Optimal Functional Occlusion Flashcards
what we need to know (3)
optimal occlusion in a stationary position (position of teeth, TMJ, muscles)
optimally occlusion during excursive movements of the mandible
occlusal philosophies during excursive movements
occlusal philosophies during excursive movements (3)
canine guidance- anterior guidance
group function
balanced occlusion
BASELINE FOR EVALUATING PATIENT’S OCCLUSION (4)
teeth
TMJ
musculature
evaluate the entire masticatory system
a patient may have an orthodontically ideal angles class 1 occlusion, this does not mean that the patient has (3)
optimal occlusal contants,
optimal condyle/mandibular position and
ideal/optimal contacts in excursive movements
conversely someone with a class 2 or 3 occlusion although not orthondontcally idea, may have
an acceptable, function occlusion
patients may have a less than ideal occlusion, however, it may still be a (2)
functionally acceptable occlusion or a
physiologically acceptable occlusion
is treatment required?
asses the masticatory system for evidence of pathology
-tooth wear, tooth mobility, TMJ dysfunction, muscle dysfunction, etc
— capacity of a patient
adaptive
if treatment is rendered, what is the optimal position for the (3)
joints
muscles and
teeth
the TMJ are in an optimum, orthopedically stable joint position when the mandible is in
centric relation
CR
term used to define a position of the condyles in relation to the disc and fossa
CR is defined as when the
condyles are in the most anterior-superior position in the glenoid fossa. braced up on the intermediate zone of the disc, and the mandible is free to rotate about the terminal hinge axis (up to but not indulging the point of first tooth contact)
CR refers to –, not
joints
teeth
mandible can freely arc up and down along the
terminal hinge axis
teeth cant contact=
deflection
why is CR the ideal position? (2)
musculature in CR
TMJs in CR
musculature in CR (4)
the muscles function harmoniously in CR
the joint is stable because the muscles attached to the joint prevent dislocation of the articular surfaces
the muscles that stabilize the TMJs are mainly the (2). contraction of these muscles results in antero-superior vector of force (stability)
the (1) muscles are most relaxed in CR
masseter and the medial pterygoids
lateral pterygoid
TMJs in CR
condyles are in the most antero-superior position in the glenoid fossa
condyles rest against the posterior slope of the articular eminence (thickest bone) therefore can tolerate higher stresses
CR
condyles are braced gently/rest against the intermediate zone of the disc (non-innervated and avascular zone) therefore
higher stresses can be tolerated
there are - other definitions for CR
7
in the past: CR was called the most — position of the mandible
retruded
in the most retruded position: the retrosical tissues are
innervated and would not tolerate stress
in the most retruded position: the posterior wall of the articular fossa is
very thin
CR questions (5)
jaw or teeth position?
how are the condyles positioned in the fossa?
how do the condyles move, when the anterior teeth open 20-25mm?
what is the axis of rotation in that position called?
how do the condyles move, when the anterior teeth open further than 20-25mm?
the muscles function
harmoniously
the TMJS are in an
optimal, orthopedically stable joint position
the TMJs are stable even when
heavy loads/forces are applied
CR
this is the position to which we restore (3)
completely edentulous patients
partially edentulous patients, when there are so few teeth remaining that there is not a stable MIP
dentate patients who are going to receive extensive restorations which will alter their occlusion completely
Recording the CR position on a patient using an — — in order to deprogram the muscles of mastication
anterior deprogrammer
optimal functional occlusion (3)
- the TMJ
- the teeth
- the excursive movements
teeth relations in optimal function occlusion (2)
in stationary position
during excursive movements
THE TEETH
(FOR OPTIMAL FUNCTIONAL OCCLUSION)
posterior teeth
multiple, even, bilateral and simultaneous occlusal contacts with the mandible in the CR position, are the most desirable
the posterior teeth are loaded mainly along the
long axis of the tooth (axial loading)
1) multiple
the more teeth that contact the more the stress is distributed throughout the arch
2) even
all posterior teeth should contact evenly. this distributes the stress over all the teeth and does not concentrate it on one tooth causing harm
3) bilateral
this is for stability. if tooth contacts occur only on the right side and not on the left, then the mandible will pivot around this right side contact and place increased pressure on the left TMJ causing problems
4) simultaneous
all the contacts occur at the same time on both sides of the arch and on all the posterior teeth
5) the teeth should be axially loaded: ie
through the long axis of the tooth. lateral forces on teeth are not well accepted. on the contrary though axial loading, heavier stresses can be applied
anterior teeth should have — occlusal contacts when the posterior teeth are in occlusion
lighter
since the anterior teeth are not loaded axially, they are not able to
withstand high loads
why should there be any occlusal contacts on anterior teeth?
