title: Evaluation of the Stress Induced in Tooth, Periodontal Ligament & Alveolar Bone with Varying Degrees of Bone Loss During Various Types of Orthodontic Tooth Movements.
abstract: BACKGROUND
  The force applied on to a tooth with periodontal bone loss may generate different magnitude and pattern of stresses in the periodontium when compared to a tooth with no bone loss & under the same force system. The intensity of the forces and moment to force ratios needed to be applied during an Orthodontic treatment must be adapted to obtain the same movement as in a tooth with a healthy periodontal support.
  
  
  OBJECTIVE
  Evaluation and assessment of the stress distribution during various types of Orthodontic tooth movement on application of Orthodontic force, at various levels of alveolar bone loss; & determination of the most ideal force system producing the Optimum Stress (i.e., stress within optimum range), uniformly (conducive to bodily movement of maxillary canine with varying degrees of bone loss).
  
  
  METHODS
  A human maxillary canine tooth of right side was simulated by means of Finite Element Method (FEM). Five different models were constructed with bone loss ranging from 0mm in model 1, to 8mm in model 5 (progressing at 2mm per model). Ten different loading conditions were applied on these models and the stress generated was charted at various occluso-gingival levels and surfaces around the tooth. The evaluation and assessment of the stress distribution during various types of Orthodontic tooth movement on application of Orthodontic force, at various levels of alveolar bone loss was done.
  
  
  RESULTS
  The results showed that there was a high positive correlation between the increase in bone loss & the stress generated, suggesting an elevation in the stress with advancing bone loss. Additionally, the type of tooth movement was found to be changed with bone loss. During the determination of ideal force system it was found that the centre of resistance of the canine migrated apically with bone loss and an increase in the moment to force ratio (Mc:F) was required to control the root position in these cases.
  
  
  CONCLUSIONS
  A high positive correlation exists between the increase in bone loss and the stress generated. Suitable modification should be done in the force system under bone loss conditions.
authors.affiliation: Reader, Department of Orthodontics & Dentofacial Orthopedics, Teerthanker Mahaveer Dental College & Research Centre , Moradabad, India .
authors.forename: Anupam
authors.initials: A
authors.lastname: Agarwal
authors.affiliation: Reader, Department of Conservative Dentistry & Endodontics, Teerthanker Mahaveer Dental College & Research Centre , Moradabad, India .
authors.forename: Shalu
authors.initials: S
authors.lastname: Mahajan
authors.affiliation: Professor and Head, Department of Orthodontics & Dentofacial Orthopedics, Kothiwal Dental College & Research Centre , Moradabad, India .
authors.forename: Santosh
authors.initials: S
authors.lastname: Verma
authors.affiliation: Associate Professor, Department of Orthodontics & Dentofacial Orthopedics, Kanti Devi Dental College & Hospital . Mathura, India .
authors.forename: Preeti
authors.initials: P
authors.lastname: Bhardwaj
authors.affiliation: Associate Professor, Department of Oral Pathology, Santosh Dental College , Ghaziabad, India .
authors.forename: Geeta
authors.initials: G
authors.lastname: Sharma
keywords: Biomechanics; Force; Hyalinization; Resorption; Tipping; Torquing