Presurgical orthodontic treatment before secondary alveolar bone grafting (SABG) is widely performed for cleft lip/palate patients. However, no randomized controlled trial has been published comparing SABG outcomes in patients with, and without, presurgical orthodontic treatment. This randomized, prospective, single-blinded trial was conducted between January 2012 and April 2015 to compare ABG volumes 6 months postoperatively between patients with and without presurgical orthodontic treatment. Twenty-four patients were enrolled and randomized and 22 patients completed follow-up. Patients who had presurgical orthodontics before SABG had significantly improved inclination (p < 0.001) and rotation (p < 0.001) of the central incisor adjacent to the defect, significantly improved ABG fill volume (0.81 ± 0.26 cm(3) at 6 months compared to 0.59 ± 0.22 cm(3); p < 0.05) and less residual alveolar bone defect (0.31 ± 0.08 cm(3) at 6 months compared to s 0.55 ± 0.14 cm(3); p < 0.001) compared to patients who did not have presurgical orthodontic treatment. In conclusion, orthodontic treatment combined with SABG results in superior bone volume when compared with conventional SABG alone.