Objective: To evaluate the dimensional changes in height and thickness at the alveolar bone and delimitating the buccolingual inclination of the lower incisors, before and after the accelerated orthodontics with a modified piezocision protocol. Materials and Methods: In this retrospective study, 37 subjects with Angle malocclusion class I, II or III, mild crowding and a thin periodontium at level of lower incisors were divided randomly into 4 treatment groups: group 1 control; group 2 lower piezocision; group 3 lower piezocision and soft tissue graft; group 4 lower soft tissue graft. In Cone beam computed tomography (CBCT) T0 before and T1 after treatment, 148 lower incisors were assessed in buccolingual inclination, alveolar bone height and thickness. Results: There was proclination of lower incisors after treatment except in group 3 (−4.7º ± 13.6º). Buccal and lingual alveolar ridge decreased vertically in all the groups, but group 3 showed less lingual decrease (0.9 mm ±1.9). All the groups showed a decrease in buccal and lingual alveolar thickness but group 3 showed less change thickness (−0.2 mm ± 0.7).