<prompt> Advent of Electrolytic etching of base metal paved a path for development ofCast perforated resin bonded fixed dental prosthesisMaryland BridgeRochette BridgeNone of the above  <response>: 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. 