Neuromuscular Dentistry



Robert Jankelson, DDS, MICCMO


Dr. Bernard Jankelson introduced the term Neuromuscular Dentistry to the dental profession in 1967. The masticatory system is a three dimensional system composed of Teeth, Temporomandibular Joints and Muscle. Without muscles the masticatory system is static and non-functional. Neuromuscular dentistry is a comprehensive concept of a dynamic masticatory apparatus that follows universal anatomic and physiologic laws.

However, dentists did not have the technology or protocols to objectively evaluate and diagnose masticatory muscle function/dysfunction or predictably restore masticatory muscles to optimum function. Yet, there is universal consensus that 90% of temporomandibular dysfunction is myogenous in origin. The dental profession operated in a two dimensional field of teeth and temporomandibular joints. Qualitative or quantitative evaluation of the important muscle component could not be possible until development of appropriate measurement technologies. Neuromuscular dentistry operates in a dynamic three dimensional field of teeth, joints and muscle.

The seed of neuromuscular dentistry begins with a little told story of how Dr. J., as he was known to friends and colleagues, became involved in neuromuscular medical research at the University of Washington and University of Oregon Schools of Medicine. In the early 1940’s his beloved wife, Cherub, developed symptoms of neuromuscular disorder characterized by muscle weakness,  vertigo, visual disturbance and other non-specific neuromuscular symptoms. He traveled the world looking for answers and a diagnosis. One of the leading experts on what is now called multiple sclerosis was a physician, Dr. Jonez, at nearby Tacoma St. Joseph Hospital. The diagnosis was made. In the early 1940s there was no known treatment. Dr. Jonez and Dr. Jankelson began a friendship and collaborative search for answers.

Drs. Jonez and Jankelson theorized that the problem was related to degenerative changes in the conductive myelin sheath of the nerves that prevented proper electric conduction. The next hypothesis was based upon the fact that myelin is a prodigious consumer of oxygen. Their early collaboration focused on ways to get more oxygen to the myelin sheath in order to prevent nerve degeneration. Dr. J continued to work with physicians and physiologists at the University of Washington and Oregon Bioengineering Departments following the hypothesis of possible beneficial therapeutic effects from increasing oxygen availability to thwart the continuing nerve degeneration. Something must have worked because his beloved Cherub lived a productive and happy 86 years.

With this early background, the genesis of neuromuscular dentistry began with the collaboration of Dr. Bernard Jankelson and Dr. H.H. Dixon, a renowned muscle physiologist, working together at the University of Oregon School of Medicine in the early 1960’s. The technology to change muscle metabolism and muscle resting states with low frequency TENS was the breakthrough that brought dentistry into a 20th Century paradigm consistent with the rapid technology associated with modern medicine. The electrical parameters established by Dixon and the insight of Jankelson to deliver the stimulus via the coronoid notch to proximate Trigeminal (V) and Facial (VII) cranial nerves exiting the cranium provided, for the first time, the technology whereby the dentist could directly alter the metabolic state of masticatory muscle to facilitate diagnostic and treatment outcome.

Dr. Jankelson assembled a R&D group of former Boeing engineers and biomedical engineers in 1970 to develop biomedical instrumentation to track jaw movement in three dimensions. Four years later, in 1974, the first clinical jaw tracking device was introduced. The system sensed the location of a small magnet attached to the labial of the lower incisor teeth helping the clinician diagnose and treat occlusal mandibular dysfunction with objective physiologic measurement data.

Technology to monitor masticatory muscle activity at rest and in function in a clinical environment was necessary to elevate diagnosis and treatment of occlusion from art to science. Surface electromyography (sEMG) is the technique by which the action potentials from muscle fibers are recorded and displayed. This technology became available to the dental clinician in 1979. Real time sEMG was integrated into the three dimensional computerized jaw tracking system in 1987, allowing clinicians to objectively correlate muscle activity and jaw position.

