It is charged up front, as all the aligners are created at once. This is probably the single biggest drawback to Invisalign, as it is a flat fee and 100% due at the initial onset.
If I am correct, the tooth of which you speak is a lateral incisor. These little rascals can be difficult to reposition with Invisalign since the neighboring teeth are so much bigger and the plastic of the aligners seems to by-pass the laterals in efficiency. But even with this...
There really IS a difference between providers, but it may seem minor. Of course, there is the office part (staff greeting you, general feelings of office, convenient location etc), but a more experienced provider may be able to direct Align (Invisalign Inc) as to how the case should progress. ...
