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Letters to the Editor
The PPR welcomes letters from readers on articles and other information that have appeared in PPR or have been posted on the ADA Web site. All communications received will be carefully considered for publication, either in print or online at www.ada.org/goto/ppr. PPR reserves the right to edit all letters and requires that they be signed. By sending a letter to the editor, the author acknowledges and agrees that the letter and all rights of the author in the letter sent become the property of PPR, and acknowledges and agrees that PPR may publish the author's name, city and state. The views expressed in published letters are those of the letter writer and do not necessarily reflect the opinion or official policy of the ADA or its subsidiaries.
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Volume 2 Issue 3
Digital Radiography, Sensor Durability
I read with interest your reply to the question regarding digital sensors and in particular the reference to the “sensitivity of sensors to damage” (PPR Volume 2, Issue 3, p.16). Considering the significant monetary investment required to convert a dental office from conventional to digital [radiography], this is a legitimate concern. It does appear, at least from our perspective, that companies have made great strides to increase the durability of their digital sensors.
We have employed digital radiographic technology as part of the forensic dental identification process at Charles C. Carson Port Mortuary at Dover AFB, Delaware, since September 2001 with great success. We average nearly 1,000 full mouth series a year and subject the digital sensors to conditions that by most standards would be considered far more rigorous than the normal dental practice. This equates to a current rate of approximately 18,000 exposures per year without a single malfunction or failure of our sensors.
Over the last decade, the technology and hardware associated with digital radiology has evolved to become a very dependable and indispensable part of the practice of dentistry. The reliability of today’s digital sensors is no exception.
Duane Schafer, D.D.S., M.S.
Armed Forces Medical Examiners System
Armed Forces Institute of Pathology
Washington, D.C.
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Volume 1 Issue 1
Why Wasn’t Conventional X-ray Film Included in this Evaluation?
I was pleased to receive and read the first issue of this publication. I think it is a great idea, and most useful.
One comment—I wish the digital x-ray evaluation had included a comparison of a film x-ray for quality comparison.
Don Smith, D.D.S.
Oklahoma City , OK
I read the Digital Radiography evaluation with great interest, but was greatly disappointed by the lack of “control” in your evaluation. Rather than simply comparing existing systems, what some of us who have not yet purchased a digital radiography might be interested in – what I am certainly interested in – why not compare how the digital resolution, as defined by specificity, accuracy and sensitivity compares with Insight (Kodak) and D speed film. For the D speed comparison I would not use Kodak, because it has recently come to my attention that Kodak has changed the formula for their D speed film. This change has resulted in a reduction in image quality, rendering their D speed film to be very similar to Insight.
I did my own little test with Kodak D, Kodak Insight, Afga D, and Schick. I photographed the exposed film with a Canon 10D camera, then subjectively compared the images, paying special attention to subtle density differences that would be indicative of incipient caries lesions. The Schick system was least clear.
From your study, the ability to identify crestal bone, a pulp chamber and the DEJ is hardly adequate to be diagnostic. For bitewing style film, the ability to detect a white spot – enamel demineralization – ought to be the standard, because the detection of these lesions can lead to preventive interaction. Similarly, the ability to distinguish subtle apical or crestal bone changes would again be significant to all doctors who wish to practice preventively and/or proactively.
Please differentiate yourselves by providing useful information that is our, not the corporate best interest.
Grant T. Chyz, D.D.S.
Seattle , WA
Editor’s comment: We have received several inquiries about why conventional x-ray film was not included as a control in the digital radiography device evaluation. There are a number of published studies already comparing conventional x-ray film to digital radiographic images from specific manufacturers. These studies (References 11-14 in Van der Stelt, JADA Oct 2005;136(10);1378-1387) generally find that digital images performed at least as well as conventional radiographs in their diagnostic ability. However, it might be interesting for readers to have another look, and we’ll consider this for future issues.
Positive feedback
I wanted to take this opportunity to congratulate you on the introduction of the PPR. I received the first one with my July, 2006 copy of JADA.
