Midterm II Flashcards
What are the principles of veneers?
- Enamel in right places, 2. Esthetics/good margins and 3. Adequate reduction
What is photopic vision?
Vision in the light - cones
What is scotopic vision?
Vision in the dark - rods
What is hue?
Color
What is chroma?
Color intensity
What is value?
Light/dark scale
Where is the best location to figure out the patient’s hue?
Cervical third of the canine
What does squinting do?
Blocks out everything but the highest value objects
What type of porcelain is the most esthetic?
Fieldspathic
What post design is the most retentive?
Parallel post
What post design transfers the least stress to the dentin?
Parallel post
What three things can be done with posts to decrease dentin stress?
- make the post longer, 2. increase post thickness and 3. bond the post
Why do we use tapered posts?
To conserve tooth structure
What is the deal with cast post and core and parallel posts?
You can’t do them together
What is a 6878K-012 used for?
Breaks proximal contacts, light veneer preps and chamfered points
What is a 6877K-018 used for?
Heavy chamfer for limited access - shorter than 6878
What is a 6878K-018 used for?
Chamfer, occlusal refinement, workhorse of prosth
What is a 5856-016 used for?
Rounding shoulder margins, rounded tip, heavy usage
What is a 6845KR-018 used for?
Partial coverage all ceramic
What is a 6379-023 used for?
Football diamond, lingual concavities
What is a 889-009 used for?
Tight spaces, small flame diamond
What is a 8862-010 used for?
Interproximal, long flame diamond, bevels margins
What is metamerism?
When light surrounding an object affects its perception by the human eye
What are four weaknesses of the human eye to adequately judging color?
- influence of surrounding colors, 2. color adaptation, 3. metamerism and 4. color blindness
What two reasons could an object appear to be yellow?
- It reflects yellow light or 2. It reflects a combination of light wavelengths that mixes together to appear yellow
What makes chroma appear higher than it really is?
Proximity of close colors with vibrant chromas - especially complimentary colors
What colors and Munsell level should be present in the op?
Pastel colors with a chroma no higher than 4 on walls, 9 on ceiling
What is the best way to avoid color adaptation?
Look away at something gray or pastel to rest your eyes
How does the Vita classic guide work?
It uses four categories of hues/chroma and then you detect value
How does the Vita 3D system work?
You first find the value, then move on to hue/chroma
What would not be a good reason to place veneers?
Minor shade changes - whitening should be tried first
What is the ideal prep depth for the lab?
Heavy half - 0.5 -0.7 mm
What is the primary reason to have a lingual chamfer?
To help seat the restoration and guide the veneer into a full seat
How far is the lingual extent of the proximal axial reduction?
About 1/2 through the tooth
As a general rule, if you are not preparing an adjacent tooth that is in the esthetic zone for veneer, what is a potential drawback/consequence of the tooth you are preparing?
You usually take more off at the margin
What are the four things we need to know about placing veneers over restorations?
- Excellent condition, 2. small in size, 3. Not discolored and 4. All classes except possibly class II
Why do we trim the silicone putty guide?
To help with the prep and verify the seat
Why is the veneer temporary technique so technique sensitive (3)?
- Debris from cutting holes, 2. Leaving too long of sprues and 3. wetting typodont with vasoline
How much gutta percha can be left when doing a post?
4-5 mm
What is the ideal post length?
2/3 to 3/4 the length of the root
For instance, if you increase the length of the post, does it decrease or increase the stress on the dentin?
Decreases
What is the ideal gap between post and radicular dentin for the passively fitting post?
0.3 mm
Do you ever use core material to cement your post with?
Yes, if the post is loose
What is one cement that you do not want to use on posts?
Glass ionomers or RMGI’s
According to Schillenberg (one of the studies that he presented), he gave a guideline for buildups. His research indicated that what is the guideline for doing a buildup?
1/2 crown is missing
Why is it that we try to keep the cavosurface margins on any ceramic restoration close to 90 degrees?
To create thick enough ceramic to avoid chipping
