title: Root canal morphology of mandibular permanent molars at different ages.
abstract: OBJECTIVE
  To investigate differences in the root canal morphology of permanent mandibular molar teeth at various ages.
  
  
  METHODS
  Four hundred and eighty permanent mandibular first and second molars were examined. First and second molars were divided into six and five groups, respectively, according to the age of the patient at the time of extraction. Root canal morphology was studied using a clearing technique. The canal morphology of the mesial root was classified into three stages depending on its developmental pattern. When the root canal system was completely differentiated, the canal classification and the number of lateral canals and inter-canal communications were recorded. Vertucci's classification was taken as the main reference. Canal morphology was compared amongst age groups.
  
  
  RESULTS
  In both first and second molars, developmental stages of canal morphology amongst age groups were significantly different (P < 0.0001). The prevalence of inter-canal communications was highly significantly different in the first (P < 0.0001) and less significant in the second molar (P < 0.05). After completion of the canal differentiation, the mesial roots of first molars had type IV and II canal forms. The majority of the mesial roots of second molars had type I and III canals. C-shaped canals were found in 3% of second molars.
  
  
  CONCLUSIONS
  Mesial roots of first and second molars mostly had one large canal until 11 and 15 years of age, respectively. In both molars, the canal system was completely defined at 30-40 years. The prevalence of inter-canal communications was low at young and old ages but high at intermediate ages.
authors.affiliation: Department of Anatomy and Physical Anthropology, Nihon University Graduate School of Dentistry at Matsudo, Matsudo, Japan. roshan.peiris@nihon-u.ac.jp
authors.forename: H R D
authors.initials: HR
authors.lastname: Peiris
authors.forename: T N
authors.initials: TN
authors.lastname: Pitakotuwage
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.forename: K
authors.initials: K
authors.lastname: Sasaki
authors.forename: E
authors.initials: E
authors.lastname: Kanazawa
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging / Q000473:pathology*; D002648:Child; D002965:Classification; D003782:Dental Pulp / Q000033:anatomy & histology / Q000254:growth & development; D003786:Dental Pulp Cavity / Q000033:anatomy & histology* / Q000254:growth & development / Q000648:ultrastructure; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible; D008963:Molar / Q000033:anatomy & histology* / Q000254:growth & development; D019227:Tooth Apex / Q000033:anatomy & histology; D055815:Young Adult