First off, this toothbrush isn't overused. This is a picture of a toothbrush I had that had a stray bristle that gave me hell. It took me a while to figure out the pain in certain parts of my gum were caused by this little bastard. I replaced mine shortly after realizing this.
If you're using regular toothbrushes don't forget to change them out after a few months (this applies to interchangeable heads, too). Don't think that because the bristles are all over the place that you're brushing more of your teeth in a less amount of time. You can harm your gums and can ineffectively clean your teeth (you can actually make them dirtier). It's also a good idea to change your toothbrush after suffering from an illness (flu, cold, etc).
This will probably be the most boring post on this blog. I just wanted an excuse to post this picture.