Mounting the Maxillary Dental Cast Using the Fox Plane

by Clayton A. Chan, D.D.S.
USING THE FOX OCCLUSAL PLANE - 3 STEPS
The task of orienting the maxillary cast is often given to the dental laboratory technician. The clinician usually has little awareness as to how the maxillary cast is technically mounted and often assumes it is being done correctly. In reality it is commonly being manipulated to position by the lab technician in the plaster room often with no accurate record or registration to go by. It is the lab that is deciding the maxillary cast orientation and mounting position. More often than most it is not the clinician. I see this as a huge problem for those clinicians wanting to take their cases to the next level. If so they need to take control and give the lab technician an accurate reference to mount the upper cast each and every time. In order to implement this simple technique it is imperative that the cervical neck is stable, if not the leveling of the Fox Occlusal Plane will challenge the clinician. This is what I do!

To orient my maxillary dental cast correctly as it relates to the patient's head orientation at level, I simply use a Fox Plane and a flat mounting table.

Sophisticated simplicity! My lab technician loves it's simplicity and accuracy.

Step 1: I record the maxilla's orientation in the patient's mouth using Dentsply's Trubyt Fox Occlual Plane. It is very simple! With the patient's head at level (eyes looking straight ahead at the horizon), I like to have the patient standing, I use a 30 second set Polyvinyl (PV) bite registration material and inject it on the bite fork. I then place the bite fork of the Fox Plane up against the anterior teeth keeping the Fox Plane level to the ground and level to the patient's leveled head. I do not press the PV Fox Plane up against the upper posterior teeth. If you do you are screwing up the occlusal plane indexing (OPI) record for your maxillary mount. Only the anterior central teeth should penetrate the PV material on the bite fork.


From the frontal view the Fox Plane is perpendicular to the long axis of the face. (I do not reference to asymmetric eye levels, neither distorted ears levels, but rather observe the overall long-axis of the face to establish a perpendicular level frontally). From the sagittal view I use an imaginary line from the corner of the eye (exocanthion) to the connecting line of the temple of the head and base of the anterior portion of the earfold (I call it the temporal helical fold). From the sagittal view I want this line level/parallel to the ground. The Fox Plane is also leveled parallel to this imaginary line when capturing this maxillary orientation record, I call the OPI - Occlusal Plane Index. Once it is set, I check for levelness both frontally and sagittally and remove it from the patient's mouth.

Step 2: I peel the set PV index from the Fox Plane bite fork and position the OPI to the flat mounting table, positioning it flat againsT the flat table in the anterior and middle of the table. [Any flat mounting table fitted to any articulator will work. There are a number of articulator companies that offer these tables (a growing trend in articulation it seems) and any table will work. I use Ivoclar's Stratos 200 Semi-Adjustable Articulator fitted with the "Flat set up table" and "Instrument carrier" (Stock #536394 and #536399)].

Step 3: Orient the maxillary cast into the PV OPI recording your took using the Fox Plane and mount the upper cast with mounting stone. You can stablize the OPI and stone cast with hot melt glue from Home Depot. It works great! Just wet the model first and blow dry the surface dampness quickly with compressed air and mount.

Note: The natural occlusal plane slant is simply transfer from the mouth accurately via the Occlusal Plane Index (OPI) record with fast set PV bite registration. (Read more to see the corresponding lateral cephalogram on "What Angle is the Occlusal Plane to the Horizon?) The maxillary cast mount is not accurately duplicated.

Now you have the maxillary cast mounted to level just as it was in the patient's mouth, with patient's head at a level position. Pretty simple! Anybody can do it! Most of you dentist all have a Fox Plane from dental school! Pull them out and use them. Your Lab Technicians will love you for this.

If you don't want to mount the upper cast yourself, then simply remove the PV OPI record from the Fox Occlusal Plane and mail it to your technician of choice. There are no moving parts to distort, more or shift during transportation or shipping to the lab. Make sure you send a frontal view photo of your patient so your lab can confirm the mounting visually.
For those clinicians not familiar with a proper head position and occlusal plant slant, what would appear as not natural may in actuality be physiologic once one learns what a proper head position is and how the position of the mandible effects head positioning and head tilt. Controlled studies have shown a normal "physiologic" occlusal slant is 6-14 degrees and not flat as many believe. Remember: If you are having difficulty in keeping the head level while recording the occlusal plane via this Fox Plane technique perhaps you may want to reconsider whether your patient's cervical neck posture is truly stable. An unbalanced cervical aligment will effect occlusal/mandibular stability.
If you would like to read more on the rationale, science and reasons why I choose to mount my complex cases in this simple way you can read my article "A Clinical Significance of the Occlusal Plane".

