39 Questions
What is the temperature of the boiling water used in the process?
100 C
What is the purpose of applying wax solvent with hot water?
To remove all traces of wax
What is the purpose of creating small retentive pot holes on the artificial teeth?
To increase the attachment between teeth and denture base
Why is separating medium applied to all surfaces except teeth?
To minimize passage of monomer to stone
What is the advantage of injection molding technique over compression molding technique?
Higher impact strength
What is the disadvantage of injection molding technique?
More expensive equipment
What is the purpose of wax contouring in complete denture construction?
To reproduce natural tissue contour
What is the purpose of heating the flask in a microwave oven?
To soften the wax
What is the next step after investing the denture in the complete denture processing sequence?
Boil out (wax elimination)
What is the final step in the injection molding technique?
Injecting acrylic resin into the mold
What is the function of the strip of wax placed from the gingival third of the teeth to the peripheral border?
To prevent cheek and lip biting
What is the purpose of festooning in complete denture construction?
To enhance retention and stability
What is the purpose of remounting in complete denture construction?
To ensure proper fit and occlusion of the denture
What is the purpose of finishing and polishing in complete denture construction?
To ensure a smooth, glossy surface for the denture
What is the purpose of curing in complete denture processing?
To polymerize the acrylic resin
What is the purpose of remounting the stone casts on the articulator?
To remove occlusal errors during processing
What is the result of contraction of monomer during polymerization?
Porosity in the denture base
What is the effect of small voids or pores within the acrylic resin denture base?
It makes the denture weaker and difficult to clean
What is the purpose of making new maxillo-mandibular relation records?
To establish the correct vertical dimension
What is the term for the appearance of small particles of stone on the surface of the denture?
Sandy appearance
What is the result of errors in processing during denture fabrication?
All of the above
What is the term for the small voids or pores within the acrylic resin denture base?
Porosity
What is the purpose of finishing and polishing the denture?
To remove any flash of acrylic resin
What is the ratio of heat cure acrylic resin polymer to monomer by volume?
3:1
What is the characteristic of the mixture in stage II (STRINGY STAGE)?
The monomer attacks the surfaces of individual polymer beads
What is the purpose of placing a piece of wet cellophane over the resin before assembling the flask?
To allow the flask to be reopened for inspection and adding or removing resin
At what stage is the mixture packed into the mold?
DOUGH STAGE
What is the pressure at which the flask is closed?
Around 3000 psi
What is removed from the flask after it is opened carefully?
The excess resin
Why is the press secured with positive pressure?
To ensure the metal edges of the flask are in complete contact
What is the final stage of the process?
The process is repeated until there is no more appreciable flash
What is a common cause of gaseous porosity in dentures?
Excessive monomer in mix
What is a common cause of granular porosity in dentures?
Excessive polymer
What is a common cause of tooth movements during denture fabrication?
Using plaster instead of stone
What is a common cause of denture base and teeth breakage during deflasking?
Using a hammer to tap the denture out of the flask
What is a common cause of fractured or cracked teeth during denture fabrication?
Packing of resin in the rubbery stage
What is a common cause of crazing of acrylic resin?
Stress induced by contraction of resin around the tooth
What is a common cause of bleaching of acrylic resin?
Contamination of the acrylic resin with acrylic solvents
What is a common cause of sandy appearance of the denture?
Too much delay in curing after packing
Study Notes
Complete Denture Construction
- The process of complete denture construction involves both clinical and laboratory steps.
Steps of Complete Denture Construction
- Clinical steps:
- Wax contouring (festooning)
- Flasking (investing the denture)
- Boil out (wax elimination)
- Packing of acrylic resin
- Curing
- Deflasking of denture
- Remounting
- Finishing and polishing
- Laboratory steps:
- Wax contouring (festooning)
- Flasking (investing the denture)
- Boil out (wax elimination)
- Packing of acrylic resin
- Curing
- Deflasking of denture
- Remounting
- Finishing and polishing
Wax Contouring (Festooning)
- The process of carving the denture base to simulate the contour of the natural tissues that are being replaced by the denture.
- Purpose:
- To reproduce natural tissue contour
- To enhance retention and stability
- To refine wax-up having self-cleansing contours
- To enhance esthetics and support for the lips and cheeks
- To prevent cheek and lip biting
Flasking (Investing the Denture)
- The process of investing the denture in a flask.
- The flask is placed into boiling water (100°C) for 5 minutes to remove the wax.
- The wax denture is removed from the mold as one piece.
Boil Out (Wax Elimination)
- The process of removing the wax from the mold using boiling water.
- The wax is eliminated, and the mold is washed with hot water to remove any remaining wax.
Packing of Acrylic Resin
- The process of packing the acrylic resin into the mold.
- The resin is mixed according to the manufacturer's ratio and is packed into the mold in the dough stage.
- A piece of wet cellophane is placed over the resin before the flask is assembled to allow for inspection and addition or removal of resin.
Curing
- The process of polymerizing the acrylic resin.
- The flask is placed in a press and subjected to pressure (around 3000 psi) to ensure that the resin is properly polymerized.
Deflasking of Denture
- The process of removing the denture from the flask.
- The excess acrylic resin is trimmed, and the metal edges of the flask are ensured to be in complete contact.
Remounting
- The process of repositioning the stone casts on the mounting plaster, which is attached to the articulator.
- The purpose is to re-establish the occlusal vertical dimension and make any necessary adjustments.
Finishing and Polishing
- The process of removing any flash or excess material from the denture.
- Any dental stone on the surface of the denture is removed, and the denture is polished to a high shine.
Processing Errors
- Porosity:
- Causes: contraction, gaseous, or granular porosity
- Consequences: difficult to clean, esthetically objectionable, and weak
- Tooth movements:
- Causes: using plaster instead of stone, incomplete closure of flask, excessive rapid pressure during trial closure, or over packing of the mold
- Denture base and teeth breakage during deflasking:
- Causes: poor removal of stone cap, using a hammer to tap denture out of the flask
- Fractured or cracked teeth:
- Causes: packing resin in rubbery stage, setting teeth directly on stone cast, or excessive pressure during packing
- Crazing of acrylic resin:
- Causes: stress induced by contraction of resin around the tooth, use of solvents to remove wax from the mold
- Bleaching of acrylic resin:
- Causes: contamination of acrylic resin with acrylic solvents, under-cured acrylic resin due to incorrect time and temperature of curing
- Color streaks:
- Causes: improper mixing of monomer and polymer, contamination of resin mix with hands, or adding resin material in layers during trial packing
- Sandy appearance:
- Causes: too much delay in curing, evaporation of monomer, or insufficient monomer in the mix
- Stone adhering to the surface of the denture:
- Causes: insufficient separating medium on the mold, application of separating medium contaminated with stone, or incomplete elimination of wax
- Space between the teeth and resin base:
- Causes: delayed curing, application of separating medium on teeth
This quiz covers the clinical and laboratory steps involved in the construction of complete dentures, useful for prosthodontics students and professionals.
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