During this haze of heavy commercial endorsement and sponsorship, your objective and independent publication is a breath of fresh air. On behalf of dental students everywhere, thank you.
I was particularly impressed by the review of the digital X-ray sensors. I purchased the Schick CDR system for my father's practice a number of years ago, and had been curious to see how it measured up to the competitors. I'm happy to say that I made the right decision
Toby M Cohen, D.D.S.
Columbia University College of Dental Medicine, Class of 2009
A pleasure to find the ADA in a leadership role again. This is the type of dental involvement that adds to the position of the organization, which is devoted to the dental profession.
Paul C. Belvedere, DDS
Edina , MN
Congrats on a truly excellent edition—research that is RELEVANT to the general practitioner—done by our own organization.
Jim Abramowitz DDS
Greenwood Village, Colo.
Negative Feedback
The summer premier issue from ADA is a big disappointment and frankly embarrassing.
The first article on Carbide Burs is as far as I got: 1) Cutting rate of selected carbide burs against ceramic: carbides are not used to cut ceramic because they are very inefficient compared to diamonds, so why test ceramic. Test enamel or dentin or something else that simulates the day to day clinical dentist. 2) is it clinically significant that one bur cuts at 575mg/min and another 450mg/min? 3) where is the "science", the evidence based decision making process in asking for dentists "experiences".
Did you note the number of respondents? If I were the owner of Miltex I would be incensed that only two respondents were used and then compared against Midwest's 205.
If ADA is going to venture forth into this arena, at least be of the caliber of research level and practical application we have come to know with CRA.
Th. 'Pat' Collins, DDS
Editor’s comment: Dr. Collins expresses a number of concerns, which the Internet allows us to address in some detail. His first concern is with the material we used to test cutting efficiency. We used Macor to test the burs because it is commonly referenced in the peer reviewed dental literature for use in cutting tests of both carbide and diamond burs. The material admittedly has its drawbacks; however, using enamel and/or dentin for a comparative study would open the results to criticism for lack of consistency. The physical properties of enamel not only vary from tooth to tooth, but within an individual tooth. This makes enamel inappropriate to use for a comparative, scientific study on cutting efficiency. We would not be able to tell whether differences in cutting efficiency were a result of the cutting tool or the material. An individual lot of Macor, on the other hand, has consistent density and physical properties and exhibits zero porosity. Furthermore, it has similar physical and thermal properties to enamel 1: density of 2.52 g/cm 3, hardness of 250 Knoop at 100 g, Young’s Modulus of 70 GPa at 25 ° C, thermal conductivity at 25 ° C of 1.46 W/mK, and thermal diffusivity at 25 ° C of 0.0073 cm 2/s. The reported values of enamel vary significantly from one publication to the next for the reasons stated above, but the following are some ranges 2-4: density of 2.97 to 3.2 g/cm 3, hardness of 300 to 431 Knoop, Young’s Modulus of 50 to 94 GPa, thermal conductivity of 0.93 W/mK, and thermal diffusivity of 0.0047 cm 2/s.
Dr. Collins questions the clinical significance of bur cutting rate. We select our tests in response to what dentists tell us in a preliminary survey they want to know about a product. Cutting efficiency topped their list for carbide burs. Carbide burs are used most often for preparing cavity outline forms and refining internal cavity margins for either amalgam or composite restorations.5 Cutting rate can be a factor in preparation time, especially in the case of larger or multiple preparations. A more efficient bur would be expected to be less traumatic to the tooth since it would spend less time in contact with the tooth, or could be used with less pressure. Though we did not report information on the energy consumed during the cutting procedure, we were able to record this information during our testing as stated in our protocol  . Based on this information the NTI instruments required 0.29 (± 0.01) J/mg of energy as opposed to 0.32 (± 0.04) J/mg for the Bluwhite instruments substantiating the fact that the NTI instruments are more efficient.
