Q7-Criteria for Optimal Functional Occlusion Flashcards
This is the exact science of mandibular movement and resultant contacts; occlusion
gnathology
What was studied in 1925 dealing with keeping dentures in balance and simultaneous working and balancing contacts (group function)
balance occlusions (sears)
What was studied in the 1950s; like canine disclusion
unilateral eccentric contact
What two things are the criteria for optimal functional occlusion
joint position
tooth contacts
This is the most retruded position of the condyles and the ligamentous position
centric relation (early definition)
What ligament restricts centric relation
inner horizontal fibers of the temporomandibular ligament
True or False
centric relation is a reproducible (repeatable) position
True
In what application can centric relation be applied to
complete denture construction
fixed prosthodontics
Early studies suggested what in regards to muscles and CR
minimal muscle activity during function when condyles in CR position (most retruded)
The findings of muscle activity and CR led to what
many patients getting occlussal adjustments to make CO (MI) coincide with CR
True or False
The definition of CR has changed many times and remains controversial
True
Why is retruded not the proper location for CR
there are a lot of nerves and vessels in the retruded location
What is the direction on the articular eminences
downward and forward
CR is also the most what position
superior
What anatomical features can we work with to find the most stable orthopedic position
mandibular fossa
condyle
articular disc
muscles; elevators stabilize
The muscles of mastication pull on which way regarding TMJ
temporal; superior
masseter and medial pterygoid; supero-anteriorly
inferior pterygoid; anterior against posterior slope of the articular eminence
True or False
There is tooth influence in the postural (resting) position
False; there is no tooth influence
This stabilizes the condyles
muscle tonus
The most orthopedically stable joint position as directed by the muscles alone does what
locates the most superoanterior position
MS stable position
This position is the newest CR position
superoanterior; musculoskeletally stable position
The superior MS position is what
CR (Dawson)
This superoposterior (SP) MS position is what
CR (Boucher) most retruded position
ligamentous position
What is the definition of CR
the position of the mandible when the condyles are in their most superoanterior position in the articular fossae, resting against the posterior slopes of the articular fossa wit the discs properly interposed
It is not advisable to do what in regards to locate MS or new CR (SA position)
place posterior forces on the mandible
use Dawson technique
True or False
The bone on eminence is thick so it can withstand forces
True
These must contact in order to hold in this “muscle stabilized” position
interior lateral pterygoids
The lowest EMG (Electromyography) activity is found in which positions
7-8mm at opening
2-4mm at rest (below ICP)
Building ICP at the lowest EMG activity position would do what
put undue stress on joint, teeth, and support tissues
During function, the elevator muscles, condyles, and posterior teeth do what
elevator muscles contract
condyles slide superiorly
posterior teeth occlude
Once the muscles are relaxed, the jaw is greatly influenced by what
gravity and head position
True or False
MS position is an optimal and reproducible position
True
What is important to establish keeping in mind that the muscles of mastication can produce a larger force than needed during function
establish an occlusal condition that can accept heavy forces with minimal likelihood of damage and also be functionally efficient
What are the optimal tooth contacts with 2 opposing molars on one side
40 lbs of functional force
joint position unstable
more load on fewer teeth (40lbs/tooth)
more load transferred to joint
What are the optimal tooth contacts with 2 opposing molars on both sides
40 lbs of functional force
joint position more stable
load more evenly distributed (20lbs/tooth)
less load transferred to joint
What are the optimal tooth contacts with 4 opposing molars on both sides
40 lbs of functional force
joint position even more stable
load more evenly distributed (10lbs/tooth)
less load transferred to joint
What is the overall goal of optimal tooth contacts
even and simultaneous contact with as many teeth as possible
mandibular condyle in its most SA position
MS (CR) coincident ICP
Forces on teeth are directed through what
periodontal ligament;
bone cannot accept pressure
What does the periodontal ligament do with the forces
it transfers compressive forces on teeth to tensile forces on bone
What type of forces are well tolerated
vertical forces; PDL acts like a sling, load is distributed to all fibers “shock absorber”
Which type of forces are not well tolerated
horizontal forces
What happens to the tooth upon horizontal forces
tooth tends to tilt; some PDL is tension and others in compression; not evenly distributed
The process of directing occlusal forces through the long axis of the tooth
axial loading
What is a method for axial loading
tooth contacts on either cusp tips or relatively flat surfaces that are oriented perpendicular to long axis of the tooth; crests of marginal ridges, bottoms of fossae
This is the cusp contact opposing fossa by contact at 3 points surround the actual cusp tip
tripodization
TMJ permits what type of movement
lateral and protrusive movements
The lateral excursive movements allow what
horizontal forces to be applied to the teeth
True or False
certain teeth can better accept these undesirable forces
True; anterior teeth cannot lateral forces
What is an escape way for opposing cusps
grooves
Where can you apply greater forces
posterior teeth
Excessive forces can do what to the mandible
make the mandible shift downward and forward
What other muscle groups aid in stabilizing the joint
inferior/superior lateral pterygoids
temporals
What teeth are best suited for accept horizontal forces
canines
Why are canines the best suited for accepting horizontal forces
long/large roots
large crown/root ratio
dense surrounding bone
fewer muscles are active when canines contact
What is canine guidance or canine rise
maxillary and mandibular canines contact in laterotrusive excursions, disoccluding the posterior teeth
What is a more favorable alternative to canine guidance
group function; several teeth contacting in laterotrusive
canines, premolars, MB cusp of 1st molar
Why are more distal contact undesirable in group function
due to the greater forces than can be applied
How can you protect the TMJ during laterotrusive movements
no mediotrusive (non-working) contacts
What is anterior disclusion
during protrusive movement; no posterior contacts
What are the 5 concepts of optimal functional occlusion
condyles in SA position
all tooth contacts in axial loading
adequate working contacts with no balancing contacts
anterior disclusion
posterior contacts heavier than anterior contacts
