PINS FOR AMALGAM RESTORATION ( CLASSIFICATION )

 There are three types of pin available for retention of amalgam restoration namely

1. Self-threading pin,
2. Friction-locked,
3. Cemented pins.

The pin-retained amalgam restoration using self-threading pins was originally described by Going in 1966. The diameter of the prepared pinhole is 0.0015 inch to 0.004 inch smaller than the diameter of the pin. However, a general guideline for pinhole depth is 2 mm.

Several styles of self-threading pins also are available. Out of which the Thread Mate System (TMS) (Coltene/Whaledent Inc.) is the most widely used self-threading pin.

Four sizes of TMS pins.

1. Regular ( 0.031 inch [0.78 mm])--gold
2. Minim (0.024 inch [0.61mm])-- silver
3. Minikin (0.019 inch [0.48 mm])-- red
4. Minuta ( 0.015 inch [0.38 mm])--pink

It was  Markley in 1958 described about  cemented pins. They are cemented into pinholes prepared 0.001 to 0.002 inch (0.025 to 0.05 mm) larger than the diameter of the pin. The cementing medium may be any dental luting cement.

In 1966, Goldstein" described a technique for the friction-locked pin in which the diameter of the prepared pinhole is 0.001 inch (0.025 mm) smaller than the diameter of the pin

REF: ART AND SCIENCE OF OPERATIVE DENTISTRY--- STURDEVENT