Quiz 1 Review Flashcards
what is the result of overdrying a preparation?
it can dessicate the dentinal tubules
in other words, it’s bad
pain can stimulate/increase ___
salivation
is esthetics an acceptable reason to do a full coverage zirconia crown?
yes
what is the appropriate method for caries removal?
slow speed with a large round bur and/or a hand instrument (spoon excavator)
what are the reduction measurements for a full zirconia crown preparation?
- occlusal reduction/clearance
- functional cusp: 1.5-2.0mm
- non-functional cusp: 1.5-2.0mm
- functional cusp bevel: 1.5-2.0mm
- axial reduction: 1.0mm at margin
what are the two typical margin types for a full zirconia crown preparation?
rounded shoulder or chamfer design
what is the target measurement of the margin above the gingiva?
0.5mm
what should the width of the non-functional cusp bevel be for a full coverage zirconia crown preparation?
about 1.0mm
for a full coverage zirconia crown preparation, all line and point angles should be ___
rounded
what is an undercut?
under-tapered preparation
what are the implications of an undercut?
- wasted chair time
- impression distortion
- difficulty with provisional
what are the 3 mechanical considerations for full coverage zirconia crown preparations?
- retention form
- resistance form
- anti-deformation form
*these are what keep the crown “fixed”
___ form prevents dislodgement of the restoration parallel to the path of insertion
retention form
what are the 4 factors that influence retention?
- magnitude of the dislodging forces (ex. caramel, taffy, gum, etc.)
- geometry of the tooth preparation
- roughness of intaglio (underside of fixed restoration) surface of fixed restoration
- material being cemented or bonded
geometrically speaking, what 3 things can increase retention?
- increased axial surface area
- increased preparation height
- decreased taper of axial walls (aka make walls more parallel)
the ideal axial wall taper is ___ degrees
6-10
what can increase intaglio surface roughness?
airborne particle abrasion (micro-etch) and acid etch with hydrofluoric acid
___ form prevents dislodgement of the restoration along a path other than the path of insertion
resistance form
this is resistance to tipping
which 3 factors influence resistance?
- magnitude and direction of dislodging forces
- geometry of the tooth preparation
- physical properties of the luting agent
what are 4 examples of factors that affect the magnitude and direction of dislodging forces?
- design occlusion to load tooth/implant axially
- parafunction
- habits (pipe smoking, nail biting, etc.)
- misuse of prosthesis
geometrically speaking, what are 5 things that can increase resistance?
- decreased preparation diameter
- decreased axial wall taper
- increased crown height
- proximal grooves and boxes
- definite line and point angles (not rounded) - remember that you want these rounded though…
what are 5 luting agent considerations that increase resistance?
- complete seating of restoration (decreased cement thickness)
- luting agents with increased compressive strength
- luting agents with increased modulus of elasticity
- chemically bonded restoration
- micro-mechanically bonded restoration
___ form prevents dislodgement of the restoration due to permanent deformation (bending) of the restoration during function
anti-deformation
what are 4 factors that influence deformation?
- material selection
- adequate tooth reduction
- proper occlusal or lingual concavity reduction form
- margin design
