RU2791989C1 - Removable plate denture with reinforced basis - Google Patents

Abstract

FIELD: medical equipment.

SUBSTANCE: invention can be used to improve the strength (reinforcement) of the polymer bases of removable laminar dentures, which are used to replace the complete absence of teeth in the upper jaw. Removable plate denture with a reinforced base has a three-layer base and artificial teeth in its design. The first - inner and third - outer layers of the basis have a thickness of 0.5 mm and are made of polymethyl methacrylate. The second - the intermediate layer has a thickness of 1 mm and is a reinforcing mesh, congruent to the prosthetic bed, the mesh made of dental polymer and manufactured by 3D printing. The boundaries of the mesh are 5 mm away from the boundaries of the basis layer of the removable laminar prosthesis adjacent to the tissues of the prosthetic bed along the entire perimeter. There are mesh stoppers on the surface of the mesh facing the prosthetic bed. The stoppers are made in the form of truncated inverse cones 0.5 mm high with a base section of 2 mm and a truncated top of 1 mm. Stoppers are located along the perimeter of the mesh 2 mm away from the outer borders of the mesh, at a distance of 10 mm from each other and 5 mm away on the left and right from the median line of the hard palate. Over the entire surface of the mesh, there are perforations 2 mm in diameter between the stoppers and along the top of the alveolar process of the upper jaw. The three-layer base is mated with artificial teeth by means of a basis polymer.

EFFECT: production of a removable laminar denture with a base reinforced with a mesh fabricated as per economically available 3D printing technology from a structural polymer material selected according to its physical and mechanical characteristics, which, in terms of strength, can adequately withstand multidirectional static and cyclic functional loads of the dentoalveolar apparatus of a particular patient.

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Description

The invention relates to medicine, namely to orthopedic dentistry, and is intended to enhance the strength (reinforcement) of the polymer bases of removable lamellar dentures used to replace the complete absence of teeth in the upper jaw.

Under the influence of functional loads, the outer surface of the removable denture base experiences tensile, and the inner surface compresses the most dangerous stresses, which often lead to structural failure. In addition, in the design of a removable plate prosthesis, along the edge of the base of the prosthesis, there are cutouts in the form of triangles on its anterior (vestibular) surface, which bypass the frenulum of the lips of the upper and lower jaws and the buccal cords of the transitional fold in order to avoid their injury and the formation of bedsores, as well as displacement and dropping of the structure from the prosthetic bed. From the point of view of the theory of cracks, such corner cuts are the centers of potential crack formation, which lead to the failure of the base and the destruction of the entire structure.

In this regard, additional reinforcement (strengthening) of the base of the prosthesis is a necessity in order to prolong the durability of the design of polymer removable lamellar dentures.

The use of a reinforcing mesh helps to strengthen the base of a removable plate prosthesis, prevent breakages of the base and the necessary labor costs for repair and reconstructive work, as well as considerable economic losses for both the patient and the clinic, which are so frequent in practical dentistry. This approach makes it possible to prolong the effective use of polymer removable plate dentures, to prevent the achievement of cracks of critical dimensions and the destruction of the prosthesis structure.

The strength and stability of complete removable dentures is one of the most difficult problems. The durability of such dentures depends on the clinical conditions, the technology of their manufacture, and on the physical and mechanical properties of the base plastics. Most widely in the practice of orthopedic dentistry, acrylic plastics are used for the manufacture of complete removable dentures, due to their high technological and aesthetic properties. But they do not satisfy specialists in terms of strength indicators, because breakage of such prosthetic structures is often observed. In this regard, methods for reinforcing the bases of removable dentures are proposed.

