title: Fracture resistance of commonly used self-drilling orthodontic mini-implants.
abstract: OBJECTIVE
  To investigate the fracture resistance of six commonly used self-drilling orthodontic mini-implants by comparing their respective fracture torques during insertion.
  
  
  METHODS
  Ninety self-drilling mini-implants from six manufacturers (Aarhus, Dual-Top, OrthoEasy, Tomas-pin, Unitek, and VectorTAS), with diameters ranging from 1.4 to 1.8 mm, were inserted into acrylic blocks using a custom-made insertion device. Insertion torques were measured using a 6-degree-of-freedom load cell fixed to the base of the acrylic blocks, and peak torques experienced at the time of fracture for each of the mini-implants were recorded. One-way analysis of variance (α  =  .05) was used to compare the fracture torques among the six different groups.
  
  
  RESULTS
  Statistical analysis revealed significant differences (P < .05) in the peak fracture torques among mini-implant groups. Mean fracture torques ranked as follows: Unitek (72 Ncm) > Tomas-pin (36 Ncm) > Dual-Top (32 Ncm) ≈ VectorTAS (31 Ncm) > OrthoEasy (28 Ncm) > Aarhus (25 Ncm), with significant differences found between all manufacturers, except for Dual-Top and VectorTAS.
  
  
  CONCLUSIONS
  Mini-implants tested showed a wide range of torque at fracture depending on the manufacturer, with only a weak correlation between mini-implant diameter and fracture resistance. This torque should be considered at the time of mini-implant insertion to minimize the risk of implant fracture, especially in areas of high-density bone without predrilling.
authors.affiliation: a  Private practice, Kelowna, British Columbia, Canada.
authors.forename: Angie
authors.initials: A
authors.lastname: Smith
authors.forename: Yara K
authors.initials: YK
authors.lastname: Hosein
authors.forename: Cynthia E
authors.initials: CE
authors.lastname: Dunning
authors.forename: Ali
authors.initials: A
authors.lastname: Tassi
mesh_terms: D000497:Alloys; D003722:Dental Alloys / Q000737:chemistry; D015921:Dental Implants; D003799:Dental Stress Analysis / Q000295:instrumentation; D004868:Equipment Failure; D006801:Humans; D008422:Materials Testing; D008904:Miniaturization; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D019904:Polymethyl Methacrylate / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors; D014025:Titanium / Q000737:chemistry; D019415:Torque
chemical_list: D000497:Alloys; D003722:Dental Alloys; D015921:Dental Implants; C031462:titanium alloy (TiAl6V4); D019904:Polymethyl Methacrylate; D014025:Titanium
keywords: Fracture torque; Insertion torque; Mini-implant; Miniscrew; Orthodontics; Temporary anchorage device