title: Torque ratio as a predictable factor on primary stability of orthodontic miniscrew implants.
abstract: OBJECTIVE
  To evaluate the torque ratio (TR) as a predictable factor on primary stability of orthodontic miniscrews.
  
  
  METHODS
  Fifty-eight orthodontic patients (17 men, 41 women; mean age, 21.9 years) with a total of 112 titanium miniscrews of 3 different diameters were subjected. Maximum insertion torque (MIT) and maximum removal torque (MRT) were measured by a digital torque checker at the screw placement. Four weeks after the placement, the stable screw was recorded as a success. Multiple logistic regression analysis was performed to estimate the influence of each clinical variable on success.
  
  
  RESULTS
  Success rates were 82.1% to 89.5%, and there were no significant differences in the 3 types of miniscrews. MIT and MRT showed a positive correlation but did not affect the success rates of miniscrews directly. On the contrary, TR was significantly higher in the success group than in the failure group. In multiple regression analysis, age, TR, and screw proximity had a significant influence on the miniscrew success.
  
  
  CONCLUSIONS
  TR might be related with the miniscrew success rates, and it can be used as a predictable factor on primary stability of orthodontic miniscrew implants. Miniscrew implants should be replaced if MRT is significantly lower than MIT at placement surgery.
authors.affiliation: *Graduate Student, Department of Orthodontics and Dentofacial Orthopedics, The University of Tokushima Graduate School of Oral Sciences, Tokushima, Japan. †Associate Professor, Department of Orthodontics and Dentofacial Orthopedics, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan. ‡Senior Assistant Professor, Department of Orthodontics and Dentofacial Orthopedics, The Tokushima University Hospital, Tokushima, Japan. §Professor, Department of Orthodontics, School of Dentistry, Kyungpook National University, Daegu, South Korea. ‖Professor and Chair, Department of Orthodontics and Dentofacial Orthopedics, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan.
authors.forename: Masahide
authors.initials: M
authors.lastname: Inoue
authors.forename: Shingo
authors.initials: S
authors.lastname: Kuroda
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yasue
authors.forename: Shinya
authors.initials: S
authors.lastname: Horiuchi
authors.forename: Hee-Moon
authors.initials: HM
authors.lastname: Kyung
authors.forename: Eiji
authors.initials: E
authors.lastname: Tanaka
mesh_terms: D001863:Bone Screws; D009970:Orthodontics; D019415:Torque