Dental prosthetics using cad cam technology. CAD CAM systems in dentistry

Candidate of Medical Sciences, Orthopedic Dentist Yervandyan Harutyun Geghamovich

Publication date — 4.10.2015

Since the invention of the computer by man, a new era has come in science, technology and simply in human life. While most people are able to use computers to the maximum to communicate in in social networks, skype and online shopping, others have long used computers to perform complex mathematical measurements, 3D design, programming, study the strength of materials and fatigue loads, as well as in the field of CAD/CAM technologies. CAD/CAM is an acronym that stands for computer-aided design/drafting and computer-aided manufacturing , which literally translates as computer help in design, development and computer assistance in production, but in terms of meaning it is production automation and computer-aided design / development systems.

With the development of technology, orthopedic dentistry has also evolved from the time of the bronze man, when they were tied artificial teeth gold wire to adjacent teeth, up to modern man which uses CAD/CAM technology. At the time of the advent of CAD / CAM, the main technologies for the manufacture of crowns and bridges were the old and flawed stamping and soldering technology, the more promising and advanced casting technology, and the less common technologies, also devoid of the disadvantages of stamping and soldering, superplastic molding and sintering. On the other hand, the last two technologies can be applied to very limited quantity materials, such as superplastic molding for titanium only. CAD/CAM technology is devoid of all the disadvantages inherent in casting technologies, such as shrinkage, deformation, including the extraction of cast crowns, bridges or their frameworks. There is no danger of technology violations, for example, overheating of the metal during casting or reuse of sprues, which leads to a change in the composition of the alloy. There is no shrinkage of the frame after applying ceramic lining, possible deformation when removing wax caps from a plaster model, pores and shells during casting, unspilled areas, etc. The main disadvantage of CAD / CAM technology is the high cost, which does not allow this technology to be widely orthopedic dentistry. The original CAD / CAM technology was a computer with the necessary software on which three-dimensional modeling was performed. fixed prosthesis followed by computer milling with an accuracy of 0.8 microns from a solid metal or ceramic block.

Respectively, consumables for this procedure, expensive blocks and cutters, mostly carbide, became. Thanks to the further evolution of CAD / CAM technology, computer milling was replaced by 3D printing technology, which made it possible to reduce the cost and made it possible to manufacture objects of any shape and complexity that could not be produced before by any of the existing technologies. For example, thanks to 3D printing, it is possible to produce a solid hollow object with any shape. inner surface. In relation to orthopedic dentistry, it is possible to make a hollow body of the prosthesis, which will reduce its weight without reducing the strength of the structure. The uniqueness of 3D printing technology can be seen in the video.

In dentistry 3D printing method depends on the printed material and therefore the technology itself can be conditionally divided into several branches:

1. Wax printing
2. Plastic printing
3. Metal printing
4. Plaster/ceramic printing

First branch It's 3D printed with wax. It refers to thermal printing technology, i.e. the wax heats up and turns into liquid state, and accordingly in this state it is applied drop by drop. After application, it cools down and turns into a solid state. In fact, this method is a more advanced technology for modeling prosthesis structures with all the disadvantages of casting inherent in it. Those. you can model on a computer and print the perfect frame from wax, but when casting, you will again encounter all the problems inherent in casting. Thus, this technology eliminates all the disadvantages of modeling a wax frame, but does not eliminate the disadvantages of casting technology.

Second branch This is 3D printed plastic. This technology makes it possible to obtain both collapsible models of the jaws, frameworks made of ashless plastic for casting, as well as finished prostheses, such as crowns or bridges made of composite, as well as printing removable prostheses.

In turn, there are two methods of 3D printing with plastic:

1. tolerating
2. Light curing printing

Thermal printing can be used for 3D printing with thermoplastics such as removable dentures or for printing with ashless plastic. Light-curing printing can be used to print both crowns made of composites and frameworks made of ashless plastic, removable dentures made of acrylates and polyurethane.

