Ask Dr. Christensen

In this monthly feature, Dr. Gordon Christensen addresses the most frequently asked questions from Dental Economics readers.

by Gordon J. Christensen, DDS, MSD, PhD

In this monthly feature, Dr. Gordon Christensen addresses the most frequently asked questions from Dental Economics readers. If you would like to submit a question to Dr. Christensen, please send an email to info@pccdental.com.

Question ...

For many years, I have been using 35 mm film to record patient photos. In recent months, it seems that every dental publication has an article about digital photography. Is it that much better? Should I change to digital? I do not have any difficulties with standard film and 35 mm slides.

Answer from Dr. Christensen ...

Over the past several years, the digital revolution has taken place in dental photography and the visuals used in dental continuing education. Seldom do you see a dental clinician/lecturer using standard 35 mm slides and a Carousel projector. A few years ago, I was one of those frustrated dentists with thousands of color slides recording many years of patient treatment. I saw the digital age coming on rapidly, and I wondered if I needed to change. I resisted the change for a couple of years. When a patient wanted to see a specific clinical situation, I had numerous slide presentations that I would use to demonstrate the before-and-after states of specific patients. There were some challenges with film slides. Sometimes the slides were under or overexposed or the layout of the slide was objectionable, and difficult modifications had to be made. Storage and filing of the slides took up space in my office, and the slides were not always easy to locate. The library of loaded Carousel trays easily filled a small room. Nevertheless, the educational value of such slide presentations is well known. However, the slides soon became scratched and dusty, and the color faded. If I were making a presentation to a group, I had to sort slides and make the presentation directly related to the specific needs of the group. When presenting several different lectures in a contiguous few days, carrying the loaded Carousel trays was very objectionable.

What is different with digital slides? In a nutshell, you make the picture. If it is crooked, too light, too dark, or has blemishes, you correct the problems on your computer using software such as PhotoShop. In addition, hundreds of slides are easily stored in your computer. The slides do not become scratched or dusty. Instead of loading Carousel trays and filling your car with them, you can carry a small laptop computer weighing as little as three to four pounds and with dimensions of 9" x 12" x 1" or less, containing hundreds of slides and many presentations. The computer and slides can be used in community or professional presentations using a small LCD projector. The computer also can be used to show the slides in your operatories to educate patients. You can record pertinent patient visual information, including slides or radiographs, under the patient's file name in your computer for access when needed. You may transmit these images to third-party payment companies as part of treatment plans, to demonstrate need for therapy, or for legal purposes. You may easily sort slides on your computer when preparing for a patient-education session or a presentation to a group.

Is the visual quality of digital slides as good as film? I am not an authority on the subject, but I have used thousands of both types of images, and I can say that with the right camera and the correct projector, the two types of images are very comparable.

What are the disadvantages of digital photography? I will not underestimate the mental and time-loss trauma of changing to digital. You undoubtedly have many conventional film slides. You must convert the ones you want to use to a digital format. That is not difficult, but you need a scanner, some time to learn how to use it, and the conversion time. You need a new digital camera. There are numerous very adequate systems including Canon, Kodak, and Lester Dine. You must learn how to get the information to your computer from the media transfer system used by your digital camera. Instructions from the dental camera systems make that transition relatively easy. How long does this transition take? It has been several years, and I am still making the change. I remember with fondness the simplicity of sitting a tray of slides on a Carousel projector and turning it on. Would I change back to film? No! Digital photography in dentistry is here and is state-of-the-art.

Question ...

I have observed many advertisements lately about resin inlays and onlays. Why would I use resin instead of ceramic inlays and onlays?

Answer from Dr. Christensen ...

You know that resin-based composite is much kinder to opposing tooth structure than ceramic, and that ceramic restorations in general will wear resin or tooth structure more than the ceramic wears. However, resin-based composite restorations do not retain their anatomical shape as well as ceramic restorations. Resin wears more than tooth structure.

Nevertheless, some of the better and well-proven brands of resin inlays and onlays can be used appropriately in the following situations. As an example, you may have a patient who requires many small, direct-placement Class II resin-based composite restorations. However, the patient requires one or more larger restorations that are too large for comfortable placement of direct resin-based composite. Wouldn't it be better if the larger restorations were made of the same material as the smaller direct-placement restorations? If the restorations are of the same material, they will wear at the same rate, occlusal relationships will be similar to the original anatomy when placed, and the restorations will feel the same to the patient.

Also, occasionally there are patients with bruxism or clenching who will not accept or cannot have metallic restorations. Ceramic restorations in these patients are not indicated, because of wear of opposing teeth by the ceramic and potential fracture of the restorations. These are the types of situations in which I suggest the use of indirect-placement resin-based composite restorations. Some well-proven brands are: belleGlass (Kerr Corporation); Sinfony (3M ESPE); Sculpture (Pentron Clinical Technologies), and a few others.

Newly released PCC presentations that are related to the topics discussed include: V4796 "Dr. Christensen's Most Frequent Failures and How to Avoid Them" and C902B "Veneers For Lower Anterior Teeth." Both titles are available in DVD or VHS. Also, please see our video on tooth-colored inlays and onlays — C101B "Predictable Ceramic Inlays and Onlays" available in VHS. For more information, call (800) 223-6569; fax (801) 226-8637; or visit www.pccdental.com.


Dr. Christensen is a practicing prosthodontist in Provo, Utah. He is the founder and director of Practical Clinical Courses, an international continuing-education organization for dental professionals initiated in 1981. Dr. Christensen is a co-founder (with his wife, Rella) and senior consultant of Clinical Research Associates, which, since 1976, has conducted research in all areas of dentistry and publishes its findings to the dental profession in the well-known CRA Newsletter. He is an adjunct professor at Brigham Young University and the University of Utah. Dr. Christensen has educational videos and hands-on courses on the above topics available through Practical Clinical Courses. Call (800) 223-6569 or (801) 226-6569.

Dr. Christensen's views do not necessarily reflect the opinions of the editorial staff at Dental Economics.

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