Objective: To compare the labio- and buccolingual inclination of the anterior and posterior teeth in subjects treated with self-ligating and conventional fixed appliances with and without rapid maxillary expansion. Methods: Seventy-one subjects with Class I malocclusion were divided into three groups. Group 1 comprised 24 subjects (17 female; seven male, with a mean age of 13.94 ± 2.87 years), treated with Roth's pre-adjusted fixed appliances. Group 2 comprised 24 subjects (14 female; 10 male, with a mean age of 13.85 ± 1.83 years) treated with Rapid Maxillary Expansion followed by Roth's pre-adjusted fixed appliances. Group 3 comprised 23 patients (12 female; 11 male, with a mean age of 14.75 ± 1.34 years) treated with Damon self-ligating bracket system. Buccolingual inclination was measured on digital dental models using a 3D software. Intergroup changes comparison was performed with one-way ANOVA, followed by Tukey tests. Results: The left maxillary lateral incisor showed labial inclination in the conventional and RME groups, and palatal inclination in the Damon group. The Damon group showed greater buccal inclination in most posterior mandibular teeth during treatment than the conventional and RME groups. The right mandibular canine and lateral incisor showed greater labial inclination in the Damon group than in the RME group. Conclusions: There was greater buccal inclination of the posterior mandibular teeth and labial inclination of the right mandibular canine and lateral incisor in the Damon group.