title: Stability comparison between commercially available mini-implants and a novel design: part 1.
abstract: OBJECTIVE
  To compare mechanical stability among five mini-implant designs--a newly invented design and four commercially available designs that vary by shape and threading; to calculate external surface area of each design using high-resolution micro-computed tomography; and to evaluate the relationship between surface area and stability results.
  
  
  METHODS
  The four commercially available mini-implants--single-threaded and cylindrical (SC), single-threaded and tapered (ST), double-threaded and cylindrical (DC), double-threaded and tapered (DT)--and a new implant that is designed to engage mostly in cortical bone with shorter and wider dimensions (N1) were inserted in simulated bone with cortical and trabecular bone layers. The mechanical study consisted of torque measurements and lateral displacement tests. External surface area was computed using a 25-µm micro-CT.
  
  
  RESULTS
  Maximum insertion torque, maximum removal torque, and force levels for displacements were the highest in N1, followed by DT, ST, DC, and SC (α  =  .05). The surface area was largest in DT, followed by N1, ST, DC, and SC. Surface area engaged in cortical bone, however, was the greatest in N1. The surface area of mini-implants had positive correlation with stability.
  
  
  CONCLUSIONS
  Among commercial designs, both added tapering and double threading improved stability. N1 was the most stable design within this research design. The new design has the potential to be clinically superior; it has enhanced stability and there is diminished risk of endangering nearby anatomic structures during placement and orthodontic treatment, but the design requires refinements to reduce insertion torque to avoid clinical difficulty and patient discomfort.
authors.affiliation: Section of Orthodontics, UCLA School of Dentistry, Los Angeles, CA 90095, USA.
authors.forename: Christine
authors.initials: C
authors.lastname: Hong
authors.forename: Haofu
authors.initials: H
authors.lastname: Lee
authors.forename: Richard
authors.initials: R
authors.lastname: Webster
authors.forename: Jinny
authors.initials: J
authors.lastname: Kwak
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Wu
authors.forename: Won
authors.initials: W
authors.lastname: Moon
mesh_terms: D000497:Alloys; D000704:Analysis of Variance; D003722:Dental Alloys; D015921:Dental Implants; D003799:Dental Stress Analysis; D004868:Equipment Failure; D008904:Miniaturization; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D014025:Titanium; D019415:Torque; D055114:X-Ray Microtomography
chemical_list: D000497:Alloys; D003722:Dental Alloys; D015921:Dental Implants; C031462:titanium alloy (TiAl6V4); D014025:Titanium