(The following is an origianal forum posting written in December 11, 2004 by Dr. Clayton A. Chan regarding the Optimizing the Neuromuscular Trajectory Using the K7 Scan 4/5 Chan Protocol named the “Chan Scan”)
The following is my brief response to a very in depth topic that has intrigued many neuromuscular dentist graduates. The Chan Scan protocol from my experience goes beyond what I can possible explain or write in this short email. I realize that over this past year many have asked and inquired many times on the forum, but each time I have personally hesitated to write because I was often afraid that the Chan Scan would be misunderstood and overly simplified in a manner that would overlook the depth and significance of such find. Thanks to Dr. Norman Thomas who has observed very carefully, questioned and watch me on numerous occasions while applying this technique and protocol with intrigue and interest. His physiologic and anatomical expertise has inspired many and has furthered my resolve that this find has clinical and scientific relevance, answering further some questions we have been all haunted by when taking a NM bite and applying NM principles to this level of dentistry. Bill Wade is also to be fully acknowledged for his kind and generous out of the box thinking who intellectually questioned the protocol with open mindedness and named it the “Chan Scan” after also discovering its validity based on his years of experience and an season K6i/K7 instrumentation trainer.
The following will first give some background into the thinking process of the Chan Scan which I believe helps lay the foundation when applying the Chan Scan technique so as not to confuse the issue as to NM bite taking techniques. As I realize there will always be some that will take bits and pieces of information and will misconstrue the original intent of such. This technique does not supersede the classic technique of the Scan 4/5 with EMGs, neither is intended to overlook or discount the profound principles that are fundamental in the use of the scan 4/5 which have been taught by the NM clinicians as Jankelson, Garry, etc for years with tremendous success. I will remind the readers that this is an advanced technique!
There are five levels of NM Bite Recording Techniques. Each are relevant and all will work and have been proven to be success. Of course success should be defined, but that would be held for a later discussion.
1. Classic TENS bite
2. Modified TENS bite
3. Classic Scan 4/5
4. Classic Scan 4/5 with simultaneous EMGs
5. Optimized the Neuromuscular Trajectory (Chan Scan) Bite technique using Scan 4/5
WHICH NM TRAJECTORY?
As many NM clinicians have recognized, especially the Neuromuscular (NM) graduates, the positioning of the mandible over time may move more anterior than the previous determined NM trajectory. This obviously results in a different isotonic path of opening and closure path (a new NM trajectory) with an accompanying physiologic rest position that has also changed over time. The Myomonitor TENS clearly has been key to establish a neuromuscular trajectory classically with a myopulse established at clinical threshold up from the physiologic rest position at that point in time of patient treatment. Muscle engrams and muscle memory play a role in overcoming low frequency TENS stimulation, yet at the same time one can also say that the Myomonitor TENS works to establish muscle relaxation, physiologic rest and begins to assist the clinician in determining a trajectory of the mandible during bite registration. It is clear that establishing an physiologic mandibular to maxillary relationship cannot be done efficiently without “physiologic” muscle relaxation, thus the importance and need to use the low frequency TENS.
As I have indicated in past and more recent lectures, there have been wonderful, yet interesting NM challenges: 1) the NM orthotics commonly need to be adjusted or resurfaced in a more anterior direction over time as the mandible moves anteriorly, 2) the NM clinician does acknowledge the fact that the mandible does move anterior over time due to muscle, joint, discal tissue resolution and decompression, 3) the NM clinician recognizes that coronoplasty is needed to keep pace with the shift in mandibular positioning over time to address the proprioceptive feedback of the afferent and efferent stimulus through the periodontal ligament and CNS, and 4) the NM clinician also recognizes condylar shift does take place as the masticatory muscles relax in an anterior direction on a neuromuscular trajectory.
A QUESTION TO THE NM CLINICIAN?
If the above is occurring and has been experienced over and over again over the past 25-39 years of NM history, has the treating clinician actually identified an optimal NM trajectory when using the Myomonitor TENS?
Fact: NM success has been nationally and internationally recognized using standard protocols that have been taught and realized over the many years of clinical application and academic study. The protocols that have been taught have shown to be very conservative and effective having given excellent clinical results, yet the above question still needs to be answered.
It is clear that low frequency TENS does not always remove muscle engrams immediately that want to continually draw the jaw back to its previous habitual bite after a 45-60 + TENS session. During NM bite recording it is imperative that the TENS stimulus remains on at all times at clinical threshold to assist in removing mandibular torque in 6 dimensions as well as reducing unwanted spastic muscle accommodations that effect the final result of optimal occlusion. TENS is very important to establish a proper NM bite registration, but one must recognize that the TENS does NOT take a bite neither gives the clinician an optimal bite position. The doctor/clinician must use all his understanding and appreciation of muscle dynamics and jaw positioning to establish where best to take the bite. The TENS tools only allows for MUSCLE RELAXATION to begins the process of establishing dental health, not without the clinicians understanding that there are restrictions and limitations that must be overcome both in their understanding as to what does the TENS do and what it does not do, how muscles function and effect jaw positioning and what must be overcome to effectively establish a better end result in clinical treatment.
