Apical Periodontitis

Acute form

Acute purulent apical periodontitis is characterized by the accumulation of a large number of neutrophils in the periodontal ligament tissues near the root apex. The inflammatory exudate causes histolysis of the periapical tissues. The process affects areas near the alveolar bone and root dentin, ultimately leading to the formation of an apical periodontal abscess.

Chronic forms: granulating and fibrous periodontitis

The chronic course of the disease manifests in several forms:

• Chronic apical granulomatous periodontitis. The main sign is the proliferation of granulation tissue (with focal or diffuse infiltration and impaired maturation) in the periapical region. The process is accompanied by alveolar bone resorption, destruction of the compact substance, periosteum, as well as cementum and dentin. A specific feature (according to B.I. Migunov) is lacunar resorption of dentin by macrophages and its replacement with osteodentin. Granulations can grow into adjacent soft tissues. During exacerbation, abscesses and fistulas (gingival or external, on the skin) occur, the location of which indicates the localization of the lesion.
• Chronic fibrous apical periodontitis. Coarse fibrous connective tissue proliferates in the periapical zone. This is an inactive form and prognostically the most favorable variant of the disease.

Chronic granulomatous periodontitis and its evolution

This form involves the development of a periapical (simple) granuloma, an oval structure firmly attached to the root apex. On a radiograph, it appears as a distinct radiolucent focus in the area of bone destruction. The basis of the granuloma is granulation tissue with an inflammatory infiltrate, surrounded by a dense fibrous capsule. Cholesterol crystals, foreign body giant cells, and Russell bodies may be present inside. It is important to understand that this formation is not related to granulomas from the general pathomorphology course.

Further progression of the process can lead to the following formations:

1. Epithelial granuloma. Strands of stratified squamous epithelium proliferate within the granulation tissue, originating from the cell rests of Malassez (remnants of odontogenic epithelium).
2. Cystogranuloma. It develops from an epithelial granuloma due to dystrophy and necrobiosis. A cavity measuring 0.5–1 cm is formed, lined with non-keratinizing stratified squamous epithelium. The cavity contains detritus and cholesterol crystals. The walls are formed by maturing granulations with inflammatory infiltration.
3. Radicular (root) cyst. The regular outcome of cystogranuloma development.

Outcomes and complications

With adequate treatment, a favorable outcome is possible: the destroyed bone tissue regenerates, and fibrous periodontitis develops. Any chronic form can undergo acute exacerbation with the formation of abscesses.

Apical periodontitis is a frequent source of odontogenic infection (where the tooth serves as the entry portal). The infection spreads by contiguous extension and causes severe complications, most often in the chronic course:

• Purulent processes of the face and neck (phlegmon, abscesses of fascial spaces).
• Intracranial pathologies (purulent meningitis, brain abscess, cavernous sinus thrombosis).
• Neck and mediastinal lesions (purulent mediastinitis, laryngeal edema with a risk of asphyxia).
• The most severe conditions include jaw osteomyelitis, odontogenic sepsis, and Ludwig's angina (putrefactive-necrotic phlegmon of the sublingual and submandibular spaces of the floor of the mouth and neck, caused by group A streptococci).

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Pathogenesis of osteodentin formation in granulating periodontitis
• Mechanisms of formation and structure of a radicular cyst
• The connection between odontogenic infection and jaw osteomyelitis
• Anatomic pathways of infection spreading into the fascial spaces of the face and neck

Other Topics in "Chapter 27. Diseases of the Dentofacial System and Oral Cavity"

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