Conservative Endodontic Retreatment of a Structurally Compromised Maxillary Premolar Using Digitally Assisted Magnetic Orthodontic Extrusion for Ferrule Recovery.

Endodontically treated teeth with severe coronal loss and insufficient ferrule pose major restorative and biomechanical challenges. Orthodontic extrusion can recover ferrule while preserving periodontal support. This report describes nonsurgical endodontic retreatment combined with digitally assisted magnetic extrusion in a maxillary first premolar. A 57-year-old man presented with decementation of a metal-ceramic crown on the maxillary right first premolar. The pulpal and apical diagnoses were previously treated and asymptomatic apical periodontitis, respectively. Approximately 1 mm of supragingival tooth structure remained on the mesial, buccal, and distal surfaces. After root canal filling removal, disinfection, and intracanal calcium hydroxide medication, a customized splint containing an opposing neodymium-iron-boron magnet was fabricated using intraoral scanning, computer-aided design, and additive manufacturing. Following circumferential supracrestal fiberotomy, limited coronal extrusion was achieved after 14 days of activation. The tooth was stabilized for 4 weeks, obturated, reconstructed with glass fiber posts and a composite core, and restored with a monolithic zirconia crown. After extrusion and stabilization, ferrule height reached approximately 2-2.5 mm. At 18 months, the tooth remained functional and asymptomatic, with physiologic mobility, probing depths of 2-3 mm, stable gingival tissues, no clinically evident relapse, and favorable periapical radiographic findings. This case supports the feasibility of digitally assisted magnetic extrusion as an adjunct to endodontic retreatment for limited ferrule recovery.