This study is a multi-center, prospective, parallel-group randomized controlled trial designed to compare the orthodontic treatment outcomes of a passive self-ligating bracket system (Damon Ultima) versus a clear aligner system. The primary objective is to evaluate and compare the total orthodontic treatment duration between the two systems in patients with Angle Class I malocclusion and moderate crowding. Secondary objectives include assessing alignment efficiency, patient pain perception at multiple time intervals, dental arch dimension changes, root volume loss percentage, and overall treatment quality using the American Board of Orthodontics Objective Grading System (ABO-OGS).