Anatomical Lower Or-tho'sis

by Clayton A. Chan, D.D.S.

The Science of Aligning Body Parts to Improve Function
"Pl. ortho'ses [Gr. orthosis making straight] an orthopedic appliance or apparatus used to support, align, prevent, or correct deformities or to improve the function of movable parts of the body." - Dorlands Medical Dictionary, 26th Edition.

This is what my Anatomical Lower Orthois looks like for most of my patient's. It is made from a 2.5 mm bisacryl clear shim base formed over a lower cast. It is then overlayed with a lab processed orthodontic acrylic and later hand carved anatomically to match the patient's occlusion. I usually do this myself. Fabrication Time: Approximately 4 hours.

Webster's dictionary defines a Splint as a "material or device used to protect and immobilize a body part". Masticatory muscle proprioception requires the most exquisite repositioning of any body part if optimal rest and function is to be achieved. Splinting implies an immobilization which is exactly opposite of the desired criteria for physiologic occlusion. A law of muscle physiology is that any obstacle to muscle action initiates excitement of muscle.

I am a firm believer of orthosis therapy, especially for any patient experiencing joint derrangement, masticatory muscle dysfunction and or pain. Most TMD pain comes from muscles that are restricted. A lower removable anatomically orthosis allows for freedom of entry to and from the established terminal contact position (myocentric) where the internal and external muscles of the jaw have freedom to move as well as rest properly. The anatomical lower orthosis specifically supports optimal disc and condylar positioning within the glenoid fossa, acknowledging the unwanted clicking and popping symptoms.

Indications for an Orthosis
Indications for an orthosis are many and are varied. "A fixed reconstruction is in a true sense a permanent orthosis." - Jankelson, R. In this blog, an orthosis is refered to as a lower anatomical removable appliance used to align and support the mandible in an occlusal position that sustains relaxed musculature and optimal function.

1. Provisional deconditioning of the TMD/TMJ/MSD symptomology of the patient. Deprogramming the muscle engrams via low frequency Myomonitor TENS allows the establishing of physiologic rest to identify a starting point to reference the neuromuscular bite registration.
2. Provisionally repositions the patient's jaw to identify both the anterior vertical as well as the posterior vertical dimension. Additionally, a very important aspect which is often overlooked is the anteroposterior relationship of the lower jaw to the upper jaw to anticipate final reconstruction and facial esthetics. It is essential that the orthosis be worn to establish muscle comfort to begin a pain free testing period of 3 months off medications prior to any finalizing restorative therapy. CMS (Computerized Mandibular Scanning/Jaw Tracking) and EMG (Electromyography) documenting jaw functioning ability and muscle status are objectively measured to determine a suitable occlusal position after 4-6 months or longer to prove stability and comfort.
3. An orthosis can be used as an intermediate holding appliance during orthodontic/orthopedic treatment of dysfunctional patients needing definitive orthodontic care. The appliance in those cases can be used as the "ORTHOPEDIC MATRIX" to help guide the clinician to the finalized treatment position via modification of the orthosis and verticalization techniques to assist in periodontal, bone, ligament and tissue remodeling and development.
4. The orthosis can be used for those patients who teeter on borderline dysfunction and are on the edge of clinical symptomology. Some of those patient's may decide to wear the appliance on an "as need basis" since orthodontics and or complex restorative treatment may pose an economic or emotional impossibility. Some may be able to wear the appliance at night time only and go about their daily activities symptom free.
5. The orthosis can also be used as a nightguard to reducing clenching and bruxing. Noctural stresses can be greatly reduced by providing a neuromuscular position free of any interferences and noxious proprioception. True clenchers are poor, high risk candidates for fixed reconstruction rehabilitation or orthodontics unless the pelvis and sacro-iliac region is properly aligned to support an aligned cervical neck (Atlas C1) with a balanced occiput. Any imbalance in the postural system will contribute to unresolved clenching actions and abnormal forces.

