NHS teeth straightening is free for teenagers under 18 who meet Index of Orthodontic Treatment Need (IOTN) grades 4 or 5 for functional dental issues. Adults rarely qualify for NHS braces because treatment is restricted strictly to severe medical necessities rather than cosmetic realignment. When approved, NHS care exclusively provides traditional metal fixed braces. Adults seeking discreet options like clear aligners or ceramic braces typically choose private orthodontic treatment. Private care eliminates multi-year NHS waiting lists and offers flexible payment plans.