RU2793523C1 - Method for replacing bone defects in the jaws with the possibility of temporary dental prosthetics for the period of dental implants integration - Google Patents

Abstract

FIELD: medicine; surgical dentistry.

SUBSTANCE: in the preoperative period, the patient undergoes a CT scan of the jaws, then the dicom format is converted to the stl format and exported to the dental CAD program. Virtual planning of dental implantation and modeling of the shape of the alveolar bone in the area of the planned operation is carried out. The restored optical model of the jaw is superimposed on the original unmodified model, a closed contour curve is constructed along the intersection of the two models, which is then attached to the restored model, followed by the creation of a surface delimited by this curve, displaying the desired shape of the base of the future titanium plate design. After that, this surface is extruded to a given thickness along the normal to each point, forming a solid model of the plate. The edges of the plate are adjusted to the specified value of curvature with a virtual modeling tool — smoothing, and a visual check of the edge fit of the plate to the original model is carried out. Further, along the lower border of the plate, 2 mm away from the edge, the holes for screws are modeled, fixing the future titanium plate to the bone, the holes are modeled in the areas of the thickest cortical bone from the lingual and outer surfaces equidistantly at a distance of not more than 5 mm from each other and with a diameter of 1.2 mm, so that the total amount of holes is not less than 10 on each side of the jaw. At the top of the plate in the projection of the missing canines and first molars, abutments are modeled in the form of truncated cones with circular retentions, while the abutment is made integral with the plate. After that, a temporary bridge-like non-removable denture is modeled based on abutments, with the possibility of its separation from the plate model. After that, the digital model of the plate is converted into a cellular structure in the form of a plate, which is exported to the 3D printer software, in which the structure is 3D printed by direct laser sintering or electron beam melting of fine titanium powder or its alloys. The resulting design is subjected to mechanical and sterilization treatment. A virtual model of a fixed bridge-like temporary denture is converted into a physical one by volumetric printing from a dental polymer, ground and polished. Then the patient is given local anesthesia in the planned operating area, a mucoperiosteal flap is formed and the bone is skeletonized. In the area of dental implants, perforations are made with a dental drill in the atrophic part of the bone to a depth equal to the thickness of the cortical bone plate. A bone-replacing mass is placed on top represented by a xenograft mixed with a bone autograft, saturated with the patient's capillary blood in a ratio of one to one, and the mass of the previously made titanium structure is fixed by means of screws through the holes to the patient's bone. The mucoperiosteal flap is laid back and sutured with resorbable threads, which are removed on the tenth day after the operation, a temporary bridge-like non-removable denture is fixed on the abutments with temporary cement.

EFFECT: method makes it possible to temporarily restore chewing efficiency during the period of restoration of jaw defects and integration of dental implants in patients with complete absence of teeth.

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Description

The field of technology to which the invention belongs

The invention relates to medicine, namely to surgical dentistry, and can be used to compensate for the lack of jaw bone tissue with the possibility of temporary prosthetics during the integration of dental implants in patients with complete absence of teeth.

State of the art

A known method of temporary prosthetics for the period of engraftment of the root part of the intraosseous implant, including the manufacture of a temporary bridge prosthesis and its removal after the end of this period, while making a fixed fiber adhesive bridge prosthesis that prevents trauma to the implant and surrounding gums (RF Patent No. 2173114 dated 10.09.2007) .

This method cannot be used in patients with complete absence of teeth.

A known method of prosthetics of teeth during the period of osseointegration of dental implants in patients with end defects of the dentition is carried out by obtaining optical impressions of the patient's dentition in the preoperative period, fixing the digital models obtained from the impressions into a virtual articulator, determining on the models the border of a removable denture of small length, having in in its composition, the base, artificial teeth and a system of clasps, so that the edge of the base of the prosthesis on the lingual side overlaps the internal oblique line, and in the places of dental implants planned for installation on the digital model, there is a gap of 2 mm between the base of the prosthesis, which is achieved by the digital reduction function model, and the system of clasps is represented by two T-shaped processes from the basis of the prosthesis, connected to the occlusal lining with the possibility of fixation on 2-3 abutment teeth located medially to the defect of the dentition, while the monolithic prosthesis is made of polymethyl methacrylate in the preoperative period by the method of three-dimensional printing, installation of dental implants and installation of one mini-dental non-integrable implant with a spherical head, as close as possible to the distal border of the dentition defect, fixation in a removable prosthesis of small extent by means of self-hardening plastic of the fixing element of the mini-dental implant system in the bed, formed in the projection of the spherical head of the dental technician cutter (Patent of the Russian Federation No. 2698625 dated 08.28.2019).