Known methods of hardening plastic bases of removable lamellar dentures with metal bases, as well as metal standard or custom-made meshes. However, along with the advantages of mechanical strengthening of removable denture bases, metal meshes have a number of disadvantages: they do not chemically combine with polymers, they shine through the thickness of the plastic, and they are potentially susceptible to corrosion. Daily cyclic loads, which are subject to the design of removable dentures during the functioning of the dentoalveolar apparatus, contribute to the delamination of the metal-polymer connection, the initiation and development of cracks, leading to breakage of the base. In the areas of delamination and crack initiation, hygienic measures are complicated, and favorable conditions are formed for the growth of a microbial biofilm (microbiota), the waste products of which change the color of the polymer and worsen the cosmetic characteristics of the prosthesis. The combination of these problems leads to the need for repair work, and often to the manufacture of a new removable lamellar denture.

An alternative solution for choosing a metal mesh is the use of a quartz mesh QUARTZ SPLINT™MESH (R.T.D., France), specially designed to reinforce the bases of acrylic prostheses by chemically bonding with a polymer due to industrial impregnation with a special binder based on methacrylate resin, which provides a chemical bond with acrylic base plastic due to the closeness of the modulus of elasticity of the quartz mesh and the base acrylic material. Impregnation prevents the formation of bubbles and voids inside the base, prevents peeling and the occurrence of microcracks, which ensures a positive long-term result of reinforcement. The technological properties of the quartz mesh allow you to individually select the required size according to the parameters of the jaw [Karaseva V.V. Experience of using a reinforcing quartz mesh for orthopedic rehabilitation of a patient with microstomy / Problems of Dentistry. - 2014. - No. 4. pp. 45-47; Karaseva V.V. Prevention of frequent fractures of plate prostheses by using a quartz mesh. / Problems of Dentistry 2014, No. 5, S. 41-44].

A known method of reinforcing the base of a removable lamellar denture with a mesh woven from aramid threads NSVI 29.4, plain weaving with cells of 1.0 mm, folded in two layers at an angle of 45 degrees and impregnated with modifying compositions. The composition is a solution of the universal BIS-GMA binder in methyl methacrylate (MMA), which contains the polymerization initiator - benzoyl peroxide (PB) - in the following ratios: 80% of the mass - BIS-GMA, 19% of the mass - MMA, 1% of the mass - PB [Gryazeva N.A. Improving the physical and mechanical properties of the bases of removable lamellar dentures by introducing high-modulus aramid threads: thesis .... Candidate of Medical Sciences: 14.00.21 / Gryazeva Natalya Anatolyevna; [Place of protection: TsNIIS]. - M., 2004. - 72 s].

However, the metal and quartz mesh cannot be set at a given level in the thickness of the base of the lamellar prosthesis, and the formation of foci of deformation and stress in the base of the structure depends on this.

In the prior art, a method for manufacturing a complete removable denture is known, which is carried out as follows. After taking an impression, casting the models, modeling the wax base and determining the central occlusion, casting into the articulator or occluder, holes are drilled on the model using a parallelometer with a bur of the appropriate size to insert at least 3 pins having a conical shape in the upper part. As pins, cut pins are used for the manufacture of collapsible models in the manufacture of metal-ceramic crowns. Pins are installed using a parallelometer, fixed with Sekunda glue or another. The model is crimped with a plate of clasp wax. Above it, in the middle of the alveolar ridge, an arcuate reinforcement 5-6 mm wide is modeled, in which holes are made. Cast fittings are installed on pins, a wax base is modeled and artificial teeth are installed. Due to the conical shape of the protruding parts of the pins, the fittings are easily put on and removed from them, and also fixed at a given distance from the model. During the replacement of the wax reproduction of the base with the plastic one, the plastic dough batch is applied in two portions. The first portion is applied, after which reinforcement is applied to the pins, and then the second portion of the dough is applied. The polymerization of the reinforced plastic base is carried out according to the manufacturer's instructions. After polymerization, the prosthesis can be easily removed from the model due to the parallelism and cone-like pins. The recesses formed are filled with plastic, which tends to self-harden [Utility Model Patent No. UA 27345 U].

