title: Stress Induced in the Periodontal Ligament under Orthodontic Loading (Part I): A Finite Element Method Study Using Linear Analysis.
abstract: BACKGROUND
  Orthodontic tooth movement is a complex procedure that occurs due to various biomechanical changes in the periodontium. Optimal orthodontic forces yield maximum tooth movement whereas if the forces fall beyond the optimal threshold it can cause deleterious effects. Among various types of tooth movements intrusion and lingual root torque are associated with causing root resoprtion, especially with the incisors. Therefore in this study, the stress patterns in the periodontal ligament (PDL) were evaluated with intrusion and lingual root torque using finite element method (FEM).
  
  
  METHODS
  A three-dimensional (3D) FEM model of the maxillary incisors was generated using SOLIDWORKS modeling software. Stresses in the PDL were evaluated with intrusive and lingual root torque movements by a 3D FEM using ANSYS software using linear stress analysis.
  
  
  RESULTS
  It was observed that with the application of intrusive load compressive stresses were distributed at the apex whereas tensile stress was seen at the cervical margin. With the application of lingual root torque maximum compressive stress was distributed at the apex and tensile stress was distributed throughout the PDL.
  
  
  CONCLUSIONS
  For intrusive and lingual root torque movements stress values over the PDL was within the range of optimal stress value as proposed by Lee, with a given force system by Proffit as optimum forces for orthodontic tooth movement using linear properties.
authors.affiliation: Professor and Head, Department of Orthodontics and Dentofacial Orthopedics, Dayananda Sagar College of Dental Sciences, Bengaluru, Karnataka, India.
authors.forename: M
authors.initials: M
authors.lastname: Hemanth
authors.affiliation: Consultant Orthodontist, Bengaluru, Karnataka, India.
authors.forename: Shilpi
authors.initials: S
authors.lastname: Deoli
authors.affiliation: Professor and Head, Department 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 Orthopedics, V S Dental College, Bengaluru, Karnataka, India.
authors.forename: M S
authors.initials: MS
authors.lastname: Rani
authors.affiliation: Reader, Department of Orthodontics and Dentofacial Orthopedics, 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; linear analysis; lingual root torque; optimum force