One of the many consequences of orthodontic treatment is root resorption, which cannot be overlooked. The root resorption associated with orthodontic treatment is external and apical in nature.  It tends to occur when pressure over the cementum overcomes the reparative capacity of the innermost cellular structures. Root resorption starts adjacent to hyalinised tissues and is associated with the removal of the zone of necrosis. 

In some of the patients root resorption is minor, however most of the cases show different levels of root resorption. Root resorption is not caused by a single but numerous factors as reviewed by Brezniak and Wasserstein. These factors include morphological features, biological features and a combination of both. For mechanical factors, the extensive tooth movement, root torque and intrusive forces, orthodontic force magnitude, duration and type of force are involved. Whereas for biological factors, genetic susceptibility, systemic factors (hormone imbalance), teeth agenesis, and medication intake influence the root resorption. The highest prevalence for root resorption is observed in upper lateral incisors followed by upper central incisors. 

In orthodontics, radiographic assessment is an essential diagnostic tool to detect root resorption. Previously histologic methods had been used for determination of root resorption but it has its own difficulties such as they are done in vitro on extracted teeth or are animal studies.  The radiographic examination includes usage of two dimensional images such as intraoral periapical films, panoramic films. While periapical images via the paralleling technique is the current gold standard for measuring root resorption. In present era, CBCT is the most frequently used three dimensional methods as it depicts 2D views in all 3 dimensions (axial, coronal and sagittal).   Both the methods have their own advantages and disadvantages. Usage of two dimensional images has its own benefits like easiness and low radiation levels, however it also has its own downsides that are incorrect projection and magnification.  On the other hand, three dimensional scans use higher radiation levels but measures it with more accuracy. Also they overcome orientation errors and overlapping problems.

Many clinical studies have been published to evaluate the magnitude of root resorption but there is still a need for the comparison amongst two dimensional and three dimensional methods so as to know which method is superior and more accurate. Furthermore, no information has been specified about the amount of root resorption occurring on the labial or lingual surfaces previously.

Thus the aim of the study is to compare the amount of the external apical root resorption between the 2 dimensional and 3 dimensional images of maxillary incisors resorption before the initiation of treatment and after the completion of space closure.