Tooth decay
The most common causes of tooth abscess are either tooth decay or a broken tooth that results in infection of the pulp, a region below the tooth that contains nerves, blood vessels, and connective tissue. Then, tooth decay and the associated infection progresses and leads to chronic inflammation of the tooth and periodontal area. In time, inflammation causes secretion of fluids and pus, which accumulate and gets enclosed in an abscess.
Thus, tooth decay is an important sign that allows the doctor to trace a tooth abscess in cases of tenderness and pain. Keep in mind that not all cases of tooth decay will lead to an abscess. You might even need additional imaging tests if you want to confirm the diagnosis of tooth abscess. So, be sure to talk to your doctor about your symptoms and you will receive the most appropriate treatment according to your condition.