Answered by Ustadha Shazia Ahmad
Does voluntarily or involuntarily touching a marriageable woman’s hair invalidate wudu?
No, it does not. One’s ablution is only invalidated by skin-to-skin contact with the opposite sex. So touching teeth, hair or nails would not invalidate the ablution. Also, remember that it is unlawful to intentionally touch the hair of a marriageable person of the opposite sex.
And Allah knows best.