The technology of wax and plastic thermal printing is similar and somewhat similar to the printing principle of a conventional color inkjet printer. The material is heated to the melting temperature and applied with microdrops, but unlike a color inkjet printer that prints only in one plane, a 3D printer prints in three planes and, accordingly, not with paint, but hard materials. Due to the application of the material with microdroplets, complete compensation of material shrinkage is achieved. In addition, there is another method of thermal plastic printing, in which a plastic wire is heated and continuously fed to the surface of the printed object (FDM 3D printing). This technology is the cheapest and most common in the world, but it has not found wide distribution in dentistry, since it does not have high accuracy.

A more advanced method of thermal printing is selective thermal sintering technology. SHS» (Selective Heat Sintering). Detailed description method is presented in the section "3D metal printing".

photopolymer printing

There are 2 ways of photopolymer 3D plastic printing in dentistry:

1. Stereolithographic 3D printing (SLA)

Inkjet photopolymer 3D printing (MJM)

Light polymerization (photopolymer) printing is similar to thermal printing and differs only in that the material does not need to be heated, since it is already liquid, and hardening i.e. polymerization occurs under the influence of light blue spectrum 455-470 nm.

Stereolithographic printing (SLA)

A radically different principle is used in stereolithographic printing technology. The essence of the method is to print in a bath filled with photopolymer plastic or composite. Unlike other printing methods, this method prints from top to bottom and the printed object is upside down. Many readers will have a question, how can you print in a bath filled with photopolymer material, since all the material in the bath must be cured. Everything is ingeniously simple. The fact is that the platform on which the growth of the printed object begins is immersed in the thickness of the photopolymer composite, not reaching the bottom by 6-20 microns (depending on the printer), i.e. there remains a layer of photopolymer material with a thickness of 6-20 microns and, accordingly, only this layer is cured in the right places. After curing, the platform rises upwards, tearing off the cured polymer from the bottom of the bath, then re-immerses without reaching 6-20 microns with the polymerized part to the bottom. Thus, a layer of uncured photopolymer material is again created between the bottom of the bath and the already printed layer. The process is repeated as many times as the number of layers needed to be printed to complete the object.

Benefits stereolithographic printing technologies are:

1. High accuracy;
2. High resolution;
3. Smooth surface.

disadvantages stereolithographic printing are:

1. Possibility to print in one color only;
2. Background illumination of the photopolymer, since a small power of light radiation is scattered in total mass photopolymer. Thus, part of the photopolymer material deteriorates, which leads to an increase in the cost of printing;
3. Limited bathroom resource. Due to the fact that the polymer must constantly come off the bottom of the bath, it is made of silicone or a similar material, and over time it fails, and therefore requires replacement;
4. Limited resource of an expensive laser.

Third branch– 3D metal printing. The essence of the method lies in the spot melting of the metal powder with a beam until a homogeneous structure is obtained. There are several ways to 3D print metal:

1. DMD« direct metal deposition» (Direct Metal Deposition);
2. LDT « laser deposition technology» (Laser Deposition Technology);
3. LCT « laser deposition technology» (Laser Cladding Technology);
4. LFMT « free-form laser production technology» (Laser Freeform Manufacturing Technology);
5. LMD « laser metal deposition» (Laser Metal Deposition);
6. LMF « metal laser fusion» (Laser Metal Fusion);
7. SLS« selective laser sintering» (Selective Laser Sintering);
8. DMLS « direct laser sintering of metals» (Direct Metal Laser Sintering);
9. SLM « selective laser melting» (Selective Laser Melting);
10. LC « laser focus» (LaserCusing);
11. EBM « electron beam melting"(Electron Beam Melting);
12. SHS « selective thermal sintering» (Selective Heat Sintering).

