Objective: This study aimed to compare the differences of final root angulation after treatment with Invisalign and fixed appliances. Methods: A retrospective study was conducted in orthodontic cases treated at the University of Maryland School of Dentistry Department of Orthodontics by clear aligner appliance (“Invisalign system, 30 patients) or fixed appliance (30 patients). Pre-treatment and post-treatment panoramic radiographs were analyzed to measure angulation of tooth axis to compare the difference in root parallelism by the two treatment modalities. Results: There was a statistically significant difference in root parallelism between the two treatment modalities. There were improvements in root parallelism after treatment with both treatment modalities. The fixed appliance group exhibited greater precision in angulation control, particularly in the maxillary lateral incisor to central incisor region. Conclusion: Both treatment modalities were similar in final root parallelism after orthodontic treatment. Despite an increase in overall satisfactory parallel teeth sites after treatment, there was also an increase in the number of pre-treatment satisfactory parallel teeth sites changing to apical convergence and apical divergence, indicating some shortcomings within both treatment modalities.