I finished my first round of Invisilign, and my back teeth did not touch, only my front teeth. This caused problems chewing. Now I'm on my refinement trays (9 months) but I'm worried that this problem won't be corrected. My ortho made the offhanded comment that this is 'common in Invisilign patients,' and didn't seem concerned, saying that your back teeth don't really need to have contact, anyway. Can you reassure me?