Selective laser sintering technology ( SLS) was invented by Carl Deckard and Joseph Beeman of the University of Texas (Austin, USA) in the mid-1980s.
Selective laser melting technology ( SLM) was invented by Wilhelm Meiners and Konrad Wissenbach of the Fraunhofer Institute for Laser Technology (ILT) (Aachen, Germany) together with Dieter Schwarze and Matthias Fokele of F&S Stereolithographietechnik GmbH (Paderborn, Germany) in 1995.

All these methods can be used in dentistry. Conventionally, they can be divided into two groups, differing only in the method of applying metal powder. The first group includes powder feeding methods with simultaneous microwelding. The second group includes methods for applying a layer of powder followed by microwelding of the powder.

Group I of metal 3D printing methods.

3D printing method by direct metal deposition ( DMD) is very similar to the powder laser welding technique. The essence of the method is shown in the diagram.

The laser beam heats the area pointwise and an aerosol of metal powder in an inert gas environment is also fed there. Under the action of the laser, the powder melts and passes into the liquid phase, which solidifies after cooling. Then the process is repeated and in this way the metal is layered drop by drop. In the case of laser welding, everything is done by a dental technician in manual mode. With 3D printing, the process is controlled by a computer, so it is produced as quickly and accurately as possible.

DMD, LFMT, LMD, LDT And LCT methods are no different, the only difference is that LDT And LCT methods are used to restore damaged objects, for example, during abrasion.

II group of metal 3D printing methods.

At layered method a layer of metal powder having a microscopic thickness (10-50 microns) is applied to the substrate and sintering or, more precisely, laser microwelding in an inert gas environment of microscopic metal grains in the necessary sections of the layer. After that, another layer of metal powder is applied on top, and laser microwelding of metal micrograins is performed not only among themselves, but also with the lower layer.

Micro welding of metal powder

Thus, a three-dimensional metal object is printed in layers. After printing is completed, the finished metal object is removed from the powder. The remaining powder can be reused. This technology is waste-free production, which ultimately leads to a reduction in the cost of construction. And thanks to the use of computer technology, high quality and accuracy of the order of 1-10 microns are achieved. The accuracy of the method is limited only by the diameter laser beam and the size of the micrograins of the printed material. But it must be remembered that the higher the accuracy of the print, the slower the print. We bring to your attention a video about 3D metal printing in dentistry.

honors SLS(selective laser sintering) from DMLS(direct laser sintering of metals) lies in the fact that the second method can only be used for metal printing. And by the method SLS can be used for printing with any thermoplastic. SLS from SLM differs only in that in the first case, sintering is performed, and in the second, powder is melted. This difference is conditional, since metal melting also occurs during sintering, and the difference in the name and description of the method is associated with commercial issues. The same goes for the method. LC And LMF. Therefore, the separation of all these methods is far-fetched, although according to the creators of technologies SLS And DMLS The density of the printed object can be adjusted using these printing methods.
electron beam melting (EBM) differs from other methods in that a high-power electron beam (beam) is used instead of a laser beam, and the printing itself is performed under vacuum conditions.
Selective thermal sintering(SHS) differs from other methods in that a thermal head is used instead of a laser or electron beam. This technology makes it possible to create 3D printers. small size. But the downside of the technology is low temperature printing and therefore it can only be used for printing fusible metals and thermoplastics.

Fourth branch– 3D printing with plaster/ceramics. The principle of plaster printing is similar to the technology SLS, but instead of a laser, a bonding agent is used, the so-called glue, connecting the particles of gypsum or ceramics. However, plaster printing did not find use in dentistry, as models began to be printed from plastic. Printing with ceramics is promising and will allow printing frameworks or finished designs of crowns and bridges.

