title: Assessment of damping capacity as an index of root proximity in self-drilling orthodontic mini-implants.
abstract: OBJECTIVE
  This study aims to investigate orthodontic mini-implant root proximity, placement torque, and damping capacity and to determine whether placement torque and damping capacity (Periotest value (PTV)) are useful indices for the estimation of mini-implant root proximity.
  
  
  METHODS
  The root proximity of 143 orthodontic mini-implants (1.6 mm diameter, 8 mm screw thread length) was evaluated in 79 patients (24 males, 55 females; mean age, 22.5 ± 8 years) using cone-beam computed tomography. The placement torque and PTV of each implant were determined using a torque tester and the Periotest, respectively. Variability in these values according to root proximity was evaluated.
  
  
  RESULTS
  PTVs of mini-implants with multiple (two or more) points of contact between the root and implant were significantly larger than those of mini-implants with no root contact in the self-drilling group. Placement torque did not differ significantly according to root proximity. In the self-drilling group, the odds ratio for root contact was 20.82 (P = 0.000) for a PTV >6.
  
  
  CONCLUSIONS
  Placement torque could not be used to estimate root proximity. The PTV was significantly affected by root proximity in the self-drilling group.
  
  
  CONCLUSIONS
  A threshold of PTV >6 could be applied clinically for the estimation of self-drilling mini-implant root proximity.
authors.affiliation: Department of Orthodontics, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyodaku, Tokyo, 1018310, Japan, motoyoshi.mitsuru@nihon-u.ac.jp.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Motoyoshi
authors.forename: Yasuki
authors.initials: Y
authors.lastname: Uchida
authors.forename: Miho
authors.initials: M
authors.lastname: Matsuoka
authors.forename: Mizuki
authors.initials: M
authors.lastname: Inaba
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Iwai
authors.forename: Yoko
authors.initials: Y
authors.lastname: Karasawa
authors.forename: Noriyoshi
authors.initials: N
authors.lastname: Shimizu
mesh_terms: D000293:Adolescent; D000328:Adult; D001863:Bone Screws; D054893:Cone-Beam Computed Tomography; D015921:Dental Implants; D005260:Female; D006801:Humans; D008297:Male; D014092:Tooth Root; D019415:Torque; D055815:Young Adult
chemical_list: D015921:Dental Implants