Acute Pulpitis

Acute pulpitis is an acute inflammatory response of the dental pulp to noxious stimuli — most commonly deep caries, but also trauma, restorative procedures, and periodontal disease. The pulp is a highly vascularized connective tissue enclosed in a rigid, non-compliant dentin shell, making it uniquely vulnerable to pressure-induced ischemia when edema develops.

Two clinically and therapeutically distinct forms exist: reversible pulpitis, in which the inflammatory response can resolve with elimination of the stimulus, and irreversible pulpitis, in which irreparable damage to pulp tissue demands extirpation (root canal treatment) or extraction.

Distinguishing between these forms at chairside is one of the most clinically challenging tasks in dentistry, relying on careful symptom history, provocative testing, and clinical judgment rather than a single definitive test.

Deep caries is responsible for the majority of acute pulpitis cases. As the carious lesion approaches the pulp, bacterial toxins and antigens penetrate dentinal tubules to elicit inflammatory mediator release from pulpal immunocompetent cells long before physical bacterial invasion occurs.

Thermal and mechanical trauma during restorative procedures — excessive frictional heat, desiccation with air, acid-etching for prolonged periods, inadequate dentinal thickness over the pulp, and galvanic currents from dissimilar metals — cause direct injury to odontoblasts and pulpal microvascular endothelium.

Periodontal pathogens may ascend the root canal via lateral canals, apical foramina, and dentinal tubules exposed by periodontal pockets, causing retrograde pulpitis. Crown fractures with exposed dentin, cracks in teeth, and iatrogenic perforations complete the etiological spectrum.