In the ML/PS group, a pre-sintered Co-Cr alloy block (Soft Metal™, LHK, Chilgok, Korea) was dry-milled using a milling machine (Zenotec T1, Wieland Dental + Technik GmbH and Co. KG, Pforzheim, Germany) to form disc-shaped specimens which were subsequently sintered to full density in a furnace (SinTagon, Denstar, Daegu, Korea) under the inert