Comprehensive Final Flashcards
What is the best combo as far as cement strength is concerned?
High compression strength and high elastic modulus (less stretchy)
What side effect can pain stimuli have on salivary flow?
It increases it
What property needs be reduced when dealing with PFM’s to reduce bond sheer strength?
Coefficient of thermal expansion
Name properties of types III-V gypsum stone:
Type III: Low strength low expansion, Type IV: High strength low expansion, Type V: High Strength high expansion
Why are PMM’s better for long span bridges?
Higher fracture toughness
What makes an irregular crown margin undesirable?
Harder to read and more likey to cause recurrent decay
What are advantages of a chamfered margin?
Distinct, easy to read, allows adequate bulk of material
What three pieces of key information about a patient are NOT captured in a triple bite technique?
Contralateral tooth anatomy, tooth balancing issues, condylar inclination
What is the result of an abraided dye margin?
Over-finished crown
How should Calcium Hydroxide be used?
As a direct/indirect pulp cap - don’t do under crowns
What chemical mechanism allows for Polycarboxylate cements to bond to the tooth?
Calcium chelation
What is the key to trimming bite registration?
Keep it perpendicular
What are the three variables of color?
Chroma, hue, and value
Where is the color of the teeth best determined?
Cervical region of the upper canines
Does increasing surface roughness of the prepared tooth increase retention?
No
Why use a coarse diamond?
They cut cooler
What height must a ferrule be to be effective?
2 mm
Why don’t we use self-adhesive cements for bonding partial coverage posterior ceramic restorations?
Due to bond strength (we use aesthetic resin cements)
Does light activation make a difference in the properties of self-adhesive cements?
Yes, catalyst causes color change over time (and should be used therefore in the posterior)
With a shortened dental arch, what characteristic was associated with an increase in joint sounds?
Posterior missing on one side
Compare solubility of resin, glass-ionomer and zinc phosphate?
Zn phosphate is most, GI is second and resin is least soluble
Self-adhesive cement Rely-x Unicem, how does it not need acid?
Acid is already inside the cement and it neutralizes in the set time
What are the two resin-modified GI’s used in the clinic?
Fujisim and RelyX 3M+
What do you use to cement a post in the clinic?
RelyX unicem
What is the problem with bonded EMax?
None
What is the problem with bonded Zirconia?
No retrievability
Are residual walls of a devitalized pulp chamber an accessible feature?
Yes
Where is GI chemistry commonly found in dentistry?
Direct fill, cements, sealants, buildups and foundations (You don’t find them in varnishes and de-sensitizers)
Ideal minimum anterior all-ceramic crown on the lingual concavity?
1.5 mm
What is the amount of axial reduction?
1.2-1.7 (PFM) and 1 mm for solid porcelain (Emax) and .5 for Zirconia
What is the amount of reduction in a posterior PFM all over?
2.0 mm
Which is the most ideal material design for Zirconia crowns?
Gold prep 0.5-1.0 mm, 1.5 on non-functional and 2.0 on functional cusps
What about all-ceramic posterior reductions?
2.0 mm
What is the minimum metal thickness in a PFM?
0.3 mm
How do you remove non-bonded crown restorations?
Sectioning the crown (bonded need to be ground down)
What metal is frequently confused with the noble metals but is not?
Silver
Why is a full-coverage crown more retentive?
Opposing axial walls are used in retention
What is the ideal range of taper?
6-10 degrees
What is the acceptable range of taper?
5-22 degrees
What variable will always increase retention, but may not increase resistance?
Surface area
What are some retentive features?
Boxes, isthuses and grooves
Which is more important, internal or external axial retention?
Neither - they are both equally important
Why is the marginal gap in the PFM worse than gold?
Porcelain contracts at the end of the firing cycle
What is the best fit for a crown?
10 microns
Why is it important to have close marginal adaptation?
Less dissolution of luting agent, perio disease, smooth transition, recurrent caries
Zinc oxide is in a bunch of different cements – name them:
ZOE, IRM, EBA, (only ones its not in is GI and resins)
What is important to know about Eugenol?
