Occlusion stuff - we have to know Flashcards
masticatory system is complex system compromised of?
muscles, bones, ligaments, teeth, and nerves
elevator muscles
- masseter
- medial pterygoid
- temporalis
contact made in how many places?
THREE -
2 TMJ’s
and the dentition
articular disc
dense fibrous connective tissue
NO nerves or blood vessels so it can endure heavy forces
retrodiscal tissues
articular disc separates, protects, and stabilizes the condyle in the mandibular fossa during functional movements
specific fibers in the lateral pterygoid?
UPPER HEAD OF THE LATERAL PTERYGOID – fibers from this area pull the disk down and forward
TMJ problems representative of the disc?
NOO - not disc itself – maybe position of them but the disc has no nerves or blood vessels
implication of imflammation in retrodiscal
we do not have a reproducible bite
major stabalizing muscles in the head
- massater
- medial pterygoid
- temporalis
- superior head of the lateral pterygoid
peripheral disc attachment
attached to fibrous capsule an the superior head of the lateral pterygoid (more anteriorly)
disc is attached to condyle how? - specific
TIGHTLY – in health — held tightly to the head of the condyle by the medial and lateral collateral (discal ligaments)
describe the medial and lateral collateral (discal) ligaments
include function too
composed of collagenous connective tissue
function to restrict the disc from moving away from the condyle and permit the disc to move anteriorly and posteriorly together with the condyle – AS A UNIT during translation
also function during the rotation of the TMJ
*translation and rotation functionoing
positional stability of TMJ determined by - basic
determined by muscles pulling across the joint to prevent dislocation
lateral pterygoid controls?
PROTRUSIVE movement
SIDE TO SIDE movement
OPENS the mouth
medial pterygoid is a
elevator muscle
describe physiologic location of CR
where the condyle goes when the lateral pterygoid releases and the elevator muscles contract
CR?
the most muscoskeletal stable position of the TMJ
MOST SUPERIOR-ANTERIOR position of the condyles
- against the posterior slopes of the articular eminences
- articular discs properly interposed
Centric slide aka
MIP
describe centric slide
when closing in centric relation results in cusp tip to cusp tip occlusal position – but then CENTRIC SLIDE – CUSP TIP TO FOSSA RELATIONSHIP WAS ATTAINED
what holds the jaw forward
lateral pterygoid contraction
stable occlusion allows for
both effective functioning AND minimal damage to all components
to be in harmony?
all must be stable
optimal functional tooth contacts?
optimum occlusal conditions, then require EVEN AND SIMULTAENOUS CONTACT of ALL possible TEETH
- this maximizes the stability of the mandible and MINIMIZES THE amount of force on each tooth
result of harmony and balance loss
two posterior contacts – force is loaded on that side causing the muscle on the OPPOSITE SIDE PULL CONDYLE on the unopposed side FURTHER into the mandibular fossa
this causes unilateral shift and possible damage to one or both sides of the TMJ
minimal # of posteiror stops?
4 – for stability (shorten dental arch)
sphere of Monson?
CS + CW
curve of spee
teeth aligned parallel to the arc of closure
protrusive disocclusion of posteiror teeth
curve that protects in protrusive
curve of spee – protrusive disocclusion of posterior teeth
curve of wilson facilitates
tongue and cheek action for POSITIONING FOOD ON THE OCCLUSAL TABLE
permits lateral mandibular EXCURSION FREE FROM POSTERIOR INTERFERENCES
lateral pterygoid more active
jaw looks more forward
cusp tip hits
we slide and move
VDO
vertical dimension of occlusion
- superior-inferior RELATIONSHIP of the maxilla and the mandible when the teeth are situated in maxium intercuspation
VDO described as
appropriate, excessive, or deficient
VDO measured by
subjective signs related to esthetics and phonetics
occlusal plan definition **
imaginary surface that theoretically touches the incisal edge f the incisors and the tips of the occluding surfaces of the posterior teeth
does VDO have anythig to do with stability?
NO – it is a RELATIONSHOP
before restore must do what?
re-establish stability
three criteria for optimum functinal occlusion
- even and simultaneous contact of all possible teeth
- condyles in their most superior anterior position against the posterior slopes of the eminence
- articular discs properly interposed
pressure and tension? good bad?
pressure = bad
tension = good
role of the PDL
the PDL helps control these forces and provide stimulation
PDL convers a destructive force (pressure) into an acceptable force (tension)
vertical stops are
support for occlusion
describe tip or fossa contact
force is directed vertically through the long axis
force is well accepted due to the alignment of the PDL fibers
AXIAL LOADING – what we want
describe contacts on inclines
a horizontal component causes TIPPING
some areas of the PDL are compressed while others are elongated
forces are not effectively dissipated to the bone
OFF AXIS LOADING
axial loading
forces of closure are directed through the long axis of the tooth
unsupported anterior tooth contacts due to
forces applied at an angle to the long axis have potential to cause harm
teeth that accept horizontal forces of occlusion and why
CUSPIDS
- long thick roots
- better crown/ root ratio
- surrounded by dense bone
- extensive periodontal ligament
- most proprioceptive sensitive tooth in the mouth
most proprioceptive sensitive tooth
cuspids
four points of contact aka
group function
when restoring best alternate occlsal scheme is?
group function / four points of contact
describe group function
no contact on non-working side during excursions
no posteiror contact during protrusive movements
optimal group function
canine lus premolars and the MB cusp of the first molar
contqacts posterior to MB cusp of first molar
more posterior than the MB cusp of first molar not desirable necause of increased force that can be generated closer to the fulcrum (TMJ) and force vectors (muscles)
anything less than __ is not group function
four points of contact
anterior group function
canines and incisors (usually just lateral incisors ) function together to disocclude the posterior teeth during lateral and lateral protrusive excursions of the mandible
anterior teeth function in ? in terms of forces
anterior guidance directs ECCENTRIC forces
- heavier anterior forces
they are NOT positioned to accept heavy forces
their LABIAL angle makes it impossible to achieve axial loading
mutually protected occlusion
posterior teeth should contact more heavily than anterior teeth in centric occlusion
three types of interferences
- tinterferences furing the desired occlusal scheme (group function or canine guidanece) – like mediotrusive/ working and non-working side interferences
- prematurity (usually high restoration)
- Deflective occlusal contact (centric interference - usually natural)
contacts on inclines aka
eccentric forces
when forces are NOT effectively dissipiated to the bone, pathologic processes that may occur?
neuromuscular reflex activity
- AVOIDANCE
- PROTECTION
location of occlusal plane*
PARALLEL TO ALA TRAGUS LINE
