RU2834812C1 - Method of making a removable dental prosthesis based on cold-curing ethyl methacrylate - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, particularly to orthopaedic dentistry, and can be used for making dental prostheses based on cold-setting ethyl methacrylate. Method involves preparation of a plaster model and elements of the prosthesis in wax, moulding into a cuvette by filling the cuvette with a silicone mass for duplication, followed by its cooling. Plaster model and the wax workpiece with teeth are removed, which are cleaned of wax. Plaster model is covered with gypsum insulation from the basic plastic, the prosthesis elements are installed in accordance with their imprints and the cuvette is assembled. Base plastic is poured into the cuvette through the extreme hole with the cuvette positioned vertically with the side holes upwards. Polymerisation is carried out, the prosthesis and the plaster model are removed from the polymeriser, followed by the final treatment of the prosthesis, wherein three upper holes and a middle lateral hole are closed in the cuvette. Two wax casting sprues are fitted to the prosthesis wax composition to be placed in the open side openings of the cuvette; after the silicone hardens, the sprues are removed. Sprues are removed and the prosthesis is polished. Polymerisation is carried out for 35 minutes. To fill the base plastic into the cuvette, plastic is used which is prepared by mixing in a ratio of polymer to monomer by weight of 3:1 at room temperature in a glass vessel without maintaining the aging time of the base plastic. Basic plastic is introduced into the cuvette under pressure with tip 5 cm long and 5 mm in diameter. Polymerisation is carried out at temperature of 65 °C and pressure of 5.0 atm.

EFFECT: creating a smooth surface and a homogeneous structure of the prosthesis, which prevents inflammatory and allergic reactions of the body during use, which reduces the length of adaptation to the prosthesis.

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Description

The invention relates to medicine, in particular to orthopedic dentistry, and can be used for the manufacture of dental prostheses based on cold-curing ethyl methacrylate.

A pressing technical problem in modern dentistry is the search for solutions to improve the properties of the base material of dentures made from polymer structural systems, which have many advantages over other materials and are therefore in high demand. At the same time, a negative aspect in their use is the residual monomers released from the target products, which have a local and general effect on the body, causing inflammatory changes in the mucous membrane of the tissues of the denture bed and various allergic reactions of the body, which is noted in numerous sources [Poyurovskaya I.Ya., 2007 (2008), 192 p.; Lebedenko I.Yu., Kalivradzhiyan E.S., 2011. - 640 p.]. In this regard, the main task of manufacturing denture bases based on polymethyl methacrylate is to minimize the content of toxic residual monomers using a simple and accessible method in practice while maintaining other important technical characteristics of the product within acceptable limits. The objective of the proposed invention is to expand the range of methods for manufacturing removable dentures using the technique of casting plastic based on cold-curing ethyl methacrylate.

There are many methods for manufacturing removable dentures. Known is patent RU No. 2557133 (published 20.07.2015), which describes a method for manufacturing a partial removable nylon denture with gingival clasps. The invention relates to the field of medicine, namely to orthopedic dentistry, and can be used to improve the effectiveness of orthopedic treatment of patients with partial tooth loss when using nylon dentures. At the stage of preparing the plaster model for duplication in the area of the supporting teeth, at the gingival margin, a plate of base wax, 1.8-2 mm thick, is laid so that it adjoins the cervical part of the tooth and the alveolar part of the jaw, respectively, the boundaries of the clasp. Its surface is modeled and a smooth bevel is created from the cervical part of the tooth towards the mucous membrane, forming the greatest thickness of the plate in the area of the cervical part of the tooth and gradually reducing it to "nothing" along the alveolar part of the jaw. The method, due to the formation of free space under the gingival clasp, allows preventing injury to the mucous membrane of the gum in the area of the supporting tooth, reducing the adaptation period and creating more comfortable conditions for using the prosthesis.

The disadvantage of this method is that if a prosthesis made of nylon-based material breaks, there is no possibility of repair or relining.

A common method for manufacturing removable dentures using traditional technology with an acrylic base is compression pressing, when the mass at the dough stage, consisting of a polymer and a monomer, is placed in a pre-prepared plaster mold in a cuvette and is subjected to pressure together with it. This is followed by polymerization in a water bath. The cuvette is placed in water at room temperature and slowly brought to a temperature of 95-98 degrees over an hour, and held for 30 minutes, and only after the water has completely cooled (about 1 hour) is the cuvette taken out, disassembled and the resulting prosthesis is removed. The process of manufacturing a removable denture using the proposed method takes more than 3 hours in total. The advantage of this method is that it does not require expensive equipment [Kalivradzhiyan, E.S. Dental Materials Science: Textbook / Kalivradzhiyan E.S. [et al.]. - Moscow: GEOTAR-Media, 2019. - 560 p.].

The disadvantage of this method is the long time required to manufacture the prosthesis, which is more than 3 hours, as well as the manufacture of prostheses from base materials that are precursors. Precursor materials are base materials containing more than 15% methyl acrylate and methyl methacrylate in the monomer; these substances are included in Table II of List IV of the list of narcotic drugs, psychotropic substances and their precursors [RF Government Resolution No. 681].

