Impressions for dentures Flashcards
(39 cards)
What is the ideal distance between the flange of the stock tray and the teeth?
4mm.
- If not 4mm, SIZE UP TRAY.
How can we ensure the full lingual sulcus depth is achieved?
Ask patient to stick tongue UP AND OUT.
2 limitations of stock trays?
- Not made to measure.
- Peripheral extension often OVEREXTENDED (especially posterior).
2 things that can happen if you overfill special trays?
- Excess material can obstruct the airway.
- Prevent full seating of tray.
What can be done to stock trays to improve fit in a PARTIALLY DENTATE PATIENT (free end saddles)?
- Addition of PUTTY.
- Take an impression with the PUTTY.
- Place alginate on top and take ANOTHER IMPRESSION.
What is the thickness of special trays/ the spacing of special trays dependent on?
- Thickness depends on the properties of the impression material to be used.
What are two main reasons for taking impressions in dentistry?
- Construction of appliances.
- Monitoring (pre/post treatment, wear, record keeping).
What are stock trays usually made of?
Metal or MAINLY PLASTIC.
3 things that can happen if you extend denture past palatine fovea?
- Lose seal.
- Patient gags.
- Denture unstable.
4 pros of special trays?
- Accurate peripheral extension.
- Uniform thickness of material.
- Reduces amount of material – less discomfort as tray fits individual mouth.
- Records denture bearing area more accurately.
4 uses of PRIMARY impressions in dentures.
- Treatment planning.
- Construction of special trays.
- Examination of occlusion on articulator (PARTIALS ONLY).
- Surveying - Determination of path of insertion and denture design (PARTIALS ONLY).
How can an overextended stock tray be reduced?
Acrylic bur
What is the advantage of perforated stock trays?
Mechanical retention to keep alginate in tray.
What is the labial frenum?
- Muscle attachment.
- Must RELIEVE around this area.
What can be done if a stock tray is overextended?
If plastic, reduce using an acrylic bur.
What is the disinfection protocol?
- 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.
What can be used to modify a stock tray that does not fit well to edentulous areas?
- Putty, red composition.
There is a sharp border at the area of the lingual pouch in the impression. What does this mean?
did not get tongue border molding correct
How short of sulcus depth should special tray extensions be? Why?
2mm, allow border moulding.
We added putty to the stock tray to record edentulous saddles. There are adjacent standing teeth. What must be done?
Use wax knife to cut putty and leave about 3MM CLEARANCE FROM STANDING TEETH.
What must we do after making adjustment to an underextended stock tray using greenstick etc?
- place into the mouth to MOULD MODIFICATIONS.
- Trim putty etc with WAX KNIFE to allow about 3MM CLEARANCE from remaining standing teeth.
Which areas may require prepacking?
High arched palate, tuberosities.
How are special trays made?
Uniform thickness of MODELLING WAX over a STUFY CAST.
- Thickness depends on the properties of the impression material to be used.
what can happen if we dont relieve around the labial frenum?
- can cause soreness.
- denture can catch on frenum and become unstable.
