Apical Abscess: Causes and Treatment

An apical abscess is a purulent inflammation of the periapical tissues in response to massive escape of virulent bacteria from the root canal system of a tooth.

Etiology

Acute apical abscess may develop primary as an outcome of acute apical periodontitis, be the result of exacerbation of chronic inflammation in the periapical area.

The etiologic factor is invasion of pyogenic microflora from the root canals of the tooth into the inflamed periapical tissues (extra-radicular infection). The microflora of apical abscess is mixed, Gram-negative anaerobic bacilli and peptostreptococci predominate.

The predominant effector cells in an acute apical abscess are polymorphonuclear neutrophilic leukocytes. After phagocytic activity of these cells and their death, a large number of tissue-destroying elements (hydrolases and oxygen radicals) appear, macrophages can no longer cope with cell cleansing and repair. Destruction of the periodontal ligament and bone in the area of the root apex occurs.

Bone loss is caused by activated osteoclasts, resorption is accompanied by immune cell invasion. There may also be direct invasion of microorganisms from root canals, which gradually causes tissue destruction.

Chronic apical abscess is characterized by a long-lasting purulent inflammatory process that drains through a fistulous passage. The inflammatory process perforates the cancellous bone and one of the cortical laminae and creates a draining fistulous passage that allows for the constant discharge of the resulting pus.

Process outcome:

1. Healing with elimination of infection in the root canal system (removal of non-viable pulp and drainage of abscess);
2. Chronicization of the process and formation of a draining fistulous passage;
3. Destruction of the cortical plate over the abscess, penetration of purulent exudate under the periosteum of the jaw and formation of purulent odontogenic periostitis of the jaw;
4. Spread of purulent inflammation through the fascial spaces of the head and neck.

Classification

• Acute apical abscess;
• Chronic apical abscess that has a communication (fistula) with the oral cavity;
• Chronic apical abscess with communication with the nasal cavity;
• Chronic apical abscess with communication with the maxillary sinus;
• Chronic apical abscess with skin communication.

Anatomy

Depending on the etiologic factor, the affected tooth may exhibit:

• A deep carious cavity that penetrates the pulp of the tooth;
• Tooth restorations adjacent to pulp tissue may show signs of compromised seal (defects, cracked restorations, pigmentation around the margin, secondary caries);
• Signs of trauma (cracks, chipped dentin, exposed part of the pulp).

The pulp of the tooth is necrotic, yellowish-gray or gray-black in color.

In acute apical abscess in the area of the root apex, an area of destruction of the periodontal ligament and alveolar bone filled with purulent exudate and surrounded by fibrovascular granulation tissue is determined.

In chronic apical abscesses, the process penetrates the cancellous bone, compact lamina, mucosa or skin and a fistulous passage is formed. The opening of the fistulous passage is a convex rounded soft tissue mass with a hole in the center from which purulent exudate is released. Fistulous passage can open as close to the focus of infection, and at a distance from it: vestibularly or lingually on the mucosa of the alveolar process, on the attached gingiva. Sometimes the fistulous passage may run along the root of the tooth and open into the gingival sulcus or furcation zone.

In this case, a deep narrow false pocket develops, masquerading as a periodontal pocket or a symptom of a vertical root fracture. Also, the opening of the fistulous passage can open into the nasal cavity, the maxillary sinus, on the skin of the face, neck.

Internally, the fistulous passage may be completely or partially lined with epithelium surrounded by inflamed connective tissue.

Diagnosis

• Collection of complaints and history;
• Clinical methods: visual inspection, percussion, palpation along the transitional fold, periodontal probing, determination of tooth mobility;
• Thermoprobe, electroodontodiagnostics;
• Radiography (intraoral contact radiography, radiovisiography, orthopantomography, cone beam computed tomography): a carious cavity, restoration or traumatic defect penetrating into the pulp chamber, a round or irregularly shaped lumen – a focus of bone destruction – is detected in the area of the root apex. Two-dimensional radiographs may show only a widening of the periodontal ligament without a lumen around the root apex, if the process affects only the cancellous bone without involvement of the cortical plate.
• Fistula tracing: a gutta-percha pin is placed in the fistula opening until resistance is felt, then intraoral contact radiography is performed. By tracing the course of the gutta-percha pin, the source of the fistulous passage can be identified.

Clinical manifestations

Acute apical abscess

The patient complains of localized pain in the area of one of the teeth, of moderate or high intensity, intensified by biting on the tooth of the cause, a feeling of pressure or a feeling of a “grown tooth”. Visualization of the tooth reveals a deep carious cavity, restoration or traumatic defect penetrating into the pulp chamber. Percussion of the tooth is sharply painful, palpation of the transitional fold can also be painful, with the involvement of the cortical plate may be present swelling and hyperemia of the mucosa in the projection of the root apex. The depth of periodontal probing is within normal limits (1-3 mm). The mobility of the tooth can be determined. There is no reaction to temperature and electrical stimuli. In addition, there may be systemic manifestations of the infectious process: increased body temperature, increased lymph nodes of the submandibular and chin area, leukocytosis.

Chronic apical abscess.

In chronic apical abscess, the patient may not report any complaints, or may indicate the presence of a mass or localized swelling on the gingiva.

A tooth with a deep carious cavity, restoration or traumatic defect penetrating the pulp chamber. Percussion of the tooth is usually painless or mildly painful. Palpation of the transitional fold is painless. On the mucous membrane or skin is determined by the opening of the fistulous passage, from which purulent exudate is released. With obstruction of the fistulous passage may develop local swelling of soft tissues.

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Treatment of an apical abscess

Endodontic treatment of the tooth is performed: extirpation of non-viable pulp or removal of old filling material from the root canals, mechanical treatment and irrigation of root canals. In the presence of exudate in the root canals, fistulous passage, it is recommended to use temporary intracanal attachments. Drainage of purulent exudate is carried out through the root canals or through the cortical plate of the jaw in the projection of the lesion. In the future, a hermetic obturation of root canals with subsequent restoration of the tooth is performed.

If access to the source of infection is difficult, in addition to conservative endodontic treatment, microsurgical methods (periradicular curettage, resection of the root apex with retrograde filling, root amputation), intentional replantation may be used.

If the prognosis of endodontic treatment is unsatisfactory, the tooth should be extracted.

Antibiotic prophylaxis during non-surgical and surgical endodontic treatment is performed in the following groups of patients:

• Patients undergoing intravenous bisphosphonate treatment (periapical surgery);
• Patients at risk of infective endocarditis (complex congenital heart disease, prosthetic heart valve, history of infective endocarditis);
• Immunodeficiency conditions (leukemia, HIV/AIDS, terminal renal failure, dialysis, inherited genetic defects of the immune system, uncontrolled diabetes mellitus, chemotherapy, taking immunosuppressive or steroidal drugs after transplantation);
• Patients after joint endoprosthesis within the first 3 months after surgery;
• Patients undergoing cranial radiotherapy.