title: [Location and negotiation of second mesiobuccal canals in maxillary molars].
abstract: OBJECTIVE
  To investigate prevalence, location, negotiation and the effect of operating microscope (OM) in the treatment of the second mesiobuccal canal (MB2) in maxillary molars.
  
  
  METHODS
  113 maxillary molars were studied. The crowns of the teeth were removed 1 mm above the chamber bottom for searching MB2 canal. Initially location and negotiation of MB2 canal were attempted without OM. Teeth in which MB2 canal were not located or negotiated were further explored under OM. Canal orifices including MB orifice, MB2 orifice and palatal orifice were filled by red gutta-percha cones, then the teeth were scanned by scanner. The images were analyzed by Image-Proplus 4.0 software to measure the relationship between MB2 canal and other canals.
  
  
  RESULTS
  The MB-MB2 distance is (1.47 +/- 0.54) mm, MB-P distance is (5.77 +/- 0.66) mm, the vertical distance from MB2 to MB-P line is (0.53 +/- 0.28) mm, the angle between MB-P line and MB-MB2 line is 23.07 degrees +/- 13.08 degrees. MB2 orifices were located in 70 teeth (61.9%) and negotiated in 53 teeth (46.9%) without OM. With OM, additional MB2 orifices were located in other 6 teeth, 4 were negotiated; and 2 were negotiated in which MB2 canal were not negotiated without OM.
  
  
  CONCLUSIONS
  MB2 canal can be located in 67.3% and negotiated in 52.2% of maxillary molars. Ability to locate and negotiate MB2 canal is facilitated by OM. The MB2 canal was located less than 1 mm mesially to the MB-P line and 2 mm palatally from the MB orifice.
authors.affiliation: Special Dental Department, Peking University School of Stomatology, Beijing 100081, China.
authors.forename: Cheng-fei
authors.initials: CF
authors.lastname: Zhang
authors.forename: Rui-yu
authors.initials: RY
authors.lastname: Ding
authors.forename: Xing-zhe
authors.initials: XZ
authors.lastname: Yin
authors.forename: Bao-hong
authors.initials: BH
authors.lastname: Zhao
authors.forename: Qiong-guang
authors.initials: QG
authors.lastname: Lin
mesh_terms: D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D006801:Humans; D008437:Maxilla; D008853:Microscopy; D008963:Molar / Q000033:anatomy & histology*