Regenerative Endodontic Procedures With Apical Microsurgery for a Mature Permanent Tooth With a Blunderbuss Open Apex and Chronic Apical Periodontitis: A 24‐Month Case Report

AIM: This case report presents the 24-month outcomes of regenerative endodontic procedures (REPs) combined with apical microsurgery in a mature permanent tooth with a blunderbuss open apex and chronic apical periodontitis. A multimodal assessment protocol integrating laser Doppler flowmetry (LDF), magnetic resonance imaging (MRI) and cone beam computed tomography (CBCT) volumetric analysis was employed to comprehensively evaluate the therapeutic efficacy of this combined approach. SUMMARY: A 25-year-old female patient presented with a mandibular right canine diagnosed with pulp necrosis, a blunderbuss open apex and a large periapical radiolucency. Despite multiple sessions of chemomechanical disinfection, persistent sanguopurulent intracanal exudate was observed, indicating an extraradicular infection. Apical microsurgery was therefore performed to eradicate the extraradicular biofilm, after which autologous CGF was compacted into both the pulp space and the apical surgical site, followed by coronal sealing with iRoot BP Plus. This combined approach aimed to promote tissue regeneration within the canal and concurrently facilitate periapical bone healing. Over a 24-month follow-up period, complete periapical osseous healing was confirmed at 12 months. At 18 and 24 months, LDF demonstrated that blood perfusion in the treated tooth was comparable to that of the contralateral healthy tooth, and MRI revealed continuous homogeneous pulp-like signal within the intraradicular tissue. The tooth also regained positive responses to cold and electric pulp testing from 6 months postoperatively, indicating recovery of sensory nerve fibre function rather than definitive pulp vitality. Concurrent CBCT volumetric analysis documented a progressive reduction in pulp space volume of 9.88% over 24 months, suggesting hard tissue deposition; however, the histological nature of this tissue remains undetermined.