Should you drop a utensil on the floor, do not pick it up and place it back on the table. You do not want to place germs or dirt from the floor on your dining surface.
Simply ask the waiter to bring you another one and direct his or her attention to the dropped utensil so they may pick it up.
If the waiter fails to pick up the dropped utensil, try to discreetly push it under your chair or table with your foot so someone does not trip on it.