title: A comparison between clearing and radiographic techniques in the study of the root-canal anatomy of maxillary first and second molars.
abstract: OBJECTIVE
  To compare a clearing technique with conventional radiography in studying certain features of the root-canal system of maxillary right first and second molars. A secondary aim was to assess interexaminer agreement for these features using radiographs.
  
  
  METHODS
  Eighty-three recently extracted permanent maxillary right first molars and 40 recently extracted maxillary right second molars from an Irish population were included. Standard periapical radiographs were taken from a buccolingual and mesiodistal direction. The specimens were then decoronated, demineralized in 10% hydrochloric acid for 8 days and then cleared using methyl salicylate. The cleared teeth were examined using a dissecting microscope (x20), and data relating to number of roots, canal type following Vertucci's classification, presence of lateral canals, presence of transverse anastomoses and position/number of apical foramina were collected. The radiographs were examined by two independent trained endodontists using an X-ray viewer and a magnifying lens (x2) in a dark room for the same features studied using the clearing technique.
  
  
  RESULTS
  The Kappa values for the agreement between the radiographic examiners A and B and the clearing technique and between the two examiners for the number of roots were 0.60, 0.64 and 0.53; for the root-canal type, 0.37, 0.41 and 0.42; for the number of roots with lateral canals, 0.21, 0.18 and 0.14; and for the transverse anastomoses, 0.29 for radiographic Examiner A. Radiographic Examiner B did not feel capable of accurately recognizing transverse anastomoses from the radiographs. For the position/number of apical foramina, the Kappa values were 0.33 and 0.24, respectively. In general, the Kappa values were low to modest for all comparisons.
  
  
  CONCLUSIONS
  It is concluded that the agreement between the two radiographic examiners and the agreement between either radiographic examiner and the clearing technique were poor to moderate, indicating the limited value of radiographs alone when studying certain aspects of the root-canal system.
authors.affiliation: Department of Restorative Dentistry and Periodontology, School of Dental Science, Trinity College, Dublin, Ireland. oomer@tcd.ie
authors.forename: O E
authors.initials: OE
authors.lastname: Omer
authors.forename: R M
authors.initials: RM
authors.lastname: Al Shalabi
authors.forename: M
authors.initials: M
authors.lastname: Jennings
authors.forename: J
authors.initials: J
authors.lastname: Glennon
authors.forename: N M
authors.initials: NM
authors.lastname: Claffey
mesh_terms: D003786:Dental Pulp Cavity / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008963:Molar; D009811:Odontometry / Q000379:methods; D011859:Radiography; D018915:Root Canal Preparation / Q000379:methods*