Reversible pulpitis: etiology, anatomy, diagnosis, clinical picture, treatment

Reversible pulpitis is a clinical diagnosis based on objective and subjective signs of the presence of mild inflammation in the pulp tissue. If the cause of inflammation is eliminated, the pulp returns to normal.

Etiology

Reversible inflammation of the pulp may be the result of a carious process, recent dental treatment, or trauma.

Carious process

Tooth decay is the main cause of inflammatory damage to the pulp. Inflammatory changes in the pulp are observed at all stages of the active carious process. Toxins, bacterial metabolic products, proteolytic enzymes and dentin dissolution products make their way to the pulp through the dentinal tubes. In response, local infiltration of the pulp tissue by macrophages, plasma cells, and lymphocytes occurs. Pulp irritation leads to activation of nonspecific inflammatory reactions with release of histamine, bradykinin and arachidonic acid metabolites. Lysosomal enzymes of polymorphonuclear leukocytes and protease inhibitors are also released. There is overgrowth of terminal portions of afferent pulp fibers with the release of pro-inflammatory neuropeptides causing vascular responses:

• Vasodilation;
• Increased blood flow;
• Increased vascular permeability.

Non-infectious causes

The pulp can be irritated by mechanical, chemical and thermal factors such as:

• Tooth preparation;
• Trauma;
• Occlusal trauma;
• Deep periodontal curettage;
• Orthodontic tooth movement.

The following factors irritate the pulp during dental treatment:

• Vibration;
• Injury to odontoblast outgrowths during dissection;
• Heating (especially when operating without air/water cooling);
• Dehydration with possible aspiration of odontoblast nuclei into dentinal tubes;
• Toxic effects of residual monomer, some dental materials and aggressive carious cavity treatment fluids.

Polymerization shrinkage of the filling material in case of violation of the technique of direct restoration leads to tearing of the material from the tooth tissues, loss of tightness of the restoration promotes microfluidation of microorganisms into the dentinal tubes and development of pulp inflammation.

Mechanism of Pain Development

Mechanical, thermal, and chemical stimuli result in rapid fluid movement in the dentinal tubules. This stimulates the myelinated A𝛅 nerve fibers of the pulp. They have high nerve impulse conduction speed and low stimulation threshold, are located superficially at the junction of pulp and dentin, transmit pain directly to the thalamus and generate sharp, stabbing localized pain.

Pulp defense mechanisms

The pulp of the tooth has increased sensitivity to damaging influences and difficult regeneration, because it is in a confined space without the possibility of expansion, and has insufficient collateral circulation. However, when exposed to a weak and/or brief stimulus, the pulp can mobilize protective responses leading to healing with minimal damage.

In response to irritation, the following reactions are activated:

• Tertiary (reparative or replacement) dentin is formed at the boundary between dentin and pulp;
• There is sclerosing of the dentin around the carious lesion, and
• Inflammatory and immune reactions in the pulp are activated.

The toxic effect is reduced by the constant flow of dentinal fluid and its buffer capacity. All these mechanisms are aimed at decreasing permeability and reducing the possibility of irritants entering the pulp.

Inflammation of the pulp can regress if the infected dentin is removed and the damaging factor is eliminated. Aspirated odontoblast nuclei can be subjected to autolysis.

The resulting tertiary dentin remains as a “scar” after previous inflammation.

Anatomy

Depending on the cause of pulp irritation, the affected tooth may have:

• Carious cavity adjacent to the pulp chamber;
• Tooth restoration adjacent to the pulp chamber;
• Restoration of a tooth with signs of impaired seal (defects, cracks in the restoration, pigmentation on the margin, secondary caries);
• Signs of trauma (cracks, chips in enamel, dentin, partial pulp exposure).

Tissue of the crown pulp in the peripheral parts is edematous, hyperemic. At the border of dentin and pulp in the projection of the carious lesion may be observed deposition of tertiary dentin.

Diagnosis

To date, no 100% accurate clinical methods have been found to reliably analyze the condition of the pulp tissue. Apart from pain, the other classic signs of inflammation (redness, swelling, fever, loss of function) cannot be determined because the pulp is not accessible for direct examination. In an inflamed pulp, the clinical symptoms usually do not correspond to the histologic picture.

• Percussion of the tooth is painless or questionable;
• Palpation along the transitional fold is painless;
• Temperature test – a cold or heat stimulus causes sharp pain that passes quickly (seconds) after it is removed;
• Radiography (intraoral radiography, radiovisiography, CLCT) – carious cavity, restoration or traumatic defect adjacent to the pulp chamber, or changes may be absent;
• History taking for recent trauma or dental treatment (dental restoration, periodontal curettage, orthodontic treatment) is very important.

Clinical manifestations

Clinically, it is often very difficult to distinguish between reversible and irreversible pulp inflammation. The patient may complain of sharp, rapidly passing pain from cold or hot things, or there may be no complaints.

Exposure to a stimulus, such as cold or hot liquid or air, can cause acute pain. Removal of the stimulus causes the pain to disappear immediately or within a few seconds.

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Treatment of reversible pulpitis

Treatment is aimed at eliminating the irritant and sealing the exposed dentin and/or vital pulp.

In the presence of carious process – preparation and careful necrectomy of infected dentin with subsequent restoration.

In traumatic injuries – restoration of lost tissue, direct coverage of the exposed vital pulp with biocompatible material, or partial pulpotomy.

Further dynamic observation with periodic control of pulp vitality is carried out. The patient should be warned about the possible development of irreversible inflammation and necrosis of the pulp, as well as the need to seek dental care if symptoms of irreversible pulpitis (prolonged pain from temperature stimuli, spontaneous pain) occur.