Simply right click on any animation and select "save as" to your computer.
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| When either or both temporalis' contract during the normal
unilateral activity of a Lateral Pterygoid muscle, the LP
encounters
a degree of resistance to its effort, and that resistance is the
occluding
of the teeth. The resulting direction of the force vector of this
effort is a fucntion of the point of resistance. Since the
temporalis
persists in the elevation of the mandible, the canine teeth
contralateral
to the translating condyle are often exploited to endure the load,
thereby
allowing the force to be directed in an anterior (and slightly medial)
direction, braced by the slope of the eminence.
This is called "canine rise, or guidance", allowing the posterior teeth to separate. In the example below, the right temporalis persists in
its elevation
of the mandible, thereby providing prolonged occluding of the right
side canine. |
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| Although the lateral engagement of the canines can help to
diffuse
the effects of parafunction, an end-to-end canine contact can serve to
perpetuate the symptoms of parafunction.
The animation to the right demonstrates a parafunctional
excursive movement
that allows
for canine-to-canine clenching. Although elevating intentisty is
reduced during the opening
stroke, it intensifies when the canine teeth are end-to-end. (Canine
teeth can allow for near
maximal
voluntary temporalis clenching intensity.) The re-closing stroke
is what creates the wear facets typically observed on incisors. |
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The misnomer of
"Outside-in" chewing.
Canine teeth (nor the incisors) do not contact and rub on each other during mastication. The above example does not really happen. Interferences are enganged by the LP upon opening (at right). |
The misnomer of :
"Inside-out" chewing.
 result of excursive parafunctional opening against resistance. Ideally, this parafunction "grinding" activity would engage a canine, but can still fatigue a lateral pterygoid depending upon the intensity of resistance provided by the occluding canines (a function of the temporalis). Occasionally, canine tip-to-tip clenching perpetuates the clinical presentation of unilateral headache and contralateral joint strain. In actual mastication, the teeth disclude in unison, and not in an excursive grinding movement. |
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