Calcification of the dental pulp and root canal system is a frequently encountered phenomenon that may range from discrete pulp stones to diffuse mineralization and near-complete obliteration of the pulp space. Although pulpal calcifications may represent physiological changes associated with aging, they may also occur in association with trauma, caries, restorative procedures, chronic irritation and other local or systemic factors. Their clinical importance lies primarily in the difficulties they create during endodontic treatment. Progressive deposition of secondary and tertiary dentin can reduce the dimensions of the pulp chamber and root canal, making canal orifice identification, negotiation, cleaning and shaping considerably more challenging. Pulp stones may be classified according to their structure as true or false denticles and according to their relationship with dentin as free, attached or embedded. Calcific metamorphosis, commonly described radiographically as pulp canal obliteration, is particularly associated with traumatic dental injuries and may present with narrowing or apparent disappearance of the pulp space. Importantly, radiographic obliteration or a negative pulp sensibility test does not by itself establish pulpal necrosis. Diagnosis therefore requires correlation of clinical findings, symptoms, sensibility testing and radiographic assessment. Contemporary management emphasizes conservative access preparation, magnification, ultrasonic instrumentation, appropriate chelating agents, careful canal negotiation and, when indicated, advanced imaging and guided approaches. The clinician must balance adequate removal of calcified tissue with preservation of sound dentin to avoid perforation, transportation and root fracture. This review summarizes the biological basis, classification, clinical presentation, diagnosis and management of calcifications affecting the root canal system.