastomogenic action on a form of an implant was revealed. Nonperforated polymers have the greatest activity. Introduction of perforated plates from the same material causes formation of a tumor in much smaller number of cases, and administration of the same substance in the form of powder does not cause tumoral growth at all. Most of researchers considers that blastomogenic effect of biocompatible polymers at rats, mice, Guinea pigs is caused not by the chemical nature, but disturbance of normal exchange in the connective tissue capsule owing to long mechanical irritation. However developing of tumors as a result of implantation of polymers at other experimental animals, and also at the person (more than 40 years are observed) it is not described. The items of m applied in a number of the fields of medicine are various and intended for various purposes (tab. 2), samples of nek-ry products are presented in the figure 2.

Reconstructive surgery. The item of m in plastic surgery (see) use for temporary or constant replacement for the lost or struck fabrics or bodies. Therefore requirements to them especially high: fiziol, harmlessness, lack of toxicity, carcinogenicity, an allergogennost, the minimum irritant action on surrounding fabrics, constant physical. - chemical and mechanical characteristics.

Physiologically inactive (bioinert) and slowly collapsing polymers are intended for constant replacement of fabrics and bodies or strengthening of their contours. They shall have high resistance to influence biol, environments of an organism, slowly to change initial characteristics, to keep functional properties of the fitted a prosthesis bodies and fabrics. The fast-collapsing physiologically inactive polymers use for temporary substitution of fabrics.

Plastic P. of m of soft tissues can be two types: cosmetic, planimetric plastics of volume defects of soft tissues (mammary glands, a fatty tissue, muscular tissue) and directed to recovery of mechanical strength (at change of a front abdominal wall owing to recurrent ventral and inguinal hernias, a relaxation and hernia of a diaphragm, diverticulums of a gullet, etc.). The planimetric volume plastics of soft tissues is carried out ready prostheses on the basis of dimethyl silicone and complex structures on its basis (compounds).

Apply mesh bezuzelkovy knitted fabrics to strengthening of mechanical strength of fabrics from polyester (lavsan) or polyamide (capron) fibers. P.'s use m for plastics of hollow bodies (a gullet, intestines, a trachea, bronchial tubes, a bladder, bilious channels etc.) is possible only for strengthening of their wall. At operations on easy, parenchymatous bodies apply only kleyushchy structures (the poly(acrylic glues and glue on the basis of polyurethane). P. by m are developed for filling of residual postoperative cavities, abscesses etc. In the 70th began to use P. of m for sealing of a pancreat duct at treatment hron, pancreatitis.

Warmly - vascular surgery. In addition to the general requirements to P. of m, at their use for prosthetics of valves of heart (see) and blood vessels (see) specific requirements are imposed: they shall not cause hemolysis of blood and formation of blood clots. Apply polyester fibers (lavsan), fibers from the fluorinated polyolefins to prosthetics of vessels, polypropylene; for prosthetics of valves of heart — Organosilicic rubbers, the segmented polyurethane, polypropylene, fibers from ftoroplasta-4. A lot of work on giving of an anti-trombogenicity to various groups of polymers is carried out. From the existing P. m the least thrombogenic are the segmented polyurethane (avcotan), silicone rubber. For intravascular occlusion at a stop pulmonary and other bleedings, treatment of hemangiomas embolization by polyhydrooxyethylmethacrylate, silicone rubber p other is widely applied (see. X-ray endovascular surgery ).

Traumatology and orthopedics. Products for external prosthetics — prostheses of extremities, splints, orthopedic tabs, etc. (see. Orthoses , Prostheses ) — make of polyethylene, polyvinylchloride, fibreglass, rigid and flexible foams. Use of polymers for the specified purposes allows to facilitate sharply a prosthesis, to improve its functional and hygienic properties, outward.

Widely use P. of m for replacement of sheaves and sinews, especially tapes from lavsan. Prosthetics of small joints of a brush and foot is made by means of the prostheses joints made on the basis of organosilicic connections, the segmented polyurethane. In designs of prostheses of large joints (coxofemoral, knee) along with metal details use parts from polyolefins. The solution of one of urgent problems of traumatology — creation of various coupling (pins, brackets) from physiologically active, slowly and quickly collapsing P. of m — will allow to refuse repeated operations for extraction of these devices after regeneration of changes.

Fig. 3. Prostheses of an ureter from silikoni-rovanny rubber: 1 — a tube, 2 — a cuff from velor for fixing of a prosthesis, 3 — the anti-reflux valve.

Urology. It is necessary to carry Organosilicic silicones, especially silicone rubber to the most widespread P.' number of the m applied in urology. Items of m in urology use for production of tools and the equipment — elastic ureteric and urethral catheters (see) and buzhy (see), devices for an endovesical removing calculus, drainage tubes which are not exposed to incrustation by uric salts in this connection they can be used without change a long time. Such property of nek-ry P. of m as semi-permeability, allows to use them for production of the dialyzing membranes in the device for hemodialysis (see), haemo filterings (see), to an artificial kidney (see). In the capillary artificial kidney having the big dialyzing surface as capillary fibers apply one of P. of m — cellulose triacetate. Separate P. m, napr, a Dacron, polytetrafluoroethylene, silikonirovanny rubber, use for the production of arteriovenous shunts of Skribner and vascular prostheses suitable for carrying out a long hemodialysis. At plastic surgeries on bodies of urinogenital system P. of m apply to substitution of defects of hollow bodies, soft tissues, and also as cosmetic prostheses. So, at a stricture of an ureter on a considerable extent for its substitution implant silikonirovanny prostheses (fig. 3) with cuffs from velor on the ends that facilitates imposing of the fixing seams; sometimes they have the anti-reflux valve on the vesical end. At substitution of defects of soft tissues of a front abdominal wall after the Urals, operations, including concerning inborn malformations (e.g., at an ekstrofiya of a bladder), use kapron or nylon grids. Use of tsianakrilatny glue for seamless compound of tissue of kidney or for a hemostasis after a nephrectomy is perspective. Items of m use at to a phalloplasty (see); at operations on an occasion impotences (see) instead of cartilaginous autografts enter perforated (stronger) polyethylene prostheses. In the absence of testicles with the Cosmetic purpose implant prostheses from plexiglass or silicone gel.

