Apical granuloma: etiology, anatomy, clinical presentation and treatment

Apical granuloma is the most common form of chronic apical periodontitis, which is an inflammatory lesion with granulomatous tissue and a predominance of lymphocytes, macrophages, and plasma cells.

Chronic apical periodontitis is a long-term inflammatory process in the tissues surrounding the apex of the tooth root that is accompanied by radiologic periapical bone resorption but does not manifest clinical symptoms.

Etiology

Chronic inflammation in the periapical region is mainly caused by bacterial infection of the root canals of the tooth. In teeth that have not undergone endodontic intervention before, apical periodontitis is a protective reaction to primary infection in the necrotic pulp. Also the etiologic factor may be a secondary infection that has penetrated into the root canal system due to endodontic treatment (poor quality isolation during treatment, inadequate obturation, insufficient coronal hermetics). Extrusion of chemicals and filling material beyond the apical opening can cause toxic tissue damage. Talc, calcium salts, cellulose from paper pins, cotton fibers can provoke the formation of giant cell granuloma of foreign body. Along with this, foreign bodies in the periapical area can be a source of bacterial biofilm.

Microbial species found in teeth with apical periodontitis:

• In primary infections: genus Dialister, Bacteroides, Pseudoramibacter, Porphyromonas, Treponema, Filifactor, Tannerella, Prevotella, Enterococcus, Veilonella, Olsenella, Pyramidobacter, Campylobacter, Propionibacterium, Streptococcus, Parvimonas, Fusobacterium, Eikenella, Actinomyces;
• In previously treated teeth: Enterococcus faecalis (the most frequently detected species), Pseudoramibacter alactolyticus, Propionibacterium, Filifactor alocis, Dialister pneumosintes, Tannerella forsythia, Parvimonas micra, Prevotella intermedia, Treponema denticola, Candida albicans.

Necrotized pulp in root canals is an ideal space for bacterial colonization with the necessary conditions for the existence of bacteria, bacterial aggregates are enclosed in extracellular matrix and organized into a biofilm attached to the walls of root canals. In this form, the microflora is protected from the immunity of the host organism, since defense mechanisms cannot function deep in the root canal due to lack of blood supply, and is also resistant to the action of antibiotics. If the microflora in the root canal has not been eliminated by eliminating or meaningfully disrupting the structure and ecology of the biofilm, apical periodontitis may proceed chronically. Macrophages and lymphocytes are the primary participants and predominant cells of the process, and sometimes foamy and giant cells are found.

The main feature of chronic apical periodontitis is bone destruction in the root apex area and proliferation of fibrovascular granulation tissue, which is an attempt to repair tissues and limit the inflammatory process. Bone destruction is carried out by activated osteoclasts. Along with the process of bone resorption, apical fragments of the root may also be destroyed.

Process outcomes

Healing of periapical tissues after endodontic treatment; development of acute or chronic abscess when the source of infection persists and the balance between bacterial infection and the body’s immune response is disturbed.

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, marginal pigmentation, 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 the area of the root apex there is a focus of destruction of the periodontal ligament and bone tissue, filled with granulomatous tissue.

Granulomatous tissue is infiltrated with mast cells, macrophages, lymphocytes, plasma cells and sometimes polymorphonuclear leukocytes. Giant multinucleated foreign body cells, foam cells, cholesterol crystals, and epithelial tissue in the form of chaotically directed strands are often present. Fibrous tissue is usually found around the periphery.

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): carious cavity, restoration or traumatic defect, penetrating into the pulp chamber, in the area of the root apex of the tooth a lumen is determined – a foci of bone destruction of rounded or irregular shape, usually with clear boundaries. Two-dimensional radiographs may show only the expansion of the periodontal ligament without lucency around the root apex, if the process does not reach the cortical plate.
• There are currently no non-invasive diagnostic tools available to differentiate a granuloma from a cyst. A definitive diagnosis can only be determined by biopsy.

Clinical manifestations

The process is usually clinically asymptomatic. A deep carious cavity, restoration or traumatic defect penetrating into the pulp chamber is visually detected in the tooth.

Percussion of the tooth is painless, palpation of the transitional fold is also painless, but may be uncomfortable if the process affects the cortical plate. The tooth does not respond to temperature and electrical stimuli. The depth of probing the gingival sulcus is within normal limits (1-3 mm). Tooth mobility is physiologic.

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Treatment

Although it is impossible to make a differential diagnosis with other forms of apical periodontitis on the basis of radiography, and the histologic status is usually unknown, the treatment consists of eliminating the etiologic factor. Endodontic treatment of the tooth is performed: extirpation of necrotic pulp or removal of old filling material from the root canals, mechanical and medical treatment of root canals, obturation with subsequent restoration of the tooth. In case of difficult access to the source of infection, in addition to conservative endodontic treatment, microsurgical methods (periradicular curettage, resection of the root tip with retrograde filling, amputation of the tooth root), intentional replantation are used.

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