Objective: The aim was to compare mandibular arch and incisor inclinational changes by comparing active self-ligating brackets used with different forms of archwires with a control group in nonextraction cases. Materials and Methods: The sample of 50 patients with Class I malocclusion was divided into three groups: Group I was treated with active self-ligating brackets (Nexus, Ormco/Orange, CA, USA) used with Damon arch form copper nickel-titanium (Cu-NiTi) and stainless steel (SS) wires; Group II was treated with interactive self-ligating bracket system (Empower, American Orthodontics, Sheboygan, Wis, USA) used with standard Cu-NiTi and SS wires; and Group III was treated with Roth prescribed conventional brackets (Forestadent, Pforzheim, Germany) with standard Cu-NiTi and SS wires which was designed as a control group. Changes in dimension of mandibular arch and inclination of incisors were assessed on dental models and lateral cephalometric radiographs at pretreatment (T1) and posttreatment (T2) periods. Paired-t test and one-way analysis of variance were used to perform intragroup and intergroup comparisons, respectively. Results: In all groups, an average increase of transversal distances occurred from pretreatment to the posttreatment period (P < 0.05). However, mandibular arch length increase was significantly different among the Groups I-III (P = 0.008) and I-II (P = 0.006). No significant intergroup difference was found with regard to incisor inclinational changes. Conclusions: Bracket type had no significant effect on the mandibular dimensional or incisor inclination changes. Besides this, archwire type had only little effect on the treatment results as active self-ligating bracket with Damon archwires increased mandibular arch length greater than other groups.