Test 2 Review Flashcards
what is the benefit of delayed cementation of fiber posts?
results in higher retentive strengths in comparison to immediate cementation and the best results were obtained when the luting agent was brought into the post space with lentigo spirals or specific syringes
___ thickness influences the pullout strength of fiber-reinforced posts. The highest bond strength values are obtained when ___
- Resin cement fill
- the cement layer oversized the post spaces but not larger than 0.3mm
When is the use of core build-up materials as post luting cements recommended?
Only one scenario: Don’t want to remove dentin to make room for a larger post. You can use the core build-up materials to cement the post in these cases. In other words, if you have a large gap, you can use the build-up materials to cement the post.
What are 4 factors for the long term success of post endodontic restorations?
- occlusion
- preservation of tooth tissue
- presence of a ferrule effect
- adhesion
Evidence shows that ___ posts are superior to metal posts or tooth-colored posts, like zirconia dowels.
fiber
T or F:
Posts should be used to reinforce the tooth
false
they are used to retain restoration and not reinforce the tooth.
___ and ___ forces influence the prognosis of restorations on endodontically treated teeth.
Functional and parafunctional
Nonaxial forces are a risk for ___
fatigue fracture of teeth, cement, and restorative material.
what are fundamental components of a complete laboratory prescription?
- patient name
- patient MRN number
- date of prescription
- due date of indirect restoration
- school of dentistry name and contact info
- tooth or teeth numbers
- desired materials for indirect restoration
- design info for indirect restoration (if indicated) – margin design, special instructions for material placement, pontic design if FPD
- other special instructions
- shade info if indicated
- photographs if indicated (no cell phone pictures)
- due date
- attending signature
- attending license number
what are the 3 considerations/parameters/stipulations of tooth preparations, and what is the goal of the dentist with respect to these parameters?
mechanical, biological, esthetic
we want to be in the center of that venn diagram with our restorative work; sometimes we have to sacrifice one of those principles to get a better overall result
what can happen if you take an alginate impression, then immediately rinse it off and put it in a plastic bag?
it can take on water (imbibition)
what are the 3 types of resin cements?
adhesive, self-adhesive, esthetic
what is an example of a self adhesive resin cement?
relyX unicem
of adhesive, self adhesive, and esthetic resin cements, which is has the strongest bond?
adhesive
of adhesive, self adhesive, and esthetic resin cements, which has to be used with a bonding agent?
esthetic
it will be incredibly strong, but not as strong as adhesive
what is bis-acryl used for?
temporary material
___ is a temporary material that has good color selection, but the shelf life is not very good. why?
- bis-acryl
- the colors start to darken after the expiration date
bis-acryl is a ___-based resin material
bis-GMA
would you want to use bis-acryl for a bridge? why or why not?
no
it is a big-GMA resin material and so it is brittle
triad material is better for bridges
what is it that makes the outer layer of bis-acryl gummy after polymerization?
the oxygen inhibited layer
when can you add to bis-acryl?
when the oxygen inhibited layer is still there
it is much more difficult if that layer is gone
___ is a methylmethacrylate that has to be light cured to fully polymerize
unifast
what is a disadvantage of unifast?
not great esthetically
what are some advantages of unifast?
- handles very nice and is very forgiving
- good for contours of gingival embrasures where you feel like material might get locked in
what type of matrix should you use with unifast?
alginate
don’t want to use the putty matrix
___ is the most esthetic version of zirconia. why?
high trans, because it has more zirconia in the cubic phase (this also means it’s slightly weakened)
___ is the strongest phase of zirconia, and it is stabilized by ___
- tetragonal
- yttria, ceria, and alumina
what is the ideal length of a post, and how much gutta percha should be at the apex?
- 2/3 - 3/4 the length of the root
- 4-5mm of gutta percha at the apex
___ posts tend to stress dentin at the coronal end, while ___ posts tend to stress dentin at the apical end
- tapered
- parallel
what happens to stress forces on dentin if you shorten a post?
it increases the stress forces
is it ok to use a green stone to adjust zirconia?
no, because it will cause a phase change to monoclinic since it’s not as strong of a material as zirconia
transformation toughening is also called ___
crack propagation prevention
transformation toughening occurs when a crack forms in zirconia, causing a phase change from ___ to ___
tetragonal to monoclinic, which is larger, so it makes it tougher and more resistant to more cracking
zirconia can break down from certain insults like heat and friction. what is the phase change that occurs, and what can it cause?
- tetragonal to monoclinic
- can cause fracture, increased abrasivity, low-temp aging degradation, increased hydrothermal solubility
is build up material harder or softer than tooth structure?
softer
is it ok to expose a pin while you are doing a buildup?
yes, but you don’t want to cut the pin while doing it
clinically, when delivering a crown, which is the first parameter to check?
proximal contacts
what is scotopic vision and photopic vision?
- scotopic - rods
- photopic vision - cones
what type of vision do you use when doing shade matching?
scotopic (rods)
when shade matching, if you’re going to err, you should err on the light or dark side, and why?
light side, because it’s much easier to darken a light shade rather than lighten a dark shade
the surface of what tooth has the most dominant hue?
cervical 1/3 of an unrestored upper canine
T or F
you should never cut dry using a high speed handpiece
false
while it is really important to keep teeth wet to avoid friction heat with high speed handpieces, it is acceptable to cut dry on a non-vital tooth, or on a vital tooth if the RPMs are really low (i.e. stall-out) and if the tooth is kept moist intermittently
*you can also cut dry with a slow speed
what is the liquid component of IRM?
eugenol (oil of cloves)
___ is a good temporary material to put on a pulp exposure of a tooth that needs endo. it keeps the tooth “calm” enough until completion of the root canal.
