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#1 How vital is the study of occlusion,
to practitioners involved with cosmetic dentistry?
Occlusion is Vital for Cosmetic Dentists.
Two of the most powerful recent changes in dentistry are conservative bonded restorations and the “Cosmetic Occlusion Connection.” Placing numerous cosmetic veneers has a significant impact on occlusion. Understanding the etiology of past trauma and optimizing the future longevity of restorations, orthodontics, and comfort is the study of Neuromuscular Occlusion.
Cosmetic Dentistry answers the questions of beauty. Neuromuscular dentistry answers the questions of function, power, forces, comfort and the foundation of beauty. Other than external trauma, all theories of occlusion agree with Dr. Spear, “muscles of mastication generate the forces that create traumatic problems.” To avoid traumatic problems, your theory of occlusion must include measured muscle activity. Just like we would not diagnose periodontal disease without measuring the depth of periodontal pockets, neither should your theory of occlusion attempt to diagnose or treat occlusion without support from actual measured muscle activity.
“Beautiful Smiles and Happy Muscles.”
A “beautiful smile” is more than nicely shaped white teeth and a shapely “gum line”. “Unhappy” spastic, tense, painful muscles of mastication and facial expression create the appearance of a worried, uptight and unfriendly smile.
The Neuromuscular Dentist understands the effect muscle activity has on supporting and adjacent structures. Lift a load with one arm and the entire body from head to foot reacts to balance and support the load. In time, the “weak link” sometimes distant from the actual load will become painful. In a similar way muscles of mastication elicit a supporting reaction from other muscles down the kinematic chain. Muscle hypertonicity required to posture and position the mandible close to malocclusion or achieve a muscle strained occlusion can cause pain in the TMJ, ears, head, neck, shoulders, and much more. The design of a beautiful smile must include the design for “happy muscles”.
Signs and Symptoms of “Occlusal Dis-ease”
The mind sees what it is trained to see. In addition to traditional dental and medical records, the Neuromuscular Dentist includes additional signs and symptoms with serious expectations to resolve or manage these problems. Signs of improper oro-facial development and neuromuscular problems can include headaches, neck pain, shoulder pain, pressure behind the eyes, TMJ pain, vertigo, ear pain, tinnitus, crowded lower and warn anterior teeth, deep bites, posterior lower hypo-occlusion, vaulted palates, abfractions, abrasions, chipped, cracked, mobile, sensitive teeth, unexplained periodontal pockets, unexplained redness, bone buttressing, tori, aberrant swallow pattern, dry mouth in the morning, tender muscles to palpation, resting the head on the hands, excessive gum chewing, lip and cheek biting habit, dry mouth in the morning , snoring and the list goes on.
If the body trashed the natural teeth, there is a good chance the body will trash your restorations unless the etiology is addressed. To understand neuromuscular disease, measure the forces generating the disease. Muscles are not doing what you think, believe or guess. The body should function with ease, not dis-ease.
The “Occlusion” Problem is Huge
The cosmetic dental exam is an ideal opportunity for a thorough diagnosis of malocclusion and poor mandibular posture. Casual surveys of dental office team members indicate more than 75% have taken pain medication for head, neck, or shoulder pain within the last two months. The number one health care concern of women is headaches. Estimates place 80-90% of head pain with a primary muscle component. As clinicians responsible for the muscles of mastication, we have tremendous power to create muscle ease or dis-ease, comfort or pain. In simple terms, “if the bite is not right, the muscles will be up tight. If the muscles are up tight the dentistry is not right.”
#2 When you perform an examination and establish a diagnosis for occlusal pathology, what specifics are you looking for, and
what are some of the diagnostic tools you employ?
Look for both Clinical and Sub-clinical Signs of Occlusal Pathology
Occlusal relationship should not result in pathology for the muscles of mastication, should be clinically reproducible, comfortable to the patient, and prevent unnecessary joint, periodontal or tooth stress. Measure the generators of stress, muscles. All occlusion theories should provide measured evidence of actual muscle activity, some don’t. Pain and clinical evidence of pathology can sometimes take months or years to be observed, thus sub-clinical evaluation is essential in preventing chronic pathology. Waiting for the patient to report pain or damage before diagnosing decay, periodontal disease, or occlusal disease is waiting too long.