The orthosis is designed to distribute even forces through out the mouth to give balance and support to the complete body to allow it to function and rest optimally. It can be worn 24/7 with proper home care.

My Personal View
The lower anatomical orthosis is my appliance of choice! It is the one appliance I use for all my TMD patients who exhibit masticatory dysfunction,pain and joint derrangement. I keep it very simple, yet sophisticated! I don't use night time appliances or day time appliances to confuse the patient. My patients wear only one appliance, no day or night time appliance, just like they don't have day time teeth and or night time wearing teeth. I design the orthosis so it does what it is suppose to do both antomically and functionally in the mouth. My patient's love it, having tried numerous kinds of appliances (uppers, lowers, soft, hard, anterior positions, anterior discluders, jigs, shims, flat plane, even some so called NM appliances, etc. etc. and etc.). Another KEY is finding the correct bite position!


The Clincians Responsibility
If the clinician understands how to properly design, adjust, modify and deliver the orthosis appliance properly, the patient should report that the lower removable anatomical "orthosis feels better in than out!" Patient's that cannot wear the appliance comfortably will naturally take it out and not resolve optimally. I do not believe the patient has to get use to something that does not feel right in their mouth. The clinician must take the proper time to make the orthosis feel right. 


There are simple things that can be done by the laboratory and the dentist to make the appliance feel totally comfortable....but that is for another blog posting.... see Orthotic Central.

Occlusion 101

by Clayton A. Chan, D.D.S.

FIVE PRINCIPLES OF NEUROMUSCULAR OCCUSION
There are 5 fundamental principles of Neuromuscular Occlusion that dentist must recognize when treating patients comprehensively.

1. There exists numerous muscle-structural and bite related signs and symptoms that effect the jaw joints, contributes to abnormal jaw function resulting in abnormal occlusal form confusing the central nervous system (CNS).
2. Homeostasis must be established in the masticating system if the the position of the mandible to the cranium is to be "Physiologically and Anatomically" correct.
3. An isotonic mandibular closure pattern must exist to produce an optimal neuromuscular trajectory for proper joint function and tooth to tooth function.
4. A terminal contact position can be established with no interfering inclines that disrupts an isotonic movement of the mandibular system contributing to disabled "Happy Muscles".
5. The clinician can validate objectively muscle function, jaw positioning and joint sounds with measurable scientific technology.

Whenever we overlook these basic keys in our dentistry (diagnosis and treatment) we will relinquish our treatment to pathologic maintanence. Our patient's deserve better. Practicing dentistry with these key principles in mind have revolutionized many dentist, bringing value to the patient and confidence to the practicioner.

ASK US - You Got Questions? We Got Answers.

Your Questions Answered

If you have a question regarding neuromuscular dentistry or NM occlusion concerns, our group will do our best to answer them. Send it to clayton@drclaytonchan.com.

Don't Feel Embaressed
I have been practicing a Jankelson/Myotronics NMD (Neuromuscular Dentistry) mixed in with hard core gnathologics for over 13 years now. I have spent eight of those more recent years teaching extensively thousands of advanced dentist and specialist around the world who have sought serious answers to serious questions regarding the occlusal challenges that have haunted them since dental school training. Admit it! We never learned the science of occlusion adequately to meet the challenges we face in todays real world of clinical (in the trenches) dental practice. Don't feel embarressed. It's OK. I may have the answers you are looking for.

Some of you have educated yourselves in various programs and still desire to further your skills, awareness and understanding of NM and classical post graduate dental teachings. I believe the answers will slowly unveil themselves right here from this site as you stay tune and keep in touch as I continue sharing my passion and perspectives.

This Is a New Season ....!


How Many Times Do You Adjust the Bite Before Problems Erupt?
What do you do when your patient is returning back to your office numerous times after you equilibrated the bite? Do you keep adjusting more teeth or do you give them an elequent exiting referral and admit you don't understand their problem?

Are they beginning to complain of temporal headaches and facial/masseter and neck soreness that they did not formerly experience? Are they experiencing ear congesting/stuffy ear feelings and or clicking and popping in their jaw joints that did not previously exist? Guess what? There is a clear connection between the bite adjustments you performed, muscles and the condyle/disc positioning within the TMJ's.