Using an article in a bibliographic list“Yervandyan, A.G.CAD/CAM technologies in orthopedic dentistry[Electronic resource] /Harutyun Gegamovich Yervandyan, 4.10.2015.–

vitreous ceramics

Nanoceramics

Zirconium

Milling process

Conclusion

Each of the stages of CAD/CAM production of dental structures (whether it is the collection of digital data, their processing with adapted software, or the process of manufacturing a prosthesis or crown itself) continues to independently develop and improve, thus ensuring even greater accuracy and efficiency of orthopedic works made by the method digital modeling and milling. At the same time, new materials of ceramics, polymers and metals are being introduced into the practice of CAD / CAM, which allow the manufacture of all types of structures: from simple caps and crowns to full-arc prostheses, removable devices, provisional units, positioners and surgical templates. CAD/CAM labs also use materials to make models, or samples, that are subject to burnout during casting or extrusion.

CAD/CAM ceramics are most often used in restorative dentistry, since the introduction of this approach has significantly changed key clinical aspects in this practice. Most of the bridge structures, as well as single crowns, are currently manufactured using CAD / CAM technologies using new types ceramic materials. CAD/CAM ceramics have evolved from the classic feldspar counterpart with high aesthetics but brittle in nature to modern branded representatives that differ greatly in terms of strength, flexibility and aesthetics. Designs made from such materials have long proved their clinical effectiveness and are a worthy replacement for traditional metal-ceramic restorations.

Until recently, clinicians were limited in their choice of CAD/CAM ceramic materials: durable materials were not aesthetically pleasing, and aesthetic materials were not sufficiently durable. But today, the aesthetic parameters of high-strength materials make it possible to achieve maximum clinical effective result regardless of the amount of work: whether it is a single crown or a full-arc design that replaces the full dentition of the jaw. Monolithic CAD/CAM restorations are less prone to failure due to the absence of a difference between the base and cover materials, and their fabrication process is quite fast and easy, without the need for laborious additional costs and highly skilled knowledge regarding the application of different coating layers.

vitreous ceramics

Vitreous ceramic is a unique CAD/CAM material that has been used for inlays, crowns and veneers for over 30 years. With adequate use of these types of materials (proper preparation algorithm, adapted ceramic processing method and reliable bonding protocol), they provide sufficient high level clinical success and aesthetic rehabilitation. However, in cases with excessively thin margins, mismatched surfaces, and insufficient adhesive bonding to the tooth structure, the performance of vitreous ceramic restorations leaves much to be desired. For some cases, other types of materials are more suitable, but for veneers best material the choice is glass ceramics. Vitreous ceramics are available in the form of multi-layer blocks that differ in shades of color. In addition, it can be additionally tinted or changed in shade by applying an additional layer, which in most cases solves the problems of individual color matching of the future aesthetic design.

Nanoceramics

This group of materials combines the elasticity of composites and the strength of ceramic counterparts. Nanoceramics cannot be oven-tinted, which limits their use for anterior restorations, but there are complete restoration kits available to give them the appropriate shade to help achieve maximum shade adaptation. More recently, 3M ESPE has stopped offering their own Lava Ultimate for crowns due to frequent bond failures. orthopedic construction with dental tissues. Inlays and onlays are direct indications for the use of nanoceramics during milling due to the absence of thin edges that are sensitive to chipping, less flexibility and better adhesion of such structures. From a clinical point of view, nanoceramic onlays and inlays are produced fairly quickly, while being accurately and easily polished during their final try-in and bonding.

Lithium silicate glass ceramic

Lithium disilicate was introduced to the dental industry by Ivoclar Vivadent under the name Empress II back in 1998. Initially, the material was too opaque, so the coating ceramic was sintered directly on the disilicate substructure. But Ivoclar did not stop and, continuing to improve the aesthetic parameters of disilicate materials, achieved success: today lithium disilicate is on the market varying degrees transparency, so it can be used for both veneers and single crowns or bridges covering the area of ​​premolars. Also, this material is effectively used for the manufacture of abutments and crowns based on implants. To date, the strength, aesthetics and fixation strength of lithium silicate structures using conventional composite cements have been scientifically and clinically proven, so the versatility of this group of materials is beyond doubt.

