title: Thickness of dentine in mesial roots of mandibular molars with different lengths.
abstract: OBJECTIVE
  To measure the minimum thickness of the distal (furcal) root dentine associated with the buccal and lingual canals of the mesial roots of mandibular first molars with different lengths.
  
  
  METHODS
  The mesial roots of 285 mandibular first molars were allocated into three groups according to their length: group I - long (24.14 mm +/- 0.85), group II - medium (22.10 mm +/- 0.65) and group III - short (19.97 mm +/- 0.75). The minimum thickness of the distal (furcal) root dentine associated with the buccal and lingual canals of the mesial roots 2 mm below the furcation was measured. The distance between the buccal and lingual canals, and the depth of concavity in the distal surface of the mesial roots were also measured. anova and Tukey-Kramer were used to test for significant differences among the groups.
  
  
  RESULTS
  The minimum thickness of the distal wall of the mesiobuccal canal was significantly different (P < 0.05) between group I (long) and III (short), with long teeth having the smallest mean values. No significant difference was found in the thickness of the distal wall of the mesiolingual canal among the groups studied (P > 0.05). The shortest distance between the mesiobuccal and the mesiolingual canals was observed in group III (P < 0.05). The distal (furcal) concavity was deeper in group I (P < 0.05) when compared with the other groups.
  
  
  CONCLUSIONS
  There was a significant difference in the minimum thickness of the distal (furcal) root wall of the mesiobuccal canal of mandibular first molars 2 mm below the furcation between group I (long) and group III (short) teeth. The thinnest walls were found in the longest teeth. The deepest concavities in the distal (furcal) walls of the mesial roots were found in the longest roots.
authors.affiliation: Endodontic Division, Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas-UNICAMP, Piracicaba, Brazil.
authors.forename: T S
authors.initials: TS
authors.lastname: Sauáia
authors.forename: B P F A
authors.initials: BP
authors.lastname: Gomes
authors.forename: E T
authors.initials: ET
authors.lastname: Pinheiro
authors.forename: A A
authors.initials: AA
authors.lastname: Zaia
authors.forename: C C R
authors.initials: CC
authors.lastname: Ferraz
authors.forename: F J
authors.initials: FJ
authors.lastname: Souza-Filho
authors.forename: L
authors.initials: L
authors.lastname: Valdrighi
mesh_terms: D000704:Analysis of Variance; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D003804:Dentin / Q000033:anatomy & histology*; D006801:Humans; D008334:Mandible; D008963:Molar / Q000033:anatomy & histology*; D009811:Odontometry; D012016:Reference Values; D018709:Statistics, Nonparametric; D014092:Tooth Root / Q000033:anatomy & histology*