Quiz 1: Cast, Post and Core Flashcards
what is the strongest post and core combo?
PFM with post and core are strongest.
Post and core are strongest of all build ups
with post what is custom fit?
Lock and key
preparation technique
- remove all unsound tooth structure
- create horizontal platform of tooth structure
- remove gutta percha to lenght of post with #2 gates glidden bur
- prepare post space
- create antirotational keyway with 170 carbide bur on LINGUAL aspect (3-4 mm down)
- Prepare small bevel margin for cast post and core
- prepare chamfer margin for PFM
what comes in the tapered post kit?
- drills
- stainless steel temporary post
- plastic analog post (for impression)
T/F short posts transfer stress to apical end of post and propogate fractures
True
How big should the bevel margin be?
1/4- 1/2 mm bevel margin using the 6878k-018 Diamond tip
T/F The cast post and core margin is always possible
False: not always possible, but when possible serves as another ferrule to resist root fracture
Impression Technique
- place retraction cord
- verify fit of blue plastic analog post in canal
- verify no interference from opposing teeth in MI
- try in anterior triple tray
- remove blue plastic analog post and apply PVS adhesive to head of post
- remove retraction cord and check 360 degree marginal visibility
- re-insert blue plastic analog post into canal
- mix impression material and inject in the following order
What order do you inject the impression material
- inject around head of blue plastic analog post, starting in anti-rotational keyway
- move to margins of tooth preparation
- add balance of syringe material all around area of tooth
- insert impression tray
how many hands do you need for a good PVS impression?
4 hands
How to remove impression
- verify complete set
- instruct patient to “snap open” while holding impression against arch with the prepared tooth
- remove impression from prepared tooth arch by pulling entire impression out parallel with the post’s line of draw (try to avoid torqueing or tipping!)
- inspect impression for accuracy
Impression pour up
- use die stone with 100 g stone per 21 ml H20
- pour arch with prepared tooth first with indices toward distal
- define each index with green handle knife 10-15 min into set
- lubricate indices and pour up next arch
- trim each model separately
Vacuum Mix procedure
- pour stone into water
- incorporate stone with spatula
- place lid with mixing blades over mixing jar
- vacuum mix for 10 seconds
- remove lid while on vibrator
- place lid into sink with trickle of water running to mixing blades
- pour up impression
- clean vacuum mixer
- store mixer with water inside
Fabrication of the temporary
- insert stainless steel post into canal
- verify fit of clear matrix with post in place with post on PALATAL SIDE of canal
- lubricating area with petrolaturm is critical with typodont
- remove clear matrix and fill prepared tooth area with acrylic
- re-insert clear matrix and initiate cure of acrylic
- Carefully tease temp from tooth while in rubbery phase
- remove most excess acrylic, including any that will lock into proximal undercuts and re-insert temp
- complete curing process and trim and polish for cementation
Cementation of Temporary
- Polycarboxylate cement is best
- only apply cement to base of acrylic. NOT ON THE POST!
- insert temporary and remove excess temporary cement while in rubbery stage with explorer
- instruct patient to exercise caution with eating and flossing while temporary is in place
Cementation of Final Restorations
- verify fit of post
- verify fit of crown with post
- adjust crown as necessary
- cement post and crown down simultaneously with chemical cure. self- adhesive cement such as C&B Metabond or Panavia
- apply vertical pressure only with cotton roll at incisal edge. DO NOT HAVE PATIENT BITE ON THESE DURING THE SET!
- carefully begin removal of excess cement while in rubbery stage. (DO NOT CAUSE GINGIVAL BLEEDING AND DO NOT WAIT UNTIL CEMENT IS COMPLETELY SET TO BEGIN REMOVAL!)
