1：Experimental Design and Method Selection:

A randomized, double-blind, placebo-controlled, parallel-group study was conducted. The sample included 11 individuals with class I malocclusion, requiring extraction of 4 first premolars. Gallium aluminum arsenide diode laser with a wavelength of 780 nm was used once a month during retraction mechanics.

2：Sample Selection and Data Sources:

Patients presenting with class I malocclusions treated with extraction of maxillary and mandibular first premolars; presence of all permanent teeth except the third molars; absence of previous orthodontic treatment, periodontal disease, systemic diseases, tooth agenesis, supernumerary or impacted teeth, within an age range between 12 and 17 years.

3：List of Experimental Equipment and Materials:

Gallium aluminum arsenide diode laser, digital caliper, periapical radiographs, E-speed Film, Eastman Kodak Company, Rochester, E.U.A, Gnatus, XR6010 model x-ray machine.

4：Experimental Procedures and Operational Workflow:

Premolar extractions were performed with a week interval on each side. After the extractions, a transpalatal and lingual arch were installed, followed by fixed appliances bonding. Initial canine retraction was initiated 30 days after the last extraction, using nickel-titanium closed-coil springs. The first application of low-level laser therapy was performed at this stage, along with the first clinical measurement.

5：Data Analysis Methods:

Comparison of tooth movement amount between the irradiated and nonirradiated sides and between the evaluated periods was performed with repeated measures ANOVA, followed by the Tukey tests. To compare the amount of root resorption and the alveolar bone crest height between the irradiated and nonirradiated sides, Wilcoxon tests were used.