Slots vs. Pins: A Comparison of Retention Under Simulated Chewing Stresses:

Extracted human teeth have been used in an experiment comparing the fatigue life of amalgam and composite resin restorations using either threaded pins or an undercut slot for retention. The fatigue lives of restorations retained by either a slot or pins were comparable when amalgam was used. When composite resin was used, the slot-retained restorations had significantly longer lives.