IRM (ZOE + acrylic powder + eugenol)
ZOE + acrylic powder + eugenol = ___
IRM (intermediate restorative material)
what should you do if you get a pulp exposure on a direct restoration, like an MO?
it needs to remain uncontaminated by saliva and other things, and must remain moist
chances are fairly good at this point to do a pulp cap and the tooth may never need endo
what should you do if you get a pulp exposure on an indirect restoration?
the risk is too high for a direct pulp under indirect restorations, so you’ll want to do an indirect pulp cap or RCT depending on how deep the pulp exposure is
___ is the liquid component of zinc polycarboxylate
polyacrylic acid
does polyacrylic acid cause pulpal sensitivity? why or why not?
no, because it’s too bit to penetrate dentin tubules
polyacrylic acid is fundamental in the development of ___
glass ionomer cement
polyacrylic acid is found in ___ and ___, and is used as a conditioner liquid for ___
- polycarboxylide cements and glass ionomer cements
- resin modified glass ionomer cements
___ describes a material that maintains the same size as it sets and as it’s removed from the mouth
dimensional accuracy
___ is how long a material stays the same size without distorting
dimensional stability
___ is an impression material’s ability to rebound back to proper dimensions
elastic recovery
putty material is an example of what type of impression material?
condensation silicone, which is a type of elastomer
what is the biproduct of condensation silicones, and what is their best use?
- ethyl alcohol
- silicone matrices only
PVS is what type of impression material?
addition silicone, which is a type of elastomer
what is the biproduct of PVS? what is the scavenger? what is the problem with cheaper PVS materials?
- hydrogen gas
- palladium
- cheaper materials don’t have the scavenger so you need to let it sit for a while so that the H2 gas doesn’t produce air bubbles
sulfur compounds (latex gloves) should not be used with what impression material?
PVS
polyether is what type of impression material?
elastomer
what are 3 disadvantages of polyether?
- most rigid of all the elastomers
- terrible taste
- dimensional stability is not on par with PVS
which elastomer has a terrible smell, is accurate, you want to pour it quickly, and cannot be used for more than one pour?
polysulfide rubber base
(not used very often)
___ describes tissue at the attachment apparatus that is very thin and more susceptible to recession
thin biotype
___ describes tissue at the attachment apparatus that is very thick, including robust crestal bone, and is less susceptible to recession
thick biotype
for anterior zirconia crown preparation, what are the reduction measurements for the following?
facial depth at margin
lingual depth at margin
lingual concavity
incisal reduction
- facial depth at margin - 0.5-1.0mm
- lingual depth at margin - 0.5-1.0mm
- lingual concavity - 1.0-1.5mm
- incisal reduction - 2.0-3.0mm
for anterior lithium disilicate crown preparation, what are the reduction measurements for the following?
facial depth at margin
lingual depth at margin
lingual concavity
incisal reduction
- facial depth at margin - 1.0-1.5mm
- lingual depth at margin - 1.0-1.5mm
- lingual concavity - 1.5-2.0mm
- incisal reduction - 2.0-3.0mm
which type of stone is use as a mounting stone and has the least amount of expansion upon setting?
type I
type ___ dental stone is used mostly as impression stone
III
type ___ dental stone is a die stone and is not as hard as type V
IV
type ___ dental stone is a die stone, expands a lot, is very hard, and is used for ceramo-metal restoration
V
___ can be added to stones to increase abrasive resistance
thin cyanoacrylate
hydrocal and densite are both ___-hemihydrate
alpha
hydrocal is used to make type ___ dental stone
III
densite is used to make type ___ dental stone
IV and V
beta-hemihydrate is used to make type ___ dental stone
I and II
alpha-hemihydrate is used to make type ___ dental stone
III (hydrocal), IV (densite), and V (densite)
how does glass ionomer adhere to tooth structure?
carboxylate (in cement) and calcium (in tooth) ionic bond
___ is the liquid component of zinc polycarboxylate
distilled water
how does zinc polycarboxylate adhere to tooth structure?
calcium chelation bonds
what is hue, chroma, and value?
- hue is the color (ex. blue vs. red vs. yellow), determined by the wavelength of the reflected and/or transmitted light observed
- chroma is the intensity of the hue (aka saturation, strength of hue, concentration of pigment)
- value is the relative lightness or darkness of a hue
does a higher value correspond to a lighter or darker appearance?
lighter
___ is the phenomenon of two colors that match under one set of conditions, but fail to match under a different set
metamerism
does a base strengthen the tooth?
no, its purpose is getting back to an ideal prep, and also serves as a thermal insulator
what does a liner provide?
chemical barrier
*not* a thermal insulator
what do build-ups do?
increase attachment/connection between a restoration and the tooth
if given the choice, would you want to use a post?
no (iatrogenic fracture)
what are posts used for?
they enhance the connection between the tooth and the restoration