An endosseous-subperiosteal implant is known from the prior art, containing a subperiosteal metal plate with holes and fasteners for a dental prosthesis, and the implant additionally contains a perforated plate with a height of not more than 10 mm and a width of not more than 4 mm, located in the central part of the subperiosteal plate along its longitudinal axis at an angle of 60-90o to the fasteners, while the area of the holes of both plates is at least 50% of the total area of the plates (RF Patent 2145819 dated February 27, 2000).

At this rehabilitation and preparatory stage, it is rather problematic to provide the patient with a temporary restoration of chewing efficiency in the absence of teeth.

Known titanium plastia, including a titanium perforated plate, repeating the geometry of the jaw area, tightly fitting along the contour, while the plate has a bulge in the area corresponding to the area where the bone-replacing mass will be distributed, and at four opposite ends of the plate there are holes for its screw fixation to jaw bones located at four opposite ends of the plate (Yu Xie, et al. Titanium mesh for bone augmentation in oral implantology: current application and progress. International Journal of Oral Science volume 12, Article number: 37 (2020). Published: 30 December 2020).

However, in this case it is impossible to make temporary prosthetics for the period of osseointegration.

A device for temporary prosthetics for the period of directed bone regeneration of the jaw includes a titanium perforated plate that repeats the geometry of the jaw area. The plate has a bulge in the area corresponding to the area where the bone-replacing mass will be distributed. Holes are made in four opposite ends of the plate for its screw fixation to the jaw bone. Additionally, the device includes at least one cylinder with circular retention elements for subsequent fixation of temporary crowns. Moreover, at least one cylinder is made on the plate in the area corresponding to the area of implantation, while the cylinder is made integral with the plate. The device ensures the manufacture of a high-precision individual titanium plate for guided bone regeneration with temporary abutments for fixing temporary fixed dentures (RF Patent 2756066 dated 09/27/2021).

The closest analogue is the method of temporary prosthetics for the period of osseointegration of the root part of the intraosseous implant, including the manufacture of a temporary bridge, its installation and subsequent removal, and when planning the operation, computed tomography of the jaws is performed, according to which stereolithographic models are made, according to which a temporary subperiosteal implant is made, repeating the anatomical contours of the jaw, exfoliate the mucoperiosteal flap, install the root parts of intraosseous implants, place a temporary subperiosteal implant with a gap above them, fill the gap with osteoplastic material, tightly sutured the wound, leaving the heads of the subperiosteal implant above the gum level, and install a temporary implant on them with cement bridge prosthesis (RF Patent No. 2393814 dated 10.07.2011).

The disadvantages of this method include the complexity of its execution associated with the manual production of the structure, which in turn requires its additional adaptation during the operation. Also, the lack of fasteners of the structure can be attributed to the disadvantage of the method, thus, it follows that the subperiosteal implant is located directly on the osteoplastic material, which adversely affects its integration and provokes atrophy.

The problem to which the invention is directed is to provide the possibility of a temporary restoration of chewing efficiency for the period of guided bone regeneration of the jaws and the integration of dental implants in patients with complete absence of teeth.

Disclosure of the essence of the invention

The technical result consists in providing the possibility of temporary restoration of chewing efficiency during the period of restoration of jaw defects and the integration of dental implants in patients with complete absence of teeth.

