Digital impressions are reality with Cadent

The Cadent iTero system scanner uses a camera with a strobe effect (rapidly flashing blue light) that is first used occlusally, then from predetermined angles to capture the buccal, lingual and interproximal areas. The unit alerts the clinician when to change the position of the scanner and to where and at what angle.

These alerts are called out verbally and visually by the computer when the system is ready to acquire the next image in the series until both the arch and then the opposing arch have been captured.

Scanning does not require the use of powder first, instead relying on a color wheel in the scanner head. The scanning technology involves parallel confocal imaging using optical scanning and red-light laser. Accuracy is achieved with these focal depth images that are microscopic distances apart, and the scanner transmits more than 300 focal depths.

There is no need to use bite registration material with this system — the occlusion is captured digitally with the patient’s teeth in occlusion after which the dentist can view the interocclusal clearance and determine if it is sufficient for the planned restoration. Because imaging and viewing is real-time, the clinician can view the images and determine if preparation adjustments or repeat scans of isolated areas are necessary.

This system does not allow scanning to begin until the prescription for the restoration has been completed in the program. The scanned images are compiled digitally and the final images transmitted to Cadent where they are reviewed prior to precise milling of a polyurethane model that is used for the working and soft-tissue model by the dental laboratory.

Digital scans take less time than conventional impressions, including the bite “registration.” This increases the efficiency and productivity of the office. If the clinician carefully follows the scanning procedure and checks the onscreen images for margin visibility, preparation form and interocclusal clearance, it is possible to make adjustments to the preparation and take additional scans to ensure a precise result.

In addition to the speed of image acquisition as compared to traditional techniques, once the imaging technique has been learned, the digital images will be accurate for the laboratory, and repeat impressions at the request of the lab will not occur.

CAD/CAM (polyurethane) models are extremely accurate and not subject to shrinkage or expansion of materials, voids or other defects as are conventional stone models. They are also strong and durable, resulting in excellent marginal adaptation and fit of the restoration, and resistant to abrasion or chipping with no risk of the restoration being too large due to abrasion of adjacent teeth interproximally on the model or the occlusal surfaces of the opposing arch.

Virtual articulation and mounting of the models (iTero) also improves accuracy, and minor displacement of the resin dyes does not occur.

Keeping in mind that it has been stated that only 20 to 30 percent of impressions made and received by dental laboratories can be classified as “clinically excellent,” we as a profession have a way to go in ensuring the quality of our clinical work is kept to as high a standard as possible.

It is the author’s belief that optical impressions taken by systems such as iTero can help raise the overall quality of the service we provide our patients.

About the author

Dr Robert A. Lowe graduated from Loyola University School of Dentistry in 1982 and was an assistant professor in restorative dentistry until its closure in 1993. He is in private practice in Charlotte, N.C., and is the clinical co-chair for Dental Products Reports and Advanstar Dental Media.