MOVING IT UP ANOTHER NOTCH IN THE THINKING PROCESS
As the NM clinician progresses in their understanding and evolution of clinical dentistry, it sooner or later becomes apparent that when using the computerized mandibular scanning (CMS) one will discover that there can be multiple NM trajectories with the use of TENS. They may also all qualify physiologically as “Neuromuscular Trajectories” since they all may also display sharp even pulses returning to baseline. They may even have accompanying low EMGs to support such claims. The question than arises as to “Which is the more Optimal Neuromuscular Trajectory” to use if one is going to finalize the restorative case? The classic TENS bite will produce a trajectory forward of the habitual trajectory, the Modified TENS bite will also produce a more anterior TENS trajectory and the Chan Scan will also produce a trajectory that can be observed and realized using CMS technology with EMGs. The status of hypertonic muscles, air way breathing factors, tongue posturing factors as well as joint health can all effect the NM trajectory and the quality of physiologic rest position which as a result will effect the NM trajectory!
To the NM graduate who is very astute to finishing his/her porcelain restorations, it is clear that one would choose the more anterior trajectory that can be clearly supported with patient resolution of the numerous musculoskeletal signs and symptoms, a repeatable non arbitrary AP positioning of the NM trajectory, proven over time with repeated terminal contact positioning in the bite after reducing bilaterally the condylar/discal tissues for optimal range of mandibular motion and function, optimizing the ligamentous constraints, supported with normalized muscle EMGs, aesthetically pleasing facial proportions of the lower one third of the face, and Golden Vertical relationships that are aesthetic. This is the trajectory that I prefer, since this trajectory will minimize the post operative occlusal/incisal adjustments, especially when finishing my full mouth rehabilitation cases or anterior aesthetic type cases.
CHAN SCAN OVERVIEW AND PROTOCOL
The Chan Scan is a clinical technique and protocol that begins with the “Classic Jankelson” scan 4/5 as its foundation! It is not a forced position beyond normal physiologic and anatomical constraints. It is a measured and quantified technique. It is a technique that requires a complete understanding of 1) jaw positioning and 2) clinical intra oral occlusal management understanding of coronoplasty principles. If one does not understand completely the coronoplasty principles as they apply to the implementation and application of involuntary and voluntary jaw movements and jaw closure patterns it is possible to misunderstand the Chan Scan and how to properly maintain this optimizing trajectory in the finishing procedures (coronoplasty). If coronoplasty principles are not followed it may appear that the Chan Scan position may appear more anterior, but remember the power of muscle engrams want to draw the mandible posterior off an optimized trajectory. This could easily lead the clinicians to a false assumption that the Chan Scan Optimizing trajectory was too anterior, but in reality they many have never realize that PROPRIOCEPTION issues and muscle engram memory issues can over ride jaw trajectory responses in a posterior position, thus loosing an opportunity to optimize lateral pterygoid and muscle physiologic responses to another level. Narrow goal posted patients with limited accommodative capacity can prove this point clearly. Patient with wider goal posts/wider adaptive accommodative abilities will not show this fact as easily.
The Chan Scan’s MAIN FOCUS is to observe the sagittal and frontal flashing cursor position and latent movements after the protruded bordered movement from CO on Scan 4/5. The scan only references to CO as a means to maintain alignment of the sensor array and accurately quantify a more optimal NM trajectory from the classic trajectory. Physiologically and proprioceptively it prefers not to use CO since this reinforces CNS memory engrams to the habitual/pathologic position. The protocols asks the patient to protrude the lower jaw and hold for about 10 seconds with the TENS on. This is designed to assist in overcoming muscle memory both the temporalis anterior, superior head of the lateral pterygoid (Hiraba, et al), digastric/suprahyoid and posterior cervical musculature. Inferior head of the pterygoid EMG activity is over come with TENS stimulation during the protrusive movement, thus jump starting the ligamentous constraints (Baragar and Osborn, 1984) and optimizing muscle tonicity and mandibular positioning in all dimensions in a “floated” up posture on an optimized neuromuscular trajectory. I have recommended that the clinician ask the patient to protrude, hold ….. and ask the patient to “slowly let the jaw hang and relax”. (I am very specific on the choice of these words) that go beyond the scope of this present email. These are the words that I have found to be effective and helpful. Bill Wade’s K7 Team Training program have confirmed that these choice of words work and are useful to get the patient to respond more efficiently during the Chan Scan trajectory/bite finding processes.
