title: Variable permanent mandibular first molar: Review of literature.
abstract: BACKGROUND
  The success of root canal therapy depends on the locations of all the canals, thourough debridement and proper sealing. At times the clinicians are challenged with variations in morphology of root canal. This review article attempts to list out all the variations of permanent mandibular first molar published so for in the literature.
  
  
  METHODS
  An exhaustive search was undertaken using PUBMED database to identify published literature from 1900 to 2010 relating to the root canal morphology of permanent first molar by using key words. The selected artcles were obtained and reviewed.
  
  
  RESULTS
  Total ninty seven articles were selected out of which 50 were original article and forty seven were case reports. The incidence of third canal in mesial root was 0.95% to 15%. The incidence of three rooted mandibular first molar was 3% to 33%. Only ninety cases reported with c-shape canal configuration. Incidence of Taurodintism without congenital disorder was very rare.
  
  
  CONCLUSIONS
  The root canal treatment requires proper knowlegde of variations in root canal morphology in order to recognise, disinfect and seal all portal of exit. This can be accomplished with proper diagnosis using newer modes, modification in access preparation, use of operating microscope, enhanced methods of disinfecting and sealing of all canals.
authors.affiliation: Department of Conservative dentistry and Endodontics, St Joseph Dental College, Duggirala, Eluru, West Godavari District, India.
authors.forename: Srinidhi V
authors.initials: SV
authors.lastname: Ballullaya
authors.forename: Sayesh
authors.initials: S
authors.lastname: Vemuri
authors.forename: Pabbati Ravi
authors.initials: PR
authors.lastname: Kumar
keywords: C-shape canal; Middle mesial canal; Permanent mandibular molar; Radix endomolaris; Radix paramolaris; Taurodontism