Invisalign braces missing attachments on 2 crowned teeth - Will the final results be less than optimal?

Generally speaking, Invisalign is still very effective without all attachments in place.  Of course it depends on which attachments (or buttons) are missing from which teeth.  If the tooth missing the attachment is one that is expected to turn or descend, then it is more important that this type of tooth has it's button on it.  However, if the tooth is expected to not move much, then the importance of the button is much less.  Just the fact a button or two are missing, doesn't mean that your case will be less than optimal.  In this case, I would trust your current dentist.  If at the end the treatment is not what you expected, then a refinement would be necessary.  Good luck to you.  Sarah Thompson, DMD   O'Fallon, IL  

Some attachments play a more important role in the treatment
than others. If your dentist made a clinical judgment not to place them, then obviously
he didn’t consider them to be crucial for your treatment.

While creating invisalign attachments have been a great way to make cases work better, we didn't use them for years and still had great results.  If crowns are present, it likley won't "stick" and would just be a matter of frustration for both doctor and patient.  If your doctor decided it wasn't needed, then it likely wasn't crucial to the case.