You know good dental habits can help prevent things like cavities and gingivitis, but you may not know what conditions like these really look like or how they can affect your mouth. Use this visual guide to learn more about some of the most common dental health issues, symptoms to watch for and the potential treatments that are available. Please note: This content is for informational purposes only. Only a dentist, physician or other qualified health care professional can make a diagnosis. Darkened Tooth There are two reasons your tooth may change color after trauma : It’s either trying to protect the nerve or it’s dying. If it’s protecting the nerve, your tooth may look a little darker than the ones next to it. If it changes colors like a bruise (from pink to gray), this means your tooth is most likely dead. You may need a root canal , usually followed by a crown . In some cases it may be necessary to remove the tooth . If it is a baby tooth , you may be ...