:D Flash knows his stuffs!
Yeah, blood is completely safe to swallow; as is just about any organic material, and people it a lot more of it then they realize; meat (and not just red meat) always has blood on it.
Blood is mostly water, protein, sugar (glucose that is), hormones, various minerals, and different levels of oxygen and/or carbon dioxide, as well as the ever so obvious blood cells and platelets.
Blood is a thick and heavy substance, that when swallowing too much is harsh on the stomach and can cause upset stomach or vomiting. To induce vomiting, at least two cups of blood have the be swallowed in an average adult.
You're safe; no tooth should bleed two cups of blood, and if it does, it certainly shouldn't do it all at once, before any of the other blood has worked its way through your digestive system.