My Orthodontist wants to grind my teeth down to make my bite fit after Braces. Why didn't wearing Braces fix my bite?

A little minor "equilibration of teeth is OK after braces but large scale grinding down doesn't sound right.  You need your doctor to explain why your bite is so off...Also, go over this with your regular dentist

Braces are a fantastic way to move teeth in big ways.  However, if one was to ask to move a tooth 0.3 mm, they would be frustrated and disappointed.  Fine tuning a bite after braces has two options, make retainers (NOT clear tray type ie essix) and let the teeth grind their way to fit naturally, or equilibrate.  Equilibration is a very minor polishing/smoothing/adjusting of teeth.  While it may SEEM like a ton of enamel is ground down, the reality is that very little is removed.  However, it IS possible that there is what is called an "open bite".  The only way to determine severity of the open bite is using instruments to measure, which is complicated and takes a bit of time.  To do well takes skill and experience.  You likely do not have a severe open bite and this is a minor situation.  Have your regular dentist weigh in on this.Do what you feel most comfortable doing, but adjusting the bite is minor and common, and nothing was likely "done poorly" by the orthodontist.