CAD/CAM in Dentistry

Activities CAD/CAM

Before the emergence of the innovative principle, casting was considered the best option, but there was also a soldering and stamping method, as well as sintering and superplastic molding. At all stages of the methods, the possibility of deformation, difficult to predict shrinkage, inaccuracies in fitting and similar problems that are leveled with a computer technique were not ruled out. Such problems could previously cause inaccuracies in the casting of blanks, their molding and fitting, non-compliance with the technology, such as overheating of the material.

If initially CAD / CAM was implemented in dentistry due to volumetric modeling of a fixed structure, which was created by milling with an accuracy of 10 microns, now science has taken a big step forward. When implementing the methodology, expensive cutters and blocks made of carbide materials had to be used. Naturally, the cost of the method was very high, but it was slightly optimized with the introduction of volume printing techniques in the everyday life of the expert community. As part of dentistry, doctors were able to create forms with any geometry of the external and internal surfaces. At the same time, the method is currently divided into several separate areas:

– wax seal;

– polymers;

– metal alloys;

– ceramics and gypsum.

The first direction involves the thermal effect, which melts the wax, the form is projected by drops. In fact, the method is considered more advanced, but requires the use of casting, which retains its drawbacks. Due to the high error when creating a casting, the accuracy of the modeling of the component practically loses its meaning.

The second direction is convenient because it allows you to create collapsible models of the whole jaw based on plastic, bearing systems made of ash-free raw materials and high-quality prostheses, including removable ones. The method is divided into two subspecies: thermal printing and light curing. The first option is good for ashless raw materials, thermoplastics, and the second for frames, crowns made of ashless raw materials, polyurethane or acrylates.

The first two methods are similar in principle to an inkjet printer, but the material is applied in three planes. Shrinkage is not observed due to the application of the composition with microscopic drops. Except for the simplest methods, which do not give high accuracy, they use the SHS (selective heat sintering) method in dentistry, which is divided into the inkjet and stereolithographic method (MJM and SLA, respectively).

Light curing is interesting in that the raw material does not need to be heated, since it is initially liquid. Its hardening occurs under the influence of blue spectrum light.

Stereolithographic technology is carried out in a bath with a liquid composite in which the object is repeatedly immersed. Hardening occurs in stages, in layers, and takes as long as it takes to create a specific object. The technology is good for high accuracy, resolution, smoothness of the finished sample. However, you can work with only one color, part of the raw material is not used for the prosthesis, in the process becomes unusable, which increases the cost of production. Similarly, the price rises due to the small resource of the bath and the laser.

The third direction, that is, metal printing, involves the fusion of the prepared material at a small point, due to the beam. Several techniques:

– direct deposition with the abbreviation DMD;

– spraying using an LDT laser;

– fusion with the participation of similar LCT equipment;

– freeform production of LFMT;

– deposition using a laser beam LMD;

– fusion using an LMF laser;

– sintering of a selective format using an SLS laser;

– direct sintering of DMLS;

– selective melting of SLM;

– focusing with an LC laser;

– melting according to the electron-beam technique of the computer;

– selective sintering SHS.

Each direction is distinguished by specific features, positive and negative sides. The final choice of technique depends on the technical equipment and the situation of a particular patient.

The fourth direction involves the usage of gypsum or ceramics. According to the release technology, the technique has much common features with SLS, with the difference that the work is not carried out by a laser, but a linking component acts as a catalyst. In this form, a special glue acts, interacting with particles of material. However, in dental practice, only the principle of working with ceramics found application, and gypsum gave way to composites that surpass it in many parameters. Ceramics, in turn, is promising for the creation of frames, bridges and crowns.

It is important to remember that not in any clinical situation an expert will be able to take advantage of volume printing when creating products. In some provisions, the best result can be obtained via using classical technology, which is not so bad due to the significant cost savings.