title: Odontometric evaluation of mandibular premolars with tooth shape deviation: a case-control study.
abstract: OBJECTIVE
  To evaluate the mean dimensions and morphologic characteristics of mandibular premolars that had mesiodistally elongated and faciolingually squeezed tooth shape deviations (MnP-TSD) and determine the population prevalence of this anomaly.
  
  
  METHODS
  Clinical photographs and study models were made for all new patients with MnP-TSD teeth who were seen over 20 years. The mesiodistal (MD) and faciolingual (FL) dimensions of the anomalous premolars were measured. MD/FL indices and MD × FL mm(2) occlusal crown areas were calculated and means and standard deviations were derived. Male and female means from the mandibular first and second anomalous premolars (MnP1/MnP2-TSD) were statistically compared against gender-specific means derived from published normative data using Student's t-tests and chi-square tests.
  
  
  RESULTS
  Fifty-six individuals (33 male and 23 female) with MnP-TSD were identified, giving a male to female ratio of 1.4:1, while the prevalence rate in the indigenous British population was estimated to be 0.6%. The MD widths of the MnP1-TSD and MnP2-TSD teeth were approximately 1 mm wider than normal, while the FL diameters were about 0.5 mm and 1.5 mm narrower respectively, for the first and second premolar teeth. The MD/FL indices, instead of being under 90 as usual were above 100, while the mean MD/FL mm(2) crown surface areas were normal.
  
  
  CONCLUSIONS
  This study supplies odontometric dimensional and morphologic data on MnP-TSD teeth that provide a reference source for future comparisons.
authors.affiliation: Department of Orthodontics, Colchester Hospital University NHS Foundation Trust, Essex County Hospital, Colchester, Essex, UK. chate@btinternet.com
authors.forename: Robert Anthony Clive
authors.initials: RA
authors.lastname: Chate
mesh_terms: D000293:Adolescent; D000328:Adult; D001641:Bicuspid / Q000002:abnormalities / Q000033:anatomy & histology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible / Q000033:anatomy & histology*; D009811:Odontometry / Q000379:methods*; D015995:Prevalence; D017678:Sex Distribution; D006113:United Kingdom / Q000453:epidemiology