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Module 5 - Removable Pros > Impressions for dentures > Flashcards

Impressions for dentures Flashcards

1
Q

What is the ideal distance between the flange of the stock tray and the teeth?

A

4mm.

  • If not 4mm, SIZE UP TRAY.
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2
Q

How can we ensure the full lingual sulcus depth is achieved?

A

Ask patient to stick tongue UP AND OUT.

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3
Q

2 limitations of stock trays?

A
  • Not made to measure.
  • Peripheral extension often OVEREXTENDED (especially posterior).
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4
Q

2 things that can happen if you overfill special trays?

A
  • Excess material can obstruct the airway.
  • Prevent full seating of tray.
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5
Q

What can be done to stock trays to improve fit in a PARTIALLY DENTATE PATIENT (free end saddles)?

A
  • Addition of PUTTY.
  • Take an impression with the PUTTY.
  • Place alginate on top and take ANOTHER IMPRESSION.
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6
Q

What is the thickness of special trays/ the spacing of special trays dependent on?

A
  • Thickness depends on the properties of the impression material to be used.
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7
Q

What are two main reasons for taking impressions in dentistry?

A
  • Construction of appliances.
  • Monitoring (pre/post treatment, wear, record keeping).
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8
Q

What are stock trays usually made of?

A

Metal or MAINLY PLASTIC.

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9
Q

3 things that can happen if you extend denture past palatine fovea?

A
  • Lose seal.
  • Patient gags.
  • Denture unstable.
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10
Q

4 pros of special trays?

A
  • Accurate peripheral extension.
  • Uniform thickness of material.
  • Reduces amount of material – less discomfort as tray fits individual mouth.
  • Records denture bearing area more accurately.
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11
Q

4 uses of PRIMARY impressions in dentures.

A
  • Treatment planning.
  • Construction of special trays.
  • Examination of occlusion on articulator (PARTIALS ONLY).
  • Surveying - Determination of path of insertion and denture design (PARTIALS ONLY).
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12
Q

How can an overextended stock tray be reduced?

A

Acrylic bur

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13
Q

What is the advantage of perforated stock trays?

A

Mechanical retention to keep alginate in tray.

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14
Q

What is the labial frenum?

A
  • Muscle attachment.
  • Must RELIEVE around this area.
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15
Q

What can be done if a stock tray is overextended?

A

If plastic, reduce using an acrylic bur.

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16
Q

What is the disinfection protocol?

A
  • Rinse in running water.
  • 2 mins in Articlor (10,000ppm/ 1%) Sodium hypochlorite.
  • Remove after 2 mins, run under water with CLEAN GLOVES.
  • Cover with damp napkin.
  • Label, place in bag, prescription, indicate disinfected.
  • Take to laboratory ASAP for casting.
17
Q

What can be used to modify a stock tray that does not fit well to edentulous areas?

A
  • Putty, red composition.
18
Q

There is a sharp border at the area of the lingual pouch in the impression. What does this mean?

A

did not get tongue border molding correct

19
Q

How short of sulcus depth should special tray extensions be? Why?

A

2mm, allow border moulding.

20
Q

We added putty to the stock tray to record edentulous saddles. There are adjacent standing teeth. What must be done?

A

Use wax knife to cut putty and leave about 3MM CLEARANCE FROM STANDING TEETH.

21
Q

What must we do after making adjustment to an underextended stock tray using greenstick etc?

A
  • place into the mouth to MOULD MODIFICATIONS.
  • Trim putty etc with WAX KNIFE to allow about 3MM CLEARANCE from remaining standing teeth.
22
Q

Which areas may require prepacking?

A

High arched palate, tuberosities.

23
Q

How are special trays made?

A

Uniform thickness of MODELLING WAX over a STUFY CAST.

  • Thickness depends on the properties of the impression material to be used.
24
Q

what can happen if we dont relieve around the labial frenum?

A
  • can cause soreness.
  • denture can catch on frenum and become unstable.
25
Q

You want to take an impression with silicone elastomers for a complete denture. What is the required spacing/ required wax thickness? What type of complete denture are this appropriate for?

A
  • No spacer.
  • Completes - REPLICA.
26
Q

what is the significance of the hamular notch for dentures?

A

Common place where dentures dig in.

27
Q

What is the significance of the mylohoyid ridge for dentures?

A

It is in the lingual sulcus. Is a lump of bone which can be quite prominent and may give DISCOMFORT under a lower denture.

28
Q

When is greenstick stops placed around the PERIPHERY of the special tray (2)?

A
  • Tray is not retentive.
  • Patient has had problems with LOOSENESS OF AN UPPER DENTURE
29
Q

What can be used to modify a stock tray that has underextended flanges?

A

Greenstick/ wax.

30
Q

What must be done prior to sending primary impressions off to the lab to make a special tray?

A

DELINEATE using INDELIBLE pencil where you want your tray to end.

31
Q

What are palatine fovea? What is their significance for denture design?

A
  • Dimples just behind where the hard and soft palate meet.
  • Do not want to extend denture over these as you can lose the SEAL, make denture UNSTABLE and cause patient to GAG.
32
Q

3 advantages of stops on special trays?

A
  • Position tray
  • Maintain space for material.
  • Allow consistent placing of tray.
33
Q

4 materials that can be used to modify stock trays?

A

HIGH VISCOSITY MATERIAL.
- Wax
- Red composition
- Putty
- Greenstick

34
Q

You want to take an impression with silicone elastomers/ polysulphides. What is the required spacing/ required wax thickness? What types of dentures can this be used with?

A
  • 3mm.
  • Partials.
35
Q

What are the 3 different materials that could be used for special trays? 1 disadvantage of each.

A
  • Light cure acrylic: easy to mold YET very rigid hence hard to remove from model.
  • Shellac: brittle and fractures easily YET soften when warmed and thus can be removed.
  • Self cure acrylic: problems rolling an even layer.
36
Q

You want to take an impression with zinc oxide eugenol for a complete denture. What is the required spacing/ required wax thickness? What type of complete denture are this appropriate for?

A
  • No spacer.
  • Complete - conventional OR replica.
37
Q

What are stops for special trays? 3 uses?

A
  • Made of greenstick.
  • Placed at POST- DAM AREA + CENTRE OF PALATE, cover in vaseline and put in mouth to mold.
  • Position tray
  • Maintain space for material.
  • Allow consistent placing of tray.
38
Q

What is the vibrating line?

A
  • Just in front of the palatine fovea, at the JUNCTION OF WHERE THE HARD AND SOFT PALATE MEET.
39
Q

You want to take an impression with alginate. What is the required spacing/ required wax thickness? What types of dentures can this be used with?

A
  • 3mm.
  • Partials and complete.

Module 5 - Removable Pros (10 decks)

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