SECONDARY RETENTION AND RESISTANCE FORM

May be performed after placing liners and bases.

1. Amalgams pins
2. Slots - No.35 inverted cone bur
3. Boxes
4. Coves
5. Skirls
6. Bevels- Reverse bevels in inlay prep

AMALGAM PINS

➢ For 2 degree retention and resistance form.
➢ Should be placed parallel to line angles.
➢ 2 mm into the dentine & 2mm in the amalgam
➢ Distance between 2 pins ー 3-5 mm
➢ Place minimum/less material and condense (if more - cracks may form)
➢ Pins need not be parallel to each other
➢ Use one pin per missing line angle, cusp or marginal ridge.
➢ Use large diameter pin whenever possible
➢ Use min no. of pins compatible with adequate retention
➢ Complication :- pulp exposure ⇒ DPC + place pin on same day.