Wenger sent Bendtner, 24, on a season-long loan to Juventus on deadline day.
He said: "It is not for nothing that I loaned him to Juventus. He is a talented player.
"There he will grow and then return to my team.
"I am convinced that at a team like Juventus, in a very difficult league, especially for strikers, he can make the final leap in quality.
"Don't forget, he is a boy of 24, the right age to prove who he is.
"The talent is not missing - otherwise I would not have bought him from Copenhagen when he was just 16."
Wenger added: "We believe in him and that is why we only gave him to Juventus on loan.
"We have not sold him, only loaned him, and next year we will bring him home.
"I think he can resolve his problems with us and prove himself."