Because of the creative insight and perseverance of Dr. Bernard Jankelson, neuromuscular principles and techniques combined with state of the art technology applying universal anatomic and physiologic principles help trained clinicians treat patients with temporomandibular disorders, complex restorative problems, restoration of edentulous patients and orthodontic treatment. The management of occlusion as a dynamic three dimensional biologic system, rather than a static two dimensional system, allows the trained neuromuscular dental clinician to diagnose and manage difficult occlusal problems with predictable outcome never before attainable.

Neuromuscular Dentistry: The Essential Elements

  1. Neuromuscular Dentistry utilizes advanced scientifically recognized biomedical instrumentation to objectively measure known physiologic parameters of mandibular function.
  2. Neuromuscular Dentistry’s basic paradigms recognize that generic universal cellular, histo-chemical, musculosketal anatomic and physiologic principles are the key to understanding masticatory function/dysfunction. Neuromuscular principles are consistent with known scientific axioms of other medical disciplines.
  3. Neuromuscular Paradigm is based upon the principle that the biomechanics of occlusion follows known neurophysiologic (not necessarily mechanical) principles involving the temporomandibular joints, the teeth and the masticatory musculature.
  4. Neuromuscular Paradigm is based upon the principle that occlusal proprioceptive sensory information (tooth contacts) can affect many other musculoskeletal systems of the body. Conversely musculoskeletal dysfunction at other levels of the body can affect occlusion.
  5. Neuromuscular Dentistry’s clinical protocol understands the need to optimize joint and muscle function BEFORE altering or restoring the dental occlusion.
  6. Neuromuscular clinical objective is to restore the dental occlusion to a relationship that minimizes the need for muscle to accommodate and compensate in order to bring the teeth into an intercuspal position. Minimizing the need to accommodate to a non-optimal intercuspal position facilitates muscle relaxation.
  7. Neuromuscular Paradigm recognizes that the TEETH are the dominant component of the masticatory triad. MUSCLE and TEMPOROMANDIBULAR JOINTS will ACCOMMODATE to whatever is required to close to the intercuspal position (habitual centric occlusion) during the act of swallowing. Swallowing occurs approximately 2000 times a day and cannot occur without bracing the mandible. This is accomplished by closing to the intercuspal position in order to create the muscle bracing needed for the forceful act of swallow. Some patients with malocclusions will brace during swallowing by intruding the tongue between the teeth to facilitate bracing. Note: Try swallowing without bracing your lower jaw.
  8. Neuromuscular Paradigm recognizes the Universal Principle of Pathophysiology. When the need for accommodation exceeds the adaptive capacity of muscles and joints, it results in pain and dysfunction of the effected structures. This is true at any level of the postural chain, not just the craniomandibular mechanism.
  9. Neuromuscular Dentistry is based upon restoration of the dental occlusion to a position ( Myocentric  defined by minimal muscle electrical activity of the mandibular posturing muscles (Rest Position of the Mandible) along an isotonic (minimal energy required) to bring the teeth into intercuspation (Myocentric). This is an objective, scientifically measurable function.
  10. Neuromuscular clinical protocols require reversible occlusal therapy until MEASURABLE PHYSIOLOGIC clinical parameters and patient response suggest a stable physiologic occlusal position has been established. The patient must be asymptomatic and stable for at least three months before Phase II final durable occlusal restoration is considered.
  11. Neuromuscular Principles recognize that deficient posterior occlusal support (POSTERIOR HYPO- OCCLUSION) is the most common occlusal finding in TMD patients. Restoration of the POSTERIOR occlusal support deficiency is initially accomplished with reversible oral appliance therapy (Phase I therapy).  Phase II irreversible long term therapy is undertaken only after measuring the patient’s physiologic data and satisfactory subjective response indicating the patient is pain free and stable.  This approach is entirely congruent with the American Dental Association-TMD Parameters of Care.