canine guidance
also called canine discussion or canine rise. when the mandible moves laterally, the canines on the working side guide the movement, causing all other teeth to disclude
anterior guidance
in protrusive movement, the anterior teeth should disclude the posterior teeth
anterior guidance
the canines, central and lateral incisors disclude the posterior teeth, when the mandible is
protruded
anterior guidance
contacts between the posterior teeth during excursive movements are considered —- and can create damaging effects on the teeth and periodontium
interferences
WHY IS CANINE GUIDANCE/ANTERIOR
GUIDANCE THE OPTIMAL OCCLUSAL SCHEME? (3)
• MANDIBLE - CLASS III LEVER
the more anterior (away from the fulcrum), the resistance (load) occurs, the lesser the impact (magnitude)
the canines(s) has the longest root, and best bone support (canine eminence)
OPTIMAL FUNCTIONAL OCCLUSION
ALSO REFERRED TO AS
MUTUALLY PROTECTED
OCCLUSION
MUTUALLY PROTECTED OCCLUSION
multiple, even, bilateral simultaneous occlusal contacts of the posterior teeth in MIP with the mandible in CR position
(MIP and CR are coincident)
MUTUALLY PROTECTED OCCLUSION
the anterior teeth exhibit lighter occlusal contacts as compared to posterior teeth in
MIP
MUTUALLY PROTECTED OCCLUSION
posterior teeth are axillary loaded in
MIP
MUTUALLY PROTECTED OCCLUSION
in excursive movements, what occurs?
canin guidance/anterior guidance
MUTUALLY PROTECTED OCCLUSION
the posterior teeth withstand the majority of the load in MIP, protecting the anterior teeth from
high loads
MUTUALLY PROTECTED OCCLUSION
the anterior teeth disclude the posterior teeth in excursive movements, thereby
protecting the posterior teeth from off-axis loading
MUTUALLY PROTECTED OCCLUSION
posterior teeth can. tolerate axial loading well so they protect anterior teeth, which are not axillary loaded, in MIP. anterior teeth can tolerate lateral forces in excursive movements (off axial loading) since they are
further away from the fulcrum and the loads are less
GROUP FUNCTION
when the mandible moves laterally, the mandible is guided by the outer inclines of the mandibular buccal cusps sliding along the inner inclines of the buccal cusps of the maxillary posterior teeth
GROUP FUNCTION
the most desirable group function consists of the
canine, premolars and MB cusp of the first molar
GROUP FUNCTION
the more posterior the contacts, the greater the force-closer to the source of power; the move — the forces
destructive
GROUP FUNCTION
on the WS, only the — cusps of the mandibular teeth guide along the inner inclines of the maxillary teeth, as far posteriorly as the first molar (MB cusp)
buccal
GROUP FUNCTION
there are no contacts on the
NWS
GROUP FUNCTION is — but not —
acceptable
ideal
GROUP FUNCTION
is the only option for patients who (4)
have no anterior vertical overlap eg anterior open bite a very large anterior horizontal overall eg class 2 div 1 have a reverse overlap eg class 3 you may see group function referred to as unilateral balance (not a term used today)
BALANCED OCCLUSION (2)
simultaneous contacts on both sides (working and non working) during lateral excursive movements (working side contacts and balancing side contacts)
contacts between the posterior and anterior teeth during protrusive movement
BALANCED OCCLUSIONif the mandible moves to the right:
on the right side (WS):
outer includes of mandibular buccal cusps contact inner inclines of max buccal cusps and at the same time
BALANCED OCCLUSION
if the mandible moves to the right
on the left side (NWS):
inner inclines of mandibular buccal cusps contact inner inclines of maxillary lingual cusps
BALANCED OCCLUSION
in protrusion:
there are contacts between posterior and anterior teeth
BALANCED OCCLUSION
on the posterior teeth:
mesial inclines of mandibular cusps occlude with distal inclines of maxillary cusps
BALANCED OCCLUSION
not acceptable for
dentate patients
BALANCED OCCLUSION
not ideal for
dentate patients
BALANCED OCCLUSION
promotes — on dentate patients
tooth wear
BALANCED OCCLUSION
NWS contacts are extremely
destructive and must be avoided
BALANCED OCCLUSION is an acceptable form of occlusion for
complete dentures
