Advent of Electrolytic etching of base metal paved a path for development of

A technique for the electrolytic etching of cast base metal  retainers was developed at the University of Maryland by   Thompson  and  Livaditis.  Etched-cast  retainers  have   definite advantages over cast-perforated restorations:  Retention is improved because the resin-to-etched metal bond can be substantially stronger than the resin-to-etched  enamel.  The  retainers  can  be thinner yet still resist flexing.  The oral surface of the cast retainers is highly polished and resists plaque accumulation.