Unique Aspects of a Neuromuscular Exam
The Neuromuscular dentist will include traditional clinical information of health and dental history, photographs, models, radiographs, palpations, sonography, etc. Recorded real time muscle activity is clinically essential when comparing occlusal theories, diagnosis and treatment documentation, long term evaluation, prevention, and sub-clinical evaluation of occlusal pathology. The Neuromuscular Dentist has specific goals and outcomes for muscle activity as measured with surface electromyography (SEMG). Examples are postured rest, muscles should have low SEMG without fatigue (Scan 9/10). Lifting the mandible to the selected MIP should result in a minimal measured SEMG increase (Scan 4/5). In maximum clench the muscles should be balanced with high SEMG measurements Scan 11). With measured first tooth contact the muscles should start to contract simultaneously (Scan 12).
The first “half” of determining optimum occlusion is finding the correct relationship between the mandible and maxilla (Scan 5) and the other “half” is precise tooth contacts. (Scan 12) Getting one or the other correct may improve occlusion, but both need to be correct for optimal results.
To Achieve Rested Muscles, Start with Rested Muscles
In an upright body position, a rested mandibular zone can be determined if muscle hypertonicity and psychological stress are controlled. Rest is usually measured from eight regions of muscle groups, anterior temporalis, posterior temporalis, masseter, and anterior digastric homologous pairs. Less than 2 microvolts of muscle activity without fatigue (Scan 18 not included) is considered normal. (Scan 9/10) Occlusion should be placed on an ergonomic trajectory closed from physiologic rest, allowing for freeway space and cosmetic desires, but maintained within a zone of least muscle tone and stress. (Scan 5).
TMJ Harmony
Harmony between the joints and teeth should be measured, not assumed (Scan 11, 12). Compare a non maximum intercuspation (MIP) maximum clench on cotton rolls with a maximum clench in MIP, measuring muscle endplate activity with SEMG. In MIP, the joints and dentition should not significantly alter the ability of muscle contraction (Scan 11).
Response from mechanoreceptors in the joint will permit maximum muscle function or limit muscle function depending on the physical stress in the joint. (Scan 11) The neuromuscular position has been found to recruit the greatest force compared to manual manipulation or leaf gage position. (Scan 11) Norms in the 150 to 300 microvolts and homologous pairs within 20% should be expected. (Scan 11)
Disability of muscles in a maximum MIP clench is a sign of muscle in-coordination, malocclusion, tooth (periodontal) sensitivity, or unacceptable pressure in the joint. (Scan 5, 11, 12) Pressure stimulating the mechanoreceptor nerves will cause lateral pterygoid and myohiod reflex reactions (Scan 11). A “synarthrodial, fully congruent, seated joint position” should be avoided. (Scan 5, 11) Mechanoreceptor nerves are physiologic sensors you must include when determining and evaluating the response of the joints to the chosen mandibular position, MIP. (Scan 11) However, in boarder excursive movements, a reduction of muscle activity with anterior teeth contact is desired. When possible, a theory of occlusal harmony must be supported with actual muscle measurements, not based on clairvoyant guesses or theoretical suppositions of muscle activity.
“First Tooth Contact”
The Neuromuscular dentist measures “first tooth contact” by evaluating the sequence of non propriocepted muscle recruitment. (Scan 12) Muscle harmony must be measured. It is impossible for the patient or clinician to determine at any given instant how the muscles are actually responding to the dentition. For coordinated muscle activity, the temporalis and masseter sEMG activity should have homologous activity with simultaneous recruitment balanced and harmonious at the first 5 microvolts. Sub-clinical evaluation of muscle recruitment harmony increases accuracy of occlusion and patient comfort. (Scan 12)
Computerized Jaw Tracking
Computerized jaw tracking records various mandibular positions clinically. (Scan 5) An ergonomic trajectory of closure is possible with an accuracy of 0.1mm, enabling a precise bite registration without manipulation rather a position based on physiologic measured activity. Simultaneous physiology and mandibular position are documented for pre and post treatment comparison. Recording deviations during mandibular movement provides objective data on the harmony of the system. (Additional Jaw tracking Scans not show)
Finished Occlusal Evaluation
Final Occlusal Evaluation may include “light teeth contact” or muscle posturing activity required to achieve MIP. (Scan 5 compare pistons) To lift the weight of the mandible into MIP in an ergonomic path, the muscles should show little more activity than rested tone and effort overcoming gravity. Ergonomic positioning of occlusion should have measured muscle harmony, balance, coordination and minimal antagonistic muscle activity. Muscles should not be hyperactive as measured in CR, Aqualizer, or NTI. (Scan 5) Final case finishing includes actual force measurements to ensure center of force is midline and anterior/posterior no further anterior than the first molar. (T-Scan II)
“A theory of dysfunction that involves areas of effort up and down the kinetic chain of movement” must be included with any theory of occlusion. Measured and recorded muscle and jaw tracking activity are critical for diagnosis and dental treatment on each unique individual.
