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- normal repose after exertion
- not pathologic
- conforming to the normal functioning or state of the body or a tissue or organ;
- A state of homeostasis
- A place to start where the problem begins.
- A reference point
” Is that position in space where all the masticatory muscles including all antagonistic muscle groups such as elevators and depressors are in the state of minimal electrical activity necessary to maintain postural rest.”
- A Starting Position – To Begin Your Assessment
- The position in which the muscles surrounding the mandible are at their anatomic resting length.
- Balanced muscle tonus is maintained.
- A state of minimal contracture, strain, compression and constriction is achieved when at physiologic rest.
Physiologic Rest Position
- It is that mandibular position in which the various mandibular muscles are simultaneously at their resting length and in balanced tonus with one another.
- It is always defined from (and only valid from) the upright postural position.
- It is the reference point for all diagnostic and treatment procedures involving restoration of the occlusal position.
A state of neutrality…where physiologic health and recovery begins.
Defining the Terms:
The term “physiologic” refers to “healthy”; a state of optimal physical, mental well-being, absent of disease, that takes into account the whole individual.
Physiologic health can be tested. It indicates clinically that the patient is able to show high amplitude EMG recruitment patterns (this is good, healthy) vs. low amplitude EMG recruitment patterns (weak, unhealthy, pathologic) when a patient clenches. Science and literature has documented this fact well. Additionally, the healthy/physiologic recruitment muscle patterns should be balanced and specifically allow the mandible to close along an “isotonic” path of closure to a terminally balanced contact position.
Isotonic denotes the solution within the body of cells showing the flow of water across the semipermeable cell membrane at a tonicity where other solutions are not showing a net gain.
An “isotonic” mandibular closing path is clinically determined and recognized when the involuntary muscles produce a closing path that equals and coincident with the voluntary closing path as observed from a sagittal (side view) jaw tracking data and frontal/lateral views. This is what is consider “Normal” healthy or “physiologic”. Mandibular jaw tracking technology combined with low frequency TENS are the devices of choice to record both voluntary habitual mandibular closure paths versus voluntary mandibular closing paths relative to CO (habitual centric occlusion/ MIP).
When there is a different involuntary mandibular closing path from the habitual voluntary closing path clinicians around the world have recognized these diverging patterns as pathologic/unhealthy (in other words, an antero-posterior mandibular slide exists, occlusal skids and or abnormal jaw closing pattern can exist, thus the mandible and occlusion are deemed unstable. Abnormal tooth wear, abnormal vector of forces will influence hyper muscle activity inducing strains, torques and skews to underlying boney structures, thus “abnormal, unhealthy, and a pathologic condition would exist.
Resting muscle activity is considered healthy and “normal” when muscles EMG patterns are showing microVolt readings 2.0 mV +/- 5% at rest. Resting activity above these values would be considered pathologic, unhealthy, and not normal.
Read more: TMJ OCCLUSAL ROBLEMS?