i found a nice tip on this thread about show>isolate select>show selected. it helped me save a lot time for extruding my teeth out of the mouth cavity itself( though i am starting to wonder if that was such a good idea ).
but, there is a problem with isolate select. when i try to use the paint selection tool or the split oplygon tool, the hidden geometry shows up as if it were a ghost. you cannot see the geometry, but the brush still recognizes it and moves as per the contours of the hidden geometry, rather than moving as per the faces that i am actually trying to select. is there any way of working around this?