Mandibular movement occurs around the TMJ and includes functional movements like chewing as well as parafunctional movements like bruxism. There are three main determinants that guide mandibular movement: condylar guidance from the shape of the glenoid fossa, incisal guidance from the shape of the front teeth, and neuromuscular control from the muscles of mastication. Mandibular movement can be described based on the axis of rotation, type of movement, extent, and dimension involved. Understanding mandibular movement is important for proper treatment and fabrication of dental prosthetics.

1. MANDIBULAR MOVEMENT

2. Introduction
• Mandibular movement occur around the TMJ
which are capable of making complex
movement.
• There are basic two movement:
1) Functional movement
2) Para functional movement

3. ANATOMY OF TMJ

4. Determinants of mandibular
movement
• Factors are :
1)Conylar guidance
2) Incisal guidance
3) Neuromuscular factors

5. Condylar guidance
• Defined as “mandibular guidance generated
by the condyle and articular disc traversing
the contour of the glenoid fossa”.
• Condyle move along “s” shape path.
• Shape of glenoid fossa determine the path of
movement of the condyle is called Condylar
guidance.

6. Incisal guidance
• Defined as “the influence of the contacting
surface of the mandible and maxillary anterior
teeth during mandibular movement”.
• Slope of the lingual surface of upper anterior
teeth determines the path .

7. Neurological factors
• Muscle of mastication are important
determents of mandibular movement.
• In normal pt muscle function is coordinated
smooth manner.
• Hypertrophy and dysfunction of one group of
muscle movement is uncontrolled and
asymmetrical.

8. muscles involved in mandibular
movement
• Masseter – closing and retrusion
• Temporalis – elevation and retrusion
• Medial pterygoid – closing and lateral
movement
• Lateral pterygoid- opening protrusive and
lateral movement
• Suprahyoid group of muscle – depress( open
the mouth) mandible assisted by infra hyoid
group

9. Type of mandibular movement
• 1) Based on the dimension involved the
movement
• Rotation around the transverse or hinge axis
• Rotation around the anteroposterior or
sagittal axis
• Rotation about vertical axis
• Translation in time

10. l• 2) based on the type of movement
• Hinge movement
• protrusive movement
• Retrusive movement
• Lateral movement
lateral rotation
Lateral translation
immediate side shift
precurrent side shift
progressive side shift

11. 3) Based on the extent of movement
• Border movement
Extreme movement in the horizontal plane
Extreme movement in the sagittal plane
Extreme movement in the coronal plane
Envelop of motion
• Function movements
Chewing cycle
Swallowing
Yawning
speech

12. • Para-functional movement
Clenching
Bruxism
Other habitual movement

13. Based on the dimension involved in
the movement
1) rotation around the transverse or hinge axis
Run horizontally from the right side of the
mandible to the left .
Rotation around this axis is seen during
protrusive and mouth opening movement.
During initial mouth opening transverse axis
passes through the head of the condyle.
During late stages of mouth opening passes
through mandibular foramen.

14. Rotation in transverse axis

15. Rotation around the anteroposterior
or sagittal axis
• Anteroposterior axis is an imaginary axis
running along the mid sagittal plane.
• During this movement condyle of one side
moves downward and medially along the
slope of entoglenoid process.
• Condyle of the opposite side move upward
and laterally.

16. Rotation around sagittal axis

17. Rotation around the vertical axis
• Run through the condyle and the posterior
border of the ramus of the mandible .
• Mandible rotates around this axis during
lateral movements.

18. Rotation around the vertical axis

19. Translation in time
• Time is fourth dimension.
• Movement of mandible in this dimension
occur during Bennett movement.
• Mandible does not rotate around an axis
instead it shifted ‘en masse’ in time

20. Based on the type of movement
HINGE MOVEMENT
This is purely rotational movement of the joint
which takes place a horizontally axis till patient
open mouth to 20- 25 mm.
Proposed by mcCollum and verified by kohno.
Occurs when there is 10 -13 degree rotation of
the condyle in TMJ which provide a jaw
separation of 20 -25 mm in incisal region .
Occur while crushing food or taking in food

21. Protrusive movement
• Occur while incising and grasping food.
• Occur after condyle rotate more than 13
degree.
• Once the condyle rotation exceed 13 degree
transverse hinge axis shifts to the level of
mandibular foramen.
• Mandible moves forward and downward .

22. Retrusive movement
• Occur when the mandible is forcefully moved
behind its centric relation .
• It is achieved by the fiber of temporalis
,digastric and deep fiber of masseter.
• The fiber of the bilamina and
temporomandibular ligament and contour of
the posterior slope of glenoid fossa
determine this movement.

