This post is written to explain the approach promoted by the Las Vegas Institute (LVI) and describe their philosophy of neuromuscular dentistry for oral rehabilitation and treatment of Temporomandibular disorders (TMD) as compared to post graduate training in most Australian prosthodontic programmes that train specialists for cosmetic dentistry, oral rehabilitation and TMD treatment. Specialist registration requires at least three years of full time education at an accredited university and teaching hospital. LVI dentists are led to believe they have joined a prestigious elite training program that is world class to treat jaw joint pain. LVI is not university based and is run by general dentists over a few weekends in Las Vegas. Many generalists and specialists are concerned about irreversible over-treatment possible with a neuromuscular philosophy. Temporomandibular disorders (TMD) can be debilitating and painful with complex origins. They comprise a group of musculoskeletal disorders that arise from jaw muscles and Temporomandibular joints (TMJ). This disorder is broadly divided, using the research diagnostic criteria into joint pain (Arthralgia), muscle pain (Myalgia) and headache. When standing upright, the lower jaw is held in place by the muscles providing orthopaedic stability counteracting the forces of gravity at a natural “clinical rest” position with the teeth slightly open and separated by about 3 or 4 mm. The muscles have some tonus and this rest position is not one of least electrical activity. This position is variable and capable of adaptation. When tested with EMG, least muscular electrical activity is almost always 8 mm lower (inferior) and 3 mm forward (anterior) from the normal “bite” position. While chewing and swallowing, closing muscles contract and the teeth come together. At this point only three things contact, the two joints, one on each side and the teeth. At all other times teeth are separated Dentists have assorted schools of thought on the best position of the joints in relation to their sockets (fossa) and tooth contact position. The most accepted method is to achieve centric relation (CR), where if the lower jaw is allowed to flop up and down like a bucket on a hinge and with the lower jaw in a comfortable, unstrained backward position (retruded) almost chewing on the molar teeth. The chosen rehabilitated “bite” position is where the teeth will contact as the jaw arcs around this hinge at the chosen vertical position. This reproducible position can be confirmed during swallowing with the back teeth lightly and evenly coming together as the tongue moves upwards and backwards. Tooth contact time during swallowing is similar to that of chewing. LVI believes that TMD has a primary physical/functional basis, and that neuromuscular dentistry and providing a therapeutic dental “bite” (occlusion) provides a scientific treatment with the joints, muscles and teeth in harmony. There are two principal schools of thought that exist regarding the aetiology and optimal treatment of TMD; one physical/functional, the other biopsychosocial. Most university based post graduate programmes teach the alternative biopsychosocial model with conservative non invasive treatment for management of TMD pain with less emphasis on bite manipulation as a definitive treatment. LVI promotes a Myo-monitor to establish a comfortable bite and a lower jaw rest position at least electrical activity of the muscles. This tool was derived from a transcutaneous electrical neural stimulation (TENS) machine and has some electrodes that are placed only on the surface of the superficial muscles of chewing (mastication). The ‘myo-monitor’ was initially promoted by Jankelson in the 1970’s and supposedly helps relax the muscles so the dentist can find the correct bite for the patient. What the Myo-monitor does is relax some muscles with TENS and the electrical current contracts other muscles on the surface. The lower jaw almost always moves downward and forward in a slightly open position with the teeth then further separated. When the electrodes are removed the bite soon returns to the natural position. LVI literature (Visions Spring 2012) states that 80% of the population is not in their physiologically correct biting position. Believers feel the magic box gives the doctor a special reading which shows the bite position that is correct for the patient. It is outstanding that 80% of the population suffers from this disease, which can be diagnosed with an expensive plastic box with a couple of electrodes. The Myo-centric brings the lower jaw more open and forward than the preferred bite used by traditional experts who preferred the jaw joint ‘centered’ (Centric) and not sliding down and forward, and out of the socket (fossa). This forward and downward position is then recorded as the ideal rest position and then closed 3-4 millimetres for a ‘myo-centric’ bite level. Remember the stimulus acts only in the periphery of some of the superficial muscles without the participation of the central nervous system, and the ability of the instrument to produce a reflexly controlled occlusal position is highly questionable (Dao et el 1988). The new relaxed bite position is always a little open, meaning the teeth no longer touch. The bite could be tested with an acrylic appliance sometimes called an ‘orthotic’ but generally the difference between the patient’s original bite and this magical new bite is made up with porcelain restorations lengthening the teeth – usually all the teeth to recreate contact. This treatment requires tooth preparation and can damage healthy teeth, is not reversible and does not last a lifetime. For some patients the downward and forward lower jaw position can relieve discomfort as the lower jaw may move away from the sensitive tissues at the back of the joint capsule if the disc is forwardly displaced. The change in bite is not always tolerated well by the patient’s body – sometimes creating extra muscle pain and breaking of the porcelain restorations with added expense and treatment time. The comparison between this Myo-centric and the established centric relation is discussed by one of the elder statesmen of restorative dentistry, Peter Dawson and is seen at this link. https://www.youtube.com/watch?v=utOr8lsw3TM&feature=youtu.be&t=51m53s Reference: Dao TT, Feine JS, Lund JP. Can electrical stimulation be used to establish a physiologic occlusal position? J Prosthet Dent. 1988 Oct;60(4):509-514. Don’t forget to share this via Twitter, Google+, Pinterest and LinkedIn.