PERIAPICAL ABSCESS: PATHOGENESIS, CLINICAL FEATURES & TREATMENT
Author: Sanketh DS, MDS
INTRODUCTION AND PATHOGENESIS
Periapical abscess or a dentoalveolar abscess is a pyogenic infection of the periapical region. This suppurative process may develop from an acute apical periodontitis or an already existing chronic lesion like a periapical granuloma. Let’s better understand how this happens.
Periapical abscess usually develops due to a carious infection of the pulp extending to the periapical region, traumatic injuries causing pulpal necrosis or even periapical insults due to endodontic procedures.The seeping infection from the necrotic pulp may trigger an acute inflammatory process of the periodontal ligament in the periapex. It is an exudative process, where the infection triggers leakage of plasma proteins or an inflammatory exudate from the nearby blood vessels into the periodontal ligament space. This is an acute apical periodontitis. In certain individuals this acute inflammatory process could exacerbate and become a suppurative process. Leukocytes recruited to the site of inflammation release numerous proteolytic enzymes in the environment. This may cause tissue damage and necrosis leading to a periapical abscess.
A point to note is that, the acute inflammatory exacerbation is so sudden, that there has not been an elapse of sufficient time to cause bone resorption. The radiograph only reveals a slight thickening of the periodontal ligament (PDL) space. Periapical abscess arising from apical periodontitis is painful and symptomatic.
Many a time acute apical periodontitis may not exacerbate. If the infection persists and is left untreated, the inflammatory process becomes chronic. The periapical tissue in an attempt to heal reacts by inducing formation of granulation tissue which is a loose matrix with numerous small blood vessels, fibroblasts and inflammatory cells. This is a periapical granuloma.
However, at times there might be an exacerbation of a periapical granuloma resulting in a periapical abscess. In this case, bone resorption may already be caused by the chronic lesion, periapical granuloma. Hence a periapical abscess arising from these lesions may appear radiolucent on radiographs. Also, they are usually asymptomatic, unlike a periapical abscess arising from acute apical periodontitis.
Periapical abscess is a polymicrobial disease where anaerobic gram negative rods and gram positive cocci have been isolated. Some common microorganisms isolated are Prevotella intermedia, Fusobacterium nucleatum, Porphyromonas gingivalis and Peptostreptococcus species.
Due to the accumulation of purulent material in the PDL space, there may be a slight extrusion of the affected tooth in its socket. The purulent exudate could exert pressure on the nerve endings and this along with chemical mediators of inflammation could cause severe pain. However, periapical abscess arising from an existing chronic periapical lesion like a periapical granuloma is asymptomatic and does not cause pain. The affected tooth is sensitive on percussion and does not respond to vitality tests. Periapical abscess could cause expansion of the bone leading to a visible swelling. At times, there may also be a sinus opening established in the gingival mucosa, draining the periapical abscess.
SPREAD OF INFECTION AND COMPLICATIONS
If a periapical abscess is left untreated, the accumulating purulent material tries to penetrate and move through a path of least resistance. The pus may move through different paths causing varying clinical manifestations. It could move through the periodontium and leak through the gingival sulcus or may spread through the medullary spaces causing osteomyelitis. The abscess may penetrate the buccal cortex and periosteum and leak into the mucosa via a sinus tract. The lingual cortical plates are rarely penetrated. Abscesses in the maxilla particularly related to lateral incisors and palatal roots of molars and premolars may penetrate the palatal/lingual cortex and accumulate under the palatal mucoperiosteum causing palatal swellings. Also, the abscess in the molar regions may penetrate the buccal cortex below (in mandible) or above (maxilla) the attachments of the buccinator muscle and spread into soft tissues of the face and neck. However, those abscesses arising from chronic lesions due to persistent low-grade infections are usually localised and show little tendency to spread.
TREATMENT AND PROGNOSIS
Treatment mandates establishment of an opening either by opening the pulp chamber or by extracting the tooth. A better approach would be to retain the tooth via root canal therapy. An incisional drainage can be done for mucosal swellings. Care must be taken to treat the lesion as soon as it is detected in order to minimize the risk of spread which could otherwise cause complications like osteomyelitis or cellulitis.
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