Quiz 6 stuff - Basic Mandibular Movements Flashcards
Centric Relation (CR)
Maxillomandibular relationship, independent of tooth contact.
Condyles articulate in the ANTERIOR-SUPERIOR POSITION against the posterior slopes of the articular eminences.
From this unstrained, physiologic maxillomandibular relationship. Good reference position.
When in centric relation, can only do pure rotation only.
what is position of the condyle in centric relation?
anterior-superior
centric relation = when the condyle is seated in the glenoid fossa in the most anterior/superior position
Digastric / Supra and infrahyoid do what?
Help with opening. Muscles below the jaw, below the mandible to pull the mandible down.
Depression of mandible (opening)
results in rotation of the condyle.
Which muscles are going to help function during retrusion?
Posterior temporalis
Which muscles are going to help function during protrusion?
Lateral Pterygoid
When you open wide, which muscles are activated?
lateral pterygoid (gliding movement)
supra and infrahyoid
Which muscles do rotation?
supra and infrahyoid only.
Which muscles help when biting down?
Masseter, Temporalis, and medial pterygoid.
Transverse Horizontal Axis:
Imaginary line goes through both condyles, which mandible may rotate within the sagittal plane.
AKA hinge axis.
Working vs non-working sides
Working side: teeth occluding together, side where mastication (chewing) occurs.
non-working side: mastication does not occur.
Right working movement, what happens?
Activation of LEFT lateral pterygoid
movement of mandible on RIGHT
mastication occurs on RIGHT
LEFT condyle translating
RIGHT condyle rotating.
Bilateral Balanced Occlusion:
Both sides have posterior occlusal contact in MIP and eccentric positions.
Causes excessive wear to natural teeth (not recommended)
good for dentures
Why we use bilateral balance occlusion for removable prosthetics?
To maintain stability of our prosthesis. Don’t need this for natural teeth bc they are anchored into the bone via the PDL, so we don’t need to stabilize the lining anyways.
When do you want to make MIP during CR?
for dentures for bilateral balance occlusion.
Group function:
Multiple contact relations between max / mand teeth in lateral movements on WORKING SIDE only.
“unilaterally” balanced.
very common. Distributes the occlusal load among teeth on the working side. Sharing the load.
Guidance:
Provides regulation / direction to movement. basically guiding it.
Anterior Guidance:
influence of the contacting surfaces of anterior teeth, limiting mandibular movements.
anterior teeth prevent posterior tooth contact
Right working anterior guidance: 6 and 27 shud be in contact
Left: 11 and 22. CANINES
Mutually protected Occlusion:
occlusal scheme in which posterior teeth prevent excessive contact of the anterior teeth in MIP., and anterior teeth disengage posterior teeth in all mandibular excursive movements.
Class I lever:
Similar to crowbar. Most powerful class
Power -> Fulcrum -> Work
Class II lever:
Similar to wheelbarrow / nutcracker
Fulcrum -> Work -> Power
Condyle -> 2nd/3rd molars -> Muscle
Only applies to 2nd / 3rd molars
Class III lever:
Most common lever system for human dentition.
Similar to drawbridge / chopsticks
Fulcrum -> Power -> Work
Condyle -> Muscle -> Anterior teeth
Criteria for Optimum occlusion:
perio very important for stability
Anterior guidance in harmony with the border movements of envelope of function
disclusion of posterior teeth
