title: Cone-beam computed tomography evaluation of orthodontic miniplate anchoring screws in the posterior maxilla.
abstract: BACKGROUND
  The purposes of this study were to evaluate the actual postplacement positions of orthodontic miniplate anchoring screws (MPAS) and to determine the risk factors for their failure and iatrogenic effects on the intraoral structures.
  
  
  METHODS
  Three-dimensional cone-beam computed tomography images were generated to examine 31 orthodontic miniplates and their MPAS (diameter, 1.5 mm; length, 4 mm), which showed good clinical stability 6 months after placement in the posterior maxilla of 18 patients. The cone-beam computed tomography data were analyzed with analysis of variance (ANOVA) statistics to evaluate the difference of placement depth and vertical distance of the MPAS from the cementoenamel junction to the center of the screw. The Fisher exact test was used to determine differences in MPAS position, root proximity, and sinus penetration.
  
  
  RESULTS
  The mean placement depth of the MPAS was 2.48 mm with no significant difference relative to their position. Twenty-six (of 74) MPAS were placed in the dentition area. Of these 26, 14 were placed in interdental spaces, and the other 12 followed the direction of the roots. Nine MPAS showed root proximity, and 7 MPAS had root penetration, all of which were placed in the central position of the miniplate. Thirty-nine MPAS penetrated the sinus, indicating a low interrelationship between placement depth and cortical bone thickness of the sinus.
  
  
  CONCLUSIONS
  Miniplates were successfully retained by MPAS even with less-than-ideal placement. Root contact and proximity of MPAS seem to have minimal effects on the successful stabilization of miniplates. Pertinent guidelines should, however, be followed during MPAS placement to minimize the risk of damage to adjacent roots.
authors.affiliation: Department of Oral and Maxillofacial Radiology, School of Dentistry, KyungHee University, Seoul, Korea.
authors.forename: Gyu-Tae
authors.initials: GT
authors.lastname: Kim
authors.forename: Seong-Hun
authors.initials: SH
authors.lastname: Kim
authors.forename: Yong-Suk
authors.initials: YS
authors.lastname: Choi
authors.forename: Young-Joon
authors.initials: YJ
authors.lastname: Park
authors.forename: Kyu-Rhim
authors.initials: KR
authors.lastname: Chung
authors.forename: Kyung-Eun
authors.initials: KE
authors.lastname: Suk
authors.forename: HyeRan
authors.initials: H
authors.lastname: Choo
authors.forename: John C
authors.initials: JC
authors.lastname: Huang
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001860:Bone Plates; D001863:Bone Screws / Q000009:adverse effects; D054893:Cone-Beam Computed Tomography; D019232:Dental Restoration Failure; D005260:Female; D006801:Humans; D008297:Male; D008437:Maxilla / Q000000981:diagnostic imaging / Q000601:surgery*; D052280:Orthodontic Anchorage Procedures / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D009971:Orthodontics, Corrective / Q000295:instrumentation* / Q000379:methods; D018709:Statistics, Nonparametric; D014092:Tooth Root / Q000000981:diagnostic imaging / Q000293:injuries*