However, the known methods of reinforcing the base of a removable plate prosthesis combine common disadvantages, in particular, the need to cut out the geometry of the prosthetic bed and adapt the cut workpiece to the shape of the arch of the upper jaw or part of the alveolar process of the lower jaw, the impossibility of locating the mesh in the thickness of the base at a given level (in the middle of the thickness , or closer to the outer or inner surfaces, depending on the design tasks), the displacement of the reinforcing elements in the process of investing and pressing the plastic polymer dough, which leads to a deterioration in the strength of the removable lamellar denture, economic losses that are associated with waste after cutting the workpiece.

The objective of the solution to which the invention is directed is the manufacture of a removable plate denture with increased strength characteristics, the design features of which are due to the individual characteristics of the anatomy of the tissues of the patient's prosthetic bed.

The technical result of the invention is the manufacture of a removable lamellar denture with a base reinforced with a mesh made using an economically available 3D printing technology from a structural polymer material selected for physical and mechanical characteristics that, in terms of strength, can adequately withstand multidirectional static and cyclic functional loads of the dentoalveolar apparatus of a particular patient.

The technical result of the invention is achieved due to the fact that a removable plate denture with a reinforced base has a three-layer base and artificial teeth in its design, while the first (inner) and third (outer) layers of the base have a thickness of 0.5 mm and are made from polymethyl mateacrylate, and the second (intermediate) layer has a thickness of 1 mm and is a reinforcing mesh congruent prosthetic bed, made of dental polymer and manufactured by 3D printing, while the boundaries of the mesh are spaced from the boundaries of the base layer of the removable laminar prosthesis adjacent to the tissues of the prosthetic bed by 5 mm around the entire perimeter, and on the surface of the mesh facing the prosthetic bed, there are stoppers in the form of a truncated inverse cone 0.5 mm high, with a base of 2 mm and a truncated top of 1 mm, located along the perimeter of the mesh, departing from outer borders of the grid by 2 mm, at a distance of 10 mm from each other and along the median line of the hard palate, departing from e by 5 mm on the left and right, while on the entire surface of the mesh there are perforations with a diameter of 2 mm in the intervals between the stoppers and along the top of the alveolar process of the upper jaw, while the three-layer base is associated with artificial teeth by means of a base polymer.

The proposed reinforcing mesh, 1 mm thick and with stoppers 0.5 mm high, is located at the level specified by the dentist and dental technician in the thickness of the base of the removable plate prosthesis, increases the durability of the removable denture structure with complete loss of teeth in the upper jaw, reduces the number of patient visits clinics, due to the prevention of breakage of prosthesis bases, significantly reduces the cost of base reinforcement technology in comparison with known analogues that require cutting a workpiece from a factory-made piece of metal or quartz mesh. Quartz mesh, the best of the reinforcing meshes used in dental practice, as it is processed with a primer-bonding system and adapts better than others to the complex configuration of the hard palate surface, but it cannot be placed in the thickness of the base of a removable lamellar denture at the level specified by the dentist.

The digital transformation of the analog technology for the reinforcement of removable denture bases makes it possible to create a printed grid of specified parameters that is congruent in the shape of the hard palate surface, to evenly position the grid in the thickness of the base exactly at a given level, which contributes to an adequate perception of static and dynamic loads, long-term use of the prosthesis design, and easy correction when necessary, due to the homogeneity of the chemical nature of the polymer reinforcing mesh and the base, without fear of the mesh being exposed during correction by grinding the prosthesis, as is the case when the mesh is metal or quartz.

The design of a removable plate denture with a reinforced base is illustrated by the drawing, where in Fig. 1:

1. Printed mesh, for reinforcing the base of a removable plate denture.

2. Perforations in the mesh to reinforce the base.

3. Stoppers to hold the mesh at a given level in the thickness of the base of the removable plate prosthesis.

In FIG. 2:

1. Printed mesh, for reinforcing the base of a removable plate denture.

2. Perforations in the mesh to reinforce the base.

3. The projection of the stoppers to hold the mesh at a given level in the thickness of the base of the removable plate prosthesis.

