title: Estimating emergence sequences of permanent teeth in Flemish schoolchildren using interval-censored biplots: a graphical display of tooth emergence sequences.
abstract: OBJECTIVE
  The aim of the present study was to investigate the pattern of emergence of permanent teeth using nonparametric techniques.
  
  
  METHODS
  Data were obtained from the Signal-Tandmobiel project, a 6-year prospective dental study conducted in Flanders (Belgium) in which 4468 primary school children born in 1989 were annually examined. A new exploratory method for interval-censored data, the IC-biplot, was applied to estimate individual sequences of emergence. In addition, the method renders a nice graphical representation of both children and teeth in the plane where the individual sequences of emergence can easily be visualized. On the basis of the estimated individual sequences, their corresponding prevalences were calculated.
  
  
  RESULTS
  The study revealed that between 7 and 13 different sequences of emergence can be expected depending on gender and quadrant. The prevalences of the most frequent sequences in girls varied from 35% to 85% depending on the quadrant, while in boys they varied from 28% to 32%. Most sequences in the maxilla start with 6-1-2 and in the mandible with 1-6-2.
  
  
  CONCLUSIONS
  The IC-biplot is a flexible procedure that allows an easy visualization of the pattern of emergence of permanent teeth. Rank orders derived from the IC-biplot confirm rank orders suggested earlier in the literature.
authors.affiliation: L-Biostat, KU Leuven and Hasselt Universiteit, Leuven, Belgium.
authors.forename: Silvia
authors.initials: S
authors.lastname: Cecere
authors.forename: Roos
authors.initials: R
authors.lastname: Leroy
authors.forename: Patrick J F
authors.initials: PJ
authors.lastname: Groenen
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Lesaffre
authors.forename: Dominique
authors.initials: D
authors.lastname: Declerck
mesh_terms: D001530:Belgium / Q000453:epidemiology; D002648:Child; D003753:Dental Health Surveys; D019229:Dentition, Permanent; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D025341:Principal Component Analysis; D011446:Prospective Studies; D012737:Sex Factors; D018709:Statistics, Nonparametric; D013997:Time Factors; D014078:Tooth Eruption / Q000502:physiology*