Can half a tooth abscess go away by itself?

Yes: But not likely. Spontaneous drainage and resolution is conceivable but the risk here is extremely high, and the benefits of waiting for this improbable cure to occur are minimal. Common sense would have you in a dental chair asap.

Not really: The symptoms can come and go usually via drainage but the underlying problem must be treated either by root canal therapy or extraction. Just because the symptoms diminish doesn't mean the problem has been solved.

Yes it can: Tooth abscesses are infections involving teeth. They don't occur overnight and your body constantly is finding ways to "fix" the problem. When the pressure builds up the body can "lead" the pressure outside the body and relieve the built up pressure and drain the infection. This drain is a method to which the body is trying to heal itself.

See any dentist: to drain the dental abscess. The infection may spread to your jaw, cheeks, sinus and to other areas of your head and neck. See any dentist for examination, x-rays and treatment.