<prompt> Gold restoration cemented with zinc polycarboxylate usually fractures at which interface?Cement-prosthesisCement itselfTooth structure - cementProsthesis failure  <response>: Zinc polycarboxylate has ability to bond chemically with tooth structure so less chance of failure at tooth cement intefaceIn case of gold restorations usually adhesive failure occurs at the interface bw gold cementIn case of non-precious metals usually cohesive failure occurs bw cement layer itself. 