What appliances are used to straighten teeth?

In the US. Best option, braces, over 90% improvement. 2nd choice is any of the removable or semi-removable appliances! including clear aligners, with about a 50% or less improvement outcome. Treatment in the hands of a specialist is more successful than in the hands of a generalist. Success has more to do with the training, skill, and experience of the practitioner than in the type of gadget.
Braces. You will need to have either traditioanl braces or one of the clear alternatives such as invisalign to straighten your teeth. The time this will take depends on how much movement is needed to correct your problem.
Many new appliances. I would see an orthodontist to see what are the best options. Aligner companies are popping up almost every few months.