Cross sectional study to investigate the relation between Smartphone addiction and temporomandibular disorders among youth population in Egypt. An online- based questionnaire study. A 296 participants who are Egyptians with age between18 and 35 years old without prior neck and upper extremity related diseases, orofacial trauma or surgeries, history of rheumatoid arthritis or congenital musculoskeletal problems. An online- based questionnaire will be sent through different social media platforms, it will include three screens, the first includes the consent form, the second includes the demographic data (year of birth, current educational status, gender and geographic information ), and the third page includes questionnaires

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Inclusion Criteria:

• both males and females adults
• Their ages between18 and 35 years old
• ability to use Smartphone

Exclusion Criteria:

• any neck and upper extremity related diseases
• orofacial trauma or surgeries
• history of Rheumatoid arthritis
• congenital musculoskeletal problems.

community sample