title: The anatomical relationship between the roots of mandibular second molars and the inferior alveolar nerve.
abstract: OBJECTIVE
  To evaluate the anatomical relationship between the roots of mandibular second molars and the inferior alveolar nerve (IAN) in relation to the risk of potential nerve injury during root canal treatment.
  
  
  METHODS
  Cone-beam computed tomography (CBCT) images from the patient record database at a dental hospital were selected. The anonymized CBCT images were reconstructed and examined in three planes (coronal, axial and sagittal) using 3D viewing software. The relationship between each root apex of mandibular second molars and the IAN was evaluated by measuring the horizontal and vertical distances from coronal CBCT sections, and the actual distance was then calculated mathematically using Pythagoras' theorem.
  
  
  RESULTS
  In 55% of the 272 mandibular second molar roots evaluated, from a total of 134 scans, the distance between the anatomical root apex and the IAN was ≤3 mm.
  
  
  CONCLUSIONS
  In over 50% of the cases evaluated, there was an intimate relationship between the roots of mandibular second molars and the inferior alveolar nerve (IAN). Therefore, root canal treatment of mandibular second molars may pose a more significant potential risk of IAN injury; necessary precautions should be exercised, and the prudent use of CBCT should be considered if an intimate relationship is suspected.
authors: Institute of Dentistry, Barts & The London School of Medicine & Dentistry, Queen Mary University of London, London, UK.
authors: B S
authors: BS
authors: Chong
authors: Institute of Dentistry, Barts & The London School of Medicine & Dentistry, Queen Mary University of London, London, UK.
authors: A
authors: A
authors: Quinn
authors: Institute of Dentistry, Barts & The London School of Medicine & Dentistry, Queen Mary University of London, London, UK.
authors: R R
authors: RR
authors: Pawar
authors: Institute of Dentistry, Barts & The London School of Medicine & Dentistry, Queen Mary University of London, London, UK.
authors: J
authors: J
authors: Makdissi
authors: Institute of Dentistry, Barts & The London School of Medicine & Dentistry, Queen Mary University of London, London, UK.
authors: S K
authors: SK
authors: Sidhu
mesh_terms: D054893:Cone-Beam Computed Tomography; D006801:Humans; D008334:Mandible / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D008340:Mandibular Nerve / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D008963:Molar / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D011857:Radiographic Image Interpretation, Computer-Assisted; D014092:Tooth Root / Q000033:anatomy & histology* / Q000000981:diagnostic imaging
keywords: anatomical relationship; cone-beam computed tomography; inferior alveolar nerve; mandibular second molar; nerve injury