Would you ride these bars?
 

Well, I'm used to quill stems and high torque and managed to dent my aluminum bars the other day with the first threadless I've ever had. Already planning on replacing them in the near future, but how dangerous are they, really?

http://i.imgur.com/0WwGkjy.jpg

I'm sure you're safe until you actually see a crack or opening.

'tis but a scratch'

The small dent is not much, but you've obviously put a lot of over torque on the Allen screw, I would be more concerned you have stretched or weakened the threads in the stem.

Just replaced it, that's how I found the dent

I can't believe you were able to dent the bar without stripping the threads! Anyway, you're probably safe as the bulge is the thickest, strongest section. As mentioned by an earlier poster, thread strength is more of a concern. Usually only 4-5 nM torque is the max for stem bolts.