CEREC
Cerec , in its own notation CEREC ( Chairside Economical Restoration of Esthetic Ceramics or CEramic REConstruction ), is a CAD / CAM method for the reconstruction of tooth restorations. The process enables dentists to save time and efficiently design, manufacture and use individual ceramic restorations directly at the treatment unit ( chairside ) in a computer-aided session. The first patient applications were successfully carried out in 1985.
Model history
The Cerec method was developed in 1980 by Werner H. Mörmann and Marco Brandestini at the University of Zurich . The first patient treatment with Cerec using the ceramic VITABLOCS Mark I took place in 1985. Siemens acquired the license to market and further develop the Cerec method in 1986 and in 1987 launched CEREC 1, the world's first CAD / CAM system in dentistry. The range of indications for the Cerec-2 system introduced in 1994 comprised inlays, onlays, crowns and veneers . Sirona emerged in 1997 from the sale of the dental division of Siemens AG . In 2000, the Windows- based Cerec 3 system was presented. While the first three model versions only worked two-dimensionally, the software introduced in 2003 enabled the dentist to create computer-aided design on virtual 3D models. Until 2007, all-ceramic crowns could only be cemented adhesively; With the MC XL generation of grinding machines, which appeared in 2007, crowns could also be cemented due to increased manufacturing precision. In 2009, Sirona switched the recording technology to (shorter-wave) blue light with the Cerec-Bluecam, which increased the recording accuracy compared to the previous 3D camera. Using a biogeneric technology mentioned that models the dentures in consideration of surrounding teeth mathematically, let the since 2010 occlusal reconstruction. In 2011, software version 4.0 made it possible to process several restorations in one work process (multiple restorations). In 2019 the Cerec Primescan intraoral camera was presented, which has improved handling, simplifies the scanning process, and is more precise and faster.
Technical process description
The tooth to be restored is digitized using an intraoral camera and a 3D model is created. This can be displayed and processed on the monitor ( computer-aided manufacturing ). In order to be able to take into account the physiological occlusion position and thus avoid subsequent grinding, a corresponding counterbite can also be included in the calculations. With the help of the copy-milling process , the calculated restoration (usually an inlay ) is milled in a three-axis milling machine ( CNC machine ) from an industrially manufactured ceramic block.
Cancer suspected in connection with the Cerec procedure
Specular reflections disrupt the image recording in the Cerec process, which can lead to errors in the 3D model. To avoid such artifacts, matting powders or sprays are used. In one case involving a dentist, which is currently being tried in court, such a powder is suspected to cause Waldenström's disease, a cancer of the lymphoid tissue.
It is a contrast powder containing titanium dioxide . Since 2018, titanium dioxide has been tested by the Community rolling action plan (CoRAP) of the European Chemicals Agency ( European Chemicals Agency , ECHA) with regard to possible carcinogenicity and mutagenicity . Due to the changed assessment, one manufacturer withdrew the powder from the market. Other manufacturers of comparable products continue to use titanium dioxide as an ingredient.
advantages
The further development of the procedure has made it possible to reduce the number of reworking and time-consuming occlusion adjustments that used to be necessary. According to studies, the strength of the material in the 10-year survival rate of computer-controlled milled inlays is higher than that of individually manufactured laboratory-made ceramic inlays.
disadvantage
Cerec crowns or inlays are usually glued ( adhesive technique ). In cases where the use of this technique is not possible, Cerec cannot be used. This applies, for example, if the tooth to be restored has the possibility of fatigue fractures.
The marginal fit and the aesthetics are better with laboratory-made inlays. The preparation shape must be adapted to the material properties of the computer-controlled milled inlays.
Furthermore, occlusal surfaces were a problem for a long time, which often required post-processing and time-consuming occlusal adjustments.
Individual evidence
- ^ WH Mörmann: Ceramic inlay - the posterior filling of the future. Lecture on March 30, 1985, Karlsruhe, “25 Years Academy for Dental Training, Karlsruhe”. 4th International Quintessence Symposium 1985.
- ^ WH Mörmann et al.: Marginal adaptation of adhesive porcelain inlays in vitro. In: Switzerland Mschr Zahnmed. 95, 1985, pp. 1118-1129.
- ↑ T. Otto, D. Schneider: Long-term clinical results of chairside Cerec CAD / CAM inlays and onlays: a case series. In: Int J Prosthodont. 21 (1), 2008, pp. 53-59.
- ^ WH Mörmann: Innovations in aesthetic restorations in the posterior region (ceramics): Computer-aided systems. In: Dtsch Zahnärztl Z. 43, 1988, pp. 900-903.
- ↑ Bernd Müller: An inlay, a crown in just ten minutes. on: welt.de , January 8, 2010.
- ^ A. Mehl, A. Ender, W. Mörmann, Th. Attin: Accuracy testing of a new intraoral 3D camera. In: Int J Comput Dent. 12, 2009, pp. 11-28.
- ↑ An interdisciplinary research group led by Albert Mehl from the University of Zurich and Volker Blanz from the University of Siegen found that all of a patient's teeth have individual characteristics that can be transferred from one tooth to another.
- ^ A. Mehl, V. Blanz: New procedure for fully automatic occlusal surface reconstruction by means of a biogeneric tooth model. In: J Comput Dent. 8, 2005, pp. 13-25.
- ^ A. Mehl, V. Blanz, R. Hickel: Biogeneric tooth: a new mathematical representation for tooth morphology in lower first molars. In: Eur J Oral Sci. 113, 2005, pp. 333-340.
- ↑ Anne Kunze: Powder under suspicion. In: The time 2019/52. zeit.de, December 11, 2019, accessed December 15, 2019 .
- ^ Substance evaluation - CoRAP , ECHA. Retrieved December 15, 2019.
- ↑ Vita Zahnfabrik: Urgent safety information on CEREC Powder from VITA Zahnfabrik H. Rauter GmbH & Co. KG. BfArM, March 20, 2018, accessed December 15, 2019 .
- ↑ 3M: Safety Data Sheet 3M ™ HIGH-RESOLUTION SCANNING SPRA. Retrieved January 23, 2020 .
- ↑ R. Hickel, K.-H. Kunzelmann: Ceramic inlays. ( Memento of the original from September 23, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. In: Ceramic inlays and veneers. Hanser Verlag, Munich 1997, accessed on April 12, 2015.
- ^ GV Arnetzl, G. Arnetzl: Design of preparations for all-ceramic inlay materials. In: International journal of computerized dentistry. Volume 9, Number 4, October 2006, pp. 289-298. PMID 17343243 .
