Mandibular lateral incisor with four root canals: A unique case of double tooth diagnosed using multidetector computed tomography
A 17-year-old female was referred to the Department of Endodontics for the treatment of the left mandibular lateral incisor. Root canal treatment had been initiated by a general practitioner for the tooth in question two months before. Clinical examination of the tooth revealed a discolored crown with an increased mesiodistal width () which elicited slight tenderness on percussion. The number of teeth in the arch was normal.\nAn intraoral periapical radiograph revealed the presence of multiple root canals of the tooth in a single wide root with diffuse periapical radiolucency (). Subsequent to obtaining informed consent from the patient, three-dimensional (3D) imaging using 64-slice MDCT scanner (Brilliance CT 64-channel, Philips Healthcare, Andover, MA, USA) was planned in order to confirm the morphology of the complex pulp space. An MDCT scan of the mandible was performed and images were acquired using dental software program DentaScan (GE Healthcare, Milwaukee, WI, USA). In addition to the increased mesiodistal width, 3D reconstructions disclosed a lingual radicular groove in relation to the left mandibular lateral incisor (). The axial view revealed three canals at the cervical level: large distal, mesial, and middle canals (). At the junction of the cervical and middle third, the middle canal merged with the division of the distal canal. An axial slice at the middle third of the root revealed two distal canals and a single mesial canal with a narrow isthmus joining all of the three canals (). A curved coronal image showed the presence of a large distal and a mesial canal (). Another coronal image confirmed that the distal canal divided into two separate canals (). A communication between the mesial and distal canals was also evident (). With the help of the axial and coronal images of MDCT, it could be assumed that the left mandibular lateral incisor, which had a single canal, was fused with a supernumerary tooth distal to it, which had two root canals. The fourth canal might have represented a connection between the root canal systems of the fused teeth. A sagittal image confirmed the presence of aberrant root canal morphology and presence of a large periapical radiolucency ().\nUnder local anesthesia administration and rubber dam isolation, an access opening was refined using an EX 24 bur (Mani, Tochigi, Japan), revealing an unusually large pulp chamber. On pulp chamber exploration, a perforation was detected on the labial surface of the tooth near the cement-enamel junction, which was immediately sealed using flowable resin (Filtek flow; 3M ESPE, St Paul, MN, USA). Three separate orifices of the mesial, middle, and distal canals were located () with the distal canal further dividing into two separate canals. The working length was determined with the help of an apex locator (Root ZX, Morita, Tokyo, Japan), which was later confirmed with a radiograph ().\nBiomechanical preparation was then carried out employing Protaper™ hand instruments (Dentsply Maillefer, Ballaigues, Switzerland) under copious irrigation with 2.5% sodium hypochlorite (KMC Pharmacy, Manipal, India) and 17% ethylenediaminetetraacetic acid (EDTA) (Merck, Dermstadt, Germany). Calcium hydroxide (Ultracal XS, Ultradent, South Jordan, UT, USA) was placed in the root canals, and the access cavity was temporized with Cavit G (3M ESPE, Seefeld, Germany). Thereafter, calcium hydroxide dressing was renewed twice at an interval of two weeks between each appointment following which the tooth was completely asymptomatic. The root canals were obturated by cold lateral compaction of gutta-percha using a zinc oxide eugenol sealer (Kemdent, Associated Dental Products Ltd., Wiltshire, UK) () and the access cavity was restored with composite resin (3M ESPE Dental Products, St. Paul, MN, USA). A one year follow-up radiograph showed satisfactory healing of the periapical lesion ().