introduction/ terminology articulators (complete) Flashcards
What is occlusion?
the relationship between all components of the masticatory system in normal function, dysfunction, and parafunction
What relationships/functions/actions make up all of occlusion
- interrelationship of teeth (natural, restored, replaced)
- actions of the temperomandibular joint
- function of the muscles of mastication
- management of functional disorders of the masticatory system
What is normal force
normal forces exerted on teeth (bite forces)
In what direction are bite forces
perpendicular to the occlusal plane
how long are bite forces
short duration
What are the three levels of function
normal function
dysfunction
parafunction
what are the two forms of parafunctions
detrimental
accessory
what is normal function in unrestored natural teeth
smooth action of teeth against each other to triturate the food bolus
does normal function of unrestored teeth lead to damage
nope, repetitive action can continue indefinately without damage or pain
what is parafunction in natural teeth
function beyond normal function
what is detremental parafunction natural teeth
misuse (intentional or not) of teeth
- opening things with teeth
- bruxism
What is accessory parafunction of natural teeth
function of teeth in swallowing, respiration, speech
can repetitive parafunction lead to damaged teeth and pain
accessory = no detrimental = yes, leads to damage and pain
what is dysfunction of natural teeth
impaired function
what can cause dysfunction of natural teeth
deformed or damaged structures
lack of coordination of co-functioning parts
does repetitive dysfunction lead to damage and pain
yes, it does
what makes up ideal normal function
- smooth masticatory action
- no interferences
- no pain, fatigue
- no damage to functioning components
(like a high end watch with each part working perfectly together)
What are examples of detrimental parafunction
nail biting
opening things with teeth
holding things between teeth
conscious/subconscious grinding
what can repetitive detrimental parafunction cause
pain fatigue destruction of chewing apparatus wear of dental surfaces damage to TMJ
What are the parts of accesory parafunction
swallowing
speech
respiration
use many of the muscles involved in mastication
what are the six causes of parafunction
- local
- systemic
- psychological
- occupational
- involuntary
- voluntary
do you swallow often with an empty mouth? if so, what does that do for you?
yes you do, it clears the mouth of saliva and helps moisten the oral structures
What is normal function on restored teeth
our objective is to reach normal function, to function like it did before the tooth needed restoring
what is parafunction of restored teeth
when a restoration isn’t perfect and results in the patient “playing” with it because it isn’t even
what is dysfunction of restored teeth
when a discrepancy is beyond the capability of the patient to accommodate to it - leads to loss of function and pain
what are intracoronal restorations
fillings and inlays
what are extracoronal restorations
onlays and crowns
what are problems common to removable dental prosthesis
- uneven wear of dentures
2. irritation to oral and perioral tissues
what angle must the forces of occlusion be for implants to be durable
the must be directed down the long axis of the tooth
What are the two bones that make up the tempomandibular joint
temporal bone
mandible
what is the mandibular fossa
the concavity (pit) in the temporal bone where the condyle of the mandible fits
what is the glenoid fossa
the same thing as the mandibular fossa
what is the condyle
the end part of the mandible that sits inside the mandibular fossa
what is the articular eminence
the protrusion on the front end of the mandibular fossa that helps to retain the mandibular condyle
is there a meniscus/disk in the TMJ
yep
are there synovial membranes in the TMJ
yes
where does the superior head of the lateral pterygoid muscle insert
the anterior capsule of the meniscus/disk of the TMJ
where does the inferior head of the lateral pterygoid muscles insert
the condyle of the mandible
what kind of joint is the TMJ
ginglymoarthroidal joint
what do the two parts of ginglymo-arthroidal mean
ginglymo = hinging arthroidal = sliding or gliding ginglymoarthroidal = joint that hinges and glides/slides
What class of lever is the TMJ
class 3 lever
what is an example of a class 1 lever
seesaw
what is an example of a class 2 lever
nutcracker
what is an example of a class 3 lever
TMJ
what is the fulcrum, force, and resistance of the TMJ
fulcrum = condyle force = muscles resistance = food
what is one unique thing about the TMJ
it is the only joint that functions as a pair of joints working in unison (both joints must both function correctly)
what are the two types of movement of the TMJ
translation - gliding
pure rotation - hinging
what is the position of the condyle and disk at rest? with the mouth slightly open? with the mouth opened wide
rest = the disk is between the condyle and the glenoid fossa
slightly open = the condyle has rotated only, the disk remains between the condyle and the glenoid fossa
fully open = the condyle rotates and translates, the disk moves with the condyle and is now between the condyle and the articular eminence
which muscle moves the disk anteriorly with the condyle
the superior head of the lateral pterygoid muscle
What is happening with the disk and condyle when there is an internal derangement at rest? slightly opened mouth? fully opened mouth?