The technical result of the invention is achieved by the following methods. The patient in the preoperative period is subjected to a CT scan of the jaws, the obtained data in the form of a file in the dicom format is converted into the stl format and exported to a dental CAD program, where, if necessary, unnecessary elements in the form of teeth, bridges, other unnecessary objects and other unnecessary objects are removed from the jaw model. carry out virtual planning of dental implantation and modeling of the shape of the alveolar bone in the area of the planned operation. Next, the restored optical model of the jaw is superimposed on the original unmodified model, along the intersection of the two models, a closed contour curve is constructed, which is then attached to the restored model, followed by the creation of a surface delimited by this curve, displaying the desired shape of the base of the future titanium plate design. Then, this surface is extruded to a given thickness along the normal to each point, as a result of which a solid model of the plate is formed, the edges of the plate are smoothed to a given curvature value and a visual check is made of the edge fit of the plate to the original model, then along the lower border of the plate, 2 mm away from the edge modeling of holes for screws fixing the future titanium plate to the bone is carried out. At the same time, holes are modeled in areas of the thickest cortical bone from the lingual and outer surfaces equidistantly at a distance of no more than 5 mm from each other and with a diameter of 1.2 mm, so that the total amount of holes is at least 10 on each side of the jaw, on at the top of the plate in the projection of the missing canines and first molars, abutments are modeled in the form of truncated cones with circular retentions, while the abutment is made integral with the plate. A temporary bridge-like non-removable denture is modeled based on abutments, with the possibility of its separation from the plate model, after which the digital plate model is converted into a cellular structure in the form of a plate, which is exported to the 3D printer software, in which the structure is 3D printed using a 3D printer direct laser sintering or electron beam melting of fine titanium powder or its alloys. The resulting design is subjected to mechanical and sterilization treatment. Then the virtual model of a fixed bridge-like temporary denture is transferred into a physical one by volume printing from a dental polymer, ground and polished. The patient is given local anesthesia in the planned operating area. Then a mucoperiosteal flap is formed and the bone is skeletonized. If necessary, remove the remaining teeth and roots. In the area of dental implants installation, spherical burs in the atrophic part of the bone are perforated to a depth equal to the thickness of the cortical plate of the bone, a bone-replacing mass is placed on top, represented by a xenograft mixed with a bone autograft obtained during the operation by means of a bone scraper, in a ratio of one to one saturated with capillary the patient's blood and fix the mass of the previously made titanium structure by means of screws through the holes to the patient's bone. The mucoperiosteal flap is laid back and sutured with resorbable threads, which are removed on the tenth day after the operation, a temporary bridge-like non-removable denture is fixed on the cylinders with temporary cement.

The method is achieved through computer modeling and precise computer production of an individual titanium structure by selective laser sintering.

The proposed method allows for temporary prosthetics in patients with a complete absence of teeth during the period of integration of dental implants, while simultaneously restoring bone defects.

Abutments, as elements of a titanium plate, are used as supports for a fixed temporary bridge. The number and location of cylindrical supports, the number of holes for fixing the titanium plate and the diameter of the fixing screws 1.2 mm, as well as their location, were worked out in a mathematical experiment by the finite element method. It is these characteristics that ensure the redistribution of masticatory pressure on the jaw body and prevent the load on the emerging bone tissue and installed implants until their secondary stabilization.

The method of replacing bone defects in the jaws with the possibility of temporary dental prosthetics for the period of integration of dental implants is illustrated by drawings, where figure 1 shows a virtual model with elements:

1. Titanium plate

2. Holes for fixing the plate

3. Abutment

4. Model of the lower jaw

in fig. 2 shows a virtual model with elements:

1. Titanium plate

2. Holes for fixing the plate

3. Abutment

5. Temporary fixed dental bridge

in fig. 3 shows a prototype polymer model with elements:

1. Titanium plate

2. Holes for fixing the plate

3. Abutment

4. Model of the lower jaw

Implementation of the invention

A method for replacing bone defects in the jaws with the possibility of temporary dental prosthetics for the period of integration of dental implants as follows:

1. The patient in the preoperative period is subjected to a CT scan of the jaws.

2. The CBCT data of the patient's jaws are exported as a DICOM file to the Diagnocat cloud artificial intelligence environment.

3. Using the built-in function of this software, 3D models of the required segments of the jaws and teeth are created in STL format.

4. The resulting models are exported to a dental CAD program, for example, Exocad, where, if necessary, unnecessary elements in the form of teeth, bridges and other formations are removed from the model.

5. Modeling of the desired shape of the bone crest is carried out.

6. The original jaw model (4) without unnecessary elements (hereinafter the original model) and the model with the restored form of the alveolar process (hereinafter the restored model) are exported to the Materialize 3-Matic program, where they are superimposed on each other.

7. On the boundary of the intersection of two models, a closed contour curve is constructed, which is then attached to the restored model. The program automatically creates a surface delimited by this curve, displaying the desired shape of the base of the future titanium plate structure (1).

8. This surface is extruded to a given thickness along the normal to each point, as a result of which a solid model of the plate is formed.

9. The edges of the plate are modeled to the specified curvature value using the virtual modeling tool - smoothing. A visual check of the edge fit of the plate to the original model is carried out under the control of a virtual ruler.

