cell density for checking certain compound - (Dec/06/2007 )

hello everybody
i want to check the toxicity of 3 compounds on my 293 cells , my professor said to seed cells 1x105/ml but i am afraid it will be 50-60% confluent nexat day when adding my compounds , my question is this a good confluncty to check toxicity or cells should be 90% or more confluent?
thankx

Less is better for true drug sensitivety. Higher density makes cells less responsive to drug actions.

thankx genehunter for your quick reply , the reseon of my question is that i tried these compounds before but on transiently transfected 293 cells (duplicate and triplicate transfection) and the wells that was 70 % confluent i noticed a greater cell toxicity than when i used 90% confluent cells so i thought may be this difference is related to transfection as my plasmids are toxic .

anyway that mean i go with my professor protocol
thankx