Wells and Pins

Question 1

What are Pins and wells used for?

Answer 1

Replacing cusps

Complex Amalgam restorations

Question 2

When are Pins/Wells needed to replace cusps

Answer 2

1) When the F-L extension exceeds 2/3 the distance from a primary groove towards the cusp tip, replace the cusp
2) When the F-L extension of the occlusal prep exceeds 2/3 the distance between F-L cusps

Question 3

What are the different types of pins?

Answer 3

Cemented - chemically adhered
Friction locked - placed via tapping
Threaded - uncommon

Question 4

What is the size difference between drill and pin diameter

Answer 4

Drill is slightly smaller than pin diameter

Question 5

Where are pins placed?

Answer 5

Approx 2 drill diameters (2mm total) from teh DEJ

Question 6

How long are pins?

Answer 6

4mm long
2mm in dentin
2mm above dentin

Question 7

T/F - pins with more than 2mm above the dentin increase amalgam retention

Answer 7

False

Question 8

What is the 2-2-2-2 rule?

Answer 8

2mm pin hole depth
2 drill diameters in
2 mm length above prep surface
2 mm amalgam coronal to pin

Question 9

What are the two types of drills used for pins? Which do we use?

Answer 9

Standard

Depth Limiting*

Question 10

What must we be aware of in placing a pin in a tooth that has inclined or shifted?

Answer 10

The pilot holes for the pin must match the inclination, otherwise root or pulp perforation could occur

Question 11

Why must we allow 1 mm of space around the pin hole?

Answer 11

Need a place to put restorative material

Question 12

When can we use a well?

Answer 12

If you’ve only lost 2mm of tooth structure

Question 13

What are the dimensions of a well?

Answer 13

1.5 mm deep
On a flat surface
Need to fit a 1mm condenser
Can have retention grooves for amalgam