title: An in vitro investigation of peak insertion torque values of six commercially available mini-implants.
abstract: This study compared peak insertion torque values of six commercially available self-drilling mini-implants [Mini Spider® screw (1.5 × 8 mm), Infinitas® (1.5 × 9 mm), Vector TAS® (1.4 × 8 mm), Dual Top® (1.6 × 8 mm), Tomas Pin® (1.6 × 8 mm), and Ortho-Easy® (1.7 × 6, 8, and 10 mm)]. Twenty implants each were drilled into acrylic rods at a speed of 8 rpm using a motorized torque measurement stand, and the values were recorded in Newton centimetres (Ncm). A further 20 Ortho-Easy® implants with a length of 6 and 10 mm were tested at 8 rpm; 20 implants of 6 mm length were also tested at 4 rpm. Kaplan-Meier estimates of the peak torque values were compared using the log-rank test with multiple comparisons evaluated by Sidak's test. There were significant differences in the maximum torque values for different mini-implants with the same length. The Mini Spider® screw and Infinitas® showed the lowest average torque values (6.5 and 12.4 Ncm) compared with Vector TAS®, Dual ToP®, Tomas Pin®, and Ortho-Easy® (30.9, 29.4, 25.4, and 24.8 Ncm, respectively). There was no correlation between the diameter of the implants and torque values. The Tomas Pin® showed the largest standard deviation (7.7 Ncm) and the Dual Top® implant the smallest (0.6 Ncm). Different insertion speeds did not result in significant differences in peak torque values but the 6 mm mini-implants showed significantly higher torque values than the 8 and 10 mm implants. Using a 'torque limiting' screwdriver or pre-drilling cortical bone to reduce insertion, torque appears justified for some of the tested implants.
authors.affiliation: Department of Orthodontics, King's College London Dental Institute, UK.
authors.forename: C Z Y
authors.initials: CZ
authors.lastname: Whang
authors.forename: D
authors.initials: D
authors.lastname: Bister
authors.forename: M
authors.initials: M
authors.lastname: Sherriff
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D018786:Bone Substitutes / Q000737:chemistry; D015921:Dental Implants; D004868:Equipment Failure; D006801:Humans; D008422:Materials Testing; D008904:Miniaturization; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D013314:Stress, Mechanical; D013499:Surface Properties; D019415:Torque
chemical_list: D000180:Acrylic Resins; D018786:Bone Substitutes; D015921:Dental Implants