How long must i take auro amoxiclav for an tooth abscess?

Antibiotics: There is no one right answer. First the cause of the abscess needs to be addressed. Second, I hope you are not self prescribing. Dosage and regimen depend upon numerous factors including your medical history, dental history, dosage, regimen, size and cause of infection, etc. Discuss this with the prescribing doctor or if you don't have one, get one.

Penicillin: For as long as your Dentist said you should take it. Usually 4x/day for at least 5 days, but a 2nd course of medication may be necessary. Antibiotics will not cure an abscess, just reduce the spread of infection to other organ systems. For a cure specific dental treatment is required. Talk this over with your Dentist before you run out of pills.

Take all medicines: as prescribed until gone.