Occlusion Flashcards
what is the action of the temporalis
elevation and retraction of mandible
what is the action of the lateral pterygoid
protrusion and depression of mandible
lateral movements
what is the action of the medial pterygoid
elevation
lateral movement
protrusion
what is the action of the masseter
elevation and protraction of mandible
lateral movement
what are the 2 major movements of the mandible
rotation and translation
what is rotation
small amount of mouth opening (only 20mm)
condyle and disc remains within articular fossa
no downwards or forwards movement
what is hinge movements
rotation of the condylar heads around an imaginary horizontal line through rotational centres of condyles
what does a facebow record
relationship of maxilla to terminal hinge axis of rotation in mandible
what is translation
lateral pterygoid contracts
articular disc and condyle move and travel downwards and forwards along incline of articular eminence
what is posselts envelope
border movements of the mandible in the sagittal plane
what are the parts of posselts envelope
ICP
edge to edge
protrusion
maximum opening (T)
retruded axis position
RCP
what is ICP
comfortable bite
maximum interdigitation of teeth
what is edge to edge
incisal edges of upper and lowers touch
what is the movement from ICP to edge to edge
teeth slide forward from ICP guiding on palatal surfaces of anterior teeth
what is protrusion
condyle moves forwards and downwards on articular eminence
no posterior tooth contacts
what is maximum opening
no tooth contacts and mouth wide open
what is the position of the condyle during maximum opening
full translation of condyle over articular eminence
what is retruded axis position
no tooth contacts
what is the position of the condyle during retruded axis position
superior anterior position of condyle head in fossa
what is RCP
first tooth contact when mandible is in retruded axis position
what is the distance between ICP and RCP
1mm
what is the movement of the mandible between RCP and ICP
slides forward into ICP
how do you establish the working side of the mandible
it is the side which the mandible slides to when eating
what causes lateral movement of the mandible
contraction of one lateral pterygoid
what is the bennet angle
angle formed by the sagittal plane and path of mandibular condyle during lateral movement when viewed in a horizontal plane
how do you mark tooth contacts
millers forceps and fine articulating paper
when do you mark tooth contacts
before preparing a tooth and removing restoration
after placement of a crown and restoration
what do tripodised contacts show
where the opposing cusps contact
(ICP stops)
what do you look at in static occlusion
incisor relationship
molar relationship
overjet/overbite
cross bites
open bites
individual contacts
RCP-ICP slide
what are functional cusps
cusps that occlude with opposing teeth in ICP
lingual cusps of uppers
buccal cusps of lowers
what are non-functional cusps
cusps that do not occlude with opposing teeth in ICP
buccal cusps of uppers
lingual cusps of lowers
what is a fossa
depression on tooth surface
what are the ICP contacts
lingual cusp of upper molar contacts fossa of lower molar
buccal cusp of lower molar contacts fossa of upper molar
how do you view ICP contacts
get patient to tap
what is overjet
relationship between upper and lower teeth in a horizontal plane
what is overbite
vertical overlap of incisors
what is crossbite
one or more teeth abnormally positioned buccal or lingually or labially with reference to opposing teeth
what is an anterior open bite
lack of vertical overlap of anterior teeth when posterior teeth in full occlusion
what is posterior open bite
failure of contact between posterior teeth when teeth are in full occlusion
what is canine guidance
mandible moves to working side and there is only contact between canines
what is a mutually protected occlusion
canine guidance
posterior disclusion in lateral excursions
no non-working/working side contacts
no protrusive interferences
what is group function
mandible moves to working side and multiple teeth contact
what type of group function is seen in toothwear
bilateral
what are the only teeth that touch in protrusion of mandible
incisors and canines
what are occlusal interferences
undesirable tooth contacts that can produce mandibular deviation during closure to ICP or hinder smooth passage to and from ICP
what are the types of occlusal interference
working side
non working side
protrusive
what is a working side interference
when teeth slide to the working side there are contacts on posterior teeth with similar cusps (buccal cusps contact)
what is non working side interference
mandible slides to working side and there are contacts on the non-working side with dissimilar cusps (upper lingual cusps and lower buccal cusp)
what is protrusive interference
any posterior contact during protrusion
why do you want to avoid posterior contacts
not designed to absorb lateral forces
musculature gets a rest if no contacts
occlusal trauma and undesirable tooth movements
what are the 2 types of bruxism
eccentric
centric
what is eccentric bruxism
parafunctional grinding of teeth
what is centric bruxism
clenching
what are the clinical signs of bruxism
toothwear
fractured restorations
tooth migration
tooth mobility
muscle pain and fatigue
headache
earache
pain and stiffness in TMJ and surrounding muscles
what are the types of toothwear
multifactorial
abrasion
attrition
erosion
abfraction
what are the types of toothwear classified as
mild
moderate
severe
what is primary occlusal trauma
occlusal trauma with an intact periodontium
what is secondary occlusal trauma
occlusal trauma with a reduced periodontium
what is fremitus
palpable or visible movement of a tooth when subjected to occlusal forces
what is the examination checklist for occlusion
incisor relationship
guidance
overjet/overbite
ICP contacts
working/non-working/protrusive contacts
pathology
what are the 3 types of articulator
arcon
average value
semi adjustable
what are the parts of the facebow
reference plane locator
bite fork
transfer jig assembly
earbow
where should the anterior reference point for the facebow go
43mm apical to incisal edge of anterior teeth
position of infraorbital foramen
what do you use to mark the anterior reference point
reference plane locator and marker
what do you apply to bite fork
bite registration paste
what do you do when the bite registration paste is in the bite fork
firmly seat to record cusp tips of maxillary teeth
what does the bite fork impression allow
accurate repositioning and mounting of maxillary cast
what does the facebow record
relationship of maxilla to hinge axis of rotation of mandible
what does the facebow allow
mounting of maxillary cast on articulator
how do you mount the lower cast
an interocclusal registration
what are the two types of interocclusal registration you can use to mount the lower cast
ICP
RCP
when would you use wax to record ICP
if ICP not obvious to technician
when would you use paste to record ICP
if ICP not obvious to technician
when would you use record blocks to record ICP
free end saddles
cannot be hand articulated
when would you not use any material to record ICP
if there are plenty of tooth contacts and ICP is obvious to technician
what is the simplest approach to mounting casts
using ICP registration without OVD increased
conformative approach
what are the 2 reorganised approaches
ICP registration with OVD increase
RCP registration with/without OVD increase
what is an unorganised approach
havent assessed occlusion before starting restoration
change occlusion with restoration
havent planned where ICP will be
provide an occlusion which does not conform to previous one
what is the conformative approach
provision of restorations in harmony with existing jaw relationships
when would we not use the conformative approach
an increase in vertical height needed
tooth/teeth out of position
change in appearance wanted
history of occlusally related failure or fracture of existing restorations
when would you use a reorganised approach
when you plan to provide new restorations to a different occlusion
ICP non-existent
need space to place restorations
RCP reproducible position of mandible
what are the reliable techniques to place a patient into RCP
bimanual manipulation
chin point guidance
chin point guidance with anterior jig
at what angle is RCP record taken at
slightly increased OVD just prior to initial tooth contact
what is the space between RCP and retruded axis position on posselts envelope known as
retruded arc of closure
where does initial tooth contact in RCP occur on posselts envelope
any point on retruded arc of closure
what type of guidance does a mutually protected occlusion have
canine guidance
