Dawson: Importance of anterior
guidance
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Adverse effects of
excessive
VDO
in protrusive
Incorrect
Correct
Click here
to hear the presense and absence of the click of an anteriorly
displaced disc as the VDO in protrusion is minimized
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Insight of "Upper" vs. "Lower"
(see additional example in lower left column)
Excessive wear,
divoting or fracture of
the DE:
The "sharpness" of
the opposing incisors influences the rate of divoting of the DE and
enhances the potential of splitting the device. Providing an
opposing "slider" (shown at far right, a "daytime" device on the
opposing upper centrals) can reduce the resistance to lateral
excursions and potential for fracture. Once a therapeutic result
has been achieved, and a divot in the DE appears a period of time
later, do not reduce the level of the DE to the depth of the divot, but
restore the divot with acrylic or composite restorative material.
Posterior contacts in
excursive parafunction:
The passage to the left from Dawson's textbook
emphasizes the importance of anterior incisor contact with lack of
posterior contact during parafunction.
The patient below presented with a history of chronic headache and
frequent migraine, sinus surgery, multiple root canal treatments on the
lower left 2nd molar, TMJ lavage on the left joint, and was being
evaluated for possible cervical fusion due to chronic neck pain.
The patient had been previously been provided an NTI device that had no
effect. (enlarged photos: click here)
The patient's right excursive movement
allowed for a posterior left contact, even with the NTI device in
place, thereby perpetuating:
--Headache and migraine
due to excessive V3 motor activity and afferent noxious feedback;
--Left
TMJ pain due to condylar strain and load to the disc during
clenching while the condyle was translated;
--Left sinus
pain, caused by the chronic pull on the pterygoid plate of the
sphenoid bone by the lateral pterygoid during excursive clenching;
--Pain at lower 2nd molar due to chronic PDL compaction;
--Cervical
strain resulting from tension in trapezius in response to
protrusive/excursive clenching.
The patient's symptoms resolved within two weeks of reducing the
occluding cusps (lower
right photo)
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