CEREC is a dental restoration product that allows a dental practitioner to produce an indirect ceramic dental restoration using a variety of computer assisted technologies, including 3D photography and CAD/CAM.
With CEREC, teeth can be restored in a single sitting with the patient, rather than the multiple sittings required with earlier techniques. Additionally, with the latest software and hardware updates, crowns, veneers, onlays and inlays can be prepared, using different types of ceramic material.
The cavity preparation is first photographed and stored as a three dimensional digital model and proprietary software is then used to approximate the restoration shape using biogeneric comparisons to surrounding teeth. The practitioner then refines that model using 3D CAD software. When the model is complete a milling machine carves the actual restoration out of a ceramic block using diamond head cutters under computer control. When complete, the restoration is bonded to the tooth using a resin. CEREC is an acronym for Chairside Economical Restoration of Esthetic Ceramics.
The treating dentist prepares the tooth being restored either as a crown, inlay, onlay or veneer. The tooth is then coated with a white powder, imaged by a 3D imaging camera and uploaded to the CEREC computer.
Using the proprietary CEREC software in various modes, a restoration can be designed to restore the tooth to its appropriate form and function. This data on this restoration is stored in a file and is sent via wireless serial transmission or direct wiring to a milling machine. The restoration can then be milled out of a solid ceramic or composite block. Milling time varies from as little as four minutes to as long as twenty depending on the complexity of the restoration and the age of the milling unit.
The design software for the CEREC system has undergone significant changes in the years since the technique was first introduced by Professor Mormann. Currently, a dentist can choose from four major design approaches.
Database This design mode uses a library of tooth shapes that is stored on the computer to suggest the shape of the proposed restoration. The proposed restoration can then be morphed to fit into this zone in an anatomically and functionally correct position. The dentist can then make correction to this proposal as he sees fit.
Reflection The dental restoration is modeled according to the antagonist tooth of the same jaw.
Copying The original tooth or a wax model fabricated by a dental technician is used as a model for the dental restoration.
Biogenerics An anatomically suitable restoration is fabricated based on the data about the reciprocal relations with the teeth of the opposing jaw.
The ceramic material has some properties that make it very suitable for use in dental restorations. It expands and contracts in response to temperature changes at a rate approximately half-way between those of enamel and dentin. It also wears away at approximately the same rate as enamel. There is also a composite material available which has some advantages in restoring smaller inlay type restorations.
Advantages Time savings. You usually only have to go one time, as opposed to two trips for a traditional crown. This also reduces the number of local anesthetic injections (shots) needed.
More conservation of tooth structure. Oftentimes a partial coverage restoration can be completed vs a full conventional crown.
Stronger porcelain. Milled ceramic is stronger than hand layered and pressed.
Esthetics. Homogenous porcelain blends in better than other porcelains.
Natural. Ability to copy what was there previously can yield restorations that are duplicates of the pre-prepared tooth.
DisadvantagesRequires investment of time and money for dentist to obtain and learn.