SECONDARY RESISTANCE AND RETENTION FORM

¨Many preparation require additional retentive features .When the tooth preparation include both occlusal and proximal surfaces each of those area should have independent retention and resistance features

¨Mechanical features

žRetention locks, grooves and coves

žGrooves extension

žSkirts

žBeveled enamel margins

žPins, slots, steps and amalgam pins.

     ¨Conditioning procedures-etching and bonding