RPD LAB - MOUNTING CASTS Flashcards
when are the two times we need to see the teeth in occlusion
when we are designing the denture
to help the technician set up the teeth
what are the two approaches technicians can design dentures in regards to the occlusion
conformist approach
reorganized approach
what is the conformist approach
keep the occlusion the same
what is the reorganized approach
change the occlusion
how can we tell how casts occlude
using upper and lower wax rims
what do the casts allow us to do
see where we have space for the different components of the partial dentures
how does seeing the teeth in occlusion help the technician set up the teeth
it allows us to place the casts correctly in the articulator and see the functional excursive movements
what are the stages to the split cast mounting technique
- trim notches
- soak casts in sodium silica solution
- place the mounting plates
- use plasticine to position casts and the registration onto articulator
- make mounting plaster
- take mix and apply to upper cast
- fill slots of mounting plate
- smooth off excess material
- set articulator upside down
- apply mix to top of cast and add some to notches as well
- lower arm of articulator to ensure the incisal table comes into contact with incisal post
- trim excess material away
- take cast and mountings off and smooth mounting plaster
- separate cast from mounting plaster
- once surveyed reunite cast with mounting plaster
why do we soak casts in sodium silica solution
provide barrier between casts and mounting plaster
what should the check post be at
0
where should the slot and hole of mounting plate be on articulator
slot - rear of articular arm
hole - front of articulator arm
why do we use plasticine to position casts
ensure that they sit an equal distance between the arms of the articulator and equally spaced between the anterior and posterior of the articulator
how many mls of water for mounting plaster
50 ml
why do we fill the slots of the mounting plates
to retain the mounting plaster on the plate once its set
why do we have to separate cast from mounting plaster
not enough space on surveyor
how do we reunite the casts
using impregnated plaster bandage
how can we record occlusion
record blocks
what are record blocks
lumps of wax which fill the waffle area
how do we record the occlusion at chair side
soften the wax and get patient to bite on it and give to the lab to mound
what is an articulator
holds casts so we can see the mandibular/maxillary relationship
what are the different types of articulators
simple hinge
average value
semi-adjustable
fully adjustable
describe the features of the simple hinge articulator
most basic form
not accurate
holds a static occlusal relationship
what are the advantages of the average value articulator
resembles the real anatomy of the TMJ more than the simple hinge
allows more movement than simple hinge
can simulate the masticatory movements of the lower jaw to some degree
what is the disadvantage to the average value articulator
the movement is prescribed by the manufacturer of the articulator - they determine the condylar angle and we cannot adjust this angle to the patient
describe the features of the semi adjustable articulator
facilitates the movement of protrusion/lateral movement
can adjust the angle of the ‘condyle’ so we can have it the same as the patients
what are the 2 types of semi adjustable articulators
arcon
nonarcon
what is an arcon articulator
the fossae (condylar guidance) are on the upper member of the articulator and the spheres (condylar element) is attached to the lower member – this articulator resembles the TMJ
what is a nonarcon articulator
fossae (condylar guidance) are on the lower member of the articulator and the spheres (condylar element) is attached to the upper member – this articulator is the reverse of the TMJ
what are the features of a fully adjustable articulator
o We can adjust condylar angle and condylar distance
o Can make it accurate and specific to patient
o It allows accurate replication of the 3 dimensional movement of recorded mandibular motions
