Denar Mark II - Condylar Movements and Occlusal Anatomy; Mandibular Side Shift Definitions

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The Dénar
®
Mark II Articulator is of the
Arcon construction; i.e., the condyles
are attached to mandibular bow and the
fossa assemblies are fixed to the maxil-
lary bow. This construction which is a
facsimile of the anatomical structures,
enables the articulator to more accu-
rately simulate condylar paths of move-
ment. In addition this construction
makes it easy to understand the relation
of condylar paths of movement to
occlusal anatomy.
An understanding of the relationships
which exist between condylar paths of
movement and occlusal anatomy is an
invaluable aid in the use of an articulator
for diagnosis and treatment. The follow-
ing exercises which utilize the articulator
as a teaching method are helpful to
enable you to quickly understand these
relationships.
Set the left immediate side shift adjust-
ment to 1 millimeter and left progressive
side shift adjustment to 15 degrees. By
observing the articulator movements
from the back of the articulator it is easy
to understand why the immediate and
progressive side shifts are so named
(fig. 18). Hold the articulator in centric
relation. Since the left medial fossa wall
is set to permit a one millimeter immedi-
ate side shift, centric relation is achieved
when the right condyle touches its
medial fossa wall.
Move the articulator in a right lateral
mandibular movement until the left
orbiting condyle contacts its medial
fossa wall and note that the rotating
condyle and mandible move immediate-
ly to the right. As you continue the right
lateral mandibular movement the orbit-
ing condyle move downward, forward
and inward. Note that during this move-
ment of the orbiting condyle the rotating
condyle and mandible move progres-
sively more to the right as the orbiting
condyle advances. Repeat this articula-
tor movement and note that the rotating
condyle moves immediately to the right
and then progressively more to the right
as the orbiting condyle advances.
mandibular side shift (Bennett Shift):
the bodily side shift of the mandible
which occurs during a lateral jaw
movement.
immediate side shift: a mandibular
side shift in which the orbiting condyle
moves essentially straight medially as
it leaves centric relation.
progressive side shift: a mandibular
side shift which occurs at a rate or
amount which is directly proportional
to the forward movement of the orbit-
ing condyle.
By observing a right lateral mandibular
movement from the front of the articula-
tor you can see that the path of move-
ment of the orbiting condyle (orbiting
path) as it moves inward, downward and
forward is guided by the superior, rear
and medial fossa walls (fig 19). This
condylar path of movement is associat-
ed with and has its principal effect on
the balancing inclines of cusps on the
orbiting side (fig. 20B).
III. RELATING CONDYLAR MOVEMENTS
TO OCCLUSAL ANATOMY
fig. 18