JUMP STARTING THE PROCESS WITH THE CHAN SCAN PROTOCOL
Most lower jaws want to regress to a less than optimal vertical due to restricted muscle tension lengthening and pathologic proprioceptive occlusal memory. Thus for most cases that are deficient vertically I prefer to use the words, “let the jaw HANG and SLOWLY relax”. The speed or rate in which the cursor movement occurs both sagittally and frontally also is very important and can correlate to condylar positioning and disc tissue health. If the cursor springs back to the original TENsed NM trajectory quickly after the first and third protrusive movement it does not always confirm neither identifies the optimized NM trajectory, but rather after the fourth and fifth trial may the clinician begin to observe and document a more optimal repeatable position and trajectory. It is on this repeatable non-forced lingering trajectory that I capture my myocentric bite, overcoming muscle engramming. It is not unusual to observe improved LTA and RTA activities along with improved LDA and RDA activity. I do not use the digastric EMGs as a guide to determine vertical, since the involuntary and voluntary combination protocol with TENS overcomes muscle and ligamentous constraints in all vertical, AP, frontal, pitch, yaw and roll domains. The cursor will 78.5% of the time slowly linger forward of the classic trajectory.. The muscle and ligamentous memory of most mandibles will begin to be overcome and will consistently float anteriorly on a now optimized NM trajectory (Chan Scan position) and will naturally self correct vertically as well, assist in identifying a conservative now over opened vertical (vertical dimension measurements that hold closure to the Golden Vertical. Remember: It is the antero-posterior dimension that has challenged most of us clinicians all our careers and not the vertical domain. That is the beauty of the Chan Scan.
There is so much more to the Chan Scan protocol that goes beyond written description to this amazing protocol and technique that any clinician desirous to learn should really consider furthering their knowledge and clinical technique by attending Chan’s Scan Interpretation program where we go over the nuisances and details of this neuromuscular discovery as confirmed and observed by Dr. Norman Thomas and many other astute case finishing/practicing clinicians.
The Chan Scan addresses clearly the lateral frontal domain as well as the sagittal domain. Again the emphasis is not necessarily on the “protrude” command to the patient, but more importantly a deeper understanding and thought process as to what is actually protruding. Thought should be give to what is actually occurring within the condylar/discal tissue/glenoid fossa complex on both left and right joints as it relates to joint position, decompression and disc reduction and muscle activity of all muscle groups. This protocol is not about bring the mandible into a class three prognathic relationship. It is also not about going outside normal physiologic parameters of muscle and joint physiology, neither going beyond sound restorative aesthetic clinical considerations as to bite management and finishing procedures. It is about being clinically more effective in treatment time management, it is about lessening chair time, less office visits, maximizing treatment patient resolution time of complex TMD paining cases and finding the END GAME as to where is a reasonable NM trajectory to finish the occlusion, “the bite” in a timely manner. It is an advanced technique!
This protocol has been clearly shown to improve EMG activity, improve maxillary to mandibular cast relationships, improves mandibular to cranial relationships (more importantly), rather than depending on mandibular to maxillary relationships as a reference. It clearly quantifies objectively via physiologic responses to assist the astute restorative finishing clinician as to what is an OPTIMAL NM TRAJECTORY to refutes confusion as to where is a correct NM trajectory. It refutes the criticism that the neuromuscular trajectory is arbitrary. It clarifies objectively with measured data that NM occlusion can be reproducible and not operator dependant as to finding the bite. It also address neck cervical and postural issues to another level beyond what most TMD clinicians and educators are aware. It has shown to assist in cervical alignment and C-1 atlas balance. Addressing the cervical postural issues by sticking to the MAIN THING ISSUES is crucial!!! The Chan Scan does press the NM paradigms and tradition in understanding what and how to identify a better NEUROMUSCULAR TRAJECTORY with objective documentable science.
Come Learn the Optimized Bite™ Training
It does take training and further ones REFINED understanding about the neurologic, anatomic (condylar/disc), muscle physiologic, facial proportions as well as the naso-maxillary to mandibular cranial complex relationships. This is an advanced NM technique that brings bite finding, bite management and bite finding issues to a higher level of awareness and understanding.
I hope that this will assist those in furthering their journey into this intriguing arena of NM OCCLUSION as well as giving all us another level of clinical success.
Happy Bite Taking!
Clayton A. Chan, D.D.S., M.I.C.C.M.O
OCCLUSION CONNECTIONS – Founder and Director, Las Vegas, Nevada, U.S.A.
All Rights Reserved® 2009
