Articulators Flashcards
A 5mm change in the intercondylar distance setting causes what at the second molar?
0.2mm error of the height of working & balancing cusps
wider IC distance = smaller angle between laterotrusive and mediotrusive pathways
The effect of increased distance from rotating condyle is ______________.
wider angle between laterotrusive and mediotrusive pathways
Okeson - Management of Temporomandibular Disorders
The effect of increased distance from midsagittal plane is ______________.
wider angle between laterotrusive and mediotrusive pathways
Okeson - Management of Temporomandibular Disorders
The effect of increased IMLT is ______________.
mesial movement of mandibular molar ridge and groove postitions
greater effect in balancing side
- shorter cusps
- wider central grooves
- wider angle between laterotrusive and mediotrusive pathways
Okeson - Management of Temporomandibular Disorders
The effect of increased intercondylar distance is ______________.
ridge and groove positions move distally on the mandibular molar
smaller angle between laterotrusive and mediotrusive pathways
balancing cusp height increased slightly
Okeson - Management of Temporomandibular Disorders
What is the effect of condylar guidance on posterior occlusal morphology?
Steeper condylar guidance allows for taller posterior cusps
Okeson - Management of Temporomandibular Disorders
What is the effect of anterior guidance on posterior occlusal morphology?
Greater vertical overlap allows for taller posterior cusps.
Greater horizontal overlap necessitates shorter posterior cusps.
Okeson - Management of Temporomandibular Disorders
What is the effect of occlusal plane on posterior occlusal morphology?
A plane that is more parallel to condylar guidance necessitates shorter posterior cusps.
Okeson - Management of Temporomandibular Disorders
What is the effect of Curve of Spee on posterior occlusal morphology?
A more acute curve necessitates shorter (most of the) posterior cusps.
Okeson - Management of Temporomandibular Disorders
What is the effect of lateral translation movement on posterior occlusal morphology?
All of the following necessitate shorter posterior cusps:
- greater lateral translation movement
- more superior movement of rotating condyle
- greater immediate side shift (also necessitates wider fossae)
Okeson - Management of Temporomandibular Disorders
Who first described separation of posterior teeth during protrusion?
Christensen
“Christensen’s phenomenon” (coined by Posselt, but would have been more accurately called Balkwill’s phenomenon since he had previously described it)
Christensen suggested the use of a PROTRUSIVE RECORD to measure the angle of the condylar paths that he believed corresponded to the observed space and to use this record to set the condylar controls of an adjustable articulator
When intercondylar distance is wider on the articular than the patient, what happens to the paths of movement on the articular?
They are more distal on the articulator than on the patient.
Also posterior cusps would be made shorter than they need to be.
As intercondylar distance increases on the articular, grooves on mandibular molars move in which direction?
distal
Average horizontal condylar inclination?
How do you adjust it on an articulator?
45-60º
adjust top wall
Average lateral condylar inclination?
How do you adjust it on an articulator?
12-18º (around 15)
adjust medial wall (mediotrusive, non-working side)
For your case, why didn’t you use a fully adjustable articulator?
IMPORTANT
I was able to control the effects of the posterior condylar guidance and anterior guidance once I recorded my prototype intraorally and verified that I had mutual protection without posterior deflections.
I also did not alter the patient’s occlusal vertical dimension
According to Posselt, what is the average AP discrepancy from CO to MIP?
1.25 +/- 1mm
On a fully adjustable articulator, what are the most difficult pantographic tracings to transfer?
rear wall and top wall adjustments
What is Bergstrom point, and what is its significance?
10mm anterior to the EAM and 7mm inferior to Frankfort horizontal plane
many earpiece facebows use this point as their arbitrary point
most accurate of the arbitrary points tested (Beck)
Frankfort horizontal plane
infraorbital rim (orbitale) to supratragal notch (tragion)
Is the Stratos 300 a fully-adjustable articulator?
No. It is semi-adjustable.
Stratos 300 allows programming of condylar inclination and Bennet angle but is considered semi-adjustable due to its inability to “time” immediate side shift and the lack of a sophisticated tracing apparatus.
Why did you choose the Stratos 300 articulator?
- arcon: condylar guidance on the same member as the maxillary cast; better simulates patient movement and condylar guidance remains in a fixed relationship to OP
- accepts facebow
- allows programming of condylar inclination and Bennet angle
- inclined support
- stable when inverted (facilitates articulation of the mandibular cast)
- my lab has this articulator in their armamentarium as well
Benefits of an arcon articulator
1) truer anatomic representation of the condylar mechanism
2) better simulates natural mandibular movements
3) condylar guidance remains stable as articulator opens and closes
because the max occlusal plane remains stable relative to the condylar guidance as they are both attached to the upper member of the articulator
(vs. non-arcon: condylar guidance angles change when the articulator is opened– as soon as you open the articulator, the Frankfort horizontal plane changes)
points of Bonwill’s triangle
- mandibular central contact point
- right and left mandibular condyles