shammasm, removable prosthodontics, intro to dentures

2. MANDIBULAR
MOVEMENTS

3. Learning outcomes
1. Define mandibular movements.
2. Describe the significance of
mandibular movements.
3. Explain the movements of
mandible.

4. Mandibular Movement: any
movement of the lower jaw.

5.  Mandibular movements are complex.
Why?
 Many different mandibular movements
occur during mastication, speech,
swallowing, respiration and facial
expression.
 Also parafunctional movements
(bruxism, clenching).

6. Why do you need to know
mandibular movements?

7. 1. To understand occlusion

8. 2. To arrange artificial teeth

9. 3. To understand and treat TMJ
problems

10. 4. To select and adjust articulators

11. NO ARTICULATOR CAN EXACTLY
DUPLICATE THE MOVEMENTS OF
THE CONDYLE

13. Basic Mandibular Movements
 Opening and Closing
 From a position of centric
relation, pure hinge
movements are possible in
opening and closing. In a
hinge movement, the
condyles rotate within the
glenoid fossa.

14. Rotational Movement
Movement of a body around
an axis.

15. Rotation

16.  Opening and closing movements,
where the measured distance
between maxillary and mandibular
incisors is greater than 25 mm,
result in combined rotation and
translation of the condyles.
Translation occurs whenever a
condyle leaves the glenoid fossa.

17. Translational Movement
Movement of a body in the same
direction and at the same rate.
Point A Point B

18. Translation

19. Protrusion of the mandible is a
good example of translation.
The teeth, condyles, and rami all move in
the same direction and to the same rate.

20. Upper joint space and lower
joint space

21. Gliding or translation movement occurs
in the upper joint space of the TMJ, whereas
rotation or hinge movement occurs in the
lower joint space.

22. Protrusion and Retrusion
 Protrusion is when the mandible
moves forward and both condyles
leave their respective fossae and
move down their eminences.
 The opposite process is called
retrusion.
 Protrusion and retrusion are
translatory movements.

23.  What are the three types of
mandibular movements?
- rotation
- translation
- combination (most movements)

24. Rotation
- process of turning about an axis
- occurs when the mouth opens
and closes
- occurs within the lower joint space
- occurs with the first 20-25 mm of
opening of mouth..

25. Translation
- every point in object (mandible)
simultaneously moving in the same
direction with the same rate
- opening of mouth (beyond 25 mm)
- occurs within the upper joint space
- eg: PROTRUSION (both condyles
translate)

26. Reference Planes
Horizontal Plane:
Parallel to the Occlusal Plane or the floor.

27. Reference Planes
Frontal Plane:
Best described by facing the patient.

28. Reference Planes
Sagittal Plane:
Also known as a side view.

29. Reference Planes
Sagittal Plane:
Also known as a side view.

30. Working Side: The side toward
which the mandible moves. When
the mandible moves laterally, the
condyle on the working side stays
in its fossa, rotates and moves
laterally.

31. Nonworking side: The side opposite
the working side. In a lateral
movement, the balancing side
condyle leaves the fossa and moves
forward down the eminence, and
medially.

32.  Projected onto the horizontal plane, an
angle between the midsagittal plane
and the curve of the non-working
condyle can be seen. This angle is
called the Bennett angle (average 15
degrees).

33. Bennett’s movement [Sir Norman Godfrey
Bennett, British dental surgeon, 1870-
1947]
Also called laterotrusion (lateral
translation)
Bodily movement
of mandible during
lateral excursive
movement on the
working side.

34. ‫أسئلة‬ ‫أي‬