That it is an obtundant
Name cements that you get sustained Fluoride release:
GI, Silicates, RMGI
With VITA classic shade guide, what is the order in which the color parameters are found?
Hue, Chroma, value
How are the surroundings critical in shade selection?
Pastel colors (less than 4 units in chroma)
What is Metamerism?
When different lighting can cause colors to appear differently
Why should we squint or glance at colors?
To engage our scotopic vision - in other words, to utilize the area with the most rods for value determination
Which color disappears last with squinting?
The one with the highest value
When do we NOT use a butt margin veneer in the anterior?
When we are working on the lower incisors
When do we use a window prep for veneers?
When we are working with the posterior teeth
What are the two keys to using a reduction guide well?
Cut it into 3 pieces and refer to it often
What post and core is the strongest?
Cast post and core
What is the downside to using cast post and core?
When they fail, the tooth is doomed
What is the guideline in posterior partial coverage with minimum amount of enamel?
Some enamel must remain on the buccal and lingual
Of all the resin cements which doesn’t have a light cure option?
Adhesive resin cements
When can viscosity become a problem?
When the cement is going into the set phase
What could be the possible consequences of cement becoming more viscous?
It doesn’t set all the way as a crown or distortion in impressions (shrunken dye)
What are the primary objectives of a complete occlusal adjustment?
No incline contact, try to direct forces axially. Seat condyles, axially directed forces and everything off the inclines, get the guidance as far to the anterior
If you were doing a buildup and you had a high chance of moisture what is the best?
Low copper amalgam
Which tooth preparation requirement (resistance, retention, anti-deformation) does occlusal reduction fit into?
Anti-deformation
What are the main advantages of a partial coverage posterior ceramic?
Conservation of tooth structure, buccal/lingual tooth structure is good, aesthetics
What are the two main disadvantages of composite resin material as a buildup?
Moisture absorption and high thermal expansion
Most important bottom line factor in longevity of endo-treated crowns is?
An occlusal scheme that limits non-axial loading
- Of all retentive features that we can do (pins, posts, etc), which have the highest iatrogenic failures?
Pins
Propantholin – the anti-sialogog – where do you have to be careful using it?
If the patient has glaucoma
What are the factors that determine final shape of the prepared tooth?
Morphology, ideal reduction, opposing occlusion, damage to existing tooth and restorative material and attending dentist
What is the one thing that you have to remember with electrosurgery?
There will be tissue shrinkage beyond the cut point
What are the hemostatic agents?
Viscostat (Aluminum chloride) and Stringadent (Ferricsulfate) and also (not in clinic) as a hemostatic agent anesthetic
Contact angle – what is it in impression?
Beading of the water, high contact angle, hydrophobic has high angle
Understand when the shortened dental arch research can and cannot be applied:
Age, # teeth, perio, occluding units, motivation, oral hygiene, no wear on their teeth
Stress breakers – why and when do you need them?
Peer abutments (fulcrum), mandibular long-span bridge that crosses the midline, extremely off-axis bridge abutment teeth, it can allow you to reduce less tooth structure
What are some reasons for sub-gingival margin placement?
Esthetics, caries/damage to the tooth, retention
Criteria for using a triple tray in the posterior:
2 opposing prepared teeth (ok), 2 teeth in the same arch (ok), 3 teeth/bridges (not okay), esthetic case (not okay), canines/2nd molars (not okay)
With pontics, from a biological standpoint what is the best shape?
Convex in every direction (some concavity can be done on the facial)
Most esthetic pontic:
Ovate
What are the cements that chemically bond to tooth structure?
All resins, GIs, RMGIs, Polycarboxylate, (Zn-phosphate can not, EBA can not)
If a crown rocks buccal/lingually, where is the first place you go to check?
Interproximal contacts
What are things that can prevent crown seating (besides interproximal contacts)?
Nodules, intaglio surface
One last thing about the 7/8’s crown, there was a unique feature call the occlusal offset – what did it do?
Added strength, esthetics (gold thinner), creates a staple effect