4. Three-layer basis of a removable denture.

5. Artificial dentition.

The proposed removable plate denture with a reinforced base is made as follows:

1) take impressions of the patient's jaws with silicone dental masses, on which working plaster models are made and transferred to the dental laboratory;

2) in the laboratory, on working plaster models of the upper and lower jaws, bite patterns with wax occlusal rollers are made, which are transferred to the clinic;

3) in the clinic, using bite patterns with wax occlusal rollers, the position of the lower jaw, the height of the lower face and the ratio of the patient's jaws are determined and recorded;

4) plaster models and the prepared bite register are scanned with a laboratory dental scanner, obtaining virtual models of the jaws oriented in space by means of a register that conveys a certain position of the patient's lower jaw, the height of the lower face and the ratio of the patient's jaws.

5) the virtual composition of the register with the virtual models of the jaws associated with it is installed in the interframe space of the virtual articulator.

6) on a virtual model of the jaw in a program for modeling dentures, the first (inner) layer of the base (4) of the future prosthesis is 0.5 mm thick, the boundaries of which correspond to the boundaries of the tissues of the prosthetic bed.

7) on top of the inner layer of the virtual base (4), congruent to the prosthetic bed, a reinforcing mesh (1) is modeled, while the boundaries of the mesh (1) are 5 mm away from the boundaries of the base (4) of the removable plate prosthesis along the entire perimeter, and on the surface mesh facing the prosthetic bed, stoppers (3) are modeled in the form of a truncated inverse cone 0.5 mm high, with a base of 2 mm and a truncated top of 1 mm, located along the perimeter of the mesh (1), retreating from the outer boundaries of the mesh by 2 mm , at a distance of 10 mm from each other and along the median line of the hard palate, departing from it by 5 mm to the left and right.

8) perforations (2) with a diameter of 2 mm are formed over the entire surface of the virtual mesh model (1) in the spaces between the stoppers (3) and along the top of the alveolar process of the upper jaw.

9) on top of the virtual grid, the outer layer of the base (4) of the removable denture border is modeled, which, along the perimeter, are connected to the boundaries of the inner layer of the future base (4) and correspond to the boundaries of the tissues of the prosthetic bed;

10) on the obtained virtual model of the base (4) consisting of two layers and a virtual reinforcing mesh (1) located between them, artificial teeth (5) are set according to the individual parameters of the anatomical and topographic features of the prosthetic bed and field, as well as the aesthetics of the face;

11) the resulting virtual model of a removable plate prosthesis is analyzed in the CAE module of the program for mathematical analysis of the behavior of the structure for possible risks of breakage under cyclic and static loads, in the event of which, the topography of the perforations (2) of the virtual model of the reinforcing mesh (1) is changed until normalization of stress diagrams in the basis of the prosthesis (4).

12) a virtual model of the reinforcing mesh (1) is converted into a physical one by means of 3D printing of a dental polymer with physical and mechanical characteristics higher than the strength characteristics of the base material used in the technology for the production of removable lamellar dentures.

13) on the working plaster model, wax 0.5 mm thick is placed and adapted to the prosthetic bed in shape and within the boundaries of the base (4) of the removable plate prosthesis.

14) a polymer reinforcing mesh (1) (intermediate base layer) (4) is applied over the formed first (inner) layer of the wax base, pressing it until it stops (contact) with the stoppers (3) with the plaster surface of the working model.

15), then the mesh (1) is covered with a second (outer) wax plate 0.5 mm thick, which is monolithically connected to the first wax plate of the basis along the boundaries of the prosthetic bed.

16) then carry out the setting of artificial teeth (5) in the articulator.

17) a wax model of a removable denture, reinforced with a polymer mesh (1) with artificial teeth (5), is packed into a cuvette and transferred to plastic according to the classical technology.

18) the resulting denture is processed from excess plastic, ground, polished and transferred to the clinic.

