Nature has amazingly design the masticatory system in such a manner to meet the functional demands in a very physiologic manner. Our occlusal, cervical, airway and postural system has been pre-determined genetically to function optimally relative to earth’s gravitational forces. An angled or slanted occlusal plane is natures design when the head is properly supported by balanced muscles.
Because of gravity, the muscles of the structural system as well as the masticatory system allows the human being to function with the head in properly balanced manner to avoid strains and fatigue to the overall postural system. A person with a forward neck posture will accommodate to maintain the flow of oxygen into his/her body. This forward neck and head posture tendency is indicative of an upward head tilt with a resulting flatter occlusal plane. The upward head tilt contributes to TMD and accommodative pathologic issues (e.g., shoulder pain, neck pain, temporal headaches). This upward head tilt is the bodies way to accommodate due a mal-aligned bite which tries to defy natures gravitational vertical forces, resulting in a flatter more leveled occlusal plane which does not represent what nature originally intended in its design.
The SN (Sella-Nasion) Plane is noted in the dental literature as a standard objective leveling reference. What you see in the lateral ceph below is one of one of my patients, male age 47 who presented with former TMD cervical neck problems. Symptoms were resolved with an orthotic. The previous upward head tilt responded positively to the orthotic therapy allowing nature to correct it’s head posture including and an improved occlusal plane. Based on this corrected and more normalized occlusal plane orientation as seen in the below lateral cephalogram I want to transfer this occlusal plane orientation to a flat analyzing table on my articulator to fabricate the upper and lower restorations for FM rehab esthetically and anatomically.
It seems to me that if SN plane is level, symptoms are gone, and patient’s head is now balanced. Recording this position is the most logical to communicate with the lab to mount the case.
- During the bite registration stage. If one use computerized mandibular scanning (jaw tracking – eg. scan 4/5 with TENS) and does not have adequate training to accurately interpret and record this kind of neuromuscular bite registration error can occur before the case is even started.
- If the EMG interpretation is not correct and one implements erroneous EMG diagnostic protocols (unable to decipher the differences between fatigued EMG patterns vs. normalized EMG patterns or does not monitor the cervical group EMGs believing that these EMG recordings are the same as SCM EMG recordings one will be greatly mistakened.
- Subjective interpretation in these areas of diagnostics will also lead to failed treatment results.
I believe in using good artistic and scientific clinical judgments to record head levelness like any diagnostic protocol, using the Modified Fox Plane technique as I have formerly indicated is a simple, inexpensive and effective tool every dentist in North America can use. (By the way, every dental student has been issued a Fox Plane in dental school as a basic learning tool). Note the angle of the occlusal plane.
(These are real time pictures that I routinely take during my clinical work up to document what I actually observed).
I check the crown ratios (they shouldn’t look funny)…reconfirm my AP…check my patient’s subjective responses. Many dentist and I have discover that when the correct occlusal plane is properly managed, the patient doesn’t experience any neck, cervical and shoulder pain problems. If one uses the classic HIP (hamular notch and incisive papilla) method to manage the case too completion that many are discovering that this can lead to unresolved TMJ/occlusal problems. If everything seems to line up I go for it!
I mount my cases and check my cases from the lab to see if they maintained the correct maxillary orientation before delivery (labs are not allowed to cheat or change the mount unless it is wrong). I check my mount. I check the photos, I check and compare what is in the mouth, I check how the angle and slant is…I analyze and re-analyze and confirm with my lateral ceph, check my EMG data (making sure my patients are comfortable and stable), I check my Scan 4/5, scan 2’s, scan 8’s, etc. and decided that this orientation got to be right from the frontal and lateral views….then a re-check the patient and I re-check at the lab bench…. Seems right to me!
I am happy…that He is happy…. “Don’t lose sight of the Power of the Bite!” I have no regrets about the Fox…because I know it works for me and it works for all the talented clinicians who understand this concept. These pictures are immediately after lower seat, before any adjusting of any crowns….I had the patient come back the next day to TENS and refine the bite.
My patient is very pleased, no neck cervical TMD problems. The bite is awesome. After gneuromuscular esthetic dentistry the patient no longer reports cervical pain, no shoulder pain, nor any TMD issues. The patient is stable and very happy. He is a public speaker and is on streaming internet video weekly and has a great pleasing smile. You can view him at: http://www.iclv.com/ or spiritflow.net on Sunday mornings and Sunday evenings.
The occlusal plane should look natural and balanced with the smile (that is how it should appear)…the mount is what tweaks our minds…the lateral ceph objectively confirms the reality, but it may be a need for a paradigm shift in occlusal thinking and re-evaluate whether your occlusal plane mount is too flat or not. It’s worth investigating.
1) We ultimately desire the cervical neck muscles balanced, thus we observed that the head tilts downward from an upward pathologic TMD position which TMD patients present with (flatter occlusal plane relative to horizontal level), 2) we desire optimal esthetics smiles lines and our patients to be asymptomatic. We observe on lateral cephalograms that the occlusal plane is angled – no symptoms and 3) we simply desire to reproduce what we actually see in a stable, symptom free system – angled occlusal plane, and not have our lab technicians guess or alter the mounts, thus the Fox plane method we advocate as many recognize as simple and logical is easily transfered via the Fox Plane method indicated at Occlusion Connections.
© 2009 Clayton A. Chan, DDS. All Rights Reserved.