7. Foundation Restorations for Vital Teeth II Flashcards
What are the different retention and resistance features of foundation restoratiosn
- Pins
- Parallelism of walls of the prep
- Proximal box form
- Retention grooves in proximal line angles
- Circumferential/partial grooves “slots”
- Amalgam Pins
What are the three types of pins which ones do we use in clinic
- Cemented
- Friction-locked
- Self-threading**
Which pin type has a pin hole diameter that is larger than the pin
cemented
How are friction locked pins placed compared to self threading pins
Friction locked
-taped into place with a mallet
Self threading
-Placed by hand wrench or a contra angle hand piece
Which pin type places the least internal stress on the tooth
cemented
Which pins are the most and least retentive
Most= self-threading Least= Cemented
What are the four sizes of self-threading pins and which one is the most commonly used
- Minuta
- Minikin*
- Minim**
- Regular
About how much smaller is the pin hole diameter than the pin for self-threading pins
0.002 inches smaller
What color are the minikin and the minim pins
red= minikin and gray= minim
(Larger/smaller) diameter pins are more retentive
larger
Compare the pin depth for minikin and minim pins
- minim= 2 mm
- minikin= 1.5 mm
Optimum depth into dentin for pins is…
2.0-3.0mm (2mm)
What are the benefits of a pin drill having a shoulder stop self-limiting feature
- Depth reference
- Reduces chance of perforation
- Prevents the tip of the pin from putting stress on the dentin
What are the factors that need to be considered when deciding how many pins to place
- Size of the pin
- Amount of remaining tooth structure
- Other mechanical R/R features employed
- Anticipated occlusal forces on the final restoration
T/F Pins strengthen the tooth
f
1 pin should be used for per missing….
- cusp
- line angle
- proximal surface
Incorporation of pins weakens composite or amalgam more
amalgam
Do pins weaken alloy-reinforced GI
no
Orienting the pins _ to the tensile stress is most favorable
parallel
As the number of pins increases the fracture resistance of amalgam (increases/decreases)
decreases
Acid treatment of the pin surface will enhance the bond to what and results in improvement of…
composite… with improvement in fracture resistance
Which has greater retention resin or amalgam cores retained with pins
no difference
What is the max number of pins you should use per tooth and why
3 because you do not achieve significantly improved R/R with more than 3 pins
How much space should be placed between pins
- Depends on the size of the pin
- Minim= 5 mm
- Minikin= 3 mm
pin placement should be _-_mm _ from the DEJ
0.5-1 mm pulpal
If the pin is placed past the CEJ if should be placed at least _mm from the external root surface
1mm (allows space for the finishline)
Where are the primary locations for pin placement and the unacceptable places
Primary= line angles Unacceptable= furcations and concavities (maxillary first PM has a mesial concavity)
What must oppose each pin you place
another retentive feature (could just be a vertical wall)
The pin is placed - mm (outside/inside) the DEJ
0.5-1 mm inside
The started hole is placed with the (fast/slow) speed handpeice with what bur
Slow with torque multiplier
-1/4 or a 1/2 round bur
What is the name of the technique called to help you determine the angulation of the pin
Twist drill alignment- place the drill along the external surface of the tooth and use the angulation to place the pin
How deep in the pin hole
2 mm
The slow speed should be running in (forward/reverse) when the pin channel is made
forward
What are the likely reasons why the drill may not be drilling
- Dull drill
- Flutes obstructed with debris
- Drill is running in reverse
- Drilling in enamel rather than dentin
How many torque reducers are needed on the slow speed to make the pin channel and for pin placements
Pin channel
-Only one either the 10:1 latch or the torque multiplexer
Pin placement
-must use both
What should you do if you placed your pin too close to a vertical wall in your prep and you can’t fit an amalgam condersor in there
reduce the wall back with a bur
If you need to reduce the height of a pin down with a bur how is the bur angled relative to the pin
bur is at a right angle to the pin
The pin is bent toward where to reduce its height and prevent prepping it
toward the center of the prep
Horizontal pins are used to
reinforce a lone-standing cusp
Horizontal pins should be placed where relative to the occlusal DEJ
1 mm below the occlusal DEJ
The most likely explanation(s) for a loose pin is
the channel prep was not precise or cutting the pin improperly
If you have a loose pin what can you do
- Use a larger pin
- Drill another channel (1.5 mm away)
- Convert the loose channel into another retentive feature
Cracks in the dentin can occur after pin placement as a result of what
the pin bottoms out in the channel
How can you tell if you perforated
- Sudden drop in drill
- Pain
- Blood
How can pulpal perforations be avoided
- Current X-ray and knowledge of pulp anatomy
- Avoid high risk areas
With a pulp perforation with a pin what should you do for the following scenarios
- Questionable pulp status
- Indirect tx planned
- Direct restoration
- Questionable pulp status = RCT
- Indirect tx planned = RCT
- Direct restoration = Direct pulp cap
What should you do if you perforated into the gingival sulcus
- Cut the pin flush
- Drop the finishline
- Or condense amalgam internally and carve it externally
What do you do if you perforate the periodontium with a pin past the epithelial attachement
- Crown lengthening to access the pin or perforation
- Seal the perforation with ….
- MTA externally
- Adhesive and resin internally
*Most complicated to handle
What are the post op instructions for a person receiving a amalgam foundation restoration
- Tooth should remain generally comfortable
- Avoid heavy chewing pressure for 24 hrs
- “occlusal awareness” requires adjustment
- Report any issues or concerns