23. Lateral movement
• Are of two types – lateral rotation and Bennett
shift
• Lateral rotation or laterotrusion
Occur when the mandibular moves away from
the mid sigattal plane.
Can occur in right and left side.
Occur during chewing food.

24. Bennett movement
• Define as the bodily movement or lateral shift
of the mandible resulting from the mandibular
fosse in lateral jaw movement.
• During lateral movement ,mandibular shift (as
whole ) by 1-4 mm toward working side.
• This shift is called Bennett movement.
• It is classified based on the timing of the shift
in relation to forward movement of the non
working condyle.

25. • 1) immediate side shift:
• Lateral translation occurs before forward
movement of nonworking condyle.
• 2) precurrent side shift : lateral translation
occur during the first 2-3 mm of forward
movement of the non working condyle.
• 3) progressive side shift :
• Lateral translation that continues linearly after
2-3 mm of forward movement of non working
condyle.

26. Bennett angle
• The angle formed by the sagittal plane and the
path of advancing condyle during lateral
mandibular movement as viewed in the
horizontal plane-GPT

27. Based on the extent of movement
• Two types
• 1) border movement
• 2) intraborder

28. Border movement
• Defined as “,mandibular movement at the
limit dictated by anatomical structure ,as
viewed in a given plane.”
• Pantograph is required to record all border
movement.

29. Extreme movement in the horizontal
plane
 Border movement
recorded in horizontal plane
produced a characteristic
“Diamond tracing”.
 Patient is instructed to
move his mandible from the
centric position to
maximum right lateral
position to maximum
protusion position to
maximum left lateral
position and return to
centric .

30. Extreme movement in the sagittal
plane
• A characteristic beak
tracing is formed.
1. Patient is instructed
move the mandible from
centric relation to
centric occlusion then
edge to edge
relationship guided by
incisal guidance ,and
forward to maximum
protrusive position and
arch down to maximum
mouth opening position

31. Extreme movement in the coronal
plane
• A characteristic “shield tracing”.
• Patient is instructed to move
mandible from centric occlusion
to canine guided disocclusion on
the right side to maximum right
lateral position then arch
downward maximum mouth
opening position.
• From this position pt is instructed
to arch upward to maximum left
lateral position return medially to
canine guided disocclusion to left
side and return to centric
position.

32. Envelope of motion
• When we combine the
border movement of all
three plane we get three
dimensional space which
mandibular space is
possible.
• Three dimensional limiting
space is called envelope of
motion.
• Envelope of motion is
longest and widest
superiorly and narrow down
to point maximum mouth
opening

33. Intraborder movement
• Occur with in envelope of motion
• Are two types .
• Functional movement: include chewing
speech swallowing and yawning
• Parafunctional movement

34. Chewing cycle
• Murphy summarise six phase in the chewing
cycle.
• They are:
1) preparatory phase : tongue position the food
within the oral cavity and mandibular deviates
toward chewing side.
2) Food contact phase: this is a phase of
momentary hesitation in movement that occur
due to trigging of sensory receptor due to food
contact.

35. 3) Crushing phase : starts with high velocity and
slows down as food gets crushed .
4) Phase of tooth contact: with the slight change
in direction without delay ; all the reflex
muscular adjustments for tooth contact are
made.
6) Grinding phase: in this phase there is grinding
movement guided by the maxillary occlusal
tables.
7) Centric occlusal : the mandibular return to a
single terminal point before it goes into the
preparatory phase.

36. swallowing
• Mandible always return to the centric relation
during chewing.
• Immediately after swallowing ,there is pause
in movement followed by movement to the
rest position.
• Tongue function seal the palate so that the
bolus can move posteriorly
• This movement of tongue help to move the
mandible posteriorly and superiorly.

37. yawning
• While yawning the mandible may move
forward and downward upto the maximum
mouth opening position .
• Elastic fiber of temporomandibular ligament
determine the movement of condyle.

38. Parafunctional movement
• Includes movement during clenching ,bruxism
and other habitual movement.
• Movement should be recorded and studied in
order to fabricate prosthesis

39. Method of recording
• Ultrasound
• Accelermeters
• Videofluoroscopy
• Cineradiography
• Arcus Digma

40. conclusion
• Knowledge of jaw movement is essential for
successful treatment of patient. It is
imperative to learn as much possible about
jaw movement ,in order to reproduce those
aspects of its motion , considered necessary
for proper functioning of the occlusion , either
natural or artificial.