Radiographic evolution of a dentigerous cyst associated with a deeply impacted mandibular first molar in a pediatric patient: a CBCT-based longitudinal case report with minimal-visit orthodontic management.

A deeply impacted mandibular first molar associated with a dentigerous cyst is an uncommon clinical presentation, particularly in pediatric patients. This case report describes a 9-year-old boy who presented with delayed eruption of the mandibular right first molar. Panoramic radiography revealed a well-defined unilocular radiolucent lesion associated with a deeply impacted tooth, while cone-beam computed tomography (CBCT) demonstrated buccolingual cortical expansion and thinning, displacement of the adjacent second molar germ, and close proximity to the inferior alveolar canal. Based on clinical, radiographic, and histopathologic findings, the lesion was diagnosed as a dentigerous cyst and treated conservatively with marsupialization followed by orthodontic traction. Longitudinal radiographic follow-up over 16 months demonstrated progressive reduction of the radiolucent lesion, gradual bone regeneration, and continuous eruption and uprighting of the impacted mandibular first molar. This case highlights the important role of CBCT and serial radiographic monitoring in evaluating lesion extent, treatment planning, and documenting healing and tooth eruption during conservative management of dentigerous cysts in children.