CEREC

[edit] Technology

CEREC 1 2 and 3 from Sirona

CEREC is a dental restoration product that allows a dental practitioner to produce an indirect ceramic dental restoration using a variety of computer assisted technologes including 3D photography and CAD/CAM. The restoration of a tooth, (or teeth), can be performed in a single sitting with the patient. 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 derived from CERamic REConstruction.

[edit] History

The system is manufactured by the Sirona dental technology company.

1980 Development of the CEREC method at the University of Zurich W. Mörmann, M. Brandestini). 1985 Treatment of the first patient with CEREC (University of Zurich, material: VITABLOCS® Mark I). 1986 Siemens acquires the license to market and further develop the CEREC equipment. 1987 CEREC 1 is introduced (chief indication: single and dual-surface inlays; material: VITABLOCS® Mark II). 1990 International CEREC Symposium at the University of Zurich. 1991 Hydraulic machining drive replaced by an electronically controlled motor. 1994 CEREC 2 is introduced (range of indications: inlays, onlays, veneers). 1996 CAD/CAM Symposium to mark a decade of CEREC (University of Zurich). 1997 Sirona was formed as the result of the sale of the Dental Division of Siemens AG. 1997 CROWN 1.0 program for producing full-ceramic posterior crowns. 1998 Second material manufacturer partnership is formed (lvoclar, ProCAD®). 1998 CROWN 1.11 program for producing posterior and anterior restorations. 2000 CEREC 3 is introduced (compact Windows®-based CAD/CAM system). 2000 Third material manufacturer partnership is formed (3M Paradigm™ MZ100). 2002 More than 2,500 CEREC users in the United States and over 5,000,000 CEREC restorations placed worldwide. 2006 CEREC Celebrates 20 Years

[edit] Technique

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.

[edit] Design Methods

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. Most commonly a recording of the bite registration (the imprint of the opposing or antagonist tooth in a wax like or rubbery material) is also added to the data the software can use when deciding the proposal. This data together with a 3D optical imression of the prepared tooth establishes the approximate zone with which the new restoration can exist. 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 and then send it to the milling unit for completion.

[edit] Materials

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.

[edit] Advantages / Disadvantages

The main advantage of the CEREC system is the possibility to create full ceramic restorations in one sitting at the chairside. This can be a tremendous convenience to the patient and reduce the number of local anesthetic injections needed. It also allows for greater efficiency in the dental office and ultimately reduce the costs to the dentist of fabricating and placing the restoration. One of the major draw backs is the need to powder the teeth prior to taking the optical impression. In addition, all ceramic restorations may not be indicated in all patients or on all teeth. The cost of obtaining this system is high and extra training is necessary to become proficient at this technique.

[edit] External links

• Sirona company on the WWW
• CEREC pages of the manufacturer
• The largest CEREC community on the WWW

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