10. On the lower border of the plate (1), at a distance of 2 mm from the edge, holes are modeled for screws (2) that fix the future titanium plate (1) to the bone, holes (2) are modeled in the areas of the thickest cortical bone from the lingual and outer surfaces equidistantly at a distance of no more than 5 mm from each other and a diameter of 1.2 mm, so that the total amount of holes is not less than 10 on each side of the jaw (4).

11. At the top of the plate (1) in the projection of the missing canines and first molars, abutments (3) are modeled in the form of a truncated cone with circular retention elements for subsequent fixation of temporary crowns (5), while the abutment (3) is made integral with the plate (1 ).

12. A temporary bridge-like non-removable denture (5) is modeled, supported by abutments, with the possibility of its separation from the plate model (1).

13. The model is restructured with a decrease in the density of the cloud of points for constructing its surface. The plate model (1) is exported to the Meshmixer program, where a three-dimensional mesh structure of the model is created.

14. The digital model of the plate (1) is exported to the 3D printer software, in which the support elements on the working platform are simulated, after the completion of the preparatory process, the individual plate (1) is 3D printed for guided tissue regeneration using a 3D printer using direct laser sintering or electron beam melting of fine titanium powder or its alloys.

15. If necessary, it is possible to print polymer prototypes for additional visualization of the structure in preparation for surgery (Fig. 3).

16. The resulting titanium plate (1) is subjected to mechanical and sterilization treatment.

17. The patient is given local anesthesia in the planned operating area.

18. In the planned operating area, a mucoperiosteal flap is formed and the bone is skeletonized, if necessary, the removal of the remaining teeth and roots, the installation of dental implants.

19. Perforations are made with a dental drill in the atrophic part of the bone to a depth equal to the thickness of the cortical plate of the bone and a bone-replacing mass is placed on top, represented by a xenograft mixed with a bone autograft obtained during the operation by means of a bone scraper, in a ratio of one to one saturated with the patient's capillary blood.

20. Screws through the holes (2) fix the bone-replacing mass with a previously made individual titanium plate (1) to the patient's bone.

21. The mucoperiosteal flap is laid back and sutured with resorbable sutures.

22. On the abutments (3), a temporary bridge-like non-removable denture (5) is fixed with temporary cement.

Clinical example.

A 36-year-old patient came to the clinic with complaints of partial absence of teeth in the lower jaw. From the anamnesis, the teeth were removed as a result of a complication of caries about 12 years ago, not previously prosthetized.

When examining the oral cavity, teeth 34, 35, 36, 37, 38, 44, 45, 46, 47, 48 are absent, significant atrophy of the alveolar bone is noted, teeth 33, 32, 31, 41, 42, 43 have mobility of the 3rd degree.

Based on the results of the examination, it was decided to remove teeth 33,32,31,41,42,43 with simultaneous dental implantation in the position of missing teeth 36,34,32,42,44,46 with a preliminary operation for guided bone regeneration according to the proposed way.

Treatment:

The patient underwent a CT scan of the jaws, the data obtained were exported as a DICOM file to the Diagnocat cloud artificial intelligence environment. Using the built-in function of this software, we created a 3D model of the lower jaw and teeth in STL format. The resulting model was exported to the Exocad program and a virtual extraction of teeth 33, 32, 31, 41, 42, 43 was performed.

Next, a virtual setting of implants was carried out in the positions of teeth 36, 34, 32, 42, 44, 46 and modeling of the desired shape of the alveolar bone in the position of teeth 33, 32, 31, 41, 42, 43, 34, 35, 36, 37, 38 , 44, 45, 46, namely, smoothing uneven surfaces by increasing the height and width of the alveolar ridge. Three-dimensional models of the jaw without unnecessary elements (hereinafter, the original model) and a model with the restored shape of the alveolar part of the lower jaw (hereinafter, the restored model) were exported to the Materialize 3-Matic program, where they were superimposed on each other. On the boundary of the intersection of the two models, a closed contour curve was constructed, which was then attached to the restored model. A surface delimited by this curve was created, displaying the desired shape of the base of the future titanium plate design. This surface was extruded to a given thickness from 0.3 mm along the normal to each point, as a result of which a solid model of the plate was obtained. The edges of the plate were smoothed to a given value of curvature. We performed a visual check of the marginal fit of the plate to the original model and modeling of holes for screws fixing the titanium plate to the bone. Holes were modeled in areas of the thickest cortical bone from the lingual and outer surfaces equidistantly at a distance of 5 mm from each other and 1.2 mm in diameter, thus, 10 holes were obtained on each side of the jaw. Further, on the top of the plate in the projection of the missing canines and first molars, abutments with circular retention elements were modeled for the subsequent fixation of temporary crowns. After that, modeling of a temporary bridge-like non-removable denture based on abutments was carried out, with the possibility of its separation from the plate model.

