In most orthodontic offices the orthodontist does not see every patient at every visit. This is especially true with invisalign. Most of the work of an orthodontist using invisalign is done behind the scenes. The orthodontist designs your smile and digitally aligns your teeth and bite on the computer. He/She decides the rate, direction and amount of tooth movement. He also decides the way the teeth will fit together in the end. All this is done on computer before you even received your first aligner. Once aligners are delivered he will likely check in on the progress of your case. If things are progressing ideally he doesn't even need to check on your treatment. A well trained assistant should be the one giving all instructions, taking impressions, putting on attachments and making sure aligners are fitting well and you are not having problems with your treatment progress. Do not forget you are paying for results not necessarily for the orthodontist to see you at every visit. Trust the process. If you are not happy with results or are having problems I wouldn't hesitate to communicate this.