Occlusion Flashcards
What are the static relation mandibular positions? (4)
- Maximal intercuspal position (centric occlusion,
maximal intercuspation, habitual occlusion) - Physiologic rest position (=mandibular RP)
- Centric relation
- Eccentric relations:
− Protrusive relation
− Lateral relation
Define maximal intercuspal position (3)
- Complete intercuspation of the opposing teeth INDEPENDENT of condylar
- maximum number of contacts
- determines occlusal vertical dimension
Can Maximal intercuspal position change along life?
Yes
Condyles can be in several positions (Lauritzen): (3)
- Centric relation
- Both condyles out of centric relation
- One condyle out and the other one in centric relation
What is THIOP? (2)
- terminal hinge intercuspal
occlusal position - Centric relation (Maximal intercuspal position)
What is MIOP? (2)
- medial intercuspal occlusal position
- Both condyles out of centric relation (Maximal intercuspal position)
What is LIOP? (2)
- lateral intercuspal occlusal position
- One condyle out and the other one in centric relation (Maximal intercuspal position)
Define centric relation? (2)
- 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)
Centric relation and tooth contact?
independent of tooth contact
Centric relation mandible?
Mandible is restricted to a purely rotary movement
about the transverse horizontal axis
Most physiological position of the mandible?
Centric relation
All mandibular movements start in …. ?
Centric relation
THIOP: 3-5% of the population….
When their mandible is in Maximal intercuspal position, it is also in CR
Centric relation position concept?
Dynamic concept: it is not a single mandibular position,
but all the positions with the condyles in CR
Centric relation condyle rotation?
can perform a pure rotation movement,
without displacement, through the transverse horizontal axis
(hinge axis)
For Lauritzen CR equals…?
THR (terminal hinge rotation)
The centric relation rotation is preformed in the first ____ mm of….
25 mm of opening movement
Define Physiologic rest position (4)
- 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
Physiologic rest position dental contacts?
none
Physiologic rest position muscles are in _____ contractual activity
minimal
Physiologic rest position position established by…? (2)
muscular tonus
Physiologic rest position condyles position?
In front and below their position in centric relation
For physiologic rest position the Mandible is ____ mm below MI position. This is called?
2-4 mm below. Interocclusal rest space (freeway space)
Physiologic rest position reproducibility is…?
difficult
The TMJ and muscles can be damaged in physiologic rest position if…
the interocclusal rest space is invaded
Interocclusal space in phsyiologic rest position can vary depending on…?
head position
Formula for interocclusal rest space?
RVD-OVD
What are the eccentric relations?
- protrusion
- lateral
How do we study mandibular dynamics at the condyle?
Condyle paths are recorded during mandibular movements
How do we study mandibular dynamics at the lower interincisal point?
Lower interincisal point paths are recorded during mandibular movements
Posselts envelope of motion is in which plane?
saggital
How many arcs are there in the posterior opening border movement of the sagittal plane?
2 arcs
Describe the first arc of the posterior opening border movement of the sagittal plane (3)
- Condyles rotate without translation, around rotation axis n.1 located at the condyle.
- 25 mm of mouth opening
- 15-18º
LIMITATIONS of the 1st arc of the posterior opening border movement of the sagittal plane (3)
−Myotatic reflex (stretch reflex)
−Temporo-mandibular ligament tension
−External and internal pterygoid muscles tension
Describe the 2nd arc of the posterior opening border movement of the sagittal plane (4)
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.
LIMITATIONS of the 2nd arc of the posterior opening border movement of the sagittal plane ? (2)
−Maximum stretch of ligaments and muscles
−Central nervous system
Describe Habitual mouth opening in the sagittal plane (3)
• 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.
Describe anterior closing border movement in the sagittal plane (3)
• From maximum mouth opening to maximum
protrusion.
• Lower interincisal point goes up and forth.
• Its path is not around any axis.
