title: Stability of miniplates and miniscrews used for orthodontic anchorage: experience with 492 temporary anchorage devices.
abstract: OBJECTIVE
  The aim of this retrospective study was to evaluate systematically the potential factors that influence failure rates of temporary anchorage devices (TADs) used for orthodontic anchorage.
  
  
  METHODS
  Data on 492 TADs (miniplates, pre-drilling miniscrews, and self-drilling miniscrews) in 194 patients were collected. The factors related to TAD failure were evaluated using univariate analysis and multivariate forward stepwise logistic regression analysis.
  
  
  RESULTS
  There were no significant differences in failure rates among the TADs for the following variables: gender, type of malocclusion, facial divergency, implantation site (buccal, lingual, or crestal/midpalatal), location (anterior or posterior), method of force application (power chain or Ni-Ti coil spring), arch (upper or lower), type of soft tissue (attached gingiva or removable mucosa), and most of the cephalometric measurements that reflect dento-cranio-facial characteristics. An increased failure rate was noted for the self-drilling miniscrew type of TAD, TADs used for tooth uprighting, those inserted on bone with lower density, those associated with local inflammation of the surrounding soft tissue, those loaded within 3 weeks after insertion, and those placed in patients with greater mandibular retrusion. Failure rates of the self-drilling miniscrews installed by an oral surgeon and by an orthodontist did not differ significantly.
  
  
  CONCLUSIONS
  Inflammation of soft tissue surrounding a TAD and early loading within 3 weeks after insertion were the most significant factors predicting TAD failure. Both orthodontists and oral surgeons who install orthodontic TADs must undergo sufficient training to achieve clinical excellence.
authors.affiliation: Department of Orthodontics, School of Dentistry, National Taiwan University, Dental Department, National Taiwan University Hospital, Taiwan.
authors.forename: Yi-Jane
authors.initials: YJ
authors.lastname: Chen
authors.forename: Hao-Hueng
authors.initials: HH
authors.lastname: Chang
authors.forename: Hsing-Yi
authors.initials: HY
authors.lastname: Lin
authors.forename: Eddie Hsian-Hua
authors.initials: EH
authors.lastname: Lai
authors.forename: Hsin-Chia
authors.initials: HC
authors.lastname: Hung
authors.forename: Chung-Chen Jane
authors.initials: CC
authors.lastname: Yao
mesh_terms: D000293:Adolescent; D000328:Adult; D001860:Bone Plates; D001863:Bone Screws; D002508:Cephalometry; D002648:Child; D003799:Dental Stress Analysis; D004868:Equipment Failure; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008904:Miniaturization; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D012189:Retrospective Studies; D014087:Tooth Movement Techniques / Q000295:instrumentation*; D055815:Young Adult