Crowding

• Faculty of Dentistry-Cairo University — Cairo, Giza Governorate, Egypt

• Specialized Dental Center for Prosthodontics and Orthodontics — Baghdad, Bab Al-Muadham, Iraq
• Z Orchida Clinic — Baghdad, Iraq
• Orthodontic department, College of dentistry, university of Baghdad. — Baghdad, Iraq

• Orofacial MRI Center at UMN — Minneapolis, Minnesota, United States

• AlHur ALriyahi and Hai Alhussein specialized dental centerS — Karbala, Iraq

• Dental Clinic "Dental-Service" - Department of Oral and Maxillofacial Surgery, 77 S. Vanzetti Street — Novosibirsk, Novosibirsk Oblast, Russia

• Orange Coast Orthodontics — Laguna Hills, California, United States
• Spillers Orthodontics — Warner Robins, Georgia, United States
• Innovative Orthodontic Centers — Naperville, Illinois, United States
• The Orthodontic Studio — Chevy Chase, Maryland, United States

• University Medical Center Groningen — Groningen, Netherlands

• The sample will be recruited from multicentre clinics (Private dental clinic, Orthodontic Department at Karbala Governmental Specialized Dental Centre, Orthodontic Department, College of Dentistry University of Baghdad). — Karbala, Iraq

• University of Baghdad — Baghdad, Al-Rusafa, Iraq

Not specified