title: Survival of palatal miniscrews used for orthodontic appliance anchorage: a retrospective cohort study.
abstract: BACKGROUND
  The purpose of this study was to examine the overall success of miniscrews inserted in the paramedian palatal region for support of various appliances during orthodontic treatment.
  
  
  METHODS
  The patients received 1 or 2 miniscrews in the paramedian anterior palate of 8.0-mm length and 1.6-mm diameter placed during orthodontic treatment by the same experienced orthodontist.
  
  
  RESULTS
  In total, 196 patients (121 girls, 75 boys; median age, 11.7; interquartile range, 3.7) who received 384 miniscrews were evaluated. Two hundred four miniscrews were used with rapid palatal expansion appliances, 136 with appliances for distalization of posterior teeth, and 44 with other appliances, such as transpalatal arches for tooth stabilization. The overall survival of the miniscrews was excellent (97.9%) in the cases examined. Cox regression analysis showed no difference in the overall survival rates of miniscrews loaded with different appliances for sex (hazard ratio, 0.95; 95% confidence interval, 0.71-1.27; P = 0.73) after adjusting for appliance and age.
  
  
  CONCLUSIONS
  This study shows that miniscrews placed in the paramedian anterior palate for supporting various orthodontic appliances have excellent survival.
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Faculty of Medicine, University of Bern, Bern, Switzerland.
authors.forename: Angeliki
authors.initials: A
authors.lastname: Karagkiolidou
authors.forename: Björn
authors.initials: B
authors.lastname: Ludwig
authors.forename: Pawel
authors.initials: P
authors.lastname: Pazera
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Gkantidis
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Pandis
authors.forename: Christos
authors.initials: C
authors.lastname: Katsaros
mesh_terms: D000293:Adolescent; D000328:Adult; D001863:Bone Screws; D002648:Child; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D010155:Palatal Expansion Technique / Q000295:instrumentation; D010159:Palate / Q000601:surgery*; D012189:Retrospective Studies; D016019:Survival Analysis; D014087:Tooth Movement Techniques / Q000295:instrumentation; D016896:Treatment Outcome; D055815:Young Adult