A number of companies have introduced analogues of these materials on the market with comparable strength parameters. These products include Obsidian (Prismatik Dentalcraft Inc.) lithium silicate and CELTRA Duo (DENTSPLY International) lithium silicate reinforced zirconium. Their final color is determined just prior to the sintering process, but there is not yet sufficient data on their performance for the fabrication of IPS e.max (Ivoclar Vivadent). In addition, these commercial lithium disilicate products cannot be layered, and the range of their transparency shades is significantly limited. This type of material is often the best choice for single restorations or for three-unit bridges in the anterior region.

Zirconium

Initially, zirconium was considered only as a substructure material due to its high opacity. The bending strength parameter of zirconium is similar to that of metals, however, when it is coated with more transparent ceramics, there is a risk of chipping during operation. Over the past ten years, manufacturers have made sure that new zirconia materials with adapted levels of translucency can be used to fabricate esthetic crowns and bridges in the anterior region. Zirconia milling blocks are currently available in a multi-shade range, thus providing the opportunity for complete fabrication of crowns that are more opaque at the gum and more translucent at the incisal edge. As a rule, the more aesthetically pleasing zirconium material is, the less durable it is, however, even these levels of strength are sufficient for bridge structures to function successfully in the frontal region. Another advantage of zirconium is its high adhesive strength even when using conventional cements, but at the same time, these materials are quite difficult to mill and modify if necessary. A practicing dentist should know which type of zirconium is better to choose for the restoration of the posterior group of teeth, since the variability in the strength of materials, as well as their aesthetic parameters, is quite wide.

Milling process

All three categories of CAD/CAM materials (polymers, metals, and ceramics) can be processed by subtractive manufacturing, in which a portion of the material is removed from a monolithic block or disk until the planned shape of the future structure is achieved. The final appearance of a crown or bridge is achieved through final milling or grinding processes of excess material, and in the case of metals, through electrical discharge machining. A significant advantage of subtractive manufacturing is that the monolithic blocks and disks are manufactured under industrial control, so there is no doubt about their quality. In addition, this moment in relation to ceramics helps to avoid the occurrence of defects resulting from internal stresses and shrinkage caused by the nature of the layering process. In the case of metals, the production of structures from a monolithic block eliminates the aspects of material deformation as a result of casting during periodic heating and subsequent cooling. Thus, any material, thanks to CAD / CAM technologies, can provide stronger and more aesthetic designs compared to traditional laboratory methods for the manufacture of inlays, crowns or bridges. On the other hand, there is a whole range of materials developed specifically for CAD/CAM production that cannot be used in a conventional laboratory.

The subtractive processing method, however, can be somewhat uneconomical, since most of monolithic block is crushed and becomes unsuitable for further use. Milling burs, which wear out over time, also do not provide sufficient accuracy with prolonged use. In the case of ceramics, the milling process can cause stresses and cracks in the material structure. But, despite such shortcomings of CAD / CAM technologies, the milling method for manufacturing structures is much more accurate and economical than the usual one. laboratory method making restorations.

The additive manufacturing method of structures is used mainly when working with plastics or metals. This process involves the application of thin layers (about 30 microns thick) of material to recreate an adequate three-dimensional object. Such a production method can be implemented through various technologies: three-dimensional printing, stereolithography and laser welding. The continuous liquid interface production (CLIP) method is a kind of know-how even in the CAD/CAM technology environment, providing unique precision and efficiency. The end product with this technology is produced from the "liquid pool" by recreating some kind of interfacial boundary. In cases with 3D printing, at first this method suitable only for the manufacture of prototypes, but at this time it has greatly expanded its capabilities. With the ability to print different colored plastics, it is becoming more and more efficient for the production of monolithic plastic prostheses. With regard to crowns and bridges, the above methods are literally revolutionary, as they allow the use of materials with the most improved mechanical properties, individualization and adaptation of the design, and also eliminate the disadvantage of the subtractive method - the presence of a huge amount of expensive, but not suitable for further production of waste.

