Endo Teeth III Flashcards
When do you need a foundation for a crown
>50% tooth structure is gone Esthetic improvement (i.e discolored tooth)
when do you need a post
inadequate remaining tooth structure to retain a core
T/F A post strengthens a tooth
f
What type of post should be done if 1/2 the clinical crown still remains
prefab
Advantages of prefab posts
- Conserves tooth structure
- Less time and cost
- Less technically demanding
Contraindications of prefab post
-Eliptical or excessively flaired canals (post space prep requires excess removal of tooth structure)
What are the three metals that a prefab post can be made from
stainless steal
titanium
CoCr
Describe the properties of carbon fiber posts
- Excellent biocompatibility
- Satisfactory mechanical properties
- Significantly weaker than stainless steal/resin core and cast metal
- Less retentive than serrated SS posts
- Inadequate radiopacity (disadvantage)
Features of fiber posts
- Lower incidence of root fracture
- Root fracture that do happpen typically restorable
- Post fails before tooth fails
- However* Long term data for these are lacking thus not as highly recommended for use as SS
Describe zirconia posts
- Stiff and strong (no plastic behavior)
- Esthetically better than metal
- Zirconia and metal posts produced catastrophic fractures of the teeth compared to fiber reinforce posts
what posts are the most retentive and least retentive
threaded… tapered
Rank the posts in order of retentivness
Threaded> Parallel serrated > Parallel serrated tapered > Parallel smooth > Tapered
What posts are the worst stress producers
tapered threaded posts **threaded posts are NOT recommended
What posts generate the lease cementation stress
tapered
What types of teeth may you consider a tapered post for
one with thin walls
Why aren’t parallel posts good for flared/eliptical canals
-only touch the tooth at the apical end thus post retention is primarily dependent on cement
It was originally thought that threaded posts should be used for teeth with short roots with adequate root thickness where other posts would not be retnetive enough however what is the recommended thearpy instead of this
replace the tooth with an implant if the root is too short
Greater post length –> (greater/lesser) retention
greater
What are the limitations for increasing the post length
- Increased risk of perforation
- Compromise the apical seal
What is the min. length of the post required
equal to the length of the clinical crown
What is the optimal post legnth
-No absolute guidelines but also long as possible without jeopardizing the apical seal and strength/integrity of remaining root
What are the disadvantages of short post
- Increases stress (root fracture)
- Low retention –> dislodgement
If you have a short post you make be fine as long as you have significant_
ferrule
The potential for perforation increases the the post is prepped more than _ mm from the canal oriface of a molar due to_ (What)
7 mm …. presence of root concavities
