Aim: To evaluate the effect of clear aligner on buccal alveolar bone after orthodontic 
treatment. Subjects and Methods: The present study composed of 14 patients (males, 
females) aged between 15-25 years who had minor to moderate malocclusion which 
were randomly selected and divided into two group: Aligner group and Fixed group both 
groups are prepared for orthodontic treatment and aligner sets and wires are changed in 
sequence. Patients are selected from the outpatient orthodontic clinic, Faculty of Dental 
medicine, Al-Azhar University, Assiut branch. The subjects presented to the orthodontic 
clinic were assessed for eligibility according to inclusion and exclusion criteria. All the 
patients were informed of the procedure and signed an informed consent form. This 
study was conducted on CBCT scans taken. Results: both aligner and braces have nonsignificant effect on bone thickness. However, bone height shows significant difference 
between both groups. Conclusion: bone height reduction in aligner group is lower than 
in fixed, while there is no significant difference representing bone thickness.