Conclusion

CAD/CAM materials continue to evolve and improve rapidly, providing dentists with more effective opportunities for the treatment of patients. Therefore, physicians must be aware of the range of available materials in order to provide an individualized approach to each clinical situation. Undoubtedly, existing materials will continue to evolve, initiating the emergence of new CAD/CAM manufacturing methods, and therefore monitoring the dynamics of progress and improvement will provide a more adaptive approach to the choice of treatment algorithm for each individual patient.

CAD/ CAM (Englishcomputer— aided design, computer— aided manufacturing) is the collective name modern technologies, allowing to automate the process of manufacturing orthopedic restorations. Before to create artificial crown or tab required 2-4 visits separated by several days of waiting. A waiting period was necessary for the dental technician to design and reproduce the metal or ceramic restoration. More details are written in the corresponding article. Today, thanks to cad/cam technology, it is possible to make a crown or inlay on a tooth within one day.

What is CAD/CAM?

Speaking specifically, CAD / CAM is a complex that includes the following equipment:

Scanner

The scanner is needed to create a virtual 3D model of the patient's teeth. There are both intraoral scanners that "digitize" the situation in the oral cavity directly, and conventional ones that scan pre-made plaster models of the patient's jaws.

Computer with appropriate software

The resulting three-dimensional model of the patient's teeth is processed in computer program, where in automatic (or semi-automatic) mode a virtual model of the future restoration (inlay, crown or veneer) is created for the destroyed tooth, which is necessary to compensate for the defect. The CAD/CAM interface is similar to a 3D editor. The doctor has the opportunity to create or change any element of the modeled restoration: the height of the cusp, the severity of the relief, the curvature of the walls, etc. When the modeling is completed, the file with the restoration model is sent to the milling machine.

Milling machine

The restoration that was modeled in the previous step is automatically turned on the milling machine. How this process looks like is shown in the video below. Standard ceramic or metal blanks are used as the material.

What are the CAD/CAM systems?

The idea of ​​using a CAD/CAM system for the manufacture of dental restorations appeared in 1971. The first prototypes were bulky and awkward to use. In addition, the scanners used to create virtual models produced strong distortions. Today these problems are solved. The accuracy of the "digital impression" is not inferior to the impression obtained by classical technique. The software has improved significantly, and the process of virtual modeling of the future restoration has turned into creativity. The accuracy of milling machines has also improved due to the simultaneous use of several cutters and the reduction in their diameter. The following cad/cam systems are presented in Russia today:

• Cerec
• organic
• Katana
• and etc.

What is the difference between crowns made by CAD/CAM technology and the classical method for the patient?

Crowns made using different technologies may not differ in appearance. In any case, the patient will receive a highly aesthetic restoration that restores the beauty of a smile and the function of chewing food. However, the use of cad/cam systems makes it possible to simplify and speed up the production of restorations:

• First, it decreases total time required to create a crown, inlay, etc.
• Secondly, instead of traditional impression materials, the doctor can use an intraoral scanner that "digitizes" the situation in the oral cavity. This eliminates the need for the patient to go through the procedure of taking conventional impressions. This is especially relevant for people with a pronounced gag reflex.
• The patient directly SEES how the doctor first models an individual crown on the computer, which is then automatically machined from the ceramic block. It is beautiful)

The use of CAD / CAM systems in dentistry allows for the design and manufacture of prosthetic orthopedic structures using a computer.

CAD, short for Computer-Aided Design, is used instead of a drawing board and allows you to create a 3D model of dentures.

The advantages of such a design include the following:

• a model designed on a computer can be viewed from different angles and its projection can be studied in a certain light;
• not only individual details of the drawing can be replaced, but the entire model can be redesigned;
• the finished project can be turned into instructions that will be passed on to machines for their consciousness of this detail.

There are state-of-the-art systems that create 3D models given structural properties materials.

CAM or Computer-Aided Manufacture refers to the manufacture of an orthopedic structure by a computer in accordance with a previously designed 3D model.

