Expertise
CEREC
CEREC 4.0
The Cerec system (manufactured by Sirona Germany and distributed by Paterson Dental Co., Sr Paul, MN) was introduced in the United States in 1996. It requires the use of an anti-reflective white powder containing titanium oxide to improve the contrast of the tooth.
A scanner with infrared CCD sensor is used to obtain a 3D image of the preparation in 0.1 second and at a resolution of 25 µm. The digital image is displayed on the screen of the stand-alone microprocessor where the dentist designs the restoration.
Cerec technology makes it possible to fabricate porcelain inlays, crowns and veneers that are both aesthetic, simple and made in one visit. Version 4 of the Cerec system makes it possible to fabricate an individual permanent or temporary restoration as well as a temporary fixed partial prosthesis from a block of acrylic. The system also contains a block that functions as a modeling unit for a cast metal crown.
Additionally, the system includes a portable milling machine that can be used in the dentist's office. The clinician can send the design and digital impression electronically with Cerec Connect to the external laboratory for the fabrication of casts , multiple units , fixed partial dentures , implant abutments and crowns in zirconium or metal. Cerec can also be integrated with the Galileos system to build surgical guides for implant installation.
Cerec's Biogenetics software can analyze the occlusion and anatomy of adjacent teeth so that the restoration is tailored to each patient. Preparation assessment software (prepCheck) is included. It is a learning tool that provides analysis of a computer simulated tooth preparation or an actual tooth preparation scan.
CAD / CAM restoration materials
The progress of CADCAM technology go hand in hand with innovations in aesthetic restorative materials. Modern ceramic materials of the “one-piece” type have been designed to resist masticatory stresses and damage caused by machining.
The feldspathic ceramic materials have been largely replaced by the ceramic enriched in silica (feldspar, Ieucite and lithium disilicate), the ceramic without silica (alumina and zirconia) and a combination of materials based on resin and ceramic, which results in 3 to 11 times the flexural strength.
Computer simulation models show that a monolithic ceramic crown has better resistance to stress compared to material with ceramic core and porcelain coating. In addition, the difference in thermal expansion coefficients of internal and external materials can lead to stress that causes internal delamination or cracking of porcelain.
Advantages of CEREC crowns
Immediate crown fabrication
Crowns can be immediately fabricated, eliminating the traditional laboratory fabrication step.
Monolithic Crowns
Single-layer ceramic materials have better strength than double-layer porcelain.
Marginal integrity
The CAM crowns have the same marginal integrity than those made with the conventional method in the laboratory.