Inclusion Criteria:  Patients who needed orthodontic treatment with aligners in both jaws. Adult patients (>18 years) Full permanent dentition (excluding third molars) Patients with non-surgical or non-extraction (excluding third molars) treatment No active periodontal disease Patients with class II molar relationship that needed molar distalization  Exclusion Criteria:  Patients with systemic diseases affecting bone metabolism or teeth or inflammatory diseases Patients undergoing treatment with immunosuppressant or bisphosphonates Patients undergoing chemo and radiotherapy Patients with any other syndrome-associated orofacial deformation, cleft lip or palate Pregnant women or non(or poor)-compliance patients with skeletal discrepancies Patients with dental or skeletal crossbite that need 3 mm or more per side of expansion