title: Peak insertion torque values of five mini-implant systems under different insertion loads.
abstract: OBJECTIVE
  To assess the effect of 1 and 3 kg insertion load on five makes of self-drilling mini-implants on peak insertion torque values to establish risk factors involved in the fracture of mini-implants.
  
  
  METHODS
  Two different loads were applied during insertion of 40 mini-implants from five different manufacturers (Dual Top(™) (1·6×8 mm), Infinitas(™) (1·5×9 mm), Ortho Easy(™) (1·7×8 mm), Spider Screw(™) (1·5×8 mm) and Vector TAS(™) (1·4×8 mm)) into acrylic blocks at 8 rev/min utilizing a Motorized Torque Measurement Stand.
  
  
  RESULTS
  Peak insertion torque values for both loads were highest for Vector TAS followed by Ortho Easy and Dual Top and were nearly three times higher than Infinitas (original version) and Spider Screws(TM). The log-rank test showed statistically significant differences for both loads for Vector TAS, Ortho Easy and Spider Screws. Unlike other designs tested, both tapered mini-implant designs (Spider Screw and Infinitas) showed a tendency to buckle in the middle of the body but fractured at the tip.
  
  
  CONCLUSIONS
  Non-tapered mini-implants fractured at significantly higher torque values compared to tapered designs under both loads. Increased pressure resulted in slightly higher maximum torque values at fracture for some of the mini-implant designs, although this is unlikely to be of clinical relevance. Tripling insertion pressure from 1 to 3 kg increased the risk of bending tapered mini-implants before fracture.
authors: Department of Orthodontics, Dental Institute, Kings College London, London, UK School of Oral and Dental Sciences, University of Bristol, Bristol, UK.
authors: Erma
authors: E
authors: Quraishi
authors: Department of Orthodontics, Dental Institute, Kings College London, London, UK School of Oral and Dental Sciences, University of Bristol, Bristol, UK.
authors: Martyn
authors: M
authors: Sherriff
authors: Department of Orthodontics, Dental Institute, Kings College London, London, UK School of Oral and Dental Sciences, University of Bristol, Bristol, UK.
authors: Dirk
authors: D
authors: Bister
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry; D015921:Dental Implants; D003764:Dental Materials / Q000737:chemistry; D004868:Equipment Failure; D006801:Humans; D008422:Materials Testing; D008904:Miniaturization; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation* / Q000379:methods; D016382:Orthodontic Appliance Design; D011312:Pressure; D012307:Risk Factors; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D019415:Torque
chemical_list: D000180:Acrylic Resins; D003722:Dental Alloys; D015921:Dental Implants; D003764:Dental Materials; D014025:Titanium
keywords: Mini-implants; insertion loads; orthodontics; pressure; temporary anchorage devices; torque