Protrusive movements

1. Occlusion that results when the mandible is protruded
forward from centric position.When the mandible is
moved into protrusion, the mandibular incisors, or front
teeth of the mandible, are moved so that they first come
edge to edge with the maxillary (upper) incisors and then
surpass them, producing a temporary underbite. This is
accomplished by translation of the condyle down the
articular eminence (in the upper portion of the TMJ)
without any more than the slightest amount of rotation
taking place (in the lower portion of the TMJ), other than
that necessary to allow the mandibular incisors to come
in front of the maxillary incisors without running into
them.

4. Forward movement
Condyles with their articular discs move
downward
forward along glenoid fossa & articular
eminence
( .sagittal condylar path)
Contraction of ext. pterygiod muscles on
each side

5. Condylar path:
The path taken by the condyle on TMJ
during various mandibular
movements.
-Protrusive condylar path: the path
followed by the condyle when the
mandible moves forward from centric
position

6. Muscles of protrusion:
Lateral pterygoid assisted by medial pterygoid
Lateral pterygoid Muscle Origin:
superior head: Sphenoid bone
Inferior head : Lateral pterygoid
plate.
Insertion: Neck of the condyle.
Function: Contraction of the 2 muscles causing
protrusion
Contraction of one muscle moves the
mandible to the other side
palpated by placing the index finger on the lateral
side of the alveolar ridge above the maxillary
molars

8. The tempo mandibular joint (TMJ):
The temporomandibular joint is the joint of the jaw and is
frequently referred to as TMJ. The TMJ is a bilateral synovial
articulation between the mandible and temporal bone. The
name of the joint is derived from the two bones which form
the joint: the uppertemporal bone which is part of the
cranium (skull), and the lower jawbone or mandible

9. Functions of articular disc
helping in smooth motion during mandibular movement
absorbing shocks to the jaw joint from chewing and
other movements
The disc divides the joint into two compartments, upper
& lower
The possible movement of lower compartment is a
simple hinge
movement
While that in the upper compartment is a sliding
movement

10. The relative factors of protrusive balanced occlusion
and the relationship among them
OBJECTIVE:
The experiment was designed to study the condition for
achieving protrusive balanced occlusion and the factors
involved in occlusal equilibration.
METHODS:
For achieving protrusive balanced occlusion, the posterior
teeth of mandible always contacted with the posterior teeth
of maxilla in the process of protrusive occlusive movement.
The angle between the line of movement track of mandible
cusp in the process of protrusive occlusive movement and
occlusion plane is called cusp movement inclination. A
formula of calculation was obtained by using mathematics
track and the conversion of coordinate axis.

11. RESULTS:
The focus of protrusive balanced occlusion is
relationship between the track of mandibular cusp
movement and working incline of maxillary cusp. The
first condition achieving protrusive balanced occlusion is
that cusp movement inclination is equal to cusp working
inclination of maxilla. The factors affecting cusp
movement inclination are condyle path inclination; incisal
path inclination and teeth coordinate. The factors
affecting working inclination of cusp are cusp inclination
and long axis obliquity.
CONCLUSION:Cusp movement inclination is the basic
and the most important concept in protrusive balanced
occlusion