“Does having orthodontics weaken teeth?”

Smart question and the answer has to be qualified. Dentists who do orthodontics without proper training, techniques and diagnostic skill can move teeth inappropriately and cause harm either because of root resorption or bone loss. Patients can cause permanent harm by not following instructions, keeping appointments, being carless with oral hygiene or DIY (do it yourself) orthodontics where treatment is "monitored by cell phone selfies. Sometimes retrieving a difficult impacted tooth like a canine can compromise the bone and gum tissue surrounding the tooth. On the positive side correct alignment of teeth will strengthen the supporting structure of teeth. At age 17 you should not be concerned with harm if you will pay attention to oral health and seek treatment from a recognized specialist in orthodontics.

Short answer is NO, but you must clean, rinse, and watch what you eat to prevent plaque/acid build-up (which can weaken teeth).

No, not at all. Orthodontics move teeth. Poor oral hygiene and a highly sugary diet weakens teeth!

Not if you use proper hygiene.