rest - the disk isn’t between the condyle and the glenoid fossa, but anterior to it
slightly open - the dist remains in front of the condyle while the condyle rotates, but keep it from fully opening comfortably
fully open - the condyle pushes forward and the disk pops into place, often with an audible sound
what is a subluxated mandible
when the condyle of the mandible slips too far foreward and goes beyond the articular eminence and become stuck foreward
what are the 4 muscles of mastication
temporalis
masseter
medial pterygoid
lateral pterygoid
what is the origin and insertion of the temporalis
origin = the temporal bone insertion = coronoid process of the mandible
what does the temporalis muscle do
cause the TMJ to rotate and close the mouth
What is the origin and insertion of the masseter muscle
origin = zygomatic arch and zygomatic bone insertion = angle and ramus of mandible
what does the masseter muscle do
pulls up on the mandible, pressing the teeth together
what does the lateral pterygoid do
depresses, protrudes the mandible. moves it side to side
what does the medial pterygoid do
elevates the mandible, closes the jaw, helps moves the mandible side to side
where do the superior and inferior heads of the lateral pterygoid insert
superior = anterior surface of the disk inferior = the mandibular condyle
where does the medial pterygoid originate
medial side of lateral pterygoid and palatine bone
where does the lateral pterygoid originate
great wing of sphenoid bone and pterygoid plate
What are the different types of treatment of TMD
direct TMD treatment
Dental interventions
behavior modifications
What are the two types of direct TMD treatment
palliative (warm, moist heat, avoidance, NSAIDS)
surgical (disc, muscles, condyle)
what are the types of dental interventions for TMD
occlusal equilibration (elimination of dysfunctional interferences)
Fixed (crowns on all teeth)
removable (dentures)
implant restrained reconstructions (full or partial)
what does behavior modification to treat TMD mean
elimination of dysfunctional habits
feedback and hypnosis
How important is precision when doing restorations in a patients mouth
the most important
is there a bit of physiological freedom of movement within the human masticatory system
yes
if the restorations done by a dentist aren’t perfectly precise, but close, can those discrepancies be overcome by the patients ability to adapt
yes
because a patient can overcome small discrepancies, does the dentist have permission to introduce interferences
nope
what happens if a dentists restorations aren’t precise
treatments don’t stand the test of time
pain and loss of function for the patient
what is the instrument that is an analog to the TMJ
the articulator
What are the types of articulators from most simple to most complex
Hinge (most simple) Average articulators Galetti hanau-Mate Semi-adjustable articulator Fully adjustable articulator
What is the difference between an arcon and a non-arcon
in an arcon style articulator the angle between the condylar inclination and the occlusal plane of the maxillary teeth remains the same between the open and closed position
in a non-arcon sytle articulator the angle between the condylar inclination and the occlusal plane of the maxillary teeth increases as you go from the open to closed position.
what is intercondylar distance
the distance between the two condyles (on our articulator this is a fixed distance)
why is a large articulator better than a smaller onw
because the larger articulators have their hinge axis position (in relation to the teeth) closer to the patients mandibular hinge axis position in relation (in relation to their teeth)
why is having the articulators hinge axis position more similar to the patients mandibular hinge axis position good.
because it mimics the patients mouth better and will lead to more accurate restorations and fewer adjustments
what type of articulator do we have
a hanau modular, semiadjustable, arcon
what part of the articulator is the analog of the condyle of the mandible
the golden ball
what is the purpose of the facebow
to relate the maxilla to the axis of rotation about the mandibular condyles
on the bite fork, which way does the notch face
upward
what is the function of the T-support
to hold the distal end of the bite fork up so that the maxillary cast can be placed on it during mounting