Occlusion 3 Flashcards
What type of articulators are there
arcon
average value
semi adjustable
What is the angles used on an average value articulator
bennet angle is set at 15 degrees
the condylar guidance angle is set at 30
What is a semi-adjustable articulator
it allows you to set the bennet and condylar guidance angles
What do face bow transfers allow
the transfer of the maxillary cast onto the articulator
How do we mount the mandibular cast in relation to the face bow transferred maxillary cast
inter occlusal reg
What are the components of the face bow
bite fork
transfer jig assembly
earbow
reference plane locator
What are the steps of doing a face bow transfer
- mark the anterior ref points
- bite registration using bite fork
- assemble ear bow and transfer jig
How do we mark the anterior reference point
on the patient’s RHS using the reference plane locator and marker
Where is the anterior reference point
43mm apical to the incisor edge to the anterior teeth (12 ideally)
What does the anterior reference point approximate
position of infraorbital foramen
How is the bite registrations taken
bite registration paste is applied to the bite fork
the bite fork arm to the right and locating notch faces up
firmly seat to record the cusp tips of the maxillary teeth
do not engage undercuts
check that it is parallel with patients coronal and horizontal planes
How do we align the bite fork
align the dental midline with the locating notch
What should we able to see in the bite reg
indentations of maxillary teeth clearly visible to allow accurate repositioning and then mounting of the maxillary cast
How do we assemble the ear bow and the jig
loosen the centre wheel to allow the ear bow to open and close
attach the vertical shaft to the measuring bow with clamp marked 2 on the patient’s right and tighten the finger screw on the ear bow
How do we assemble the face bow on the patient
by sliding the bite fork arm through the clap marked 2
fit the measuring bow’s earpieces tightly into patient’s ear
tighten the centre wheel on the bow
raise or lower the bow so that the pointer aligns precisely with the anterior reference point
if you are aligned with the reference point, tighten the clamps 1 and 2
be careful not to alter the bow while tightening the clamps
How do we remove the face bow
ensure bow is parallel to the inter pupillary line and floor
make sure the 1 and 2 clamps are secure
loosen the finger screw on the measuring bow, slide open the bow and remove the face bow from the patient
detach the measuring bow from the transfer jig by loosening the finger screw
disinfect
What have we recorded so far
the relationship of the maxilla to the hinge axis of rotation of the mandible
now we can mount the maxillary cast in an equivalent relationship on the articulator
What are the two choices of inter occlusal reg that can be sued to mount the lower cast
ICP (confirmative approach)
RCP (reorganized approach)
When we can we use no material for ICP reg
When the intercuspal is obvious
there is multiple tooth contacts when the px bites together
When can we use wax or paste for ICP reg
when ICP is not obvious to the technician
When do we use a record block for ICP reg
when there’s free end saddles and the casts cannot be hand articulated
What can happen if too much wax is used
the OVD is increased and the restoration will be high in bite when placed
when using wax ensure it is thin and cusp tips are visible
What is the registration paste
silicone paste sets quickly small amount is needed too thick and it will increase the OVD occlusal contacts must be visible through the material
What are the registration position options
RCP registration WITH or WITHOUT OVD increase (reorganized approach)
ICP registration WITH OVD increase (reorganized approach)
ICP registration WITHOUT OVD increase (confirmative approach)
What is an unorganized approach
You haven’t assessed the occlusion before starting restorations
You change the occlusion with your restoration
You haven’t planned where your ICP will be and what the related jaw relationship is
You provide an occlusion which does not conform to the previously tolerated one
What is the conformative approachdefined as
provision fo restorations ‘in harmony with the existing jaw relationships’
What does the confirmative approach mean
that the occlusion of the new restoration is provided in such a way that the occlusal contacts of the other teeth remain unaltered
When do we not use the confirmative approach
an increase in vertical height is needed to make space for restorations
tooth/teeth significantly out of position (i.e over erupted, tilted or rotated)
a significant change in appearance is wanted
there is history of occlusal related failure or fracture or existing restorations
What is the reorganized approach
plan to provide new restorations to a different occlusion
the occlusion is defined before the work has started
provide restorations that change the occlusion but are well tolerated by px
Why do we do reorganized approach
ICP is non existent or no use
you need space to place restorations
the retruded axis position of the mandible is a reproducible position independent of the teeth
How do we take an inter occlusal record in RCP
the patient is guided into a terminal hinge closure to detect where initial tooth contact occurs (RCP)
The RCP record is taken at a slightly increased OVD just prior to this initial tooth contact (the mandible is rotating about its terminal hinge axis)
What are the most reliable techniques for interocclusal record in RCP
bimanual manipulation
chin point guidance
chin point guidance with anterior jig
What do we need when we use wax or paste for RCP reg
must use a registration medum
may use an anterior jig
When do we need to take a record block for the RCP reg
free end saddles
casts cannot be hand articulated
What is the retruded arc of closure
from the RCP to R
Where can RCP occur
it is the initial tooth contact
it can occur at any point on the retruded arc of closure
this is sometimes called a centric relation premature contact
If the initial contact is on posterior teeth what is there most likely to be
a slide from RCP to ICP as the patient tries to achieve maximum inter causation
In what % of patients are RCP and ICP the same
10%
What is the position of RCP compared to ICP usually
0.5-2mm
What are the options for guidance
when restoring anterior teeth we can copy existing guidance or change it
What is the check list for occlusal analysis
TMJ function and muscles of mastication activity incisor relationship molar relationship open and/or cross bites guidance wear facets/severity of tooth wear restoration fractures occlusal contacts deflective contacts working/non working side contacts mount casts on an average value or semi adjustable articulator and review all of the above
