Endodontic disease: Remove the source of infection - DVM
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Endodontic disease: Remove the source of infection
Root-canal therapy remains an important alternative to extraction; offers clients a choice


DVM InFocus


Endodontic disease is a pathologic process dealing with the pulp cavity. To get a deeper understanding, one first must have knowledge of the anatomy of the tooth, especially the pulp.

The tooth is divided into three areas. The first area is the crown, the visible portion of the tooth coronal to the gingiva. The second area is the root, the portion of the tooth below the gingiva and encased in the alveolar bone. The third area is the neck, which is the junction of the root and the crown.

Typically, the neck is inside the gingival sulcus. The bulk of the tooth is made of dentin, which becomes thicker as the tooth ages. In the area of the crown, the dentin is covered by enamel. In the area of the root, the dentin is covered by cementum.

The cementum and the enamel meet at the neck of the tooth. Within the dentin is the pulp cavity. Above the gum, it is referred to as the pulp chamber, whereas below it is referred to as the root canal. The pulp is comprised of nerves, blood vessels, collagen fibers, elastic fibers and cells, including odontoblasts. The odontoblasts line the periphery of the pulp and produce dentin. The tip of the root is termed the apex and contains the apical delta. The apical delta is an area of many small canals extending from the root canal through the dentinal walls to the periapical space. It is through this delta that the blood and nerve supply enter the pulp cavity. It is important to remember that the tooth is a vital structure, so it is sensitive and responsive to a variety of stimuli.

•Endodontic pathology Inflammation of the pulp tissue is termed pulpitis, which can be either reversible or irreversible. If the pulpitis is reversible, the pulp returns to a healthy state when the cause of the inflammation is removed. An example of this would be a carious lesion. Restoration of the caries removes the irritation and allows the pulp to return to normal.

With an irreversible pulpitis, the inflammation of the pulp tissue within the unyielding dentinal walls results in a cessation of the circulation to the pulp tissue. As a result, the necessary nutrient supply and gas exchange is halted, resulting in pulpal necrosis.

There are multiple causes of pulpitis, including trauma, bacterial penetration from resorptive or carious lesions, extension of periodontal disease into the pulp cavity via lateral canals or through the apical delta and anachoresis (blood-borne bacteria). Trauma resulting in crown fracture and pulp exposure creates an avenue for bacterial invasion and subsequent pulpal death. Concussive force from blunt trauma can result in pulpal inflammation and death of the pulp tissue without the bacterial influx seen with pulp exposure. Bacteria then can invade the necrotic pulp tissue through the apical delta via anachoresis.


Figure 1: Note the presence of periapical lucency, a presentation of endodontic pathology.
When irreversible pulpitis occurs, periapical inflammation and apical periodontitis follow. The classic presentation of endodontic pathology is the periapical lucency seen on radiographs with chronic disease (Figure 1).

•Diagnosis of endodontic disease Signs of endodontic disease include discolored teeth, fractured teeth with pulpal exposure, pain with chewing or chewing on one side of the mouth, reluctance to hold objects in the mouth, excessive salivation, sensitive teeth, sinus tract formation (apical to the mucogingival junction).


Figure 2: Concussive trauma can cause a pink to purple discoloration of the crown.
  • Discolored teeth: This is a result of concussive trauma without pulp exposure. Blood and its breakdown products enter the dentinal tubules resulting in a pink to purple discoloration of the crown. If the pulpitis is irreversible, the color typically changes to a purple-gray or brown (Figure 2).


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Source: DVM InFocus,
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