Finally, Dr. Collins questions the reporting of “dentist experiences” with the products we evaluate. We decided to gather clinical data via practitioner surveys for several reasons. First, ADA access to a very large percentage of practicing dentists is one of the unique things PPR has to offer its readers. We’ve been delighted with our members’ willingness to get involved in the ADA ACE panels. The number of participants is over 1,500 and still growing.
Also important to our decision are the rules governing the ethical conduct of clinical research. We aren’t willing to ask our members to conduct clinical research in their offices without the protection of these rules for dentists and their patients. The practice-based research networks that are being formed around the country with federal funding will apply these protections to office-based clinical research. We hope to be able to use these kinds of networks to expand our clinical research in the future. In the meantime, our readers told us they want to know about the experiences of their colleagues with dental products, and that’s what we’ll deliver.
Dr. Collins raises a good point about the low number of respondents for certain products. We gave a lot of thought to whether to report these results. The decision could have gone either way. Finally, we decided in favor of giving our readers more information, and using disclaimers to put it in context. The growing number of ACE panel participants has hopefully put this dilemma behind us, but we would be pleased to hear from more readers about whether they found this information useful. In the next issue of PPR (October 2006) we will omit reporting responses from five or fewer dentists.
1. Macor Machinable Glass Ceramic: Product Data Sheet, Corning Incorporated, Corning, NY. 2006.
2. Anusavice, K. J., Ed. Phillip's Science of Dental Materials. St. Louis, MO, Elsevier Science. 2003.
3. O'Brien, W. J. Dental Materials and Their Selection. Quintessence Publishing Co, Inc. 2002.
4. Xu, H. H. K., D. T. Smith, et al. Indentation damage and mechanical properties of human enamel and dentin. J Dent Res 1998;77(3):472-80.
5. Siegel SC, Von Fraunhofer JA. Dental Burs – What Bur for Which Application? A Survey of Dental Schools. J Prosthodont 1999;8:258-63.
Printing Digital Radiographs
I have been an ADA member for more than 30 years, and the ADA PPR is a great addition.
One question on digital radiograph systems: why not print “hard copies” of radiographs, and tape them on a sheet in the patient’s chart?
Charles Halterman, D.D.S.,M.A.
Half Moon Bay, Calif.
Editor’s Comment: One of the advantages of “going digital” is the creation of a paperless work system. Digital files do not have the aging problems associated with hard copies and they allow for integration of all images into one electronic patient file. We also learned from experts and manufacturers of digital radiography systems that cost-effective printer technology to make diagnostic quality prints is not yet readily available. The resolution and the size at which you are able to view the image on a good quality monitor is much higher than can be obtained on standard-size paper using a reasonably priced home or office printer.
Graphs: Spell Out “Better” and “Worse” Performance
The PPR is excellent. The graphics are fine, but could you label the graphs to show whether preferred performance is indicated by higher or lower data scores?
Keep up the good work,
Jim McGivney, DMD
St. Louis, MO
Editor’s Comment: Thank you for your question. Unfortunately, many material and instrument properties do not lend themselves to a simple “better” or “worse” characterization. For example, a high flexural modulus may be considered as a desirable quality, but if the flexural modulus is too high, the material may be too stiff for some applications. Also, performance data differences between products do not always mean that the difference in practice will be clinically significant. This is why we use dentist and educator comments along with the Editor’s Bottom Line to put all the data in a clinical perspective.
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Submission Guidelines
You may submit letters by e-mail to ppreditor@ada.org , by fax to 312-440-2536, or
by mail to:
ADA Professional Product Review
211 E. Chicago Ave, 4th floor
Chicago, IL 60611-3528
- The PPR does not publish statements that are libelous or might otherwise
expose the ADA to legal liability.
- Letters should be relevant to topics covered in the PPR or of general interest
to PPR readers.
- Factual errors may be corrected in an editor’s note.
- PPR may elect to publish only a sample of multiple letters that contain the same information or make the same point.
- Brevity is encouraged. Letters may be edited to make them acceptable for publication.
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