The following are just some questions we have answers to to meet the demands of refined clinical dentistry.

How Do You Use the Myomonitor?
The sole purpose for the TENS Myomonitor is to relax the masticatory muscles. It is a non-invasive modality that either the patient, support team and or clinician can easily use. The J5 Myomonitor comes with 3 leads that connect silicone gel surface electrodes which are simply place bilaterally over the coronoid notch (ground leads) and in the middle of the upper neck (common lead). Synchronized bilateral pulse levels are usually around 4-6 on the amplitude dial, just enough to produce a 0.5-1.0 mm rise of the mandible. 45-60 minuets of TENS stimulation will begin to produce a therapeutic response of muscle relaxation.

Are EMG's Really That Important in Clinical Dentistry?
Although great emphasis has been placed on electromyography to scientifically validate objectively physiologic muscle activity in the scientific community, I have found that it is not always required when establishing a physiologic bite relationship "Clinically". I use habitual resting EMGs to document the base line status to assist in my overall "diagnosis" and use functional EMGs to validate "treatment" effectiveness. I do not rely on resting EMGs to determine my bite position since they do not give me the definitive location to establish a bite. CMS jaw tracking is a far better tool to visualize a specific position and location of the bite then resting EMGs.


Where Can I Learn More About NMD?
Where Can I Learn More Advanced TMJ Problem SolvingTechniques?
Stay tune and connected! We will post locations and dates in the future, but for now if you have questions, don't hesitate to comment and blog your thoughts.


How Do I Coronoplasty the Bite?
Hands on demonstration is really the best way to visualize and see how I do it. But for now, first establish the myocentric bite position, land the dots as I have instructed in previous courses in the past.

Note the bilateral point contact DOTS that are balanced to the neuromuscular position. Precision is required in order to calm the hypertonic muscle activity of those patients with high level of detailed proprioception (ie. clencher/bruxers, TMD paining patients).


QUESTIONS:

Are You Accommodating Your Dentistry to Worn Down Dentition?

Is Worn Down Dentition Dictating Your Type of Dental Practice and Are You Accommodating Your Style of Practice to Routine Dentistry vs. Optimal Care?

What is the Difference Between Equilibration, Coronoplasty and Micro-Occlusion Management?

What is the Significance of Proper Head Balance and the Occlusal Plane?

Pathologic or Physiologic Occlusal Plane? How Do You Relate the Maxillary Cast to the Articulator to Avoid Long Term Pitfalls in Your Full Mouth Reconstructions?

Why is TENSing Important Before Taking a Bite Registration?

How Do You Properly Use the K7 To Capture a Myobite? Is it Necessary?

How Do You Take A Proper "Chan Scan" 4/5? Ask Chan
Designing a Comfortable Orthosis and How to Properly Fabricate the Orthosis?

How to Properly Deliver the Orthosis to Your Patient for Optimal Resolution?

Can the Dentist Orthopedically Verticalize the Posterior Teeth Without Surgery and Correct a Skeletal Class II Relationship?

The answers to all these questions area answered at my Advanced Courses. (Click Advanced Neuromuscular Clinicians - "Advanced Problem Solving for the Complex Cases" and “Micro-Occlusion/Coronoplasty – Level II” ) for course dates and location.

Relaxing the Muscles with TENS

by Clayton A. Chan, D.D.S.

When patient's come to me for help regarding their TMJ problems I always use low frequency muscle stimulation (J5 Myomonitor, Myotronics, Inc, Kent, WA) to relax the muscles that are in spastic tension. After a thorough evaluation and comprehensive work up, I will use this simple non-invasive modality to help me find and establish a more physiologic jaw/bite relationship for lower orthotic laboratory fabrication. Relaxing all the muscles of mastication first is the first fundamental principle that is missed among dental professionals when therapeutically treating these kind problems. Without establishing the mandible to a more neutral state as it relates to the cranial base, the dentist will not effectively be able to calm the many head and neck pains that trigger the Central Nervous System and back to the jaw, teeth, head and neck region. This is a key principle that more and more clinicians are now recognizing.