Capabilities and types of cad/cam systems

Making a dental bridge on a machine

CAD CAM systems allow you to make:

• and various lengths;
• For ;
• provisional crowns.

There are 2 types of CAD CAM systems:

• closed systems that work with a specific consumable, usually produced by one company;
• open systems that work with various consumables from different manufacturing companies.

Stages of prosthetics using CAD CAM systems

Prosthetics using CAD CAM systems is as follows:

1. The dentist prepares one or more teeth. Then he scans the teeth and bite with a 3D camera, as a result of which an optical model is obtained. Ordinary casts can also be scanned.
2. Next, the resulting image is processed with a special program that draws a 3D model of the restored teeth. She chooses the shape of the future restoration herself, taking into account the rest of the teeth, but the doctor can correct the proposed design with the movement of a computer mouse. The amount of time to create a 3D model depends on the skill of the specialist and on the complexity clinical case. This can take anywhere from a few minutes to half an hour or more.
3. When the simulation is completed, the file with the design of the manufactured part is transferred to the control unit of the milling machine. And here, from a piece of solid material, a 3D model of a part is cut, which was previously modeled by a computer. In time it takes about 10 minutes. To make the design look more natural, it can be covered with translucent and reflective ceramics.
4. When used as a material, then the fabricated structure is then placed in a sintering oven, as a result, it acquires the final shade, size and strength.
5. After firing and hardening of the material, the part is ground and polished. Next, you can install the product on the prepared tooth.

Advantages and disadvantages of computer prosthetics

The advantages of using CAD CAM include the following:

The disadvantages include the following:

• not any prosthetics can be performed using CAD CAM systems, whether it is possible to use it in each specific case should be decided by the dentist;
• some restorations may look opaque and unnatural;
• high price.

CAD CAM system allows you to make crowns and bridges to the maximum short time. Therefore, for those who dream of having beautiful and healthy teeth, but does not want to visit the dentist over and over again, it is worth contacting a clinic where such technologies are used.

CAD/CAM stands for "Computer Assisted Design/Computer Aided Manufacturing", which translates into Russian as "Computer Assisted Design/Computer Aided Manufacturing".

CAD/CAM systems have been successfully used for a long time in various branches of mechanical engineering, as well as in the jewelry industry.

In dentistry, CAD/CAM systems are used to produce denture frameworks by computer-assisted design and CNC milling.

This is the most modern, to date, technology for the production of denture frameworks.

What can be produced using CAD/CAM systems?

single crowns and bridges of short and long length;

telescopic crowns;

individual abutments for implants;

Recreate the full anatomical shape for models of press-ceramics applied to the frame (overpress);

· create temporary crowns in full profile and various molded models.

What materials are used in CAD/CAM?

zirconia, titanium, cobalt-chromium alloy, plastic, wax.

Advantages of CAD/CAM systems compared to the traditional method:

· The highest precision of work (deviation of the sizes 15-20 microns in comparison with 50-70 microns when casting)

· High qualification and extensive experience of the system operator is not required

The system can be operated by one person

・Work space saving

Saving working time (five times faster)

Cleanliness of work

High productivity (up to 120 units per day)

Stages of the CAD / CAM system:

CAD/CAM (Computer- aided Design, Computer- aided manufacturing) is the collective name for modern technologies that automate the process of manufacturing orthopedic restorations. Previously, it took 2-4 visits, separated by several days of waiting, to create an artificial crown or inlay. The waiting period was necessary for the dental technician to model and reproduce the metal or ceramic restoration. Today, thanks to CAD/CAM technology, it is possible to make a crown or inlay on a tooth within one day.

Speaking specifically, CAD / CAM is a complex that includes the following equipment:

The scanner is needed to create a virtual 3D model of the patient's teeth. There are both intraoral scanners that "digitize" the situation in the oral cavity directly, and conventional ones that scan pre-made plaster models of the patient's jaws.

