title: Stress Induced in Periodontal Ligament under Orthodontic Loading (Part II): A Comparison of Linear Versus Non-Linear Fem Study.
abstract: BACKGROUND
  Simulation of periodontal ligament (PDL) using non-linear finite element method (FEM) analysis gives better insight into understanding of the biology of tooth movement. The stresses in the PDL were evaluated for intrusion and lingual root torque using non-linear properties.
  
  
  METHODS
  A three-dimensional (3D) FEM model of the maxillary incisors was generated using Solidworks modeling software. Stresses in the PDL were evaluated for intrusive and lingual root torque movements by 3D FEM using ANSYS software. These stresses were compared with linear and non-linear analyses.
  
  
  RESULTS
  For intrusive and lingual root torque movements, distribution of stress over the PDL was within the range of optimal stress value as proposed by Lee, but was exceeding the force system given by Proffit as optimum forces for orthodontic tooth movement with linear properties. When same force load was applied in non-linear analysis, stresses were more compared to linear analysis and were beyond the optimal stress range as proposed by Lee for both intrusive and lingual root torque. To get the same stress as linear analysis, iterations were done using non-linear properties and the force level was reduced.
  
  
  CONCLUSIONS
  This shows that the force level required for non-linear analysis is lesser than that of linear analysis.
authors.affiliation: Professor and Head, Department of Orthodontics and Dentofacial Orthopaedics, Dayananda Sagar College of Dental Sciences, Bengaluru, Karnataka, India.
authors.forename: M
authors.initials: M
authors.lastname: Hemanth
authors.affiliation: Consulting Orthodontist at Vasan Dental Care, Bengaluru, Karnataka, India.
authors.forename: Shilpi
authors.initials: S
authors.lastname: Deoli
authors.affiliation: Professor and Head, Department of Oral and Maxillofacial Surgery, Dayananda Sagar College of Dental Sciences, Bengaluru, Karnataka, India.
authors.forename: H P
authors.initials: HP
authors.lastname: Raghuveer
authors.affiliation: Professor and Head, Department of Orthodontics and Dentofacial Orthopaedics, Vokkaligara Sangha Dental College, Bengaluru, Karnataka, India.
authors.forename: M S
authors.initials: MS
authors.lastname: Rani
authors.affiliation: Reader, Department of Orthodontics and Dentofacial Orthopaedics, Dayananda Sagar College of Dental Sciences, Bengaluru, Karnataka, India.
authors.forename: Chatura
authors.initials: C
authors.lastname: Hegde
authors.affiliation: Reader, Department of Conservative Dentistry and Endodontics, Dayananda Sagar College of Dental Sciences, Bengaluru, Karnataka, India.
authors.forename: B
authors.initials: B
authors.lastname: Vedavathi
keywords: Finite element method; intrusion; lingual root torque; non-linear analysis