denture processing Flashcards

1
Q

Which casts require relining?

A
  • new dentures (lose adaptation
  • old dentures (bone resorption)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is rebasing?

A

replacement of entire denture base with a new material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

relining and rebasing should be done without changing which relationship?

A

occlusal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When is relining indicated?

A

when denture loses its adaptation to tissues due to bone resorption while other points (occlusion, aesthetics, occlusal vertical dimension and denture base material) are all satisfactory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the procedure of relining of complete denture?

A
  • remove the denture out of the patient’s mouth for 48 hours to give time for the mucosa to rest
  • reduce the denture borders 2mm (to allow the flow of impression material to reach
    the depth of vestibule)
  • remove undercuts from the fitting surface of the denture.
  • take impression while the patient is closing in centric occlusion under closed mouth technique (to preserve occlusion)
  • make boxing and pour the cast
  • make flasking
  • throw away the impression material to make space for new acrylic resin
  • pack heat cured acrylic resin in the place of impression material
  • curing (45° for 20 minutes) (long curing cycle)
  • deflasking then laboratory remounting
  • finishing and polishing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

If both upper and lower dentures need to be relined, which one is relined first and why?

A

lower denture as upper denture is supported by the palate but lower denture is not supported

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What to do if vertical dimensions are not correct?

A

remake

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the steps of rebasing?

A
  • remove the denture out of the patient’s mouth for 48 hours to give time for the mucosa to rest
  • reduce the denture borders 2mm and drilling 3 holes through the palate to allow the flow of impression material to reach the
    depth of vestibule
  • remove undercuts from the fitting surface of the denture
  • take impression while the patient is closing in centric occlusion under closed mouth technique to preserve occlusion (to preserve VDO)
  • make boxing and pour the cast
  • mount the cast and the denture on Hooper articulator or simple hinge articulator (to preserve occlusion and VDO)
  • grind the denture base and throw it
  • make new denture base from wax
  • flasking → wax elimination → packing of acrylic resin → curing → deflasking →
    laboratory remounting → finishing and polishing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

When is rebasing done?

A

when denture contains cracks but occlusion must be right

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does polishing of denture consist of?

A

making denture smooth and glossy without changing its contour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When is finishing and polishing done?

A

after laboratory remounting (processing)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the procedure of wax elimination?

A

placing flask in hot water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens before wax elimination?

A

flasking

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens after wax elimination?

A

acrylic resin packing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens after flasking is done?

A

wax is flushed out with hot water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How is the cast remounted?

A

cast has indices or v-notches

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

When is laboratory remounting done?

A

after processing and before finishing and polishing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Who does the laboratory remounting?

A

lab technician

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why do we remount the cast?

A

refining of occlusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What needs to be done if cusps are high in centric relation only?

A

deepen opposing fossa

21
Q

What needs to be done if cusps are high in centric and eccentric relations?

A

grinding working and non-working cusps

22
Q

What are the working sides of teeth of casts?

A
  • BULL
  • buccal upper
  • lingual lower
23
Q

What is grinded in both sides?

A

non-functional cusps

24
Q

What should acrylic resin be glued to?

A

teeth

25
Q

What is the procedure of acrylic resin packing?

A
  • put cellophane on cast before adding acrylic resin
    a- dd acrylic resin then close the flask and bench press
  • remove cellophane and excess
  • add cellophane again and close the flask, then open to remove excess, put cellophane then close the flask and bench press
  • repeat until no excess is left
  • cure in oven
  • cooling
  • deflasking
26
Q

In which stage is acrylic resin packing done?

A

dough stage

27
Q

Why is long cycle better than short cycle?

A

short cycle causes crazing

28
Q

Which cycle is better for curing: long or short?

A

long

29
Q

What are the ways of packing acrylic resin?

A
  • injection method
  • open flask method (easier)
30
Q

What are the types of flasks?

A
  • flask for upper cast
  • flask for lower cast
31
Q

What are the components of a flask?

A
  • base (in the form of a cup)
  • middle part
  • top part (lid)
32
Q

What are the steps of flasking?

A
  • place cast in lower part of flask and fill it up with stone until level of cast and then ass separating medium
  • place second part of flask and add stone but don’t cover occlusal surface of teeth with stone then add separating medium again
  • add last layer of stone then close flask and it should touch occlusal surface of teeth
  • put flask in hot water and wax should melt
  • throw away trial denture base and add acrylic resin
33
Q

Why is the lower flask higher than upper?

A

presence of retromolar pad

34
Q

Do we add separating medium on occlusal surface of teeth?

A

no

35
Q

What is cap layer?

A
  • last layer that covers occlusal surface
  • this makes sure teeth don’t dislodge
36
Q

What happens before deflasking?

A

acrylic resin packing

37
Q

What happens after deflasking?

A

laboratory remounting

38
Q

What happens during deflasking?

A

flask cools to room temperature

39
Q

What is the objective of deflasking?

A

remove denture from investment material without breaking the denture or dislodging denture from cast for laboratory remounting

40
Q

What should the contour of the labial and buccal flange be and why?

A
  • concave
  • help stabilisation of denture
  • adaptation of oral muscles
  • muscles are stronger than the denture
41
Q

What should the contour of the lingual flange be and why?

A
  • convex then concave
  • convexity directly beneath the teeth
  • tongue may lie in this undercut and dislodge the lower denture
  • concavity away from teeth in the middle of the flange (not at any undercuts)
42
Q

Why should the palate be kept thin?

A
  • pronunciation of “s” sound
  • it is the space between tongue and rugae area
  • tongue never touches the rugae area
43
Q

What is lisping?

A
  • “th” sound replaces “s” sound
  • the the tongue is crowded against palate particularly on posterior region
44
Q

What are the causes of lisping?

A
  • increase in thickness of acrylic at rugae area
  • backward arrangement of upper anterior teeth which leads to no space to pronounce “s”
45
Q

What is whistling?

A

”s” sound is pronounced too sharply

46
Q

What causes whistling?

A
  • forward arrangement of upper anterior teeth
  • decrease thickness of acrylic in rugae area (insufficient waxing up)
  • low V.D.O. (short teeth and excessive freeway space)
47
Q

Why do we stipple gingiva?

A

to show rough appearance

48
Q

What should be contoured properly when contouring the root?

A

canine eminence