Ok, now, in Oxford dictionary:
to express: to show or make known a feeling, an opinion, etc. by words, looks or actions source
so they got the structure "express something", ex: "Teachers have expressed concern about the changes".
However, there is no structure "express something (to somebody)". So, I am not sure I can say "Teachers have expressed concern about the changes to students"
In fact, there is a structure "express something (to somebody/something) (North American English)" which means "to send something by express post As soon as I receive payment I will express the book to you" source.
So, I think the dictionary got a shortcoming here.
So, Why isn't there a structure of "express something (to somebody)" in the dictionary?