title: Analysis of C-shaped canal systems in mandibular second molars using surgical operating microscope and cone beam computed tomography: A clinical approach.
abstract: OBJECTIVE
  The study was aimed to acquire better understanding of C-shaped canal systems in mandibular second molar teeth through a clinical approach using sophisticated techniques such as surgical operating microscope and cone beam computed tomography (CBCT).
  
  
  METHODS
  A total of 42 extracted mandibular second molar teeth with fused roots and longitudinal grooves were collected randomly from native Indian population. Pulp chamber floors of all specimens were examined under surgical operating microscope and classified into four types (Min's method). Subsequently, samples were subjected to CBCT scan after insertion of K-files size #10 or 15 into each canal orifice and evaluated using the cross-sectional and 3-dimensional images in consultation with dental radiologist so as to obtain more accurate results. Minimum distance between the external root surface on the groove and initial file placed in the canal was also measured at different levels and statistically analyzed.
  
  
  RESULTS
  Out of 42 teeth, maximum number of samples (15) belonged to Type-II category. A total of 100 files were inserted in 86 orifices of various types of specimens. Evaluation of the CBCT scan images of the teeth revealed that a total of 21 canals were missing completely or partially at different levels. The mean values for the minimum thickness were highest at coronal followed by middle and apical third levels in all the categories. Lowest values were obtained for teeth with Type-III category at all three levels.
  
  
  CONCLUSIONS
  The present study revealed anatomical variations of C-shaped canal system in mandibular second molars. The prognosis of such complex canal anatomies can be improved by simultaneous employment of modern techniques such as surgical operating microscope and CBCT.
authors.affiliation: Department of Conservative Dentistry & Endodontics, Army Dental Center (R&R), Delhi Cantonment, New Delhi, India.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Chhabra
authors.affiliation: Maulana Azad Institute of Dental Sciences, Bahadur Shah Zafar Marg, New Delhi, India.
authors.forename: Seema
authors.initials: S
authors.lastname: Yadav
authors.affiliation: Maulana Azad Institute of Dental Sciences, Bahadur Shah Zafar Marg, New Delhi, India.
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Talwar
keywords: C-shaped canal systems; Cone beam computed tomography; Indian population; mandibular second molar; surgical operating microscope