title: A new method to evaluate the positional stability of a self-drilling miniscrew.
abstract: OBJECTIVE
  To evaluate the positional stability of miniscrews during orthodontic treatment change in cone-beam computed tomography (CBCT).
  
  
  METHODS
  Twenty adult volunteers were enrolled.
  
  
  METHODS
  In all participants, at least two maxillary first premolars were extracted because of protrusion. Each volunteer received six miniscrews in the maxilla, including two loaded miniscrews to retract anterior teeth and four unloaded miniscrews. CBCT scans were obtained at the beginning of space closure (T1) and approximately 11.8 months later (T2). Three-dimensional miniscrew models were constructed at T1 and T2, and the central axes were calculated using a principal component analysis (PCA) technique. Finally, we measured and compared the angle change of all the miniscrews from T1 to T2.
  
  
  RESULTS
  The angle change values of the unloaded and loaded miniscrews were 1.64 ± 1.25° and 1.67 ± 1.15°, respectively. No significant differences in the angle change were observed.
  
  
  CONCLUSIONS
  Cone-beam computed tomography images revealed both the unloaded and loaded miniscrews to be positionally stable during en-masse retraction in this study.
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: G
authors.initials: G
authors.lastname: Chen
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: S
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: X Y
authors.initials: XY
authors.lastname: Zhang
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: R P
authors.initials: RP
authors.lastname: Jiang
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Key Lab of Machine Perception, MOE, Peking University, Beijing, China.
authors.forename: F H
authors.initials: FH
authors.lastname: Shi
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: T M
authors.initials: TM
authors.lastname: Xu
mesh_terms: D000328:Adult; D001641:Bicuspid / Q000601:surgery; D001863:Bone Screws; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008311:Malocclusion, Angle Class I / Q000628:therapy; D008312:Malocclusion, Angle Class II / Q000628:therapy; D008437:Maxilla / Q000601:surgery; D008904:Miniaturization; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D019516:Orthodontic Space Closure / Q000295:instrumentation*; D025341:Principal Component Analysis; D013314:Stress, Mechanical; D014081:Tooth Extraction / Q000379:methods; D055815:Young Adult
keywords: cone-beam computed tomography; miniscrew; orthodontic treatment; stability