Apical abscesses

An abscess is a localized collection of pus in a cavity formed by the disintegration of tissues. Based on the degree of exudate formation and its discharge, the severity of pain, and the presence or absence of systemic signs and symptoms, apical abscesses can be divided into symptomatic or asymptomatic conditions.

Symptomatic Apical Abscess A sudden egress of bacterial irritants into the periradicular tissues can precipitate an SAA and its more severe sequelae, acute osteitis and cellulitis. The clinical and histopathologic features of these conditions appear to be related to either the concentration and toxicity of the irritant or the local proliferation of invading organisms with their destructive activities. Chemical or bacterial irritation of the periradicular tissues through immunologic or nonimmunologic reactions can cause release of biologic substances similar to those involved in SAP and produce the same microvascular changes.

An SAA is an inflammatory process in the periradicular tissues of teeth, accompanied by exudate formation within the lesion. A frequent cause of SAA is a rapid influx of microorganisms, or their products, from the root canal system.

An SAA may occur without any obvious radiographic signs of pathosis. The lesions can also result from infection and rapid tissue destruction arising from within AAP, another example of the so-called phoenix abscess. The patient may or may not have swelling. When present, the swelling may be localized or diffuse. Clinical examination of a tooth with SAA shows varying degrees of sensitivity to percussion and palpation.

There is no pulp reaction to cold, heat, or electrical stimuli as the involved tooth has a necrotic pulp. Radiographic features of the SAA vary from a thickening of the periodontal ligament space to the presence of a frank periradicular lesion. Spread of inflammatory response into the cancellous bone results in apical bone resorption. Since inflammation is not confined to the periodontal ligament but has spread to the bone, the patient now has an acute osteitis. These patients are in pain and may have systemic symptoms such as fever and increased white blood cell count. Because of the pressure from the accumulation of exudate within the confining tissues, the pain can be severe. Spread of the lesion toward a surface, erosion of cortical bone, and extension of the abscess through the periosteum and into the soft tissues is ordinarily accompanied by swelling and some relief. Commonly, the swelling remains localized, but it also may become diffuse and spread widely (cellulitis). The extent of swelling reflects the amount and nature of the irritant egressing from the root canal system, the virulence and incubation period of the involved bacteria, and the host’s resistance. The location of the swelling is determined by the relation of the apex of the involved tooth to adjacent muscle attachments.

Immunologic or nonimmunologic inflammatory responses contribute to the breakdown of the alveolar bone and cause disruption of the blood supply, which, in turn, produces more soft and hard tissue necrosis.

The suppuration process finds lines of least resistance and eventually perforates the cortical plate. When it reaches the soft tissue, the pressure on the periosteum is relieved, usually with an abatement of symptoms.

Once this drainage through bone and mucosa is obtained, suppurative apical periodontitis or an asymptomatic periradicular abscess is established.

Дата добавления: 2015-10-16