Research Article
Chandrashekhar BS, Chandralekh
Abstract
The aims of this investigation were to define the modified location of CRES and CROT in a maxillary central incisor with different alveolar bone heights. A three dimensional finite element model of the upper central incisor with its supporting structures was created using ANSYS software on a PIII computer. Five three dimensional models of an upper central incisor with 1 to 6.5 mm of alveolar bone loss were formulated and used by the author. Center of resistance and center of rotation were located for the various stages of alveolar bone loss. The results revealed that the moment/force ratio (at the bracket level) required to produce bodily movement increases in association with alveolar bone loss. Bone loss causes center of resistance movement towards the apex, but its relative distance to the alveolar crest decreases at the same time. Greater amounts of displacements of incisal edge and apex were observed with increased alveolar bone loss for a constant applied force. Center of rotation of the tipping movement also shifted towards the cervical line. Among the many differences between orthodontic treatment of an adolescent and an adult patient is the presence of alveolar bone loss in the adult cases. Alveolar bone loss causes change in center of resistance as a result of alteration in bone support. This necessitates modifications in the applied force system to produce the same movement as in a tooth with a healthy supporting structure.