In fact, I find the opposite. Most of my patients wearing invisalign are so excited about the entire experience there is a noticeable improvement in their oral hygiene. Yes, saliva is an important part of oral health, but the reason people get cavities is because they eat too much of the "wrong" foods and do not brush & floss enough. When you are wearing your aligners you are not snacking, eating as much, and as I mentioned you usually brush/floss more. Although I have never seen it, I suppose you could get more cavities while wearing aligners, if you don't brush/floss and eat a lot of sticky, sugary sweets. When you are considering Invisalign treatment, you are evaluated by a Dentist,. During this initial visit, your Dentist is checking to see if you are a good candidate for treatment; will you be compliant with eating, brushing, flossing, cleaning appointments? Ideally, you will not even start Invisalign unless you demonstrate great oral habits and commitment. Good Luck.