Intentional Replantation of C-shaped Mandibular Second Premolar with Radicular Groove.

C-shaped roots with radicular grooves are uncommon in mandibular premolars. Bacteria residing in the radicular groove and associated accessory canals can contribute to persistent periradicular infections. Eradicating bacteria in these less accessible areas remains a significant challenge in endodontic procedures. This report describes the successful management of a left mandibular second premolar (#20) with a persistent lesion related to a lingual radicular groove through an intentional replantation procedure. A 31-year-old Chinese male complained of a gum swelling related to tooth #20 which was endodontically treated and crowned 6 years ago. Clinical examination revealed a lingually located sinus tract and a clinically intact crown restoration. The tooth was not tender to percussion or palpation, with probing depths not exceeding 4 mm, and showed physiological mobility. A periapical radiograph showed the lingual sinus tract traced to the mid third of the root, which had an adequate root canal filling and an intact periodontal ligament around the apical region. A cone-beam computed tomography image revealed radiolucency at the mid third region and on the lingual aspect related to the radicular groove of this C-shaped premolar. Intentional replantation was performed due to the location of the mid-root lesion related to the lingual radicular groove. Tooth #20 was extracted atraumatically, a stained radicular groove was identified, cleansed and sealed with Biodentine, and the tooth replanted. At 2.5-year follow-up, the patient was clinically asymptomatic. Tooth #20 presented with normal probing depths and mobility and healing was observed on the cone-beam computed tomography images.