title: Parturition lines in modern human wisdom tooth roots: do they exist, can they be characterized and are they useful for retrospective determination of age at first reproduction and/or inter-birth intervals?
abstract: BACKGROUND
  Parturition lines have been described in the teeth of a number of animals, including primates, but never in modern humans. These accentuated lines in dentine are comprised of characteristic dark and light component zones.
  
  
  OBJECTIVE
  The aim of this study was to review the physiology underlying these lines and to ask if parturition lines exist in the third molar tooth roots of mothers known to have had one or more children during their teenage years.
  
  
  METHODS
  Brief retrospective oral medical obstetric histories were taken from four mothers and compared with histological estimates for the timing of accentuated markings visible in longitudinal ground sections of their wisdom teeth.
  
  
  RESULTS
  Evidence of accentuated markings in M3 root dentine matched the age of the mother at the time their first child was born reasonably well. However, the dates calculated for inter-birth intervals did not match well.
  
  
  CONCLUSIONS
  Parturition lines corresponding to childbirth during the teenage years can exist in human M3 roots, but may not always do so. Without a written medical history it would not be possible to say with confidence that an accentuated line in M3 root dentine was caused by stress, illness or was a parturition line.
authors.affiliation: Department of Cell and Developmental Biology, UCL , London , UK .
authors.forename: M Christopher
authors.initials: MC
authors.lastname: Dean
authors.forename: Fadil
authors.initials: F
authors.lastname: Elamin
mesh_terms: D000293:Adolescent; D000366:Age Determination by Teeth / Q000379:methods*; D001721:Birth Intervals; D001722:Birth Order; D002648:Child; D005260:Female; D006801:Humans; D008964:Molar, Third / Q000033:anatomy & histology*; D012189:Retrospective Studies; D014092:Tooth Root / Q000033:anatomy & histology*; D055815:Young Adult
keywords: Dentine; inter-birth interval; parturition lines; wisdom teeth