Many patients find abscesses or granules in the gums around one of their teeth, usually without obvious pain, sometimes good and sometimes bad, repeatedly, not knowing what is going on, and some are even very worried if they have cancer. In fact, most of this is caused by chronic inflammation of the roots of the adjacent teeth, also known as chronic periapical periodontitis. Generally, the teeth will have lesions such as decay, chips, cracks or have a history of treatment, and dental films can mostly see the lesion images of bone destruction at the root tip. The vast majority of periapical infections develop from pulpitis, when pulpitis is not treated in a timely manner and the pulp becomes infected and necrotic, progressing toward the root of the tooth, causing inflammation of the tissues surrounding the root, which is called periapical inflammation. It can be considered that periapical inflammation is formed when the inflammation inside the tooth spreads to the outside of the tooth. With periapical periodontitis, the tooth will have biting pain, some times severe and some times relatively mild. Some patients with periapical periodontitis do not experience much discomfort because their resistance is strong and suppresses the inflammation of the tooth roots keeping the inflammation in a chronic progression. When the person is physically ill or fatigued the resistance decreases, the inflammation flares up and pustules or granules (fistulas) appear in the gums. Acute attacks of inflammation can cause some degree of tooth loosening, sometimes swelling of the tooth bed or overflowing pus, and severe pain. Once the cause is understood, there is no need to worry excessively. With timely and thorough root canal treatment, removal of the infected material inside the root, thorough disinfection and tight filling, it is possible to eliminate the inflammation and save the affected tooth.