From USA Today. April 6, 2014
Suffer a cracked or broken tooth and your dentist is likely to recommend a crown, a custom-fitted cap to cover it and restore the tooth’s shape, strength and appearance.
Traditionally that meant having a model of the tooth and surrounding area made using a mold, sending the impression to a dental laboratory to make the crown, having a temporary restoration put in place, waiting a week or more for the finished crown to be sent back to the dentist’s office and returning for a second visit where the temporary is removed and the new crown is cemented into place.
In the last several years, however, an increasing number of dentists have embraced a quicker option. Using computer-aided design and computer-aided manufacturing (CAD/CAM) technologies, many have begun making crowns in one-office visit while the patient waits.
After taking a digital scan of the mouth using an intra-oral camera (think of an over-sized pen with a video camera on the end), a 3-Dimage of the teeth and gums appears on a computer screen. Based on the position, size and shape of the damaged tooth, computer software suggests the ideal dimensions of the needed crown. The dentist fine-tunes the virtual restoration and sends the digital information to a “milling” machine that carves the crown out of a ceramic block, ready to be bonded to the patient’s tooth. The entire process takes less than two hours
Commonly referred to as a “same-day crown,” or a “crown while you wait,” the procedure is one of several advancements that reflect the growth in digital dentistry. Others include:
•Digital radiography or X-rays. Compared to traditional film X-rays, these computer-generated images produce a clearer image in a shorter time and have been shown to produce significantly less radiation.
•Cone-beam computed tomography (CT) imaging. The dental equivalent of a medical CT scan, the X-ray rotates around the patient’s head capturing a 3-D view of the teeth, jaw, gum and nerves. It can also identify possible tumors and other diseases that don’t appear on traditional X-rays.
•Digital dentures. Made using computer design and digital manufacturing, they offer the convenience of a permanent digital record that can be duplicated easily if the original denture is lost or damaged.
From the recording and creation of restorations to office management, “a full digital integration of clinical care, diagnostics and patient communication” is occurring at some dental offices today, says John Weston, a cosmetic dentist and director of the Scripps Center for Dental Care in La Jolla, Calif..
Adopting these advances is about finding ways “to improve the experience for patients,” says Steven Spitz, a prosthodontist (specialist in the restoration and replacement of teeth) at Smileboston Cosmetic and Implant Dentistry in Brookline, Mass.
Special lasers, for example, can be used in procedures from detecting cavities and placing fillings, to placing dental implants, often eliminating the need for scalpels, drills and sutures. “That means less pain and trauma for the patient and often the need for little or no anesthetic,” Spitz says.
And before cone beam CT imaging, there was a lot more guess work involved in placing implants, he says: “Today, this can be done with precision.”
Many dentists use digital imaging technology solely to make virtual models that they then send to dental labs where ceramists fabricate the actual crowns or bridgework, says Leila Jahangiri, professor and chair of the Department of Prosthodontics at New York University College of Dentistry.
The use of digital technology to make crowns and other dental restorations is not new. The first dental CAD/CAM system for the in-office production of ceramic crowns and inlays was introduced about 25 years ago. And dental labs have been digital “for years, using commercial milling machines and all kinds of digital processes,” Weston says.
“Initially, it was just a few early adopters” using it in the office, he says. Even now, research suggests that “a small percentage, maybe about 10%,” have implemented it,” he adds, noting that purchasing the equipment and getting started with the needed supplies can cost $150,000 to $200,000.
Over the years, “the materials have gotten better, the mills have gotten better, but the main thing is that the digital capture has gotten more accurate,” Weston says. “And when you improve that, now you can improve the fit and that’s the goal.”
Because the in-office equipment saves on lab costs, dentists say they don’t charge more for a one-day crown than the traditional version. That’s supported by a limited analysis in New York that found “the costs were identical, whether chair-side or lab fabricated,” Jahangir says. “People are not very tolerant of a huge difference (in dental prices) in the same geographical area,” she says.
“The technology is expensive, but on the other hand it makes me more efficient,” Spitz says. “I can prepare and finish four or five crowns in half the time another dentist may do half as many.”
Both types of crowns are typically covered by dental insurance, says Bill Kohn, vice president of dental science and policy for Delta Dental Plans Association, the nation’s largest dental benefits carrier.
“When dentists submit for a porcelain crown, we just look at it as crown. We don’t’ know whether it was done chair-side or whether it was done in a laboratory,” he says.
Dentists who offer same-day crowns often limit it to a single restoration at a time, Weston says when multiple crowns, a bridge or a very visible restoration in the front of the mouth requiring “a more accurate and more aesthetic” fabrication is needed, it’s typically sent to a lab. That kind of time-consuming and sophisticated work “just can’t be done chair-side as easily,” he says.