To compare the effects of Smartee S11 expander with conventional clear aligner expansion using cone beam computed tomography (CBCT).

The secondary objective is to evaluate the degree of orthodontic expansion and the type of tooth movement achieved with Smartee aligners on the maxillary arch.

Each patient will be randomly allocated, and the entire patient included in this study will be divided into two groups.

Inclusion Criteria:

• 1- healthy cooperative female and male patients who will undergo maxillary expansion with Smartee aligners, A young adult/adult patients starting from age of 18 up to 35 years old.

  2- patients with maxillary compression of non-skeletal origin, moderate dental crowding in the upper arch (4-8mm). 3- patients with unilateral or bilateral crossbite, patients will be treated with intermaxillary elastics without distalization or mesialization of the dental arches.

  4- patients with sufficient clinical crown height (greater than 4 mm), no mesial rotation of the upper first molar. 5- there is good compliance during the treatment (wearing aligners for 20 hours per day).

  6- good quality x-rays with appropriate visualization of landmarks and control of head rotation. 7- absence of periodontal disease, and absence of previous prosthodontic treatments of the upper molars.

Exclusion Criteria:

• 1- signs and/or symptoms of temporomandibular abnormalities (TMDs). 2- active periodontal disease. 3- prosthodontic rehabilitations of the maxillary molar or ankylosed teeth, and endodontic treatments of the maxillary molars. 4- patients requiring orthognathic surgery

The dataset contains sensitive patient information, and sharing it could compromise participant confidentiality despite de-identification efforts. Access to the data is therefore restricted in accordance with institutional review board (IRB) guidelines.