Seeing through to the margins

D4D Technologies has big plans to improve digital impression capabilities through the use of optical coherence tomography.

Digital impressioning and CAD/CAM technologies offer clinicians and lab technicians numerous efficiencies in designing and fabricating dental restorations, but their impressive capabilities still have certain limits. Quite often these limits come into play when subgingival margins need to be incorporated into the design of the final restoration.

D4D Technologies' E4D™ CAD/CAM systems now use a laser and micromirrors to capture a 3D image of the true intraoral anatomy. However, as with other digital impression systems currently on the market, a clinician using an E4D system must properly prepare the tissue in order to expose subgingival margins for an optical scan.

"If the camera can't see margins and tissue separated then you can't see it on your computer screen," explained Lee Culp, CDT, Vice President of Technology Development for D4D.

Enter OCT

But Culp said D4D will eventually be able to simplify the preparation and make the scanning process far more comfortable for patients by supplementing the current laser scanning technology with new proprietary optical coherence tomography (OCT) technology that can scan through tissue and capture margins subgingivally. OCT imaging is already in use in ophthalmology and will offer a range of diagnostic advantages including caries detection, periodontal assessment and oral cancer screening when it is available for dental use; more importantly, D4D sees a huge opportunity for OCT use in optimizing the capture of digital impressions.

"It will be a tremendous added value to what we are doing now," Culp said. "With OCT you can scan right under the tissue and the computer will be able to separate tooth structure from tissue."

In fact, from the time they founded D4D Technologies, brothers Mark and Henley Quadling envisioned using OCT imaging to produce the digital impressions used by their CAD/CAM systems. They've always been aware of the potential benefits of the technology since it was invented approximately 20 years ago, but have not yet implemented it because OCT scanning speeds and costs are not yet practical for clinical use by dentists and lab technicians.

"In CAD/CAM, as well as a lot of the diagnostic applications, it's far superior to x-ray," said Henley Quadling, who described the imaging technique as a laser version of ultrasound that provides higher resolution images because the laser has a smaller wavelength than the sound waves used in ultrasound. OCT imaging is capable of penetrating solid tissues to a depth of 3 to 4 mm.

"OCT works in the infrared domain. There are absolutely no radiation issues like you have with x-ray," he said. "You look at the light scattered from inside along the beam of laser into the tooth or the gums, and you look at the returned light and you can, just like in ultrasound, detect all the surfaces along that beam of light. Not only can you see all the structures that are below the surface, but you can detect what kind of materials they are."

OCT and digital impressions

These capabilities can add a lot to a digital impression captured intraorally. OCT scans provide an extremely high level of detail of the anatomies being scanned. Culp said OCT is capable of capturing more details than the current scanning technologies, and the additional digital details can lead to even more precisely designed and milled restorations.

Accurately capturing margins subgingivally will mean an easier digital impression process for both dentists and patients. The process will require fewer pre-scanning preparation, and with retraction of tissue no longer a part of the process, it should be more comfortable for patients. In addition to capturing subgingival margins for crowns, OCT technology will also make it possible for digital impressions to examine and measure periodontal pockets without intrusion, Mark Quadling said.

Implementation obstacles and opportunities

The technology required to capture intraoral scans via OCT exists today, but Culp said D4D is still several years away from incorporating it into their systems. Henley Quadling said the company is working on improving the technology in ways that will increase the scanning speed while simultaneously reducing the cost to manufacture and deliver the technology.

When D4D develops OCT to the point where it can integrate seamlessly with their current laser scanning technology in terms of those two issues, the company plans to make it their standard digital impression technique. The implementation of OCT will also bring all of the technology's diagnostic applications to E4D dentists. Still, Mark Quadling said he believes the CAD/CAM applications have the biggest potential to benefit practices and labs using the E4D systems.

"Our main interest is in the tremendous opportunities on the CAD/CAM side, but the diagnostic aspect also has great potential," he said. "For us it's very important that every solution we offer leads to a better diagnosis and treatment, ultimately resulting in a better patient experience and better dentistry."

This article was written by Noah Levine, Senior Editor of Dental Products Report. you can read the original article at http://www.dentalproductsreport.com/articles/show/dpr0909_we_d4d-digital.