Ask Dr. Christensen

May 1, 2007
Q In February, I attended a panel discussion at the Chicago Midwinter Meeting, and you were one of the panelists.

by Gordon J. Christensen, DDS, MSD, PhD

Q In February, I attended a panel discussion at the Chicago Midwinter Meeting, and you were one of the panelists. The panel discussed numerous questions and answers concerning the so-called "neuromuscular" concept of dental occlusion. The discussions were intense, and there was significant disagreement about the value of this concept. What are your personal views on this subject? Should I be involved in it since I was not taught anything about the "neuromuscular" occlusion concept in my dental education?A Anything I say about "neuromuscular" occlusion will upset someone, but bear with me. Many years ago, I encountered the concept as a young graduate student at the University of Washington. I saw the use of the Myomonitor in study clubs in that geographic area, and heard the inventor, Dr. B. Jankelson, speak about its characteristics. I was interested in the concept of relaxing the muscles of mastication to fi nd the true physiological relationship of the mandible, the maxilla, and the teeth in coordination with the temporomandibular joints. I was fascinated by the potential of electrical stimulation of the muscles to fi nd their relaxed state.

I soon became busy as a dental educator, researcher, and practitioner, and I did not involve myself with the Myomonitor concept again for many years. However, during that period, while completing the treatment of hundreds of difficult patients, I found the use of electrical stimulation was an excellent means to relax masticatory and facial muscles. I used various TENS (transcutaneous electrical neuro stimulation) devices to achieve relaxation of muscles to assist in manipulating the mandible during complete denture fabrication and in some fixed prosthodontic situations.

Anyone who has taken an occlusion course from me knows that TENS has always been a part of my occlusion courses. You know the difficulty in in moving the mandible for a person who has worn a flat tooth set of dentures for years. The mandible will not move in a posterior direction, and it is positioned significantly anterior to that individual"s apparent previous maximum intercuspated position.

I have used several brands of TENS units for local anesthesia and have published studies about their use in the "CRA Newsletter." Electricity is used in most health professions to relax muscles for race horses with stiff muscles, for human athletic injuries, and pain relief. Please go to the Internet and do a search using the word "TENS." You will find hundreds of devices ranging from $30 to thousands of dollars. This is not a new concept.

As a prosthodontist, I have treated temporomandibular dysfunction using both conventional methods (such as splints and occlusal equilibration), as well as augmenting my therapy with muscle relaxation using TENS. In my community in Utah, there are some strong advocates of "neuromuscular" occlusion. Some of them are CRA Evaluators or "CRA Newsletter" subscribers. From time to time when I have failed with my conventional TMD therapy, I have referred patients to one of them. Interestingly, I have had some of those practitioners refer patients to me after their failures.

There is no question that electrical stimulation can relax muscles. The controversy with the "neuromuscular" concept of occlusion, as stated by its antagonists, is: Does the device used in the concept relax all of the muscles of mastication, including the lateral pterygoid muscles? If it does not do so, is the "neuromuscular" position one that can be reproduced? Agreeing on the answers to those questions would require hours of debate and bodyguards for both "camps."

If you want to stimulate an active discussion, just get a "neuromuscular" advocate and a conventional occlusion advocate together, have a few drinks, and let the "fur fly"!

My conclusion is that there is truth in both concepts. I have used conventional concepts when successfully reconstructing the mouths of hundreds of patients (about 45,000 units of crown and bridge) and placed thousands of dentures; however, I often augment my conventional concepts with muscle relaxation by TENS as a part of the therapy.

I suggest that you look up "neuromuscular occlusion" on the Internet. If the concept interests you, there are many testimonials listed there. Talk to some of the dentists whose names are on the Web sites. I know I have not fully answered your question, but I have shared my beliefs -- backed by both experience and research -- for you to evaluate for yourself.

I have made many videos on occlusion. If you want to know my personal thoughts on the subject and the techniques I use, see V3104, "Occlusal Splints" -- Predictable, Frequent Use"; V3106, "Simple TMD Therapy for Your Practice"; V3105, "Uncomplicated Occlusal Therapy"; and C500A, "Occlusal Disease Therapy Simplified (NTI-Tension Suppression System)." For more information, call Practical Clinical Courses at (800)223-6569 or visit our Web site at

Q I know that much of the lab work in the U.S. takes place in developing countries. I am concerned about the content of these restorations and the infection-control standards on crowns, bridges, and other prostheses. How can I learn about these challenges, and should they worry me? Additionally, what do you feel is the future for the so-called "offshore laboratory work"?A You are completely correct in your statement that much of the laboratory work in America is now being made in developing countries. You will be interested to know that estimates are that somewhere between 15 and 20 percent of lab work is being fabricated out of this country. Should you be concerned? I have spoken with numerous laboratory technicians and dentists who have traveled to China to observe some of the labs producing the challenged laboratory work. I have had generally positive responses. Although the cost of making prostheses in China and other developing countries is about one-fourth to one-third of the cost of making it in the U.S., the quality of most of the work is good. Obviously, the soil on which the prostheses are made is not as important as the quality of the work and the education of the technicians making the prostheses. My concern is not for the quality of the work, which can be supervised and controlled, but about the following:
  • If U.S. labs are obtaining lab work at grossly reduced prices, are they passing the savings on to the dentists by lowering their lab fees?
  • Assuming dentists receive lower fees from laboratories,are these reductions being passed on to patients?
  • Are dentists being informed about the location of fabrication of their lab work?
  • Assuming dentists are informed about the location of their lab-work fabrication, is this information passed on to patients? Most of the clothing you wear probably was not made in this country. Does this bother you?
  • What are the constituents of the prostheses from developing countries? Are they up to U.S. standards? Are these ingredients readily known to the dentists?
  • As you mentioned, what are the infection-control standards used in foreign labs?
  • What is happening to the U.S. lab industry? Accredited lab educational programs have dropped from 60 programs to 20 in the last few years. Are we producing enough lab technicians?
  • Will CAD/CAM planned and milled crowns and prostheses take over the U.S. market? We know that they will soon become a major part of it. Will the offshore labs take over this aspect of the market also?

I have asked many questions related to your question. The real answer is -- we don"t know what is going to happen! We know that offshore lab work is gradually taking over the U.S. lab industry. Major profi ts are being made by U.S. labs, and the windfall profits are being made by dentists. We exist for patients, not ourselves. It is time to become involved in your local and national organizations to help solve this challenge. It is not going to go away!

As a summary, I am not overly concerned about the quality or infection-control standards of the offshore labs, but I do have many concerns as I have expressed. Have a long lunch or breakfast with your lab tech and find out where your prostheses are being made. Then, inform your patients about the entire situation.

Dr. Christensen is a practicing prosthodontist in Provo, Utah. 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 profession in the well-known "CRA Newsletter." 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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