Both SEMG scans show four muscle pairs Temporalis Anterior (LTA, RTA), Masseter (LMM, RMM) Temporalis Posterior (LTP, RTP) and Digastric (LDA, RDA) sEMG measured at rest in upright posture. The right scan shows reduced muscle hypertonicity of the same muscle pairs after 60 minutes of ultra low frequency TENS. Mean Hz decrease (scan not shown) shows fatigue in left temporalis anterior and left masseter.
Scan 5: Posturing muscle activity at various mandibular positions.
(Resting not biting) 
Scan 11: Maximum Clench at various mandibular positions
Scan 5 and 11 are the same subject, same set of positions. First note the zone of least muscle tone and ergonomic path of closure, VDO between # 1 and #3. Anterior/posterior and lateral positioning is generally more critical than VDO.
Note three consistent reproducible positions on a neuromuscular trajectory over a period of one year by three different clinicians (#1, #3, and current tracking). The colored pistons show muscle activity at each position of the mandible at rest. The CR (#5) is most superior of all positions, with least muscle coordination, least muscle balance, greatest antagonistic muscle activity and disharmony. The NTI (#2) shows the most inferior anterior position. Note digastric muscle activity increases when retruding the mandible, CR and Aqualizer, reducing in the NM positions and then increasing again opening the jaw to the NTI position.
Scan 11. Six maximum clenches, evaluating muscle and nerve response to various joint and occlusal positions.
Note the significant reduction (about two thirds) of masseter muscle activity in CR indicating significant joint stress and lack of muscle harmony. The year old Neuromusuclar (NM) Orthosis should have slight adjustments to enable better muscle coordination and balance. Natural teeth in CO position has some reduction in masseter activity, again indicating possible joint stress and lack of muscle harmony. The cotton rolls and Aqualizer provide a target for maximum clench in a non propriocepted position or more balanced muscle function. Reduced muscle ability with an NTI but higher masseter activity than CR.
 Scan 12 For the final case finishing, sequence of muscle recruitment helps the clinician determine
actual tooth contact. The clinician should have temporalis and masseter muscles recruit in balance and harmony. This can only be confirmed with measured muscle activity. In this illustration the adjustments are very close with a slight anterior interference. The “avoidance” of a prematurity by the neuromuscular proprioceptive system, creating the subjective contact sensation in a different area, is common.
Bite forces do not appear to be affected by ethnicity, gender or age[i] and should be centered midline at about the first molar. [ii] If the clinician desires to restore normal A/P (anterior to posterior) dentate function and uses T-Scan II® equipment, the “bulls eye” or “ellipse” on the T-Scan II® is an artist’s fixed conception and should be imagined on a line between the first molars. Patient arch sizes vary whereas the artist’s drawing is stationary.
[i] Shinogaya T, Bakke M, Thomsen CE, Vilmann A, Sodeyama A, Matsumoto M., Effects of ethnicity, gender and age on clenching force and load distribution. Clin Oral Investig. 2001 Mar;5(1):63-8.
[ii] Toda S., Kokubyo Gakkai Zasshi. [A clinical and physiological evaluation of masticatory center in unilateral shortened arch and RPD treatment] 1999 Jun;66(2):170-88. R
#3 How do you determine if mandibular elevator muscles (temporalis, masseter) are involved in parafunction, and how do you deprogram lateral pterygoid muscle if in hyperfunction?
