title: Posterior occlusion changes with a Hawley vs Perfector and Hawley retainer. A follow-up study.
abstract: OBJECTIVE
  To characterize postorthodontic settling of the posterior occlusion of patients wearing Hawley retainers vs patients who initially wore Perfector retainers and then switched to Hawley retainers.
  
  
  METHODS
  This follow-up study was based on 40 patients (25 Perfector and 15 Hawley), who were part of a larger sample of 50 patients randomly assigned to wear either Hawley or Perfector retainers. The Perfector patients were given Hawley retainers 2 months after retainer delivery. Occlusal bite registrations were scanned and traced to quantify posterior areas of contact and near contact (ACNC). A seven-item questionnaire was used to assess the patient's perception of occlusion. Measurements were obtained at the on the day of retainer delivery, 2 months post delivery, 6 months post delivery, and 8 months post delivery.
  
  
  RESULTS
  ACNC increased significantly (P < .05) during the first 6 months of retainer wear. The ACNC of the Hawley and Perfector/Hawley groups increased by 129% and 105%, respectively, over 8 months of retention. The greatest increases in ACNC occurred during the first 2 months. The ACNC further increased between 2 and 6 months in both groups. The Perfector/Hawley group also showed slight increases in ACNC between 6 and 8 months. Overall group differences were not statistically significant. The Perfector/Hawley group perceived greater improvements in occlusion than the Hawley group, but group differences after 8 months were small.
  
  
  CONCLUSIONS
  Substantial amounts of settling occurred at decelerating rates during the first 6 months after retainer delivery. No significant differences in ACNC were found between the Hawley and Perfector/Hawley groups after 8 months of retainer wear.
authors.affiliation: Department of Orthodontics, Saint Louis University, St Louis, MO, USA.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Bauer
authors.forename: Rolf
authors.initials: R
authors.lastname: Behrents
authors.forename: Donald R
authors.initials: DR
authors.lastname: Oliver
authors.forename: Peter H
authors.initials: PH
authors.lastname: Buschang
mesh_terms: D001294:Attitude to Health; D001641:Bicuspid / Q000033:anatomy & histology; D001732:Bite Force; D003760:Dental Impression Materials / Q000737:chemistry; D003766:Dental Occlusion; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007574:Jaw Relation Record / Q000295:instrumentation / Q000379:methods; D008297:Male; D008409:Mastication / Q000502:physiology; D008963:Molar / Q000033:anatomy & histology; D016382:Orthodontic Appliance Design; D018704:Orthodontic Retainers / Q000145:classification*; D013997:Time Factors
chemical_list: D003760:Dental Impression Materials