The obtained three-dimensional model of the patient's teeth is processed in a computer program, where a virtual model of the future restoration (inlay, crown or veneer) necessary to compensate for the defect is created in automatic (or semi-automatic) mode for the destroyed tooth. The CAD/CAM interface is similar to a 3D editor. The doctor has the opportunity to create or change any element of the modeled restoration: the height of the cusp, the severity of the relief, the curvature of the walls, etc. When the modeling is completed, the file with the restoration model is sent to the milling machine.

The restoration that was modeled in the previous step is automatically turned on the milling machine. How this process looks like is shown in the video below. Standard ceramic or metal blanks are used as the material.

The idea of ​​using a CAD/CAM system for the manufacture of dental restorations appeared in 1971. The first prototypes were bulky and awkward to use. In addition, the scanners used to create virtual models produced strong distortions. Today these problems are solved. The accuracy of the "digital impression" is not inferior to the impression obtained by the classical method. The software has improved significantly, and the process of virtual modeling of the future restoration has turned into creativity. The accuracy of milling machines has also improved due to the simultaneous use of several cutters and the reduction in their diameter. The following cad/cam systems are presented in Russia today: Cerec, Organical, Katana, etc.

Crowns made using different technologies may not differ in appearance. In any case, the patient will receive a highly aesthetic restoration that restores the beauty of a smile and the function of chewing food. However, the use of cad/cam systems makes it possible to simplify and speed up the production of restorations:

Firstly, the total time required to create a crown, inlay, etc. is reduced.

Secondly, instead of traditional impression materials, the doctor can use an intraoral scanner that "digitizes" the situation in the oral cavity. This eliminates the need for the patient to go through the procedure of taking conventional impressions. This is especially relevant for people with a pronounced gag reflex.

The patient directly SEES how the doctor first models an individual crown on the computer, which is then automatically machined from the ceramic block. It is beautiful)

The preparatory stage for prosthetics using CAD / CAM technology coincides with the traditional preparation of the oral cavity for treatment. It includes professional hygiene and sanitation of the oral cavity, restoration and preparation of abutment teeth.

For ideal aesthetics, individualization of the finished restoration is required: its tinting by a dental technician. This may require a separate visit.

High cost of treatment.

Using CAD / CAM, you can create any fixed structures: both all-ceramic and metal. Crowns, inlays, veneers, custom abutments, bridges, surgical guides. The range of application of this technology is constantly growing.

Before prosthetics, as a rule, it is required to perform some preparation of the oral cavity. The volume of preparatory treatment is determined by the treatment plan, which is drawn up during the consultation at the first visit to the dentist. This preparation is called “oral sanitation” and may include the following steps:

Removal of dental deposits (calculus and plaque) not only immediately improves appearance teeth, but also eliminates the source of possible future inflammation. This procedure is performed by a hygienist. At this stage, you will also learn how to properly care for your oral cavity. This is a guarantee of the long-term functioning of any restoration and structure after the completion of the main treatment.

It is performed by a dental surgeon. Often, before prosthetics, it is necessary to remove teeth or roots of teeth that cannot be restored. Such teeth include severely destroyed, mobile teeth, teeth with foci chronic inflammation at the tops of the roots. In case of insufficient volume of bone tissue for implantation of teeth, a preliminary operation is performed to increase it.

Treatment of caries, periodontitis, diseases of the oral mucosa, replacement of old fillings. Endodontic treatment of teeth before restoration and crowning. The need for the described manipulations in each case is decided individually. An orthopedic doctor must be confident not only in his work, but also in the quality of the work done before him. Therefore, in some cases, retreatment of the root canals of the teeth is necessary.

Bleeding gums, bad breath, loose teeth, and periodontal pockets. These symptoms are indicative of periodontal problems. They must be eliminated before dental prosthetics.

Thanks to orthodontic treatment methods, it is possible to move or change the inclination of the teeth. This preparation takes certain time(from 2-3 months to 2-3 years). However, it allows you to avoid depulpation and "grinding" of protruding or deformed teeth.