Muscles are the “Engines” of the Mouth
Muscles are the source of power for function and parafunction, and nerves control the muscles. Neuromuscular Dentistry measures these generators of force and positions the mandible and dentition where muscle hyperfunction is avoided. Muscle function, parafunction, and hyperfunction are clinicially measured with surface electromyography (sEMG). (Scans 5, 11, 12) Simultaneous jaw tracking with SEMG muscle measurements, provide real time muscle function at each mandibular position and activity. (Scan 5) Clinically, the results of parafunction are evaluated after the damage to teeth, periodontium, bones and joints have transpired. Sub-clinical evaluation of forces prior to the damage is essential for prevention of damage and pain.
Function Involves More Than One Muscle.
The questions posed recognize oral muscle function, parafunction, hyperfunction are usually not an isolated muscle activity. “A single, discrete muscle rarely works on its own in a real and varied life situation. . . To think of testing one muscle is entirely too simplistic” Even thinking of a single muscle as causing a single direction of movement is inadequate. The lateral pterygoid (LP) has functional heterogeneity with two heads and heterogeneity within each head.
Parafunction is more than a “one way movement”, the return movement must be considered and certainly can be clinically measured. LP parafunction is best evaluated clinically by measuring its antagonistic and synergistic muscle groups; areas of the temporalis anterior and posterior, masseter/medial pterygoid, anterior belly of the digastric. Certainly the temporalis posterior fibers and digastric muscles are active during a “return” movement of parafunction and they are clinicially measured by Neuromusuclar Dentists.
LP Hyperfunction
“Our understanding of LP function in TMD patients is even less than our limited understanding of its normal function, with no reliable studies having ever been performed in TMD patients.” Our best understanding of the inferior head of the lateral pterygoid ( IHLP) and superior head (SHLP) is to measure as many other muscles of the joint as possible.
If hyperfunction of the IHLP were in isolation, the jaw would translate without much or any tooth contact, leaving the mouth open. Hyperfunction with only IHLP and no masseter, medial pterygoid, temporalis, SHLP, or digastric activity would hardly result in damage to the dentition as is typically seen in oral parafunction. Lifting elevator forces must also be taking place for damage of the dentition. To only consider deprogramming the IHLP muscle is unacceptably simplistic.
Hibino did find the SHLP to be “qualitatively similar to but quantitatively distinct from jaw closing muscles such as masseter and temporal muscle,” but did not find the SHLP to act in isolation.
Is “Deprogramming” the LP the Answer?
What is causing the LP to contract? To focus on deprogramming or preventing the muscles of mastication from functioning, assumes the parafunctional or hyperfunctional activity is itself the pathology and not possibly a “protective” or “purposeful” response to a more serious underlying etiology and pathology. Temporarily deprogramming the muscles may have significant palliative benefits but not address primary pathologic degeneration. Neither will palliative methods provide the clinician with an optimal occlusal position for orthodontics or restorations. Pharmacology, nutrition, neurosurgery, psychology, and anterior appliances preventing the teeth from occluding all play roles in helping the patient tolerate pain but do not address the primary etiology. Dental therapy should improve function not be limiting or disabling. Preventing natural neurologic warning signals from reaching the brain does not treat the cause. For example, if you have a rock in your shoe, palliative treatment might be to hobble the foot, to prescribe analgesics, to seek psychiatric counseling or to surgically sever the nerves from the foot, but definitive therapy would remove the rock and prevent rocks from getting in the shoe.
Understanding why the body appears to “mutilate” itself in parafunction with an apparent intense dislike for the teeth or their current position by grinding is important. Just because the LP muscles are not clinically measured in isolation, is no excuse not to measure the other muscle groups. To consider diagnosing or treating muscle and joint hyperfunction without measuring any of those force generators is nothing less than a diagnosis based on faith and clairvoyance.
“Hotter Than a Pistol”
Watching live SEMG activity when a person protrudes, retrudes, closes, opens, and the symphony of muscle action becomes clear. It is unreasonable to expect the LP muscle to contract in para- or hyperfunction without any help or even bracing from the other muscles.
