How many times have we heard dentists tell us, “Change out your toothbrush on a regular basis,” right? Dr. Biderman has been pleading with his patients for over 30 years to do just that. And yet, we find time, and time, again that patients will wait six, seven, even as long as nine months before they change their toothbrush.

If you really want to know why this is a horrible idea, read this: Stuff Can Grow on Your Toothbrush