Dentists don't make any money on doing just hygiene (cleanings) alone, and so they always try to diagnose something else. The "something else" is what makes them profitable.
Always ask to see the x-rays, what the consequence of (not) getting the procedure, and ask a lot of questions.
I am in the dental industry, and even my own dentist tried to tell me I needed work on 2 teeth. On a gut feeling, I told him "no".
A new dentist opened up near my house, and when I went to him, I asked him his opinion about these 2 teeth. He told me they were fine. (He took still pictures to prove to me.) So, be careful.