Packing and processing PMMA

Question 1

What is packing?

Answer 1

Involves the removal of wax and any temporary base plate - lost wax technique

Then created void filled with acrylic resin - this is called packing

Question 2

What is processing?

Answer 2

After packing…

flasks placed into water based heat source or dry heat oven in order to cure resin

Question 3

What do you do with the flasks with plaster and stone in them?

Answer 3

Placed in boiling out tank - water run onto flasks for 7-10 mins

Question 4

How long should flask with cement and stone in it be placed in the boiling out tank?

Answer 4

7-10 mins

Question 5

Temp of water bath for flask with cement and stone?

Answer 5

100 dc

Question 6

What is the base plate made of?

Answer 6

shellac based base plate

Question 7

What is occuring here?

Answer 7

Wax knife used to tease apart flask

Question 8

Wet is this going?

Answer 8

Boiling out tank to remove left over wax

Using hand held water other residues

Question 9

After the flask has returned from its second boiling out session - what material should you mix?

Answer 9

Acrylic resin

Poly (polymer powder)

Methyl methacrylate (liquid)

Question 10

What consistency do you want for the poly methyl methacrylate to know it’s mixed?

Answer 10

Wet sand - cover

Question 11

What consistency do you want for the poly methyl methacrylate after 5 mins and ready to use?

Answer 11

Doughy state

Question 12

After boiling out wax, how do you secure loose teeth?

Answer 12

Super glue

Question 13

What is being brushed on?

Answer 13

Separating medium - sodium alginate

Prevent absorption of monomer into the plaster

When it has dried, remove excess with air nosel

Question 14

Why apply sodium alginate to plaster?

Answer 14

Prevent absorption of monomer into the plaster

Question 15

What sheets have been placed over upper and lower model?

Answer 15

Polythene separating sheets

Question 16

Why place polythene separating sheets?

Question 17

How to place doughy POMA into flask?

Answer 17

Roll into a sashes shake and cover mould with other half of flask

Question 18

What machine is used to press the flak?

Answer 18

Pneumatic press

Question 19

How do you add pressure to the flaks in the pneumatic press?

Answer 19

Twist handle to secure flasks

Slowly apply pressure to the pump handle

Question 20

How do you slowly apply pressure to flasks?

Answer 20

Pump pressure handle a few tie and leave for 45 seconds

Repeat process

Question 21

After pneumatic press - what is happening here?

Answer 21

Wax knife used to remove most of the excess resin

Leaving only a rim of around 5 mm around denture

Question 22

Do you related the press procedure after removing excess acrylic?

Answer 22

Yes. Ever to apply more sodium alginate and remove separating sheets

Question 23

Do you fully tighten the flaks here?

Answer 23

No

Release pressure by quarter turn

Question 24

Why do you not fully tighten flasks here?

Answer 24

Release pressure slightly by quarter turn

Accommodate for initial expansion in water bath

Question 25

What is this called?

Answer 25

Spring clamp

Question 26

What are the flasks in the sling co placed in?

Answer 26

Water bath - 72 Celsius 16 hours

Or dry heat processor - run overnight

Question 27

Water bath temp for setting acrylic?

Answer 27

72 dc 16 hours

Question 28

How long does the dry heat processor run?

Answer 28

Overnight