After Developing a Posterior Open Bite from Invisalign Treatment, the Doctor Recommended Doing Crowns, is This Correct?

This can happen, especially in clenchers due to the thickness of the plastic between the back teeth.  The aligners should be cut behind the canines and allow the back teeth to re-erupt and settle.  Please do this with your dentist's supervision.  Do not have crowns placed to correct this.

It is possible to develop a small posterior open bite after invisalign however you can correct this by doing a refinement with invisalgn to intrude the front teeth and tighten up the posterior bite. The refinement should be included in the intial invisalign treatmet.  If the open bite is not too big you can also cut off the back part of the aligner or retainer to allow the back teeth to erupt a bit. This may happen anyway once you are wearing your retainers only at night. You can also do a bite adjustment of the front teeth to get the back teeth to touch. You can do a combination of all these, but do NOT allow the dentist to grind on your teeth to make crowns on what I would assume are healthy teeth. If the teeth are broken down and need  crowns anyway, then that is a different story.

Your gut instinct is right, this is not only drastic but inapropiate and malpractice( based on the limited information given). I would seek another opinion. Your dentist is either incompetent or unethical.

Good luck

Dr. T

 A Slight Posterior open bite may occur with invisalign, but should be easily corrected by relieving the final alignerer or retainer.  If the open bite is too large for this then something needs to be corrected orthodontically.  Cutting down healthy teeth to close and open bite is probably the last resort after all else fails. You should definitely question someone willing to place 12 crowns just to correct this.  Also $8000 for 12 crowns is VERY low which also sends a red flag.  Please seek the advice of a Board certified Orthodontist before you go through any other treatment, having crowns placed may cause serious issues with your bite and teeth which will haunt you for years to come.

To fill the space, it can be done quickly with porcelain crowns or onlays, or braces (brackets and wires, NOT Invisalign).  

$8000 for 12 crowns is EXTREMELY low, so I would suggest a second opinion as well.

Invisalign is meant to improve your bite, not worsen it. I'm surprised you first developed the posterior open bite AFTER the Invisalign. You should see a dentist experienced in occlusion before going any further. A dentist that can do 12 crowns for $8000 is not going to be able to properly diagnose and treat your occlusion.