Stomatology. On the physicomechanical properties P. the m applied in stomatology shall approach firm and soft tissues of an oral cavity, be painted in the colors imitating natural color of teeth and soft tissues, to have small specific weight, to be rather strong, to have the minimum water repellency, not to change initial outward, durability and other fizikomekhanichesky indicators under the influence of the environment of an oral cavity, and also not to make the irritating and other negative impact on surrounding body tissues. Simplicity of the production technology of polymers is necessary to provide individual production of dentures with use of the simple equipment and plaster molds, simplicity of manipulations with these materials in the conditions of daily therapeutic activity.

The domestic and foreign medical industry releases stomatol. products, for production to-rykh are used the following polymers: acrylates of cold and hot hardening (polimermonomerny compositions of polymethyl methacrylate), copolymers, methylmethacrylates with other monomers of acrylic group, and also about vinyl acetate, fluoroelastomer, polyvinylchloride and copolymers of vinyl chloride about butyl acryle atom, silicone rubbers of hot and cold vulcanization, pentasulphides, cellulose derivatives, synthetic wax, thermolayers, etc.

According to the destination the polymers applied in stomatology are divided into the following groups: materials for therapeutic stomatology — sealing materials (see); sealants — materials for sealing of chewing surfaces of teeth for the purpose of prevention of caries; polymeric basis of physiologically active materials for treatment and prevention of caries of teeth, and also for treatment of diseases of a mucous membrane of an oral cavity and paradontosis; varnishes (see. Lucky, in stomatology ) for temporary protection of seals; polymeric materials for orthopedic stomatology — basic materials, including elastic materials for soft linings to bases of dentures; false teeth; materials for crowns and bridge-like dentures (see). Also supporting materials — modeling belong to the materials applied in orthopedic stomatology, slepochny materials (see), dividing varnishes; The Item of m for a plastic surgery of the person — materials for endoprosthesis replacement (implants); materials for ektoprotez of the person. As a basis of sealing materials acrylates and epoxyacrylates, and also difficult connections with addition of a significant amount of a finely dispersed silikonizirovanny filler are applied. Acrylates are a basis of basic materials, materials for repairs and relocation of dentures, false teeth, bridge-like prostheses. Silicones of cold vulcanization use as slepochny materials and materials for elastic linings, and silicones of hot cure are a basis of implants for elimination of defects and deformations of the person. On the basis of cellulose derivatives produce materials for bandages on a mucous membrane of an oral cavity, kariyesprofilaktichesky gels, and also some slepochny materials.

Ophthalmology, the Main ranges of application of polymers in ophthalmology are prosthetics of an eye,-point and contact correction, medicinal therapy, including use of physiologically active polymers, proteins, synthetic analogs of nucleotides, the ophthalmologic equipment. Widely use the polymeric suture and dressing materials, drainages etc. of P. of m applied in ophthalmology except usual medical requirements, in some cases shall have transparency and wettability.

In reconstructive ophthalmology the greatest distribution was found by polymers from acrylate — polymethyl methacrylate of the ST-1 brand, dakril-4B, etc. They are used for production artificial crystalline lens (see), keratoprotez (see. Keratoprotezirovaniye ), prostheses of an eyeglobe (see. Prosthesis eye ), and also corneal and scleral rigid contact lenses (see), points (see) etc. Silicone rubbers apply at treatment of amotio of a retina, to production of an artificial vitreous, intraocular lenses, kislorodopronitsayemy soft contact lenses. The water bulking up polymers on a basis gomo-and copolymers of monomethacrylate, ethylene glycol, and other similar monomers use N-vinyl-pirrolidona for production of soft contact lenses. A wedge, researches showed that thanks to good optical properties and high biocompatibility hydrogels are also perspective class P. of m for eye endoprosthesis replacement.

Water soluble polymers find application for preparation of eye emulsions, suspensions, drops which, as a rule, possess the prolonged action. In the USSR water-soluble cellulose derivatives, polyethyleneglycol and some other polymers, and also eye medicinal films of the prolonged action are recommended to pharmakol, to use (see. Medicinal films ).

See also High-molecular compounds .

Tables

Table 1. SOME RESEARCHES of BIOLOGICAL ACTIVITY of CONSTRUCTION POLYMERIC MATERIALS IN MODELIROVANNY CONDITIONS (according to A. N. Bokov, 1977)


Table 2. PURPOSE of SOME POLYMERS IN MEDICAL PRACTICE




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T. T. Daurova; A. H. Sides, E. V. Turbin (gigabyte.), D. M. Karalnik, I. Ya. Poyurov-skaya (ostomies.), Yu. E. Kirsch (biochemical), N. A. Lopatkin, L. G. Kulga (Urals.), S. G. Starodubtsev (oft.).

Яндекс.Метрика