title: Influence of Manual Screwdriver Design in Combination With and Without Predrilling on Insertion Torque of Orthodontic Mini-Implants.
abstract: OBJECTIVE
  The study focused on the influence of screwdriver design in combination with and without predrilling a pilot hole of inner implant diameter on insertion torque of orthodontic mini-implants, controlling for cortical thickness and vertical insertion force as cofactors.
  
  
  METHODS
  One hundred twenty mini-implants (Forestadent) of 1.7 mm in diameter and 6 and 8 mm in length were manually inserted into 120 swine rib bone samples. Maximal insertion torque as a measure of primary stability and vertical force were measured. The study included procedures with and without pilot hole and different screwdriver handles and shaft length and 2 implant lengths.
  
  
  RESULTS
  Design of manual screwdriver does not modify insertion torque to a significant extent. In multiple linear regression model, significant predictors of insertion torque are thicker cortical bone (explaining 16.6% of variability), higher vertical force at maximal torque (13.5%), 6-mm implant length (2.5%), and the presence of pilot hole (2.3%).
  
  
  CONCLUSIONS
  Handle type and shaft length of manual screwdriver do not significantly influence insertion torque, whereas predrilling a pilot hole has low impact on torque values of manually inserted self-drilling orthodontic mini-implants.
authors.affiliation: *PhD Student, School of Medicine, University of Rijeka, Rijeka, Croatia. †Research Fellow, Department of Orthodontics, School of Medicine, University of Rijeka, Rijeka, Croatia. ‡Associate Professor and Department Head, Department of Orthodontics, School of Medicine, University of Rijeka, Rijeka, Croatia.
authors.forename: Andrej
authors.initials: A
authors.lastname: Katalinic
authors.forename: Magda
authors.initials: M
authors.lastname: Trinajstic Zrinski
authors.forename: Zlatka
authors.initials: Z
authors.lastname: Roksandic Vrancic
authors.forename: Stjepan
authors.initials: S
authors.lastname: Spalj
mesh_terms: D000818:Animals; D003758:Dental Implantation, Endosseous / Q000295:instrumentation* / Q000379:methods; D015921:Dental Implants; D003762:Dental Instruments; D017268:Dental Prosthesis Retention; D003799:Dental Stress Analysis; D012272:Ribs / Q000601:surgery; D013552:Swine; D019415:Torque
chemical_list: D015921:Dental Implants