RPD LAB - MOUNTING CASTS

Question 1

when are the two times we need to see the teeth in occlusion

Answer 1

when we are designing the denture

to help the technician set up the teeth

Question 2

what are the two approaches technicians can design dentures in regards to the occlusion

Answer 2

conformist approach

reorganized approach

Question 3

what is the conformist approach

Answer 3

keep the occlusion the same

Question 4

what is the reorganized approach

Answer 4

change the occlusion

Question 5

how can we tell how casts occlude

Answer 5

using upper and lower wax rims

Question 6

what do the casts allow us to do

Answer 6

see where we have space for the different components of the partial dentures

Question 7

how does seeing the teeth in occlusion help the technician set up the teeth

Answer 7

it allows us to place the casts correctly in the articulator and see the functional excursive movements

Question 8

what are the stages to the split cast mounting technique

Answer 8

1. trim notches
2. soak casts in sodium silica solution
3. place the mounting plates
4. use plasticine to position casts and the registration onto articulator
5. make mounting plaster
6. take mix and apply to upper cast
7. fill slots of mounting plate
8. smooth off excess material
9. set articulator upside down
10. apply mix to top of cast and add some to notches as well
11. lower arm of articulator to ensure the incisal table comes into contact with incisal post
12. trim excess material away
13. take cast and mountings off and smooth mounting plaster
14. separate cast from mounting plaster
15. once surveyed reunite cast with mounting plaster

Question 9

why do we soak casts in sodium silica solution

Answer 9

provide barrier between casts and mounting plaster

Question 10

what should the check post be at

Answer 10

0

Question 11

where should the slot and hole of mounting plate be on articulator

Answer 11

slot - rear of articular arm

hole - front of articulator arm

Question 12

why do we use plasticine to position casts

Answer 12

ensure that they sit an equal distance between the arms of the articulator and equally spaced between the anterior and posterior of the articulator

Question 13

how many mls of water for mounting plaster

Answer 13

50 ml

Question 14

why do we fill the slots of the mounting plates

Answer 14

to retain the mounting plaster on the plate once its set

Question 15

why do we have to separate cast from mounting plaster

Answer 15

not enough space on surveyor

Question 16

how do we reunite the casts

Answer 16

using impregnated plaster bandage

Question 17

how can we record occlusion

Answer 17

record blocks

Question 18

what are record blocks

Answer 18

lumps of wax which fill the waffle area

Question 19

how do we record the occlusion at chair side

Answer 19

soften the wax and get patient to bite on it and give to the lab to mound

Question 20

what is an articulator

Answer 20

holds casts so we can see the mandibular/maxillary relationship

Question 21

what are the different types of articulators

Answer 21

simple hinge
average value
semi-adjustable
fully adjustable

Question 22

describe the features of the simple hinge articulator

Answer 22

most basic form
not accurate
holds a static occlusal relationship

Question 23

what are the advantages of the average value articulator

Answer 23

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

Question 24

what is the disadvantage to the average value articulator

Answer 24

the movement is prescribed by the manufacturer of the articulator - they determine the condylar angle and we cannot adjust this angle to the patient

Question 25

describe the features of the semi adjustable articulator

Answer 25

facilitates the movement of protrusion/lateral movement

can adjust the angle of the ‘condyle’ so we can have it the same as the patients

Question 26

what are the 2 types of semi adjustable articulators

Answer 26

arcon

nonarcon

Question 27

what is an arcon articulator

Answer 27

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

Question 28

what is a nonarcon articulator

Answer 28

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

Question 29

what are the features of a fully adjustable articulator

Answer 29

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