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by Clayton A. Chan, D.D.S.

The Websters dictionary defines occlusion as: the bringing of the opposing surfaces of the teeth of the two jaws into contact, also the relation between the surfaces when in contact.

The following article is posted on this website with personal permission from Dr. Robert R. Jankelson. It is taken from the Forward of his textbook titled “Neuromuscular Dental Diagnosis and Treatment”.

“Occlusion” is such a fundamental element in dentistry that almost all departments of dentistry are concerned with it. It has been one of the key issues for many years for every generation of our profession.

In prosthodontic dentistry where the aim is artificial reconstruction of occlusion to harmonize with the entire stomatognathic system, two major schools of theory have been advocated: One is the mechanical occlusion theory initiated by Dr. Gysi, where emphasis is placed upon mandibular movement. The other is a theory of functional occlusion system based on neuromuscular physiology.

The mechanical occlusion theory has been dominant in prosthodontics over the past 100 years and has led to the development of numerous adjustable articulators and related clinical techniques.

On the other hand, the oral physiology theory indicates that the functional occlusion system is made up of three major components: teeth, muscles, and temporomandibular joints. Occlusion is maintained by the activities of the masticatory muscles which are controlled by neural integration of the feedback from peripheral proprioceptors and the reflex mechanism from the central nervous system.

Unfortunately, however, this functional occlusion system theory based on neuromuscular physiology was overshadowed by the mechanical and geometric occlusion theory until about 1970. This was due to lack of scientifically supporting technology to link observations to clinical practice.

In 1970, Dr. Bernard Jankelson successfully developed electronic instrumentation for the diagnosis and treatment of stomatognathic disorders.

Review of the mechanical occlusion theory was triggered by his concept that a clinical approach to occlusion should not be hypothetical, but must have a firm theoretical and experimental basis derived from the total physiological phenomenon of the organism. The masticatory muscles, which position and connect the mandible to the skull, should be the focal point of correct occlusion.

His physiologic approach to occlusion and techniques with scientific back-up has brought about new dimensions not only to patients suffering from stomatognathic pain which could not be cured by conventional occlusion theory, but also to the dentist seeking to understnad what the true occlusion should be.

His concept has further been developed by many researchers and distinguished clinicians, and is now recognized as an established clinical procedure with scientific verification.

Written by: Professor Atsushi Yamashita, D.D.S., Department of Prosthetic Dentistry Okayama University Dental School, Okayama City, Japan

PHYSIOLOGIC OCCLUSION: The Occlusion of Choice
Physiologic occlusion is the most natural and highest order of teeth fitting together in relation to unstrained TMJ’s (temporomandibular joints or jaw joints), jaw bones, muscles, ligaments and soft tissue of the mouth. In the dental profession we have observed that nature has given us a template or a blue print which can be followed in order that this complex anatomy can function in harmony with one another and in a manner that prolongs the health of our teeth while biting and chewing.

The aim and goal of physiologic occlusion is to have all the teeth fully occluded when the jaw joints are in the unstrained, rested, physiologic (neutral) posture. This occlusion should allow all the teeth to harmoniously separate in all the natural chewing and sliding motions without creating harm and interferences of one another, neither causing antagonistic muscle splinting to stimulate myofacial pain disorders.

Dr. Clayton A. Chan is a strong advocate of a physiologic/ gneuromuscular occlusion. Formerly trained and practiced the gnathological concepts for years, he is vary aware and understands both sides of the occlusion issue. He realizes that these issues hit home to those in the academic, lecturing and teaching arena of dentistry. He also realizes that ignoring these issues will not perpetuate changes that are absolutely needed in the educational arena of the dental profession. He is an advocate for reform and change in this area of dental care.