title: Do dual-thread orthodontic mini-implants improve bone/tissue mechanical retention?
abstract: OBJECTIVE
  The aim of this study was to understand whether the pitch relationship between micro and macro thread designs with a parametrical relationship in a dual-thread mini-implant can improve primary stability.
  
  
  METHODS
  Three types of mini-implants consisting of single-thread (ST) (0.75 mm pitch in whole length), dual-thread A (DTA) with double-start 0.375 mm pitch, and dual-thread B (DTB) with single-start 0.2 mm pitch in upper 2-mm micro thread region for performing insertion and pull-out testing. Histomorphometric analysis was performed in these specimens in evaluating peri-implant bone defects using a non-contact vision measuring system.
  
  
  RESULTS
  The maximum inserted torque (Tmax) in type DTA was found to be the smallest significantly, but corresponding values found no significant difference between ST and DTB. The largest pull-out strength (Fmax) in the DTA mini-implant was found significantly greater than that for the ST mini-implant regardless of implant insertion orientation. Mini-implant engaged the cortical bone well as observed in ST and DTA types.
  
  
  CONCLUSIONS
  Dual-thread mini-implant with correct micro thread pitch (parametrical relationship with macro thread pitch) in the cortical bone region can improve primary stability and enhanced mechanical retention.
authors.affiliation: *Student, Department of Mechanical Engineering, Chang Gung University, Taoyuan, Taiwan. †Professor, Department of Mechanical Engineering, Chang Gung University, Taoyuan, Taiwan. ‡Associate Professor, School of Dentistry, China Medical University, Taichung, Taiwan. §Professor, Department of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Yang-Sung
authors.initials: YS
authors.lastname: Lin
authors.forename: Yau-Zen
authors.initials: YZ
authors.lastname: Chang
authors.forename: Jian-Hong
authors.initials: JH
authors.lastname: Yu
authors.forename: Chun-Li
authors.initials: CL
authors.lastname: Lin
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D066298:In Vitro Techniques; D012272:Ribs / Q000601:surgery; D013314:Stress, Mechanical; D013552:Swine; D019415:Torque
chemical_list: D015921:Dental Implants