Clinical example No. 1.

A patient came to the clinic with complaints of missing teeth in the upper jaw. The patient received impressions of the jaws with silicone dental masses, and made plaster models. Using a bite template with occlusal ridges, the position of the lower jaw, the height of the lower face, and the ratio of the patient's jaws were recorded. Plaster models of the jaws and registers were scanned with a laboratory dental scanner. Virtual models of the jaws, oriented by the registrant in space, were installed in a virtual articulator.

On a virtual model of the upper jaw in the program for modeling dentures (ExoCad, ExoCad GMBH, Darmstadt, Germany), the inner (first) layer of the base of the future prosthesis 0.5 mm thick was modeled, the boundaries of which correspond to the boundaries of the tissues of the prosthetic bed. On top of the virtual inner (first) layer of the base, congruent to the prosthetic bed, a reinforcing mesh 1 mm thick was modeled, while the mesh boundaries were 5 mm away from the boundaries of the removable plate prosthesis base along the entire perimeter, and stoppers were modeled on the surface of the mesh facing the prosthetic bed. in the form of a truncated inverse cone 0.5 mm high, with a base with a cross section of 2 mm and a truncated apex of -1 mm, located along the perimeter of the mesh, retreating from the outer borders of the mesh by 2 mm, at a distance of 10 mm from each other and along the midline of the solid the sky departing from it by 5 mm to the left and to the right. Perforations 2 mm in diameter were formed over the entire surface of the virtual mesh model in the spaces between the stoppers and along the apex of the alveolar process of the upper jaw.

On top of the virtual mesh model (the second layer of the base), the outer surface of the base (the third layer) of a removable lamellar denture was modeled, so that the perimeter boundaries were connected to the boundaries of the inner layer of the virtually formed base until they corresponded to the boundaries of the tissues of the prosthetic bed. On the obtained virtual model of the base, consisting of the inner (first) layer and the outer (third) layer, as well as the virtual reinforcing mesh (second) layer located between them, artificial teeth were set according to the individual characteristics of the anatomical and topographic features of the prosthetic bed and field, and as well as the aesthetics of the patient's face. The resulting virtual model of a removable lamellar denture was analyzed in the CAE module of a mathematical modeling program (SolidWorks, SolidWorks Corporation, manufacturer Dassault Systemes, France) for possible risks and breakages under cyclic and static loads. The virtual model of the reinforcing mesh was converted into a physical one by 3D printing (NextDent 5100, 3D Systems, South Carolina, USA) from a dental polymer (NextDent Ortho Rigid). On a gypsum wax model 0.5 mm thick, the basis of a removable plate prosthesis was modeled. A printed polymeric reinforcing mesh was applied on top of the wax base and fixed in the thickness of the wax until the stoppers touched the plaster surface of the prosthetic bed. A wax plate 0.5 mm thick was placed over the grid, the borders of which, along the perimeter, were connected to the boundaries of the first wax plate of the basis along the boundaries of the tissues of the prosthetic bed. Carried out the setting of artificial teeth in the articulator. A wax model of a removable denture, reinforced with a polymer mesh with artificial teeth, was packed into a cuvette and transferred to plastic according to the classical technology. The resulting denture was ground, polished and transferred to the clinic.

Clinical example No. 2.

A patient came to the clinic with complaints of complete loss of teeth in the upper jaw. After receiving impressions of both jaws with dental silicone masses, working plaster models were made, and bite patterns with wax occlusal rollers were made according to them, through which the position of the lower jaw, the ratio of the jaws and the height of the lower face were recorded. Plaster models of the jaws were set in the registered ratio using bite templates with wax occlusal rollers and then plastered into the articulator. An articulator with plaster models fixed in a predetermined position was scanned using a laboratory dental scanner, obtaining a virtual composition - jaw models oriented in space in accordance with the previously determined position of the patient's lower jaw and interalveolar height.

