New Technologies in Dental Prosthetics

Razvoj računalne tehnologije podigao je dentalnu medicinu na novu razinu funkcioniranja. Razvojem CAD/CAM sustava počeli su se upotrebljavati novi materijali za strojnu obradu poput oksidnih keramika, glinične keramike i staklokeramike. CAD/CAM sustavi imaju tri osnovne jedinice: skener, računalo s primjerenim softverom te stroj za glodanje. Postupak počinje snimanjem usne šupljine intraoralnom 3D kamerom ili uzimanjem otiska konvencionalnom tehnikom pa snimanjem radnog modela. Računalo na monitoru očitava podatke iz kamere, koje je potom moguće virtualno obraditi. Stroj za glodanje, zatim, na principu suptrakcije iz bloka pripremljenog materijala, oblikuje nadomjestak po zadanim parametrima. Blokovi za glodanje mogu biti presinterirani ili sinterirani. Presinterirane blokove potrebno je predimenzionirati, ali ne izazivaju napetost u strukturi nadomjeska. Alternativno, nadomjestak je moguće izraditi adicijskom metodom, 3D printanjem. Stroj obrađuje mješavinu praška i tekućine u slojevima i pomoću potpore gelastog materijala iz njih oblikuje nadomjestak. Adicijskom metodom ne mogu se obrađivati keramike. Materijali koji se mogu obrađivati strojno su kobaltove krom legure, titan i njegove legure, polimeri, keramike i voskovi. Staklokeramički nadomjesci pogodni su za prednji segment zubnog luka zbog translucencije slične onoj prirodnim zubima. Oksidne keramike odlikuju se biokompatibilnošću, otpornošću na trošenje i estetikom. Njihova dobra mehanička svojstva proizlaze iz malog udjela staklene faze i velikog udjela kristala. Cirkonij oksidna keramika prvi je potpuno keramički sustav iz kojeg se mogu izrađivati veći protetski radovi i sanirati lateralni segmenti zubnog niza.The development of computer technology has raised the dental medicine to a new level of functioning. With the development of the CAD/CAM systems, the usage of new materials for milling processes such as oxide ceramics, alumina ceramics and glass-ceramics had begun. CAD/CAM systems have three basic units - a scanner, a computer with an appropriate software, and a machine for milling. The procedure begins by scanning the mouth with an intraoral 3D camera, or by making dental impressions with the conventional technique and scanning the working model. A computer monitor reads the data from the camera, which can then be virtually processed. The machine for milling then uses the principle of subtraction to form a restoration from a block of the material by the given parameters. Blocks for milling can be presintered or sintered. Presintered blocks need to be oversized but do not cause tension in the structure of the restoration. Alternatively, restoration can be made with an addition method, 3D printing. The machine processes the mixture of powder and liquid in layers and, by using the gel material as a support, forms the restoration. The addition method cannot process ceramics. Materials that can be processed by machine are cobalt-chromium alloys, titanium and its alloys, polymers, ceramics and waxes. Glass-ceramic restorations are suitable for the front segment of the dental arch because of translucency similar to natural teeth. Oxide ceramics are praised for their biocompatibility, wear resistance and aesthetics. Their good mechanical performance is a result of a low share of glass phase, and the large proportion of crystals. Zirconium oxide ceramics are the first all-ceramic material which can be used to rehabilitate the lateral segments of the dental arch, and to create bigger restorations