A crossover study will be conducted on 20 pediatric patients aged 7-11 years. For each participant, the upper and lower study models will be processed using two methods: the conventional method, which involves alginate impressions, and the digital method, which utilizes a 3D intraoral digital scanner (CEREC Omnicam scanner or equivalent). Measurements of arch length, arch width, and arch depth will be taken from both model types using the conventional method with a brass wire and a digital caliper. At the same time, in the scan cast, they will be calculated digitally by 3D shape software. Statistical analysis will be done to compare the results of both methods.

Inclusion Criteria:

1. Healthy Children aged 7-11 years old (ASA 1).
2. Class I with normal development of occlusion .
3. Absence of dental extractions.
4. Absence of previous removable or fixed orthodontic treatments.
5. Patients with fully erupted permanent first molars.
6. Children with Frankel behavioral rating scale 2,3 and 4.

Exclusion Criteria:

1. Delayed erupted 1st permanent molar.
2. Teeth with severe rotation.
3. Dental agenesis.
4. Oligodontia.
5. Frankel behavioral rating scale 1.
6. Patients with special health care and medically compromised patients.

statistician