title: The long-term benefits of orthodontic treatment.
abstract: OBJECTIVE
  This study aimed to evaluate post-treatment changes at least five years out of retention in a cohort of 100 consecutively started patients treated by a postgraduate student in a UK orthodontic department.
  
  
  METHODS
  Analysis of study models using recognised occlusal indices. Setting Patients initially treated at Newcastle Dental Hospital were recalled for record collection.
  
  
  METHODS
  Study models and clinical photographs were taken for each patient attending for post-retention records. Weighted Peer Assessment Rating (PAR) Index and Index of Orthodontic Treatment Need (IOTN) scores were recorded for cases at the beginning, end and at least 5 years post-retention. Main outcome measures Post-treatment changes were evaluated using PAR Index and IOTN to evaluate extent and likelihood of change and to compare treatment modalities.
  
  
  RESULTS
  Seventy-eight patients attended for post-retention records. Overall PAR reduction immediately post-treatment was 68.6% and at a mean of 6.5 years post-retention was 55.5%. Dual arch fixed appliance treatments achieved the greatest reduction in PAR score, and maintained the reduction beyond the retention period better than other treatment modalities. Eighty-four per cent of the cohort still had some demonstrable improvement after a mean of 6.5 years post-retention. There was a residual need for treatment in 8% of cases on aesthetic grounds and in 24% of cases on dental health grounds.
  
  
  CONCLUSIONS
  Occlusal deterioration after orthodontic treatment is almost universal. Dual arch fixed appliance treatment provides the best post-treatment and post-retention result.
authors.affiliation: SpR(FTTA), Orthodontic Department, Edinburgh Dental Institute. linctus@waitrose.com
authors.forename: R A
authors.initials: RA
authors.lastname: Linklater
authors.forename: N A
authors.initials: NA
authors.lastname: Fox
mesh_terms: D015331:Cohort Studies; D004955:Esthetics, Dental; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008310:Malocclusion / Q000145:classification / Q000628:therapy; D008312:Malocclusion, Angle Class II / Q000628:therapy; D008313:Malocclusion, Angle Class III / Q000628:therapy; D003765:Models, Dental; D015588:Observer Variation; D009967:Orthodontic Appliances / Q000145:classification; D018704:Orthodontic Retainers; D009971:Orthodontics, Corrective; D018024:Peer Review, Health Care; D010781:Photography; D012008:Recurrence; D013223:Statistics as Topic; D018709:Statistics, Nonparametric; D016896:Treatment Outcome