title: Impact of implant design on primary stability of orthodontic mini-implants.
abstract: OBJECTIVE
  Skeletal anchorage with mini-implants has greatly broadened the treatment possibilities in orthodontics over the last few years. To reduce implant failure rates, it is advisable to obtain adequate primary stability. The aim of this study was to quantitatively analyze the impact of implant design and dimension on primary stability.
  
  
  METHODS
  Forty-two porcine iliac bone segments were prepared and embedded in resin. To evaluate the primary stability, we documented insertion torques of the following mini-implants: Aarhus Screw, AbsoAnchor, LOMAS, Micro-Anchorage-System, ORLUS and Spider Screw. In each bone, five Dual Top Screws were inserted for reference purposes to achieve comparability among the specimens.
  
  
  RESULTS
  We observed wide variation in insertion torques and hence primary stability, depending on mini-implant design and dimension; the great impact that mini-implant diameter has on insertion torques was particularly conspicuous. Conical mini-implants achieved higher primary stabilities than cylindrical designs.
  
  
  CONCLUSIONS
  The diameter and design of the mini-implant thread have a distinctive impact on primary stability. Depending on the region of insertion and local bone quality, the choice of the mini-implant design and size is crucial to establish sufficient primary stability.
authors.affiliation: Poliklinik für Kieferorthopädie, Heinrich Heine Universität Düsseldorf, Moorenstrasse 5, Düsseldorf, Germany. wilmes@med.uni-duesseldorf.de
authors.forename: Benedict
authors.initials: B
authors.lastname: Wilmes
authors.forename: Stephanie
authors.initials: S
authors.lastname: Ottenstreuer
authors.forename: Yu-Yu
authors.initials: YY
authors.lastname: Su
authors.forename: Dieter
authors.initials: D
authors.lastname: Drescher
mesh_terms: D000818:Animals; D001863:Bone Screws; D003758:Dental Implantation, Endosseous / Q000295:instrumentation*; D017267:Dental Prosthesis Design; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D013552:Swine; D019415:Torque