If you see blood on your toothbrush or in the sink after you spit out after brushing your teeth, this is a sign of a low grade (or worse) infection in your gums. This may be due to inadequate home care strategies (are you using floss/interproximal brushes on a regular basis?), but is often a sign that the hardened build-up, called calculus (scale/tartar) is starting to return and it may be time for your oral health care provider to remove these deposits.