September 11, 2000
Volume XXXIII, No. 33




HSC Profile

In Memoriam

Newly Granted

Question to the President



Endodontics draws on digital dental radiology


Digital dental radiology is more than the mere storage of patient X-rays; it’s a time saver. More important, it reduces a patient’s, dentist’s and assistant’s exposure to X-rays while also helping to keep the environment safer.

This latest technology, first employed by the Health Science Center’s Department of Endodontics more than a year and a half ago, has been integrated into treatment protocols to help diagnose and treat dental diseases.

"Digital imaging takes about one-fourth to one-sixth the exposure time that a traditional dental X-ray machine does; therefore the patient is subjected to less radiation during the exposure of a radiograph," said Dr. Bill Walker, endodontics program director and associate professor at the Dental School. "It’s instantaneous. There’s no need for sending films to get processed or waiting to see what they look like."

Patients still have to "open wide" and "bite down" with digital radiography, but instead of biting down on dental X-ray film, patients close their mouths around electronic sensors inserted by endodontists, who use Dell 266 Pentium II laptop computers to store and view the images and advise their patients on the best course of treatment. The result: No more trips to the developing tank for the dental assistant and no time wasted for the patient or dentist. While the images still resemble traditional X-rays, they’re captured at a higher resolution than film images and viewed as larger images on the 13.3-inch laptop screens.

Photo by Fernando Serna
Dentists work on root canal

Jeff Dryden, D.D.S., works with Tara Hodges, DS-IV, on Joseph Zavala’s root canal.

"The images pop up seconds after they’re taken; the patient can watch them come up on the laptop computer screen," said Dr. Walker, who notes the Dental School’s desire is to be totally digital. "The direct digital sensor is slightly larger than a traditional X-ray film."

The conventional way to X-ray teeth is with a piece of thin film that is moderately sensitive to X-rays. The greater the amount of X-ray beams passing through the mouth and teeth and exposing the film, the darker the image will be on the film. The soft tissues in the body (such as blood, skin, fat and muscle) allow most of the X-ray to pass through; they appear dark gray on the film. Bone, tumors and teeth, which are denser than the soft tissues, allow little radiation to pass through and appear white on the X-ray.

High-speed film and new equipment have made dental X-rays safer; they’re a common procedure during a patient’s initial visit. X-rays are otherwise taken only when necessary to identify problems for treatment before they become serious. In addition to pinpointing cavities, X-rays uncover cysts, abscesses, tumors and periodontal disease, and identify malformed or impacted teeth. The Dental School currently uses Ektaspeed Plus film, the fastest dental film on the market.

The images captured by Health Science Center endodontists are easily saved on computer memory — a RAID 5 Server (Redundant Array of Inexpensive Drives) — for future reference. This server contains four 9-gigabyte drives. Image information is written across several of these drives to ensure its safety in case one drive fails. Patient confidentiality is protected with password access to this server.

"There are roughly 1,218 patients and 13,092 radiographic images occupying about 7.4 gigabytes on the server," said Dr. Walker, whose department started with just one laptop two years ago. "They can be easily retrieved to supply more information, and the chemical waste of processing film has been eliminated."

The searchable database nature of the software program greatly enhances information retrieval. Currently the department uses seven laptop computer digital systems in all its resident and faculty practice patient care. This revolutionary system prevents time loss, and the high-quality, digitally encoded information can be adjusted electronically to alter contrast density or to magnify specific areas, such as tiny calcified root canals.

The amount of energy used by the flat sensor device to generate the image is 65 percent of the total X-ray radiation emitted. As a result, the patient is exposed to only a minute amount — perhaps one-tenth — of the radiation dose of conventional X-rays.

In September 1998 Dr. Dale Miles, from the Indiana University School of Dentistry in Indianapolis, discussed the proliferation of digital radiographic technology in the marketplace during the fifth symposium on digital imaging in dental radiology. In his presentation, “Digital Radiography: Out of the Classroom, Into the Community,” he observed that although digital dental imaging was very much available, “the education of dentists and their personnel in these methods has lagged behind.” He also noted manufacturers were not providing adequate training, so it was the responsibility of the educational institutions to bridge the training gap.

The Health Science Center has done just that by integrating digital imaging into the endodontics department as a routine part of a patient’s visit.

Before the arrival of digital imaging, the radiologist was forced to repeat nearly one out of four X-ray sessions due to incorrect exposure levels. The digital techniques, on the contrary, offer a much wider fault tolerance.

Dr. Walker praises "the speed and accuracy with which we can measure the length of a root canal with the tap of a finger on the laptop."

His remaining concern is the size of the sensor that has taken the place of the X-ray film. It can be a bit bulky. But, as with anything technological, that may soon change.

Not long from now standard X-ray film, developing tanks and chemicals will be replaced by electronic detectors, high-definition display screens and computer-stored data. The Dental School is currently using digital panoramic radiographic technology in its Dental Diagnostic Science Department on all patients.

— Fernando Serna