title: The relationship between the ABO discrepancy index and treatment duration in a graduate orthodontic clinic.
abstract: OBJECTIVE
  To test the hypothesis that there is no relationship between the components of the American Board of Orthodontics (ABO) discrepancy index (DI) and duration of orthodontic treatment.
  
  
  METHODS
  A retrospective review of 732 patient records with permanent dentition was performed. Pretreatment radiographs and casts were used to determine the DI score. Other data collected were total treatment duration, age, sex, ethnicity, and the date fixed appliances were removed. Reliability tests showed substantial agreement between examiners (Cohen's kappa 0.68-0.94). Pearson and Spearman correlation coefficients were used to assess the association between the DI scores and length of treatment. A multiple variable regression analysis was used to determine which variables predict treatment duration (P < .05 significant).
  
  
  RESULTS
  There was a significant association between the DI and treatment duration. There was a significant multivariate association for DI components (occlusions, crowding, overjet, cephalometrics, overbite, lateral open bite, and tooth transposition) and treatment duration.
  
  
  CONCLUSIONS
  The hypothesis was rejected. This retrospective study of university clinical records showed that the average increase in treatment duration was about 11 days for each point increase in total DI score. Treatment duration was differentially increased by various components of the DI: approximately 6.5 months for tooth transposition; approximately 1 month for crowding, overjet, or overbite; approximately 3 weeks for occlusion discrepancies; approximately 2 weeks for lateral open bite; and approximately 5 days for cephalometric discrepancies.
authors.affiliation: Indiana University, Indianapolis, USA.
authors.forename: Laura D
authors.initials: LD
authors.lastname: Parrish
authors.forename: W Eugene
authors.initials: WE
authors.lastname: Roberts
authors.forename: Gerardo
authors.initials: G
authors.lastname: Maupome
authors.forename: Kelton T
authors.initials: KT
authors.lastname: Stewart
authors.forename: Robert W
authors.initials: RW
authors.lastname: Bandy
authors.forename: Katherine S
authors.initials: KS
authors.lastname: Kula
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D003740:Dental Clinics; D017050:Episode of Care; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000628:therapy*; D008875:Middle Aged; D009970:Orthodontics / Q000193:education; D009971:Orthodontics, Corrective / Q000592:standards*; D012015:Reference Standards; D012044:Regression Analysis; D012189:Retrospective Studies; D013044:Specialty Boards; D018709:Statistics, Nonparametric; D013997:Time Factors; D055815:Young Adult