On a virtual model of the upper jaw in the program for modeling dentures (ExoCad, ExoCad GMBH, Darmstadt, Germany), the first layer of the base of the future prosthesis 0.5 mm thick was modeled, the boundaries of which correspond to the boundaries of the tissues of the prosthetic bed. On top of the virtual base, congruent to the prosthetic bed, a reinforcing mesh was modeled, while the boundaries of the mesh were 5 mm away from the boundaries of the base of the removable plate prosthesis along the entire perimeter, and on the surface of the mesh facing the prosthetic bed, stoppers were modeled in the form of a truncated inverse cone with a height of 0, 5 mm in which the base with a cross section of 2 mm, and the top 1 mm, located along the perimeter of the grid, departing from the outer borders of the grid by 2 mm, at a distance of 10 mm from each other and along the midline of the hard palate, departing from it by 5 mm to the left and right . Perforations 2 mm in diameter were formed over the entire surface of the virtual mesh model in the spaces between the stoppers and along the apex of the alveolar process of the upper jaw. On top of the virtual mesh model, the outer part of the base of the removable denture of the border was modeled, which, along the perimeter, was connected to the boundaries of the inner layer of the virtual base until it corresponded to the boundaries of the tissues of the prosthetic bed. On the obtained virtual model of the base, consisting of two layers and a virtual reinforcing mesh located between them, artificial teeth were placed according to the individual characteristics of the anatomical and topographic features of the prosthetic bed and field, as well as the aesthetics of the patient's face. The resulting virtual model of a removable plate prosthesis was analyzed in the CAE module of the mathematical modeling program (SolidWorks, SolidWorks Corporation, manufacturer Dassault Systemes, France) for possible risks and breakages under cyclic and static loads. The virtual model of the reinforcing mesh was converted into a physical one by 3D printing (NextDent 5100, 3D Systems, South Carolina, USA) from a dental polymer (NextDent Ortho Rigid). On a plaster model of wax 0.5 mm thick, the basis of a removable lamellar denture was modeled. A pre-printed polymer reinforcing mesh of individual geometry was applied over the wax base and placed at the level determined by the stoppers. A wax plate 0.5 mm thick was placed over the grid, the borders of which, along the perimeter, were connected to the boundaries of the first wax plate of the basis along the boundaries of the tissues of the prosthetic bed. Then, artificial garniture teeth were placed on a wax base reinforced with a printed mesh in an articulator using a silicone key. A wax model of a removable denture, the basis of which is reinforced with a polymer mesh printed according to the individual parameters of the patient's upper jaw, was packed into a dental cuvette and transferred to plastic according to the classical technology. After polymerization of the polymer, the resulting denture was removed from the dental flask, ground, polished and transferred to the clinic, where it was installed on the patient's upper jaw, the occlusion of the dentition, the quality of retention and stabilization of the orthopedic structure were checked.

Claims (1)

Removable plate denture with a reinforced base, containing in its design a three-layer base and artificial teeth, while the first - inner and third - outer layers of the base have a thickness of 0.5 mm and are made of polymethyl methacrylate, and the second - intermediate layer has a thickness of 1 mm and is a reinforcing mesh, congruent to the prosthetic bed, made of a dental polymer and manufactured by 3D printing, while the boundaries of the mesh are separated from the boundaries of the layer of the base of the removable plate prosthesis adjacent to the tissues of the prosthetic bed by 5 mm around the entire perimeter, and on the surface of the mesh, facing the prosthetic bed, there are mesh stoppers made in the form of truncated inverse cones 0.5 mm high with a base section of 2 mm and a truncated top of 1 mm, located along the perimeter of the mesh, 2 mm away from the outer borders of the mesh, at a distance of 10 mm each from a friend and along the median line of the hard palate, departing from it by 5 mm to the left and right, while over the entire surface The awn of the mesh has perforations 2 mm in diameter between the stoppers and along the top of the alveolar process of the upper jaw, while the three-layer base is connected to the artificial teeth by means of the base polymer.

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