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81 Cards in this Set
- Front
- Back
What are the three main axises of the jaw?
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Horizontal, Vertical, Sagittal
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The horizontal axis moves in the ___ plane.
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Sagittal
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The sagittal axis is through (1/both) condyle(s)
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1
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The vertical axis is through (1/both) condyle(s)
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1
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The horizontal axis is through (1/both) condyle(s)
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both
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Which axis is also called the "terminal hinge axis"?
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horizontal
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The vertical axis moves in the ___ plane.
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horizontal
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The sagittal axis moves in the ___ plane.
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frontal
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Average patient is __ mm from each vertical axis to midsagittal plane
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55mm
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Variations in the horizontal axis can alter cusp position in (closure/working and nonworking) movements.
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closure
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Variations in the vertical axis can alter cusp position in (closure/working and nonworking) movements.
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working and nonworking
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A patient typically measures 55mm from the midsagittal plane to the ___ plane
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vertical
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What is the terms for when the condyles are in the most superior anterior position of the glenoid fossa with the disc interposed?
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Centric relation
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Centric relation is a term for when the condyles are in the most superior and (anterior/posterior) position of the glenoid fossa with the disc (relaxed/interposed)
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anterior, interposed
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What two things determine centric relation?
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1. muscles
2. articular surface of TMJ |
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True or False, centric relation is a relative area
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False, it is an EXACT position
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True or False, centric relation is the most orthopedically stable position
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True
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True or False, centric relation is stable for the joint, but NOT for the muscles
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False, it is the MOST STABLE for the muscles as well
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True or False, centric relation is the most repeatable position
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True
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True or False, centric relation can easily be altered in a short amount of time
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False, it is UNchangable in the short term
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Centric relation is the limit of the mandibular movement (anteriorly/posteriorly)
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posteriorly
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The horizontal rotation axis typically measures __mm
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20-25mm
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What is centric occlusion?
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the closure in CR to first tooth contact
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What is defined as the deflection of the mandible anteriorly or laterally from the first tooth contact to centric occlusion
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centric slide
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What is the term for the maximum interdigitation of the teeth?
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intercuspal position
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True or False, intercuspal position is determined by our habits or tendencies
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True
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Centric occlusion = centric relation in __% of the population
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10%! This means in 90% of the population, CR is not maintained when we fully close our mouths
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True or False, intercuspal position can be altered
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True
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What establishes the most superior position of the mandible?
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intercuspal position
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When you are in postural position, your jaw is about __ to ___ mm below intercuspal position when the muscles of mastication are at rest
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2-4
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When your jaw is at rest, 2-4mm below intercuspal position, we call this ___ position
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postural (or rest)
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What determines postural position?
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muscles
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True or False, postural position is arbitrary
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True
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*What are the 7 requirements of optimum occlusion?
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1. Both the right and left condyles are in a supero-anterior position in fossae.
2. The articular disc is properly interposed. 3. There is even and simultaneous contact of all teeth. 4. Lighter contacts occur on the anterior teeth than on the posterior. 5. Occlusal forces are directed down long axis of teeth. 6. During laterotrusive movement, the mediotrusive side is discluded immediately. 7. During protrusive movement, all the posterior teeth are discluded immediately. |
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Protrusion is GUIDED by what 2 things?
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1. teeth
2. TMJ |
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Maximum protrusion is determined by the ___ of the TMJ, NOT the TMJ itself.
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ligaments
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Which specific ligament limits protrusion?
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stylomandibular
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What is the normal opening range in mm?
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40-60mm
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If I told you a patient's condyles are fully rotated with maximum anterior translation, you could assume they were doing what?
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opening their mouth as wide as they can (aka maximum opening)
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True or False, you only need 2 out of the 3 axises to be recreated on the articulator to get an accurate duplication of the cuspal movement
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False, need all 3
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The horizontal axis describes movement of both condyles (at the same time/separately) through the sagittal plane
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at the same time
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About how far can the jaw open (in mm) before the outer oblique portion of the temporomandibular causes the condyle to slide forward?
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20-25mm
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What ligament limits the horizontal axis?
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outer oblique portion of temporomandibular ligament
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Translation occurs in the (upper/lower) joint space
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upper
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Rotation occurs in the (upper/lower) joint space
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lower
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Which two axises (of the 3) describe movement through 1 condyle only?
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Vertical and sagittal (these are AXISES, not PLANES... the horizontal axis is movement through 2 condyles in the sagittal PLANE)
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Mediotrusive = working OR non-working?
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non-working
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Lateriotrusive = working OR non-working?
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working
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True or False, the rotating condyle is on the mediotrusive side
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False, either orbiting condyle on mediotrusive, OR rotating condyle on laterotrusive
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Which axises are in motion in left or right lateral excursion?
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ALL 3!
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How far down can sagittal rotation be? (think inside the TMJ)
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the bottom of the eminence
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Which axises are in motion in a protrusive movement?
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NONE of them!
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True or false, you can have centric relation if the disc is out of place... all we care about is the condyle
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False, disc must be properly interposed
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The condyle rests on the (anterior/posterior) slope of the eminence in centric relation
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posterior
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True or false, the muscle of mastication help determine CR
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True
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What does CR stand for?
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centric relation
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True or False, CR is an exact position
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True
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How can CR change over a LONG period of time?
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bone remodeling can slowly alter the position of the condyle due to changing fossa dimensions
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True or False, movement beyond CR is normal
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False, it is pathologic... aka, a car wreck or a baseball bat to the face. Or a Yugo to the face.
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Rotational movement is limited to __-___ mm
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20-25
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True or False, because our CR is relatively similar, our Posselt's Envelope of Motion is almost exactly the same from person to person
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False, varies depending on person but maintains a relatively similar shape
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What ligament limits protrusive movement?
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stylomandibular
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What ligament stops rotation?
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outer oblique portion of temporomandibular
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The maximum opening of the jaw is determined by ___.
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muscles of mastication
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The superior limit of the mandible is determined by ___
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intercuspal position
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What is represented by red 1?
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Maximum protrusion
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What is represented by red 2?
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The pt where you are protruding and your posterior teeth have slid past your anterior teeth and are now completely in front of them
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What is represented by red 3?
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The pt at which you are protruding and your posterior teeth are about to complete their slide on the anterior teeth and begin sliding down the facial of them
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What is represented by red 4?
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The end of anterior guidance (in a protrusive movement)
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What is represented by red 5?
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CR and ICR, this is rare (10%). Most of the time, ICR will be slightly higher and then CR will be a bit lower [Note: also, the beginning of anterior guidance if shifting to red 4)
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What is represented by red 6?
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When the outer oblique portion of the temporomandibular ligament is tight and changing rotation to translation
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What is represented by red 7?
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Maximum opening
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The black line between red 1 and red 7 represents what type of movement?
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When you go from protrusion to max opening, or max opening to protrusion (1 = protrusion, 7 = max opening)
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What does blue 1 indicate? (ignore the direction)
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Anterior guidance
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Which blue line (2 or 3) is rotation?
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2
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Which blue line (2 or 3) is translation?
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3
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What is indicated by the orange dot?
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Postural position... when your mouth is relaxed open
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When CR and ICR are the same (as in red 5), we call this what?
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Centric occlusion
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What is indicated by the orange dot?
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Centric relation (assuming this person is NOT one of the 10% with matching CR and ICR)
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What is indicated by 1 and 3?
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Maximum side excursion (right and left respectively)
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What is indicated by red 2?
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ICP (could be CO if person is one of the 10% with matching ICP and CR)
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