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 ...
Recently, I received a letter from an insurance company stating that the restorations I had placed in one of my patient's teeth had carious lesions too small to be restored. They further stated that I should not have placed the restorations in the teeth until they had become larger. When I cut the tooth preparations, the teeth were decayed deeper than the dentino-enamel junction. When should incipient Class 2 carious lesions be restored?

Answer from Dr. Christensen ...
In the past, dental radiographs of Class 2 caries showed nearly the exact depth of the lesions. As radiographic films changed and less radiation was needed to expose the films, the contrast of the lesion with tooth structure diminished. The clinical result has increased the difficulty for clinicians to interpret the actual clinical depth of caries. Many shades of gray are evident on dental radiographs today, making differentiation of dental caries and tooth structure difficult.

You were probably taught in school to restore Class 2 lesions when the depth of the carious lesion represented on the radiograph penetrated the dentino-enamel junction. That guideline was acceptable in the past. However, with current research demonstrating that radiographs show only about one-half of a typical Class 2 carious lesion, it is desirable to restore Class 2 caries when the radiographic representation of the carious lesion has not penetrated the dentino-enamel junction. A good guideline is one-half or more penetration to the dentino-enamel junction.

However, third-party payment companies and their consultants may not be convinced of this suggestion. If you are restoring such clinical situations and you want to be assured that you will not be in trouble with a third-party company, I suggest that you make a photograph of the carious lesions when you have opened them to the extent that the maximum depth of lesions are exposed to view. When challenged, you will have proof of the lesion's depth.

A logical question arises when considering conservative tooth preparations instead of waiting until the lesions are larger. Why should restorative dentistry be accomplished at an early stage? There are several excellent reasons. If teeth are prepared when the lesions are very small, less tooth structure is removed. The resulting restoration is stronger because of the greater amount of remaining tooth structure. It follows that less breakage of restored teeth will occur in the future and fewer crowns will be required. In my opinion, everybody wins when teeth are restored at an early stage of caries activity: The patient has a stronger tooth; the dentist has a smaller restoration, requiring less time and effort; and the third-party payment company has fewer crowns required as teeth fracture.

A recent Practical Clinical Courses video demonstrates the only device currently on the market that shows the level of activity in Class 1 and Class 5 carious lesions — Item C501A, "DIAGNOdent — Scientific Diagnosis of Caries." To purchase the video, call (800) 223-6569, fax to (801) 226-8637, or visit our Web site at www.pccdental.com.

Question ...
I often feel like I am being too heroic when I restore carious teeth that have many previously placed restorations in them. When should a tooth be extracted instead of charging the patient hundreds of dollars to build-up and restore the tooth?

Answer from Dr. Christensen ...
Your question has many answers. The most important variable is the patient's financial status. If the patient does not have financial limitations, my suggestions would be different from the case of a patient who has severe financial limitations. There is a point at which the patient becomes your treatment-planning guide. What can he afford? The patient without severe financial limitations has the possibility for an easier treatment plan.

The following characteristics of a given tooth would make me want to remove it:

1. Severe periodontal disease, with tooth mobility at a 2 or 2+ level.

2. Endodontic therapy completed, and the treatment looks acceptable from all clinical observations, but the tooth still has chronic, lingering pain. Unless re-treatment appears to be a necessity, the tooth should be condemned.

3. No tooth structure remaining coronal to the supporting bone. Unless orthodontic extrusion is a viable alternative, the tooth should be removed. Post-and-core therapy in such teeth seldom lasts more than a short time.

4. Vertical crack in the tooth, pain symptoms, and the crack can be observed into the root area.

5. Horizontal root crack observable on radiograph, coronal to the apical one-third of the root. If the crack is apical to the one-third of the root, an apicoectomy and root canal therapy may save the tooth.

6. Tooth has been moved orthodontically out of the supporting bone, and it has significant mobility.

7. Tooth is in a position in the arch that will not allow proper arch-form in planned rehabilitation, and the patient does not want orthodontic therapy.

8. Tooth is the last remaining tooth in the mouth, and implants and/or prosthodontic rehabilitation is planned.

With only these exceptions, I suggest that most teeth can be saved and that they will serve well the planned treatment. Patients with or without financial acceptability should be allowed to know their options and voice their opinions on whether or not their tooth should be removed.

Our Practical Clinical Courses video, V19-93, "Long-Term Maintenance and Repair of Fixed Prostheses," suggests alternatives and clinical techniques for some of the situations described in this article. To purchase the video, call (800) 223-6569, fax to (801) 226-8637, or visit our Web site at 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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