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
Not only is this type of pun most common (99% of the time used), but is also the most RETENTIVE:
self-threading
Increased diameter of a pin =
increased retention
If you place a pin and it breaks, you should place another one:
1.5mm away from broken pin
What is the diameter of the most frequently used threaded pin? What is it called?
0.021 inches; Minim
What is the general rule with pin placement?
use one pin per missing cusp, axial wall, or line angle and use NO MORE than 4 pins per tooth
T/F: The pin should be placed in the 2.0mm into the dentin, have 1.0mm of dentin minimum surrounding it, be placed with the long axis of the tooth, and be placed in the line angles (the greater area of bulk)
True
What type of hand wrench is used at UMKC?
Link Series and Link Plus
Pinhole location depends upon:
- pulpal anatomy
- external tooth anatomy
- patient age
The best sties for pin placement are at:
line angles (DF, DL, MF, ML)
Site to AVOID for pin placement (to avoid pulp exposures include):
- MF corner of maxillary and mandibular 1st molar
- Distal mandibular molars
- Lingual of maxillary molars
- Mid-facial, Mid-mesial, and Mid-distal furcations of maxillary 1st and 2nd molars
What concavities should you watch out for when placing a pin?
- mesial concavity over max 1st PM
- Mid-lingual and Mid-facial of mand 1st and 2nd molars
- mid-facial, mid-mesial, and mid-distal furcations of maxillary 1st and 2nd molars
The pin should be placed a minimum of ____ mm inside the DEJ
or a minimum of ____ from external surface of the tooth, whichever is greater
0.5 mm (preferably 1.0 mm inside the DEJ)
1.0 mm
If planning to place a crown, the pin should be placed ____ mm inside the DEJ
1.0-1.5 (earlier it was 0.5-1.0mm inside the DEJ with no crown)
When placing a self-threading pin, make sure you have a:
postive stop
What should be done at the end of placing the self-threading pin?
quarter turn refers (reduces stress)
There must be ____ of amalgam over the top of the pin otherwise the amalgam may fracture
2.0mm
When cutting the pin, it should be stabilized using:
forceps
When cutting the pin if yo notice that its loose, what should you do?
remove and use a larger size pin
T/F: Use a condenser to push on the pin and flatten it:
false- use pin bender only!
Summary of procedures for drilling pin holes:
1) Place ____ inside the ___
2) Place ____ with a ____ bur
3) Confirm correct ___
4) Continuous (in and out ___)
5) Interpin distance of ____
1) 0.5mm; DEJ
2) pilot hole; 1/4 round bur
3) angulation
4) drilling; one time
5) 3-5 mm
Although both are scarrrrry scarrrrry, what is more preferable? pulpal perforation or PDL perforation with pin placement?
Pulpal perforation because extirpation of the pulp solves the problem
A periodontal perforation with a pin usually results in:
abscess
slots and grooves should be placed ____ inside the __
0.5mm inside the DEJ
Slots are similar to grooves but are:
larger
Slots are created with a ____ but
33 and 1/2 inverted cone bur
How wide and deep should slots be?
0.5-1.0mm wide and 1mm deep
Slots should be sightly ____ to provide retention
undercut
Allow for restorative material to act as “pin”
locks
With ____, more tooth structure is removed
a- slots
b- pins
c- grooves
d- locks
locks (maybe slots??)
____ result in fewer microfractures compared to pins
slots
When creating an amalgam pin, use a ____ bur. Drill the hole ____ wide and ____ deep and then ____.
245 bur; 1mm wide & 2mm deep; condense amalgam into pin hole
Benefits of using amalgam build up:
- Can ____ when preparing crown
- Ease of ____
- Good ____ properties
- Not as ____ as composite resin
- Good _____ stability
- Good ____ resistance
- Relatively _____
- visualize
- ease
- mechanical
- technique sensitive
- dimensional stabliilty
- wear
- inexpensive (dat shit cheaaaaoooop)
What is absolutely critical when performing an amalgam buildup?
stabilization of matrix band
ROCK CHOCK LETS GO Chiefs
Slots, locks, grooves and amalgam pins and pins can all be combined to provide retention and resistance for a complex amalgam restoration.
Place ____, ___, ____ BEFORE placing ____
slots, lock grooves; pinhole
pop lock this slot and drop it
