Sometimes, teeth with nonvital or "dead" pulps will become stained from the blood products from the injured pulp seeping into the dentin from the inside, outward.  This is very different from an external stain, such as from coffee.  Even after root canal treatment is completed, the tooth may remain stained an orange-brown hue.  In these cases, we can often lighten the tooth by inserting a sodium perborate bleaching paste into the tooth, letting it diffuse into the dentin, and reevaluating 7-10 days later.  This process may need to be repeated once or twice; negligible enhancement tends to occur beyond that.  Sodium perborate is a safe oxidant which is more stable and milder than the traditional 30% hydrogen peroxide, yet can produce very favorable esthetic results when dealing with organic stains.  Results are much less predictable for discolorations resulting from metallic fillings, tetracycline, calcification, or other restorative materials, which often do not respond to any oxidants at all.  Ask us about your concerns!