In all cases where I have measured or seen muscle activity measured on subjects in centric relation (CR), the muscles were “hotter than a pistol” just to achieve condylar position with light MIP. (Scan 5) Certainly it is unreasonable to position the mandible or teeth where a theory speculates the LP is deprogramed yet results in measured pathologic hyperactivity of all or several other muscles.
When the mandible is positioned at postured rest based on the measured SEMG activity of the anterior and posterior fibers of the temporalis, masseters and digastrics measured clinically, the LP should also be at rest.
Neuromusuclar dentistry positions the occlusion for minimal muscle tone in postural rest, (Scan 9/10) minimal increase to achieve light tooth contact in MIP (Scans 5 and 12), maximum functional ability (Scan 11), optimal aesthetics, optimal physiologic joint position (Scan 11), and patient comfort.
#4 Many of our recent dental graduates have little occlusion training. More seasoned clinicians may also have little background in the study of occlusion. What specifics can you recommend these colleagues, who may wish to pursue more training in the field of occlusal study?
Advanced Dental Studies
A relentless pursuit of life long learning is extremely rewarding, and our professional responsibility. A diploma and license are just the first chapter in a professional education. Technology, materials, research, knowledge and communication are facilitating an explosive growth in Dental Continuing Education. Dental Continuing Education can be found at several locations, however the American Institute for Advanced Dental Studies (AI) offers the finest in live patient Neuromuscular Occlusion Courses with and without measuring equipment.
If occlusion were a product, pill, piece of plastic, or machine, manufacturers might sell it to us for “a dollar a drop or pill, a few dollars for the plastic, or many dollars for equipment” and occlusion would have financial popularity. Occlusion is not a product rather it is as fundamental as understanding how the mouth opens and closes. The mastery of occlusion must include education.
The Cosmetic Occlusion Connection
Dentistry in 2003 is in its adolescence, the future is exciting, limitless and opportunities to help our patients without precedent. Both junior and senior dentists are discovering a new world of cosmetic neuromuscular dentistry, the “Cosmetic Occlusion Connection”. Neuromuscular dentistry at the American Institute helps clinicians answer the questions, “where do I position the mandible so these beautiful restorations last, the muscles are not hypertonic, the patient has both optimal function and rest, and the clinician avoids iatrogenic occlusal pathology?” Since muscles are the power sources for occlusion, measuring muscle activity tells the clinician what those “power sources” are really doing. With confidence the clinician is able to provide a beautiful smile and comfortable muscles. Give your patients the excuse for accepting cosmetic dentistry with improved muscle, joint, and functional health.
Have You Become The Best That You Can Be?
What if you could treat the patients you wanted in the way you knew was best? What if you could provide life changing beautiful smiles and have the bonus of reducing headaches, TMD, and muscle fatigue? What if you didn’t have to run from chair to chair seeing numerous patients each day, and usually providing them with the “least expensive alternative?” What if you could provide your family with the best of your time and support? Regardless of your experience level, the American Institute offers an opportunity for your next step in the Cosmetic Occlusion Connection. Neuromuscular Occlusion is for every Dentist.
“The less you know, the more normal your patients appear.” The more you know, the more inclusive your definition of success. Expand your definition of success at the American Institute for Advanced Dental Studies.
Dale was clear, “Scientific study of anatomy, biochemistry, physiology, and objective analysis with kinesiology, electromyography and sonography, along with case history all point to the same thing; occlusion affects the joint and the muscles. This is our profession's "crown jewel". We diagnose, construct and modify our patient's occlusion. It is about time we all agree, understand, take responsibility and start cooperating in preventing and treating this common malady (TMD) that seriously affects the quality of life of many.”
Years ago Graber presented, “static analysis is important, but equally important is a dynamic appreciation of how these parts function.” For a clinically measured dynamic appreciation of each unique individual’s functioning system, consider the “Cosmetic Occlusion Connection” at the American Institute for Advanced Dental Studies.
Murray G, Phanachet I, Single motor unit activity in human lateral pterygoid muscle during defined motor tasks, Australian Dental Journal ADRF Special Research Supplement 2002:47:4
Dale R., TMD: it's our responsibility; J Gen Orthod 1999 Fall;10(3):15-20
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