Known is patent RU No. 2721581 (published 05/20/2020), the closest to the proposed one in terms of the set of features, which describes a method for manufacturing a removable denture. The invention relates to medicine, in particular to orthopedic dentistry, and can be used to manufacture dentures based on ethyl methacrylate. The method for manufacturing a removable denture based on ethyl methacrylate includes preparing a plaster model, prosthesis elements and a prosthesis in wax, molding in a 1.0 SHARK cuvette included in the polymerizer of the Aveyron company, by filling the cuvette with a silicone mass for duplicating with its subsequent cooling, after which the cuvette is disassembled, the plaster model and the wax blank with teeth are removed, which are cleaned of wax. Then the plaster model is covered with plaster insulation from the plastic, the prosthesis elements are installed back in accordance with their prints and the cuvette is reassembled, the base plastic is poured into the cuvette through any of the extreme openings with the cuvette positioned vertically with the side openings upward until the plastic begins to flow out of the opposite opening, it is placed in a container for polymerization, polymerization is carried out in an Aveyron polymerizer for 30 minutes, the prosthesis and the plaster model are removed. After that, the final processing of the prosthesis is carried out. In this case, the three upper openings and the middle side opening are closed in the cuvette. Two 3 mm thick casting sprues are preliminarily installed to the wax composition of the prosthesis with the possibility of their placement in the side openings of the cuvette left open. After the silicone has hardened, the sprues are removed. Moreover, for pouring the base plastic into the cuvette, Belakril-EGO plastic is used, prepared by mixing in a polymer and monomer weight ratio of 5:3 at room temperature. The plastic is introduced into the cuvette under pressure by introducing a tip 3 cm long and 3 mm in diameter, equal to the diameter of the said casting channels, into any of the extreme lateral casting channels formed after removing the sprues. Polymerization is carried out at a temperature of 110°C and a pressure of 4.5 atm. Processing of the prosthesis includes only removing the plastic sprues and polishing according to the standard method. The technical result is to obtain a prosthesis based on ethyl methacrylate with a smooth surface and a uniform structure, which prevents the occurrence of inflammatory and allergic reactions of the body during the use of the prosthesis, and also facilitates hygienic care of the prosthesis. An additional technical result is a reduction in the content of residual monomer compared to known methods for producing prostheses from ethyl methacrylate-based plastics.

The disadvantage of the closest analogue is that the method is intended only for the use of hot polymerization plastics, so it is impossible to obtain a prosthesis based on cold-curing ethyl methacrylate using this method.

The objective of the proposed invention is to use a method for manufacturing a removable dental prosthesis based on cold-curing ethyl methacrylate with a smooth surface and a uniform structure in order to prevent the occurrence of inflammatory and allergic reactions of the body during the use of the prosthesis, which in turn reduces the adaptation period to the prosthesis, and the proposed method allows for the manufacture of a removable dental prosthesis with a reduced content of residual monomer compared to known methods for manufacturing prostheses from plastics based on cold-curing ethyl methacrylate, the possibility of using the proposed method for repairing removable prostheses and orthodontic appliances.

The technical result of the proposed invention consists in creating a method for manufacturing a removable dental prosthesis based on cold-curing ethyl methacrylate with a smooth surface and a uniform structure, the use of which prevents the occurrence of inflammatory and allergic reactions of the body, which in turn reduces the period of adaptation to the prosthesis, and the proposed method allows for the manufacture of a removable dental prosthesis with a reduced content of residual monomer compared to known methods for manufacturing prostheses from plastics based on cold-curing ethyl methacrylate, the possibility of using the proposed method for repairing removable prostheses and orthodontic appliances.

The proposed method for manufacturing a removable denture based on cold ethyl methacrylate is carried out as follows:

- prepare a plaster model and prosthesis elements in wax;

- the prosthesis is formed in a 2.0 SHARK cuvette, which is part of the Aveyron polymerizer, by filling the cuvette with silicone mass for duplication, after which the silicone mass is cooled;

- polymerization is carried out in the Aveyron polymerizer for 35 minutes;

- disassemble the cuvette, remove the plaster model and wax blank with teeth, which are cleaned of wax;

- the plaster model is covered with insulation of the plaster from the base plastic;

- the prosthesis elements are installed back in accordance with their imprints and the cuvette is reassembled;

- pour the base plastic into the cuvette through any of the extreme openings with the cuvette positioned vertically with the side openings facing up until the base plastic begins to flow out of the opposite opening;

- for pouring the base plastic into the cuvette, use the plastic "Belakril ethyl methacrylate cold curing", which is mixed in a polymer to monomer ratio by weight of 3:1 at room temperature in a glass vessel, do not maintain the curing time of the base plastic, introduce the base plastic into the cuvette under pressure by inserting into any of the extreme side casting channels formed after removing the sprues, a tip 5 cm long and 5 mm in diameter, equal to the diameter of the specified casting channels;

- placed in a container for polymerization;

- polymerization is carried out in an Aveyron polymerizer at a temperature of 65°C and a pressure of 5.0 atm.;

- remove the prosthesis and plaster model from the polymerizer;

- carry out the final processing of the prosthesis: in the cuvette, the three upper holes and the middle side hole are closed, two sprues made of casting wax are first installed to the wax composition of the prosthesis with the possibility of their placement in the side holes of the cuvette left open, after the silicone has hardened, the sprues are removed and polished using the standard method.

