Hemisection of an immature mandibular first permanent molar with vertical root fracture: preserving arch space and supporting second premolar eruption

Vertical root fracture (VRF) in an immature permanent tooth is uncommon and presents a treatment challenge, particularly in a growing child where premature tooth loss may compromise arch integrity and eruption of the succeeding dentition. A male child in the mixed dentition period presented with a grossly carious mandibular left first permanent molar with chronic hyperplastic pulpitis. Further clinical and radiographic evaluation revealed a VRF involving the mesial root. Considering the developing dentition and the importance of preserving the first permanent molar, complete extraction was avoided. Hemisection was performed with removal of the fractured mesial segment and preservation of the healthy distal segment, followed by MTA apexification, obturation, and definitive restoration. At 6 months, the patient remained asymptomatic with satisfactory clinical and radiographic healing, while the mandibular second premolar continued to erupt through the space created by hemisection and progressed toward a favourable position. This case highlights hemisection as a conservative, developmentally oriented approach for preserving a functional portion of an immature permanent molar while maintaining arch space and facilitating favourable eruption of the successor premolar.