lec 7 Flashcards
MATERIAL FOR POURING:
- Type 3 stone/ dental stone
- Can be used for most final impression except alginate impression (wax does not adhere to alginate material).
METHOD 1: BOXING USING BOXING WAX
- Suitable for alginate impressions.
METHOD 2: PUMICE-PLASTER METHOD
MASTER CAST
Dimensions: (3)
- 3 mm wide – land area
- 2-3 mm – sulcus depth
- 1.5 cm – base
à An interim denture base used to SUPPORT the record rim material for recording maxillomandibular records.
RECORD BASE (TRANSFER BASE, TRIAL DENTURE BASE, TEMPORARY DENTURE BASE)
- Serve as a base to fabricate and support the wax occlusion rims and trial denture.
- Determine accuracy of impression by checking the retention, stability and border extension of record base.
- Check for gag reflex.
- Observe adequate salivary flow.
RECORD BASE (TRANSFER BASE, TRIAL DENTURE BASE, TEMPORARY DENTURE BASE)
REQUIREMENTS OF RECORD BASE (6)
- Well adapted to the final cast.
- Stable and retentive in the mouth.
- Rigid and dimensionally stable.
- Smooth and not irritate the oral tissue.
- 1mm thick on the crest and facial slope of the ridge, and 2mm thick in the palatal and lingual flange for rigidity.
- Borders should be smooth and rounded.
MATERIALS USED
A. TEMPORARY BASES
- Shellac
- Auto polymerizing acrylic resin
- Vacuum formed vinyl or polystyrene
- Baseplate wax
MATERIALS USED
B. PERMANENT BASES
- Heat-cured acrylic resin
- Gold alloy
- Chrome cobalt alloy
- Chrome nickel alloy
- Swaged metal base
- Thermoplastic material
SHELLAC
SHELLAC * Precautions
overheating can cause the material to stick to the cast resulting in breakage during removal. It also causes bubbling, smoking and blackening.
- Inexpensive and easily available .
- Easy to use and adapt.
SHELLAC
- Brittle.
- Tends to warp or distort when heated repeatedly.
- Difficulty in recording jaw relations if distorted and unstable.
SHELLAC
*self-cured acrylic resin is cured in a pressure pot (20-30mins) for improved strength and properties.
AUTO POLYMERIZING RESIN
AUTO POLYMERIZING RESIN (3)
A. Non-flasking or Adapting method
B. Sprinkled on technique (Alternate applications)
C. Flasking method
- Using a sheet of thermoplastic resin and a thermal vacuum machine surface.
VACUUM FORMES BASES
- Inexpensive
- Easy to form
- Esthetic
- Easy to set teeth when interridge space is less.
BASEPLATE WAX
- Lacks rigidity and dimensional stability.
BASEPLATE WAX
- A wax pattern of the denture base is made on a duplicate cast and processed with heat cured resin
HEAT CURED RESIN
- Rigid, accurate, and dimensionally stable
- Retention and stability can be tested before delivery of denture
HEAT CURED RESIN
- Duplicate cast is required
- Time consuming and more expensive
HEAT CURED RESIN
- Occluding surfaces fabricated on interim or final denture bases for the purpose of making maxillomandibular relationship records and arranging teeth.
OCCLUSION RIM (RECORD RIMS, BITE RIMS, OCCLUSAL RIMS)
USES:OCCLUSION RIM (RECORD RIMS, BITE RIMS, OCCLUSAL RIMS)
- Determination of lip support and facial esthetics
- Determination of arch form
- Determination of plane of occlusion
- Aids in establishing teeth size and position
- To establish the contour of the polished surface
- For the (tentative) establishment, recording and transfer of jaw relation
- To see the patient’s response to a denture-like form
- Arrangement of artificial teeth
FABRICATION OF OCCLUSION RIMS (5)
- Soften a sheet of pink wax with Bunsen burner.
- Roll into soft cylindrical shape.
- Bend to form an arch and adapt to the record base.
- Seal the wax to the base with hot spatula.
- Finish the contour with a broad bladed spatula following proper dimensions.
SHAPE OF OCCLUSION RIMS
Arch forms:
A. Square (U shaped)
B. Tapering (V shaped)
C. Ovoid