The advantages of the proposed method are as follows: the method of manufacturing a prosthesis based on cold-curing ethyl methacrylate ensures a smooth surface and a uniform structure of the prosthesis, which allows for a reduction in the time for final processing of the prosthesis surface by eliminating grinding. At the same time, the content of free monomer is significantly reduced and, as a consequence, the pronounced reactivity of the tissues of the prosthetic bed is less pronounced compared to the traditional method of manufacturing plastic prostheses based on cold-curing ethyl methacrylate.

Example of implementation of the invention:

Patient F. complained of discomfort in the oral cavity while using a prosthesis, which also did not satisfy her aesthetically. The indication for the use of the method of manufacturing a prosthesis based on cold-curing ethyl methacrylate by patient F. was the wear of the existing prosthesis and partial absence of teeth.

After checking the placement of the patient F.'s teeth, a plaster model and elements of the prosthesis in wax were prepared. Two 5 mm thick casting sprues are installed on the wax composition of the prosthesis and placed in a special SHARK 2.0 cuvette from Aveyron.

Then the cuvette was filled with silicone mass for duplicating models Siloff Medium 22 (KrasTekhnoMed, Russia). The duplicating silicone was poured into the cuvette on a vibrating table in a thin stream, which ensured the release of possible air bubbles from the duplicating mass. The silicone was cured at room temperature for 20 minutes.

After the silicone had hardened, the cuvette was disassembled, the plaster model with the wax composition of the prosthesis was removed, and the sprues were removed. After that, steam-jet treatment was carried out to remove wax residues, the prepared teeth were dried and placed in the silicone mass in accordance with their prints, and then the cuvette was assembled.

Then the base plastic "Belakril-E XO" (cold-curing ethyl methacrylate) was mixed in a ratio of 15.0 grams of polymer and 5.0 grams of monomer for 1 minute at a temperature of 23°C, taking into account that an increase in the room temperature requires a reduction in the mixing time. The finished mixture was immediately poured into a twenty-cubic-meter syringe with a 5-cm-long tip and an external diameter of 5 mm, equal to the diameter of the removed sprue, the base plastic was introduced into the cuvette under piston pressure through one of the extreme casting channels in the silicone mass formed after removing the sprues until it began to flow out of the opposite hole, so as not to create an air lock. The cuvette was held strictly vertically, with the side holes facing up. Excess base plastic was removed from the surface of the cuvette. The cuvette was installed in the loading basket, which is included in the PMA 3 "Averon" polymerizer kit. The filled cuvette was placed in the "Averon" polymerizer, and the following polymerization mode was set: temperature 65°C, pressure 5.0 atm., time 35 minutes.

The cuvette was then disassembled and the prosthesis was removed. After this, the prosthesis was finally processed by removing the plastic sprues and polished using the standard method and installed in patient F.

Claims (1)

A method for producing a removable denture based on cold-curing ethyl methacrylate, comprising preparing a plaster model and denture elements in wax, molding into a flask entering a polymerizer by filling the flask with a silicone mass for duplicating, followed by cooling it, disassembling the flask, removing the plaster model and wax blank with teeth, which are cleaned of wax, covering the plaster model with insulation from the base plastic, installing the denture elements back in accordance with their prints and reassembling the flask, pouring the base plastic into the flask through the outer opening with the flask positioned vertically with the side openings upward until the base plastic begins to flow out of the opposite opening, placing it in a container for polymerization, polymerizing in the polymerizer, removing the denture and plaster model from the polymerizer, after which final processing of the denture is carried out, while in the three upper openings and the middle side opening in the cuvette are closed, two wax sprues for casting are preliminarily installed to the wax composition of the prosthesis with the possibility of placing them in the open side openings of the cuvette, after the silicone has hardened, the sprues are removed, while the processing of the prosthesis consists of removing the plastic sprues and polishing, characterized in that the polymerization in the polymerizer is carried out for 35 minutes, and for pouring the base plastic into the cuvette, cold-curing ethyl methacrylate is used, prepared by mixing in a polymer to monomer ratio by weight of 3:1 at room temperature in a glass vessel, without maintaining the maturation time of the base plastic, while the introduction of the base plastic into the cuvette is carried out under pressure by introducing into the extreme side casting channel formed after removing the sprues, a tip 5 cm long and 5 mm in diameter, equal to the diameter of the said casting channels, and the polymerization is carried out at a temperature of 65 ° C and a pressure 5.0 atm.