The plate model was exported to the Meshmixer program, where a three-dimensional cellular structure of the model was created. The digital model of the wafer was exported to 3D printer software and converted into titanium by direct laser sintering. The resulting plate was subjected to mechanical and sterilization treatment. A virtual model of a fixed bridge-like temporary denture was converted into a physical one by volumetric printing from a dental polymer.

Under application and infiltration anesthesia Sol.Ultracaini 4% - 3.4 ml, a mucoperiosteal flap was formed and the mandible was skeletonized. Removed teeth 33, 32, 31, 41, 42, 43. A spherical burr in the atrophic part of the bone formed perforations to a depth equal to the thickness of the cortical bone plate. On the surface of the bone and in the sockets of the extracted teeth, a bone-replacing mass was placed, represented by a xenograft mixed with a bone autograft obtained during the operation by means of a bone scraper, saturated with capillary blood in a ratio of one to one. In the position of teeth 36, 34, 32, 42, 44, 46, perform dental implantation. The titanium structure was fixed to the jaw body through the holes with fixing medical screws. The mucoperiosteal flap was immobilized and sutured, leaving titanium cylinders uncovered by the mucosa. A temporary non-removable denture was fixed on the cylinders with temporary cement.

When assessing occlusal contacts during articulation movements using the Tscan apparatus, multiple fissure-tubercle contact was determined, which indicated the restoration of masticatory function.

On the 10th day after the operation, the sutures were removed.

After 3 months, the titanium plate was removed and the integrated implants were replaced with a fixed ceramic prosthesis.

Claims (3)

1. A method for replacing bone defects in the jaws with the possibility of temporary dental prosthetics for the period of integration of dental implants, characterized in that the patient is given a CT scan of the jaws in the preoperative period, then the dicom format is converted to the stl format and exported to a dental CAD program, and virtual dental planning is carried out. implantation and modeling of the shape of the alveolar bone in the area of the planned operation, then the restored optical model of the jaw is applied to the original unmodified model, a closed contour curve is constructed along the intersection of the two models, which is then attached to the restored model, followed by the creation of a surface delimited by this curve, displaying the desired shape of the base of the future design of the titanium plate, after which this surface is extruded to a given thickness along the normal to each point, forming a solid model of the plate, the edges of the plate are adjusted to the specified value of curvature with a virtual modeling tool - smoothing and a visual check is made of the edge fit of the plate to the original model, further along the lower border of the plate, 2 mm away from the edge, holes are modeled for screws that fix the future titanium plate to the bone, the holes are modeled in areas of the thickest cortical bone from the lingual and outer surfaces equidistantly at a distance of no more than 5 mm from each other and with a diameter 1.2 mm, so that the total amount of holes is not less than 10 on each side of the jaw, on the top of the plate in the projection of the missing canines and first molars, abutments are modeled in the form of truncated cones with circular retentions, while the abutment is made integral with the plate, after that, a temporary bridge-like non-removable denture is modeled based on abutments, with the possibility of its separation from the plate model, after which the digital model of the plate is converted into a cellular structure in the form of a plate, which is exported to the 3D printer software, in which the structure is 3D printed using the direct method laser sintering or electron beam melting of finely dispersed titanium powder or its alloys, the resulting structure is subjected to mechanical and sterilization processing, the virtual model of a fixed bridge-like temporary denture is converted into a physical one by volumetric printing from a dental polymer, ground and polished, then the patient is given local anesthesia, in of the planned operating area, a mucoperiosteal flap is formed and the bone is skeletonized; to one saturated with the patient's capillary blood, and the mass of the previously made titanium structure is fixed through screws through the holes to the patient's bone, the mucoperiosteal flap is laid back and sutured with resorbable threads, which are removed on the tenth day after the operation, a temporary bridge-like non-removable denture is fixed on the abutments for temporary cement. 2. The method according to p. 1, characterized in that excess elements in the form of teeth or bridges are removed from the jaw model. 3. The method according to claim 1, characterized in that the remaining teeth and roots are removed in the area of dental implantation.

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