Each month, Dr. Gordon Christensen answers a question from our readers about everyday dentistry.
Q: I have been practicing for many years and have lived through the analog radiograph era as well as the introduction, use, and current state of dental digital radiographs. I like certain aspects of the currently available complementary metal oxide semiconductor (CMOS) sensor concept, but the limitations far outweigh the advantages. Can’t we do better than this? A day does not pass when I don’t complain about some aspect of the current CMOS digital sensors. What is in the future for this major void in dental practice? Rvg Dental
A: Many older dentists have had experience with analog radiographs, which are not used to a significant degree at this time. They had numerous disadvantages, including the need to maintain a darkroom and developing area, deal with developing and fixing solutions, purchase and change the solutions routinely, organize and save the images, and tolerate patients’ worry about the relatively high radiation required with their use.
But the analog radiographs were thin, flexible, easy to place and use on a positioning device, easy to place in the mouth without causing patient discomfort, relatively inexpensive, and they actually showed initial caries relatively well.
What are the complaints dentists make concerning the current digital CMOS sensors and the images they make? The sensors or the images are:
Yes, there are a few:
The following concepts are proven adjunctive techniques for detecting dental caries:
Air polisher (Prophy Jet, KaVo, or similar)—to clean the occlusal grooves of stain and plaque. If color remains in the groove, the likelihood of class I caries is very high.
Logicon (if you have Carestream or Kodak sensors only) to determine presence and activity of class II and III areas.
Microlux Transilluminator to determine the presence of class II and III caries.
Silver diamine fluoride to stain caries black in occlusal grooves, easily showing class I caries.
CariVu to show the location and depth of class II and III caries.
Digital Doc LUM to show the location and depth of class II and III caries.
CamX Spectra Caries Detection Aid to locate class I caries.
SoproLife and SoproCare to identify class I caries.
Canary System to locate class II caries.
There is another very good alternative—the use of phosphor plate digital radiographs.
As you know, CMOS and CCD (charge-coupled device) digital sensors have been used in dentistry for many years, and currently CMOS sensors are the most popular. But the use of phosphor plate digital sensors is a viable alternative to replace CMOS sensors for some clinical situations. This technology has been available for many years.
The most popular brands are ScanX from Air Techniques and Soredex Digora Optime from KaVo. Over the past several years, phosphor plate sensors have nearly replaced the previously dominant CMOS sensors in numerous European and Asian countries.
These are the advantages of phosphor plates:
There are several limitations of phosphor plates:
An immediate image is not obtained. A short time is required to convert the latent image on the plate to digital in a processor. With experience, this time is short—just a minute or two. However, this limitation is a challenge when an immediate image is desirable during complex endodontic treatment, impactions, and implants.
While sensors can be used about 200 times before replacement and cost is less than $100 USD, they must be replaced when they develop artifacts, including lines, across the sensor. It is a limitation to have to replace sensors frequently.
The sensors are light-sensitive and must be protected from light exposure.
Some dentists are using phosphor plates for situations not requiring an immediate image, such as dental hygiene appointments and initial exams, and they’re using CMOS sensors for difficult endodontic procedures, removal of impactions, and implant placement. The same dental x-ray unit can be used for both concepts.
Radiographs are taken on almost every patient during almost every appointment. They are essential for many oral diagnostic and treatment procedures. Various surveys report diverse estimates of the number of radiographs made in dental practices. It is obvious that hundreds of images are made monthly in a typical busy practice.
I consider the inadequacies of the current generation of digital sensors to be among the worst voids in everyday oral care. What are the major clinical radiographic challenges?
Lack of ability for current digital sensors to show initial dental caries. Clinicians have to wait too long before restoring teeth, which weakens the teeth, requires more time for the procedure, uses more material, and results in more difficult restorative procedures. Apparently, this problem cannot be overcome with the current generation of digital radiographs. Use of caries-detecting devices and careful magnified visual observation are the only current solutions.
Inconsistency of diagnostic data on images. Making images of a specific anatomic area often provides information that leads to different diagnoses of the same situation. Dentists admit that a definitive diagnosis often cannot be made because the radiographs differ in the digital images shown. Making more than one image of a specific suspicious location is one useful solution, but careful clinical visual observation with magnification is usually necessary.
Difficulty properly positioning the sensors. Positioning in both a sensor-holding device and in the mouth are nearly impossible procedures to accomplish due to the thick, rigid, and often painful CMOS sensors. These challenges can be overcome by adding phosphor plate sensors to your practice. Phosphor plate sensors are as easy to use as film, and you can still use CMOS sensors for situations that require an immediate image.
The transition from analog radiography to digital radiography has brought about some advantages, but most dentists agree that these advantages are outweighed significantly by the limitations of this concept. Until improvements in digital dental radiography occur, this article outlines several ways to mitigate the challenges presented by the current generation of digital radiographs.
Author’s note: The following educational materials are available from Practical Clinical Courses to help you with oral radiography.
For more information about these educational products, call (800) 223-6569 or visit pccdental.com.
Mouth Scanner GORDON J. CHRISTENSEN, DDS, PhD, MSD, is a practicing prosthodontist in Provo, Utah. He is the founder and CEO of Practical Clinical Courses, an international continuing education organization founded in 1981 for dental professionals. Dr. Christensen is cofounder (with his wife, Rella Christensen, PhD, RDH) and CEO of Clinicians Report