title: Comparison of third-order torque simulation with and without a periodontal ligament simulant.
abstract: BACKGROUND
  This in-vitro study presents the development and validation of an artificial tooth-periodontal ligament-bone complex (ATPBC) and comparison of its behavior with that of rigid dowels during third-order torque simulation.
  
  
  METHODS
  ATPBCs were coupled using a 1:1 mixture of room-temperature vulcanization silicone and gasket sealant to act as a periodontal ligament simulant (PDLS). PDLS thicknesses ranging from 0.2 to 0.7 mm, in increments of 0.1 mm (n = 5 for each thickness), were tested using a linear crown displacement procedure. A suitable PDLS thickness was selected for use in third-order torque simulations to compare ATPBC (n = 29) and rigid (n = 24) dowel behavior. Their results were compared for archwire rotations up to 20° for both loading and unloading curves with repeated-measures analysis of variance.
  
  
  RESULTS
  When used in third-order torque simulations, the ATPBC dowels with a 0.5-mm PDLS thickness showed a statistically significant difference from rigid dowels (P = 0.020), with a 95% confidence interval (0.254, 2.897 N·mm) and a mean difference of 1.575 N·mm.
  
  
  CONCLUSIONS
  Inclusion of a PDLS in an ATPBC resulted in a statistical difference when compared with rigid dowels; however, the region where behavior differed was at low angles of archwire rotation, and the resultant torque was arguably outside a clinically relevant range.
authors: Undergraduate research assistant, Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada.
authors: Michael G
authors: MG
authors: George
authors: Postdoctoral fellow, School of Dentistry, University of Alberta, Edmonton, Alberta, Canada.
authors: Dan L
authors: DL
authors: Romanyk
authors: Undergraduate research assistant, Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada.
authors: Andrew
authors: A
authors: George
authors: Graduate student, Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, Alberta, Canada.
authors: Yin
authors: Y
authors: Li
authors: Associate professor, School of Dentistry, University of Alberta, Edmonton, Alberta, Canada.
authors: Giseon
authors: G
authors: Heo
authors: Professor and department chair, School of Dentistry, University of Alberta, Edmonton, Alberta, Canada.
authors: Paul W
authors: PW
authors: Major
authors: Professor and associate chair, Undergraduate Program, Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada. Electronic address: jason.carey@ualberta.ca.
authors: Jason P
authors: JP
authors: Carey
mesh_terms: D000539:Alveolar Process / Q000033:anatomy & histology / Q000502:physiology*; D001696:Biomechanical Phenomena; D003187:Compliance; D003722:Dental Alloys / Q000737:chemistry; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology / Q000502:physiology*; D008689:Methacrylates / Q000737:chemistry; D008953:Models, Anatomic; D009967:Orthodontic Appliances; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D010513:Periodontal Ligament / Q000033:anatomy & histology / Q000502:physiology*; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011897:Random Allocation; D015203:Reproducibility of Results; D012399:Rotation; D012828:Silicones / Q000737:chemistry; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D014087:Tooth Movement Techniques / Q000295:instrumentation*; D020390:Tooth Socket / Q000033:anatomy & histology / Q000502:physiology; D014093:Tooth, Artificial; D019415:Torque
chemical_list: D003722:Dental Alloys; D008689:Methacrylates; D012828:Silicones; D013193:Stainless Steel; C038690:Loctite; D019904:Polymethyl Methacrylate