I haven't had any dental problems in over a year, so I just hadn't paid attention to looking out for cracks or what not. I can only see it with a direct light shining on it and even then it's barely noticable. A few years ago I did run into a steel enforced wall in my kitchen mouth first so it could have come from that. And I have no pain.
well since you don't have any pain associated with it and you had to use a flashlight to even see it...the only concern it SEEMS that you may have is esthetics... how did you crack the tooth? did you get hit? bump your tooth? if it's trauma, you should keep a lil watch because injury to teeth from trauma could damage the nerve inside the tooth and possibly cause a discoloration of the tooth...most of the time though...for that to happen you'll certainly remember trauma or something...