Statement of Problem: One of the major outcomes of orthodontic treatment is the apical root resorption of teeth moved during the treatment. Identifying the possible risk factors, are necessary for every orthodontist.Purpose: The aim of this study was to compare the rate of apical root resorption after fixed orthodontic treatment with standard edgewise and straight wire (MBT) method, and also to evaluate other factors effecting the rate of root resorption in orthodontic treatments.Materials and Method: In this study, parallel periapical radiographs of 127 patients imaging a total of  737 individual teeth, were collected. A total of 76 patients were treated by standard edgewise and 51 patients by straight wire method. The periapical radiographs were scanned and then the percentage of root resorption was calculated by Photoshop software. The data were analyzed by Paired-Samples t-test and the Generalized Linear Model adopting the SPSS 15.0.Results: In patients treated with straight wire method (MBT), mean root resorption was 18.26% compared to 14.82% in patients treated with standard edgewise technique (p< .05). Male patients had higher rate of root resorption,statistically significant (p< .05). Age at onset of treatment, duration of treatment, type of dental occlusion, premolar extractions and the use of intermaxillary elastics had no significant effect on the root resorption in this study.Conclusion: Having more root resorption in the straight wire method and less in the standard edgewise technique can be attributed to more root movement in pre-adjusted MBT technique due to the brackets employed in this method.