Following this procedure, the gingival cuff tightens around the tooth, which may be enough to trap the bacteria left in the pocket. A gingival retraction cord which is accidentally left in situ is an occasional cause of a periodontal abscess. Penetrating injury to the gingiva--for example, with a toothbrush bristle, fishbone, toothpick or periodontal instrument--may inoculate bacteria into the tissues. Trauma to the tissues, such as serious impact on a tooth or excessive pressure exerted on teeth during orthodontic treatment, can be a possible cause as well. Occlusal overload may also be involved in the development of a periodontal abscess, but this is rare and usually occurs in combination with other factors. Bruxism is a common cause of excessive occlusal forces. Systemic immune factors such as diabetes can predispose a person to the formation of periodontal abscesses. Perforation of a root canal during endodontic therapy can also lead to a periodontal abscess which if left untreated could become "prolonged" ultimately rupture then enter the blood stream and could lead to serious situations such as endocarditis. Diagnosis
Periodontal abscesses may be difficult to distinguish from periapical abscesses. Since the management of a periodontal abscess is different from a periapical abscess, this differentiation is important to make (see Dental abscess#Diagnostic approach) For example, root canal therapy is unnecessary and has no impact on pain in a periodontal abscess. Classification
There are four types of abscesses that can involve the periodontal tissues:
Gingival abscess—a localized, purulent infection involves only the soft gum tissue near the marginal gingiva or the interdental papilla.
Lipomas growing in internal organs can be more dangerous; for example, lipomas in the gastrointestinal tract can cause bleeding, ulceration, and painful obstructions (so-called "malignant by location", despite being a benign growth histologically). Malignant transformation of lipomas into liposarcomas is very rare, and most liposarcomas are not produced from pre-existing benign lesions. A few cases of malignant transformation have been described for bone and kidney lipomas, but it is possible that these few reported cases were well-differentiated liposarcomas in which the subtle malignant characteristics were missed when the tumor was first examined. Deep lipomas have a greater tendency to recur than superficial lipomas because complete surgical removal of deep lipomas is not always possible.The presence of multiple lipomas, lipomatosis, is more commonly encountered in men. Some superficial lipomas can extend into deep fascia and may complicate excision. Liposarcoma is found in 1% of lipomas and is more likely to occur in lesions of the lower extremities, shoulders, and retroperitoneal areas. Other risk factors for liposarcoma include large size (>5 cm), associated with  calcification, rapid growth, and/or invasion into nearby structures or through fascia into muscle tissue. Epidemiology
Around 2% of the general population has a lipoma. These tumors can occur at any age, but are most common in middle age, often appearing in people from 40 to 60 years old.