Occlusion

Question 1

What are the static relation mandibular positions? (4)

Answer 1

1. Maximal intercuspal position (centric occlusion,
   maximal intercuspation, habitual occlusion)
2. Physiologic rest position (=mandibular RP)
3. Centric relation
4. Eccentric relations:
   − Protrusive relation
   − Lateral relation

Question 2

Define maximal intercuspal position (3)

Answer 2

• Complete intercuspation of the opposing teeth INDEPENDENT of condylar
• maximum number of contacts
• determines occlusal vertical dimension

Question 3

Can Maximal intercuspal position change along life?

Answer 3

Yes

Question 4

Condyles can be in several positions (Lauritzen): (3)

Answer 4

• Centric relation
• Both condyles out of centric relation
• One condyle out and the other one in centric relation

Question 5

What is THIOP? (2)

Answer 5

• terminal hinge intercuspal
  occlusal position
• Centric relation (Maximal intercuspal position)

Question 6

What is MIOP? (2)

Answer 6

• medial intercuspal occlusal position

- Both condyles out of centric relation (Maximal intercuspal position)

Question 7

What is LIOP? (2)

Answer 7

• lateral intercuspal occlusal position

- One condyle out and the other one in centric relation (Maximal intercuspal position)

Question 8

Define centric relation? (2)

Answer 8

• THIOP
• Condyles articulate with thinnest avascular portion of respective discs w/complex in the ANTERIOR-SUPEROIR position against shapes of the ARTICULAR EMINENCIES (GLENOID FOSSA)

Question 9

Centric relation and tooth contact?

Answer 9

independent of tooth contact

Question 10

Centric relation mandible?

Answer 10

Mandible is restricted to a purely rotary movement

about the transverse horizontal axis

Question 11

Most physiological position of the mandible?

Answer 11

Centric relation

Question 12

All mandibular movements start in …. ?

Answer 12

Centric relation

Question 13

THIOP: 3-5% of the population….

Answer 13

When their mandible is in Maximal intercuspal position, it is also in CR

Question 14

Centric relation position concept?

Answer 14

Dynamic concept: it is not a single mandibular position,

but all the positions with the condyles in CR

Question 15

Centric relation condyle rotation?

Answer 15

can perform a pure rotation movement,
without displacement, through the transverse horizontal axis
(hinge axis)

Question 16

For Lauritzen CR equals…?

Answer 16

THR (terminal hinge rotation)

Question 17

The centric relation rotation is preformed in the first ____ mm of….

Answer 17

25 mm of opening movement

Question 18

Define Physiologic rest position (4)

Answer 18

• static relation mandibular position
• the head is upright
• involved muscles (esp elevator and depressor groups) are in equilibrium in tonic contraction
• Condyles are in a neutral, unstrained position

Question 19

Physiologic rest position dental contacts?

Answer 19

none

Question 20

Physiologic rest position muscles are in _____ contractual activity

Answer 20

minimal

Question 21

Physiologic rest position position established by…? (2)

Answer 21

muscular tonus

Question 22

Physiologic rest position condyles position?

Answer 22

In front and below their position in centric relation

Question 23

For physiologic rest position the Mandible is ____ mm below MI position. This is called?

Answer 23

2-4 mm below. Interocclusal rest space (freeway space)

Question 24

Physiologic rest position reproducibility is…?

Answer 24

difficult

Question 25

The TMJ and muscles can be damaged in physiologic rest position if…

Answer 25

the interocclusal rest space is invaded

Question 26

Interocclusal space in phsyiologic rest position can vary depending on…?

Answer 26

head position

Question 27

Formula for interocclusal rest space?

Answer 27

RVD-OVD

Question 28

What are the eccentric relations?

Answer 28

• protrusion

- lateral

Question 29

How do we study mandibular dynamics at the condyle?

Answer 29

Condyle paths are recorded during mandibular movements

Question 30

How do we study mandibular dynamics at the lower interincisal point?

Answer 30

Lower interincisal point paths are recorded during mandibular movements

Question 31

Posselts envelope of motion is in which plane?

Answer 31

saggital

Question 32

How many arcs are there in the posterior opening border movement of the sagittal plane?

Answer 32

2 arcs

Question 33

Describe the first arc of the posterior opening border movement of the sagittal plane (3)

Answer 33

• Condyles rotate without translation, around rotation axis n.1 located at the condyle.
• 25 mm of mouth opening
• 15-18º

Question 34

LIMITATIONS of the 1st arc of the posterior opening border movement of the sagittal plane (3)

Answer 34

−Myotatic reflex (stretch reflex)
−Temporo-mandibular ligament tension
−External and internal pterygoid muscles tension

Question 35

Describe the 2nd arc of the posterior opening border movement of the sagittal plane (4)

Answer 35

Condyles rotate and translate, going down and forward.
• The projection of this movement is higher (more
superior) than the lateral movement.
• 20 mm of mouth opening.
• 8-10º
• Mandible rotates around rotation axis n.2 located at the insertion of stylomandibular ligament.

Question 36

LIMITATIONS of the 2nd arc of the posterior opening border movement of the sagittal plane ? (2)

Answer 36

−Maximum stretch of ligaments and muscles

−Central nervous system

Question 37

Describe Habitual mouth opening in the sagittal plane (3)

Answer 37

• Goes from CR to MMO.
• It’s an intra-border movement.
• Goes through physiologic rest position.
Condyles rotate and translate, going down and forward
(through all the movement).
• It can happen around rotation axis n.3, located at X-Y point or centroid, near Spix’s spine.

Question 38

Describe anterior closing border movement in the sagittal plane (3)

Answer 38

• From maximum mouth opening to maximum
protrusion.
• Lower interincisal point goes up and forth.
• Its path is not around any axis.