Inclusion Criteria:  Space deficiency in the upper arch > 5 mm, and < 8 mm. Non-extraction lower arch. Full upper dentition up to the second molars. Third molar present in both sides, not yet erupted.  Exclusion Criteria:  Systemic disease or syndrome. Evidence of root resorption. Poor oral hygiene. Previous orthodontic treatment Evidence of bone loss. Active periodontal disease. Pregnant females. Presence of oral habits