Tooth Ache?

My big sister says her tooth hurts. How can we tell if it's a cavity?

Tooth Ache?
It's Probably gone further than a cavity... It might be time for a Root canal... Sorry! Advil worked great for a toothache I had..





GO TO THE DENTIST!
Reply:look and see it theres a big dark hole in the tooth.
Reply:look at the tooth, is it gray or black...
Reply:contact a dentist.
Reply:Go visit dentist. U will get the result rather than giving wrong guessing. Cos' personally myself feel the pain from my stupid tooth before really damm painful %26amp; distracting! Ouch!
Reply:Look at the tooth that hurts and see if you see a black spot and if you do she's got one. Tell her no more sweets!