I am advised not to use Acceledent. Does the device cause increased root resorption?

I am 37 years old. When I was 14 I have worn traditional braces. Now I started with Invisalign. 25 trays. Go my first 3 trays and was told to wear the first one 14 days and tray #2 and tray #3 for 10 days. I bought Acceledent from a different dentist. My dentist tells me now NOT to use the acceledent as I can lose my tooth because of this device. Why did she started me on invisalign in the first place as I understand that any orthodontic work will cause some increased root resorption.