Sorry to hear it, it's true many dentists in Berlin have questionable practices. I assume because there are so many dentist offices they have to get the money somewhere. I've been to at least 5 and it's usually "you're ok see you in 6 months" but one doctor told me I needed an Anti Grinding Teeth Protector (I didn't but it's covered by insurance so whatever) and one did a filling that had to be remade later by another. So I would recommend to find good busy dentist in Berlin as they don't need to extract money from insurance because they have many patients anyway