title: Selective use of hand and forearm muscles during mini-implant insertion: a natural torquimeter.
abstract: OBJECTIVE
  To compare maximum torque produced by different muscular groups and its influence on mini-implant insertion torque and fracture prevention.
  
  
  METHODS
  A prospective study involving in vivo and in vitro laboratory experiments.
  
  
  METHODS
  Eighty-seven professionals were evaluated for maximum torque produced using a screwdriver with combined action between thumb and index fingers [maximum digital torque (MDT)] and by forearm supination movement [maximum brachial torque (MBT)]. Ninety mini-implants distributed over nine different diameters and twenty commercially available mini-implants of two different diameters and trademarks were fractured to determine the fracture torque (FT). The fracture resistance index (FRI) was obtained from: FRI_MDT = FT/MDT and FRI_MBT = FT/MBT. The analysis of variance (ANOVA) and t tests were used to compare the groups.
  
  
  RESULTS
  MDT was smaller than MBT and both were smaller in females. FT increased for each 0·1 mm of diameter increment. FRI_MDT was greater than FRI_MBT for all diameters. FRI_MDT>1 was found when the diameter was greater than or equal to 1·5 mm. FRI_MBT>1 occurred with diameters equal or greater than 1·7 mm for females and 1·8 mm for males. The 1.5 mm and 1.6 mm diameter of commercially available and mini-implants presented FRI_MBT<1 and FRI_MDT>1.
  
  
  CONCLUSIONS
  Digital torque was 42% smaller than brachial torque, and it was mechanically safer and biologically more compatible, allowing fracture prevention of 1·5 mm or thicker mini-implant diameter due to insertion torque limitation at 15 N/cm.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil. sergioestelita@yahoo.com.br
authors.forename: Sérgio
authors.initials: S
authors.lastname: Estelita
authors.forename: Guilherme
authors.initials: G
authors.lastname: Janson
authors.forename: Kelly
authors.initials: K
authors.lastname: Chiqueto
authors.forename: Eduardo
authors.initials: E
authors.lastname: Ferreira
authors.forename: Marcos
authors.initials: M
authors.lastname: Janson
mesh_terms: D001696:Biomechanical Phenomena; D015921:Dental Implants; D004868:Equipment Failure; D005260:Female; D005385:Fingers / Q000502:physiology; D005542:Forearm / Q000502:physiology*; D006225:Hand / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D011446:Prospective Studies; D012737:Sex Factors; D013484:Supination / Q000502:physiology; D013933:Thumb / Q000502:physiology; D019415:Torque; D054159:Torsion, Mechanical
chemical_list: D015921:Dental Implants