The Gnathological vs. The Neuromuscular Approach to Dentistry

Clayton A. Chan, D.D.S., F.I.C.C.M.O.

There are two rivaling philosophies of treatment in this country today by which clinical dentists are treating their patients.

The first and oldest philosophy is that of Gnathology which is based on a belief that the temporomandibular joints hinge on an axis of rotation in the glenoid fossa of the skull. All occlusion is guided and brought together to a finally tuned order, determined by the axis of jaw joint rotation. The emphasis is on occlusion and joint position, which is fundamentally, called "centric relation".

The second newer philosophy is Neuromuscular, based on the understanding that the temporomandibular joints are in a physiologic resting position based on the guidance of muscles and stabilized by the occlusion of both the upper and lower teeth. Emphasis is on a physiologic position of the jaw/ mandible position to the skull (neuromuscular rest position), the physiology of rested muscles to support a physiologic occlusion for stability of all three entities: the TM joints, the muscle and the teeth.

The Great Debate

Both these philosophies are strongly debated among treating clinicians that have been seeking the answers to the mysteries of occlusion (the manner in which teeth fit together). With all it's challenges (which include the treatment and management of the mandible, the muscles of mastication, the supporting hard and soft tissue structures of the temporomandibular joints, the physical as well as the emotional factors that effect their patients), jaw joint position has been a major contention among the various schools of thought, with strong opinionated feelings to support each ones view, clinical experience and teachings they have received.

A Battle to Success

It has been a battle as well as a struggle to reach this present day success of acknowledgement. Due to the natural obstacles that any newly developed innovation encounters, the neuromuscular principles that are presented are often misunderstood and are mercilessly and often illogically criticized. Those who criticize this success would not nor could not renounce their obsolete convictions regarding traditional thinking about the physiology of the masticatory complex involving the mandible, skull, musculature, temporomandibular joints and teeth.

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What is Gnathology?

Dr. Harvey Stallard, of San Diego first coined the term "Gnathology". This term stems from the Greek word gnathic or gnathos in origin referring to the jaw.

Gnathology refers, in its broad and all-inclusive sense to the gnathic system - the system of measuring jaw relations and functions. Dentistry is a branch of medicine and deals with the teeth and supporting tissues whereas gnathology is a specialty of dentistry that concentrates on the entire gnathic system and the whole patient.

Dr. Harvey Stallard, a dentist and a founding father of the gnathological concept stated, "Gnathology includes the exact relations existing between the teeth and the morphological border movements of the condyles: the lateral, the anterior and the rearmost positions... and most importantly, gnathology includes knowing how the nine various directions the condyles move laterally and medially in vertical chewing movements. How the chewing cycle of cusp points may be related to centricity related cusp-fossa occlusion, is wanted gnathological knowledge."

I myself for years emphasized that gnathological treatment endeavors to relate the teeth properly to each other in such a way that they will have a cooperative relation to the jaw motions and joints. I later realized through clinical practice that even though the concept and philosophy sounded well and good, it fell short of physiologic science and objective ideals purported when treating my patients daily in clinical practice, especially in those more challenging cases.

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Outdated Dental Concepts

Gnathological principles originated in the 1930's by some very innovated doctors who had the desire to understand mandibular/ jaw movement by means of mechanical instrumentation called (articulators). These mechanical devices were designed based on notions and opinions of persistent doctors who believed the jaw joints functioned in a certain particular hinging-rotating manner, thus influencing their understanding of dental occlusion, mandibular movement and jaw function. Since these misleading concepts have continued to persist through time to the present day, these notions are still pervading the present day dental curriculum handed down from the early inventors to today's learning dental student.

Future of Gnathology

Dr. Harvey Stallard stated, "What gnathologist should now make up their minds to do are: First, become proficient by learning the movements of the condyles and the effects of these movements upon cusp heights, cusp shapes, and cusp paths. Second, master the techniques of gathering the necessary data to put into the articulator, which will reproduce the necessary jaw relations. Third, acquire an understanding of the anatomy and physiology of the mandibular joints. Fourth, comprehend how the neuro-muscular system assists us to fix the teeth for the best oral automation. Fifth, give greater attention to the nature, structure and health of the periodontium. A gnathologist has arrived when he will be as interested in having glowing health of the gingivae as good form in the occlusion."

There is certainly still many inroads that need to be made into the present day establishment of dentistry; organized dentistry, dental school curriculum, dental continuing education programs, insurance companies, medical health organizations and programs, as well as current literature. Many of the older established instructors and leaders are hesitant to make changes in dental curriculum and continuing educational programs realizing the great sacrifice that they will have to make both professionally and personally. Years of established habits and entrenched concepts need to be altered. CHANGE IS ALWAYS DIFFICULT! Careers and reputations are at stake! The system is presently well established. To rock the boat and change the system after many years is always unwanted.

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As a former gnathologist and still a practicing gnathologist in all its purist sense, I have realized that all true gnathologist's, when understanding the complete craniomandibular/ neurovasomuscular/ cervical components as well as the occlusal concepts that impact the stomatognathic system is truly striving towards the Neuromuscular Approach. If all the dentists that practice the so called gnathological concepts/ philosophy as taught by doctors Harvey Stallard, B.B. McCollum, Charles Stuart, Peter K. Thomas and all the followers, would perpetuate these teachings to their highest level, they would soon realize that the neuromuscular approach, as confirmed by scientific instrumentation, addresses the missing link of understanding all border movements of the mandible, the determinants of occlusion and the physiology between occlusion (teeth), the supportive and functioning muscles, and the physiologic temporomandibular joint position.

A new and upcoming breed of forward thinking neuromuscular dentists are following in the paths of the innovative Dr. Bernard Jankelson and his son Dr. Robert Jankelson who have been opposed by the establishment for years. Responding to this call of rising to a "higher standard of care" for our patients is our professional obligation to reach this goal. From this neuromuscular perspective any dentist can begin to treat in a complete and comprehensive manner.

Dr. Chan is a trained gnathologist. He has practiced gnathology for many years realizing that gnathologics did not answer nor confront the issues that were being faced with his patients under his care. After persisting to do the best dental care for his patients within the confinements of the standards of that philosophy, he soon realized that there had to be another way that addressed the issues that have been presented. He is pleased that he could share these thoughts with those that are seeking another side to the story of clinical dental care.

Today he practices Neuromuscular Dentistry with great success and predictability. If the viewer has any questions or concerns regarding what was presented, Dr. Clayton Chan will be please to hear from you.

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