Ask Dr. Christensen

Nov. 1, 2007
Q I have some nearly hopeless patients in my practice who wear mandibular dentures.
Q I have some nearly hopeless patients in my practice who wear mandibular dentures. I am not doing many implant-supported overdentures, but some of my colleagues are very pleased with the success of their implant-supported overdentures. What technique do you consider to be an effective, affordable procedure for these patients, most of whom are discouraged with their lower dentures?A The differences in patient tolerance of mandibular dentures amaze me. Some wear ridiculously poor-fitting dentures with almost no complaints while others are not satisfied with dentures that appear to be nonirritating and fit well. Consider first how patients are getting along in their current situation. If they are tolerating their current prosthesis, they can continue to wear it. If it is not acceptable, there are several good prosthodontic alternatives that vary widely in function, cost, difficulty, and esthetics.

Here are my observations and conclusions about the implant-supported mandibular overdenture alternatives, ranging from simple, noninvasive, and relatively inexpensive, to difficult and expensive:

1 Overdenture over four or five small-diameter (<3.0mm) implants, placed anterior to the mental foramen. The dentures are retained by “O” rings that fit over the spherical heads of the small-diameter implants. This is the least invasive and least expensive, and the most immediate, but the least proven alternative. Surgically oriented general dentists can provide the entire procedure, or the surgical portion can be delegated to a surgical specialist. I find that most patients accept this technique easily. During the seven years I have used this technique, it has had good service. The dental literature now contains positive reports on its success.2 Overdenture over two or more conventional (>3.0mm) implants, retained by “O” rings, locators, ERA attachments, or many other simple retentive devices. These techniques are relatively simple, and most labs can accomplish the techniques well. This moderately invasive, moderately expensive concept is highly successful and well-proven. I have yet to accomplish such treatment on a patient who did not appreciate the improvement in his or her oral health and ability to chew.3 Overdenture over several conventional implants, with a bar connecting the implants and various retainers connecting the removable denture to the bar. This concept is my favorite. It is moderately invasive and significantly expensive, but it is comfortable, easily repaired, highly esthetic, and the patient can chew well and clean both the denture and bar with ease.4 Fixed denture placed over five or more conventional implants that can be removed only by the dentist. This concept satisfies the desire of some patients to have their teeth fixed in their mouths. It somewhat sacrifices the esthetic result because the base of the attached denture must allow adequate cleaning, and the base cannot be built out to optimum facial fullness. It is by far the most expensive, difficult to repair, and time-consuming to construct; however, the clinical success and patient acceptance of these attached implant-supported restorations has been excellent in the past 20 years.

The answer to your question requires significant discussion with your patients to determine their expectations clinically, their financial capability, their past and current oral hygiene habits, and their overall physical health. I prefer to use the less invasive, easily repaired alternatives.

For detailed information on this subject, please see our newest DVD, V2326 “Successful Fixed and Removable Restorations for Dental Implants.” Contact Practical Clinical Courses at (800) 223-6569, or visit our Web site at

Q I am concerned about the suggested deep-tooth preparations required for all-ceramic crowns. There seems to be two diametrically opposed views on restoring teeth. Some clinicians recommend “minimally invasive” tooth preparations and restoration with resin-based composite while others advocate use of crowns for almost every restorative-need situation. What do you think about the current confusion in restorative dentistry?A Your question has frustrated me, too. The current generation of resin-based composites has evolved to a very effective level, both functionally and esthetically. When carious lesions are found at a minimal stage, restoring with resin-based composite provides highly acceptable and long-lasting restorations. Diagnosing caries at an early stage is relatively easy. Those patients who appear to want to stay with you for the long term should be advised about the desirability of finding and restoring lesions early. Patients should also be advised that some dentists prefer to watch caries for a longer time before restoring than other dentists do. The treatment plans may vary significantly depending on which concept the dentist practices. It will become obvious to your patients that the minimally invasive concept is better. All of us see new patients who avoid visiting the dentist until the carious lesions progressed deeply into the teeth, causing significant need for caries and tooth-structure removal. Large restorations are mandatory for these patients. As they become long-term patients, they can be converted to the minimally invasive restorative concept for their remaining natural teeth.

A desire for improved esthetics prompts some dentists and patients to choose a crown or veneer instead of restoring the teeth conservatively and retaining the original anatomy and contour of the mature dentition. In the diagnostic appointment, such patients should be advised of the eventual necessity to replace the crowns or veneers and the recurring cost of such requirements. Placing aggressive restorations in the 20- or 30-year age range requires redoing the restorations a few times in the patient’s life. Endodontic therapy may be needed as the teeth become traumatized with repeated treatment.

A simple answer to your question is not easy, but I suggest the following: New patients should be educated about the minimally invasive concept of restorative dentistry. Most accept it eagerly. If the teeth are stained, they should be bleached before restoring them conservatively. Accomplish crowns or veneers only when necessary and with proper patient education and consent. There are always patients who have waited too long for treatment for whom more aggressive restorative dentistry is the only choice.

In other words, try to be conservative. Learn how to use the current generation of resin-based composite well and emphasize the minimally invasive orientation for new patients for whom minimal dentistry is appropriate.

See our new video for patients requiring more extensive restorative therapy. Practical Clinical Courses has just finished producing an in-depth, close-up, live video comparing the most adequate tooth preparations for full-metal, PFM, and all-ceramic crowns and ceramic veneers.

Ask for V1925, “Optimal Fixed Prosthodontic Tooth Preparations.” For more information, contact Practical Clinical Courses at (800) 223-6569, or visit our Web site at

Dr. Christensen is a practicing prosthodontist in Provo, Utah, and Dean of the Scottsdale Center for Dentistry. He is the founder and director of Practical Clinical Courses, an international continuing-education organization initiated in 1981 for dental professionals. 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.

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