Neuromuscular Occlusal Objectives

  1.  Provide occlusal relationship of the mandible to maxilla that minimizes the need for muscle accommodation and posturing.
  2. Provide an occlusal relationship that allows for optimal decompression of nerve, muscle and vascular structures of the facial and masticatory system.  Decompress the retro-discal tissues of the temporomandibular joint.
  3. Reduction or elimination of nerve entrapment by restoring muscles to their optimal resting length.  Hypertonic muscle spasm shortens muscle which can entrap nerves intra-muscularly or as the nerve passes between the muscles or other anatomic structures.
  4. Decompression of the temporomandibular joint is facilitated by a stable and measurable neuromuscular intercuspal position.  The temporomandibular joint is the only joint in the body where anatomical relationships within the joint are dictated by an external terminal contact end point i.e. habitual (centric) occlusion.
  5. Restoration of optimal posture of the head and neck with minimal muscle activity at rest of all related muscle groups.

Temporomandibular Disorders and Dental Occlusion Restoration

Neuromuscular occlusion is the common denominator

Historically, TMD’s were referred to as TMJ or  TMJD when the disorder was considered only to involve the temporomandibular joints.  Currently, the name TMD is used to describe a group of diseases that can involve the jaw joints, the muscles that control jaw movement and the dental occlusion.  They are physical/functional disorders arising from an imbalance in the delicate working relationship of the jaw and skull with the muscles that move the jaw and the nervous system associated with them. This imbalance results in muscle fatigue, spasm and/or joint dysfunction, and even changes in the form and position of the teeth, which in turn cause a variety of symptoms.

In order to understand what appears in some patients to be global manifestations of TMD, we must understand that the complex stomatognathic system is comprised of the central nervous system in conjunction with the dentition, masticatory muscles and temporomandibular jaw joints all functioning in harmony with one another and its interconnections with the entire musculoskeletal system. Everything is connected and dysfunction in one part can affect dysfunction in other parts. In contradistinction, healthy function in all parts of the stomatognathic system along with proper cranio-cervical posture and healthy airway contribute to homeostasis.

Various concepts of dental occlusion are used in dentistry today.  Members of ICCMO have adopted the neuromuscular occlusion philosophy.  This physiological approach is based on the creation of dental occlusion position synchronized with relaxed balanced masticatory muscle function.  How this is achieved and how neuromuscular occlusion is applied in various fields of dental practice including complex restorative dentistry and orthodontics that will be described in this website.

For patients suffering from various manifestations of TMD, neuromuscular dentistry has allowed clinicians the opportunity to help a growing number of patients that were unable to obtain alleviation of their clinical problems previously by dentists and other health care providers.

The study of neuromuscular dentistry allows the clinician to understand orthopedic principles and dynamic physiologic occlusion concepts more comprehensively than traditional static dental paradigms.  Computerized measurement devices record and permit analysis of mandibular movements, dental occlusion, masticatory muscle function and TMJ joint sounds provide objective information to help dentists treat patients successfully, rather than only relying on subjective symptoms reports from patients and clinical observations throughout treatment.

The recognition of musculoskeletal clinical signs including occlusal flags and subjective patient symptoms aid in the establishment of an accurate diagnosis of acute and chronic pain patients as well as patients requiring the establishment of a new dental occlusion.  In the initial stabilization phase of TMD therapy through the creation of a physiological therapeutic neuromuscular occlusion, it is necessary to identify an optimal starting point of physiologic rest and then select a therapeutic stable occlusal position.  This phase of treatment utilizes a fixed or removable oral orthotic appliance.

Removing all afferent and efferent noxious proprioceptive stimuli of occlusion and objectively measuring all muscle and postural responses of the mandible will allow the dentist to remove harmful muscle torques and strains that relate to the health or dysfunction of the trigeminal system.

In summary, the importance of a physiologic occlusion cannot be over-emphasized in treating TMD patients.

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