Quizzes Flashcards
What is the composition of dental porcelain?
Quartz Kaolinite Feldspar Metallic oxides Borax
When would you chose an all ceramic over a Pfm crown?
When tooth loss has been extensive (may not be possible to prep PFM)
When the patient wishes to due to aesthetics
If the patient has an allergy to the metal used in PfM crown
Tell me about a shoulder finish (angle, depth, position, instrument to hell prepare) ?
90 degree finish
Depth minimum 1.3mm
Placement depends in appearance/lip line
Use enamel chisel to help prepare
Tell me about a chamfer finish (angle, depth, position, instrument to hell prepare) ?
135 degree finish
Depth 0.5-0.1 mm
Placement not dependent on appearance (supra gingivally)
Use 877K bur to prepare
What are the advantages of the wingless PfM crown prep design?
It’s easier to prepare and there is less chance of leaving an undercut
What are the terminal groups of addition cured polymers?
Vinyl
What are the terminal groups of condensation cured silicones?
Hydroxyl
Which common polymer are addition and condensation cured silicone impressions based on?
Polydimethyl siloxane
What is present in the base paste of pump addition cured silicones?
Polyvinyl siloxane
Silanol
Filler
What is present in the catalyst paste of pump addition cured silicones?
Polyvinyl siloxane
Platinum catalyst
Filler
What is the typical detail reproduction of a light bodied silicone impression material?
Less than 20 microns
What materials can be used in astringent solution?
Ferric sulphate
Aluminium chloride
Aluminium sulphate
What is an astringent substance?
A chemical that tends to shrink or constrict body tissues
(Useful when impressions of a tooth/ teeth need to be. Made and the gingivae is preventing clear impressions being taken
What are the current theories on how porcelain attaches to the metal in a PFM crown indirect restoration?
Chemical = oxide formation
Mechanical locking
Compressive forces
What concentration is the disinfectant solution for impressions?
1000 ppm available chlorine
Which chemical tablets are dissolved in water to produce the disinfectant solution?
Sodium dichloraisocyonurate
What does maxi temp HP consist of?
Urethane dimethacrylate Aromatic dimethacrylate Glycol methacrylate Glass powder Silica
What are the advantages of a directly fabricated temporary crown such as maxi temp vs. A pre fabricated temporary crown such as directa?
No need to have different sized crowns
Can use different shades
May be used for greater variety of uses such as bridges, inlays, on lays and veneers
What are the different types of temporary crowns available?
Preformed crowns
Lab made temp crowns
Direct syringing
Lab made temporary crowns
What are the functions of temporary crowns?
Protecting tooth vitality if not root filled Maintaining function Preventing movement of teeth Aesthetics Diagnostic purposes
What are the steps in using the retraction cord?
- Select diameter of card that you estimate will fill the smallest and most delicate area of the sulcus
- Place the cord in a dappens dish containing an astringent solution
- Begin packing where the sulcular tissue is least likely to get damaged (I.e. Palatial aspect of maxillary preparations or deepest part of sulcus)
- Pack the soaked cord once around the tooth in a deliberate manner so that all of the sulcus receives and is displaced by the cord
- Cut off any remaining excess length of cord leaving an unpacked tag end to aid removal
- Wait approx 5 mins, long enough for tissues to be displaced but shirt enough to minimise schematic damage
What’s the use of ultra pack size #00 cord?
Preparing and cementing veneers
Restorative procedures with thin friable tissues
What’s the use of ultra pack size #0 cord?
Lower anteriors
Luting near gingival and subgingival veneers
Class III, IV, and V restorations
Second cord or double cord technique
What’s the use of ultra pack size #1 cord?
Non impregnated are effective for tissue control and/or displacement when soaked in hemostatic solution prior to and/or after crown preparation
As a protect pre preparation cord for anteriors
What’s the use of ultra pack size #2 cord?
Upper cord for double cord technique
As a protective pre-preparation cord
What’s the general setting reaction of amalgam?
Ag3Sn + Hg -> Ag3Sn + Ag2Hg3 + Sn7-8Hg