Buyers Guide: Digital Impression Systems

Facebook

What I Need to Know
The Questions to Ask
Definitions

Dentalcompare

Clinical Director

Why Digital Impressions?

Switching over to digital impressions can seem like a tremendous hurdle. But similar to switching to digital x-rays, you will find the accuracy and efficiency of these systems to be superior to your current workflow. And you’re likely to find yourself reluctant to ever go back.

Consider the traditional impression: You inject some material into the patient’s mouth, and this material fights air, water or blood to cover over the surface of the tooth. The material has its own inherent characteristics of hydrophilicity, expansion and contraction that can lead to inaccuracies. Pulling the impression away from the other teeth tests it elasticity and ability to return to the exact same shape. Then, during the next couple of days, the impression gets shipped in a hot UPS truck to your lab where stone is poured into the impression, adding its own potential for setting expansion or bubbles in the equation. Then with all these potential problem points, add in the fact that the gagger patient has not had the greatest experience in your office.

Benfits of Digital Impressions

Highly accurate
Faster than using traditional impression material
Digital storage of models
Better fitting restorations
Faster turn-around time in lab
Practice builder

Digital impressions skip all of that. Most systems now can capture a digital copy of the tooth in under a minute, making the process efficient and gag-free. The digital model can immediately be read for any inaccuracies, and can be sent to the lab over an internet connection for approval and fabrication of the crown, bridge or other restoration. The finished restoration returns from the lab sooner and because of the accuracy of the digital model, they rarely need much in the way of adjustments prior to seating.

An often overlooked benefit is that, there is no model for you to store. Every dentist has a lab filled with case pans filled with old models being kept for a variety of reasons. Digital impressions can be stored on a hard drive, taking up minimal space. This feature alone would change the architectural design of most orthodontic practices out there.

Perhaps one of the more intangible benefits to digital impressions is the reaction from the patient. Not only is it an improved experience, but it highlights your office as progressive and high-tech.

How Digital Impressions Work: Each of the available digital impression systems relies on a proprietary imaging system to capture a three-dimensional digital picture of the intraoral anatomy. But while the specific methods of image capture differ, the basic principles are the same. The surfaces being scanned are illuminated under a specific light—usually a laser beam or a projected pattern—and the way the light interacts with the surfaces is recorded to plot distances from the camera. A computer processes these plot points—sometimes combining it with reference points from simultaneously captured 2D images—to create an accurate 3D digital model of the area being scanned.

Why Some Scanners Require Powder: Some scanners measure the reflection of projected light and require a uniform reflective surface in order to capture data accurately. Because substances such as enamel, dentin, gingiva, blood and saliva have different reflective qualities, a scanning medium (powder) is used coat the intraoral surfaces to give them identical reflective properties without altering their contours.

What Will Be Different After Going Digital: One of the most important things to understand is that your workflow will be different, but more efficient. If you are used to your dental assistant handling all the impressions, her or she can be trained to use the machine to continue in this role. Shifting to digital impressions frees up time for them by eliminating the time for setting, possible re-takes, packaging and more. With digital impressions your office also can eliminate much of the cost of dental impression consumables.

		
			Questions to Ask
	
What is the size of the scanner camera? Does that feel comfortable in for me and my assistant to use?
Does the system use powder for scanning? Most say this is not a difficult step, but it is important to understand the workflow you’ll be introducing to your practice. 
What type of cases can the scans be used for? (i.e. restorative, orthodontic, etc.)
What type of training and support is available?
What options do I have with where I can send scan data?
Are there data fees or scan fees after the initial purchase?
Is there a fee for submitting the scan to my lab?
Which labs work with this particular scanner?
Is there an upgrade path to in-office milling?

Active Triangulation – A laser or other light source is used to scan the object with a camera used to detect the laser’s reflection to determine the precise distance of the object from the scanner via trigonometric triangulation.

Active Wavefront Sampling – Multiple image sensors capture live images from different perspectives, capturing distance information by using a wide aperture and measuring the distance of the object being scanned from the focal plane of the lens. These images are stitched together via software algorithms to create a real-time 3D model.

Computer Modeling – Scan data is collected by a computer and recorded as data points in a three dimensional space which is processed by the software to create the virtual model. In some systems a camera also records color and texture information in 2 dimensions which is overlayed on the 3D model and incorporated into the final outcome.

Confocal Imaging – A technique that allows images to be captured at various focal depths and then reconstructed by a computer to create three-dimensional topographic models of complex objects.

Structure Light scanning – A series of linear patterns are projected on the object being scanner with either a white or blue light and a camera detects the edges of the lines in the pattern to determine the distance of the object from the scanner.