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April 2009 | Dental Products Report
Technology Technique 

How to use the latest in cad/cam
With CEREC AC powered by Bluecam, imaging technology takes a leap forward.

by Dr. Sameer Puri

Chances are you’ve been exposed to some aspect of CAD/CAM in your life. Everyday objects, from simple to complex, most likely have been designed by a computer and fabricated from a computer-generated design. There is no reason, then, that CAD/CAM cannot have the same influence on dentistry.   

CEREC® AC powered by Bluecam Features

• The CEREC AC powered by Bluecam is a significant leap forward in dental imaging technology, and will result in accurate imaging with a minimum amount of complexity.
• Senses optimal moment for digital impression acquisition; captures it automatically
  Advanced optical technology yields precise 3D models
  Speedy acquisition times 

Sirona Dental Systems
cereconline.com  800-873-7683 

With tens of thousands of users worldwide, a leader in dental CAD/CAM technology is the CEREC® System from Sirona Dental Systems. Users have successfully placed millions upon millions of restorations over the years using the system. Its success has led to the evolution of competitive products, some of which can design and mill chairside similar to the CEREC, while others only image the prepared tooth and send that information to the lab digitally, thereby eliminating the need for traditional impressions.

Through a natural evolution, the next generation of the CEREC System, CEREC AC powered by Bluecam, is now available. The CEREC AC (Acquisition Center) uses a newer, more accurate and precise camera system based on improved optics as well as an intense blue wavelength LED. Other technologies have converted to the blue wavelength of light including Blu-ray Disc players, which were created to replace the red laser in CD and DVD players and are the new standard of extremely high-resolution playback technology available to consumers. Because of the accuracy of this technology, it is only natural that this precision be adapted to the dental imaging application. 

The indications with the CEREC AC are increased. While the previous version of CEREC was extremely capable with single-tooth images, larger quadrants were more difficult for the novice user to capture.

With the CEREC AC powered by Bluecam and the latest CEREC software, users now are able to image quadrants for fabrication of temporary bridges (Fig. 1). These bridges can be milled from different high-strength composite materials (Fig.  2) in either of the two available milling units from Sirona. This material also is optimal for long-term provisionals, implant stents and mockups for anterior restorations. 
Quadrant and full-arch models can be created (Fig. 3) with ease and accuracy, allowing the user to open a new range of indications such as larger, more comprehensive cases, multi-unit anterior and posterior cases, as well as the ability to send this data to the laboratory with CEREC Connect for fabrication using virtually any material.

The following procedure using the CEREC AC requires the dentist to apply a light coating of opaquing medium (CEREC Optispray) on the operative field. This step, which takes a matter of seconds, provides a slight opacity to the operative field so the camera can most accurately see what is being imaged. Once the field is prepared, the user holds the camera over the teeth. As the camera is held still, it automatically captures the information from the teeth and creates a digital impression. It is no longer necessary to click a foot pedal  to capture an image.
As the dentist moves the camera further along the arch and holds it still again, it will take another image. The dentist continues to acquire images until the desired amount of arch form is captured.

Clinical case

(refer to slideshow for figures) 

The patient presented with defective amalgam restorations in the upper arch that required replacement (Fig. 4). To fabricate the most accurate anatomy, the built-in Database Design technique was chosen for this case.

Septodont’s Septocaine® anesthesia (septodontusa.com) was given to the patient, and an Isolite™ (isolitesystems.com) was placed for isolation. The teeth were definitively placed.

In areas of subgingival preparation, a laser was used to remove inflamed gingival tissues and to allow access to the margins of the restoration  for imaging and bonding (Fig. 5).

The teeth were prepared with Optispray opaquing medium (Fig. 6) and images were made of the prepared quadrant (Fig. 7). The resulting high-resolution digital impression can be checked for accuracy from any angle.

Once the model was fabricated, a bite registration was taken to gain occlusal information. I used DMG America’s Dental’s LuxaBite™ (zenithdental.com), and the resulting bite registration was trimmed, opaqued and imaged.

The design time for creating the two restorations (Fig. 8) was about 2 minutes per tooth, after which the restorations were sent to the Sirona MC XL milling unit. The milling chamber mills out the partial-coverage restorations in approximately 5 minutes each, after which they can be tried in for fit.

The restorations were stained, glazed and cemented with Ivoclar Vivadent’s Multilink® dual-cure resin cement (ivoclarvivadent.com). The occlusion was verified, and the patient was sent home with new all-ceramic restorations (Fig. 9).

The resulting procedure can be completed quickly with minimal discomfort to the patient and, more importantly, in one visit.