title: Age-related long-term posttreatment occlusal and arch changes.
abstract: OBJECTIVE
  To evaluate differences in long-term postretention changes between adolescents and adults.
  
  
  METHODS
  The sample included 96 subjects, 51 adolescents and 45 adults (14.2 +/- 0.8 and 21.5 +/- 6.8 years of age, respectively, at the end of treatment) retained for 3 years and followed approximately 16 years post treatment, who were randomly selected from two private practices. Prior to treatment, 38 and 58 had Class I and Class II malocclusions, respectively.
  
  
  RESULTS
  With the exception of adult midlines, all of the occlusal variables (overjet [0.50-0.77 mm], overbite [0.85-0.95 mm], the maxillary incisor irregularity [0.69-0.80 mm], the mandibular incisor irregularity [0.85-1.50 mm] and the PAR score [0.86-1.92 points]) showed significant increases over time. Adolescents consistently showed greater increases of the occlusal variables than adults, with mandibular incisor irregularity and the PAR index attaining statistically significant (P < .05) levels. Arch length and mandibular intercanine width showed statistically significant decreases over time in both groups; maxillary intercanine and intermolar widths did not change significantly. Overjet increased significantly more in Class II patients than in Class I patients, whereas Class I patients showed significantly greater decreases in mandibular intermolar width than Class II patients.
  
  
  CONCLUSIONS
  Over the 16-year posttreatment period, adolescents showed significantly greater increases in mandibular incisor irregularity, and the PAR index than adults. Treated Class I patients demonstrated less increase in overjet and greater decreases in mandibular intermolar width than Class II patients.
authors.affiliation: Department of Orthodontics, Baylor College of Dentistry, Dallas, TX 75246, USA.
authors.forename: Hyunjung
authors.initials: H
authors.lastname: Park
authors.forename: Jim C
authors.initials: JC
authors.lastname: Boley
authors.forename: Richard A
authors.initials: RA
authors.lastname: Alexander
authors.forename: Peter H
authors.initials: PH
authors.lastname: Buschang
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002508:Cephalometry; D003724:Dental Arch / Q000473:pathology*; D004955:Esthetics, Dental; D005260:Female; D006801:Humans; D008297:Male; D008311:Malocclusion, Angle Class I / Q000628:therapy*; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D008445:Maxillofacial Development; D009971:Orthodontics, Corrective; D011336:Probability; D012008:Recurrence; D018709:Statistics, Nonparametric; D016896:Treatment Outcome; D055815:Young Adult