<prompt> A 45 year old female patient returns to your clinic with complaint of food lodgement in interproximal area of 47. On intraoral examination, 47 is restored with mesio-disto-occlusal amalgam restoration. Which type of matrix is used for this preparation?AutomatrixCompound supported matrixUniversal matrixIvory matrix  <response>: When little tooth structure remains and deep gingival margins are present, the Tofflemire matrix may not function successfully, and the Automatrix system is beneficial. 