title: Clinical crown length changes from age 12-19 years: a longitudinal study.
abstract: OBJECTIVE
  The objective of this study was to investigate the relationship between age, gender and clinical crown length using a longitudinal study design.
  
  
  METHODS
  Four hundred and fifty-six sets of study models initially obtained for a large prospective longitudinal cohort study of orthodontic needs were examined. Each set of models corresponded to subjects at three different ages: 11-12, 14-15 and 18-19years old. The clinical crown height of the maxillary right central incisor (11), maxillary right canine (13), maxillary left lateral incisor (22) and mandibular left central incisor (31) was measured from gingival crest to the incisal edge using digital calipers.
  
  
  RESULTS
  Analysis revealed a significant (p<0.0001) age effect on crown length for all four teeth investigated. A significant gender effect was found in relation to the maxillary right canine, maxillary right central incisor and maxillary left lateral incisor. Pairwise comparisons of the means for each age group for the maxillary right canine, maxillary right central incisor and maxillary left lateral incisor revealed significant (p<0. 0001) increases in clinical crown length between each assessment period.
  
  
  CONCLUSIONS
  The findings of the present study indicate that, the process of passive eruption, resulting in increased clinical crown length appears to continue throughout the teenage years. This finding is considered to be of importance to the clinician making treatment decisions for teenagers and young adults requiring treatment in the anterior segments of the mouth.
authors.affiliation: Restorative Dentistry, University Dental Hospital of Manchester, Higher Cambridge Street, M15 6FH, Manchester, UK. leean.morrow@man.ac.uk
authors.forename: L A
authors.initials: LA
authors.lastname: Morrow
authors.forename: J W
authors.initials: JW
authors.lastname: Robbins
authors.forename: D L
authors.initials: DL
authors.lastname: Jones
authors.forename: N H
authors.initials: NH
authors.lastname: Wilson
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging / Q000473:pathology*; D000704:Analysis of Variance; D002648:Child; D015331:Cohort Studies; D003481:Cuspid / Q000033:anatomy & histology; D005260:Female; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology; D008137:Longitudinal Studies; D008297:Male; D009811:Odontometry; D011446:Prospective Studies; D012737:Sex Factors; D019228:Tooth Crown / Q000033:anatomy & histology*; D014078:Tooth Eruption / Q000502:physiology