title: [Clinical evaluation of preadjusted appliance based on Chinese normal occlusion].
abstract: OBJECTIVE
  To evaluate the effect of the preadjusted appliance (Z1 appliance) based on Chinese normal occlusion.
  
  
  METHODS
  Thirty non-extraction patients were treated with Z1 appliance. No wire bending was made during treatment. The results of these 30 cases had been evaluated by five senior orthodontists. Models were analysed quantitatively to testify and evaluate the efficiency of the appliance.
  
  
  RESULTS
  The average score for post-treatment models was 91.2 (total score was 100). The model measurements indicated that average projective distance on occlusal plane between proximal contact points of adjacent teeth was less than 0.3 mm, which demonstrated good alignment. The prominence of crowns was almost coincident with the data of Chinese normal occlusion. For the average tip of most teeth, there was no statistical difference between the study group and the normal control group. The crown torque variation tendency from anterior to posterior was similar to that in the subjects with normal occlusion. However, the cases treated with Z1 appliance achieved more negative torque in the lower posterior segment.
  
  
  CONCLUSIONS
  The result of the non-extraction patients treated with Z1 appliance was quite satisfied. Wire bending could be reduced during treatment. It was necessary to adjust the crown torque values for lower posterior teeth.
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.forename: Xue-Mei
authors.initials: XM
authors.lastname: Gao
authors.forename: Xiang-Long
authors.initials: XL
authors.lastname: Zeng
mesh_terms: D000293:Adolescent; D044466:Asian People; D002648:Child; D003766:Dental Occlusion; D005260:Female; D006801:Humans; D008297:Male; D016382:Orthodontic Appliance Design; D009967:Orthodontic Appliances; D009971:Orthodontics, Corrective / Q000295:instrumentation* / Q000379:methods*; D055815:Young Adult