How can i tell whether i have a cavity?

Let us review your q: The best way to evaluate for a cavity is to see a dentist regularly. xrays of your teeth are taken once a year. If they are small you may not have any signs or symptoms. The larger ones increase your risk of tooth abcess.

Training: By the time you can tell (discoloration, hole, pain, temperature sensitivity, etc) you no longer have a little easily fixed cavity. Now you have the Grand Canyon requiring extensive expensive repair. Would be infinitely better to see your Dentist regularly. Dentist trained all those years to find and repair incipient problems before you have an acute painful problem.