Accessory Retention Flashcards
Additional retention; more than the primary retentive features of the prep:
accessory retention
Accessory retention is often used with large restorations especially:
amalgam
Amalgam relies completely on:
mechanical retention
Accessory retention does NOT:
seal or increase strength
Accessory retention has no effect on:
resistance form
Accessory retention is required when:
the residual tooth structure does not provide adequate retention
Indications for pin placement include:
- to improve retention
- extensive preparations
- prognosis of tooth is uncertain
Contraindications for pin placement include:
- severe loss of tooth structure
- endo treated teeth
- large pulp canals
- difficult access
- tooth already serves as abutment for partial denture
The pin does NOT _____, its only function is to provide additional ____ or ___.
strengthen the amalgam; retention and or resistance
What do the placement of pins REDUCE in amalgam?
compressive and transverse strength of amalgam (disadvantage)
Pin placement may introduce stresses in to the ____ which can lead to crazing or even fracture
dentin
Types of accessory retention in VITAL teeth include:
- pins
- slots & grooves
- amalgapins
What accessory retentive feature in vital teeth remove the least amount of tooth structure?
pins
Because you CANNOT use pins in eddo-treated teeth due to fracture risk, you can instead use:
- amalgam core (retention from pulp chamber)
- post retained amalgams (post placed in actual canal not dentin)
The pin is always placed into the:
dentin
What type of pins are available?
- cemented
- friction lock
- SELF-THREADING*
A self threading pin is ____x as retentive as a cemented pin
5-6 times
There should be atleast ____mm of ____ around the pin hole with a self threading pin
1mm of dentin
What type of pins are used most frequently at UMKC?
self-threading
Self threading pins are ____, meaning:
self-shearing; they break off on their own during placement
If multiple pins are placed, they should be placed ideally ___ mm apart from each other but at a minimum ____ mm apart of each other
5mm; 3mm
How far away from the wall of the prep should pins be placed?
1.0 mm but a minimum of 0.5mm
How deep into the dentin should a pin go?
2.0mm