How should i convince my orthodontist to let me have braces to correct an openbite and some crooked teeth? my dentist says (my teeth and gums are healthy) and i'm a great candidate for braces but my ortho is unwilling to let me get them again?

There is so much more information needed to give you a meaningful answer. Apparently you've had orthodontic treatment in the past. It may be time to get a second opinion from a different orthodontist.

THERE ARE VARIOUS SCHOOLS OF THOUGHT AND TREATMENTS IN ORTHODONTICS. YOU SHOULD SEEK ANOTHER OPINION FROM AN ORTHODONTIST OR GO TO A DENTAL SCHOOL WHICH HAS AN ORTHODONTIC CLINIC FOR ADVICE.

If you had Orthodontic treatment and a resolved open bite reopened, a combination of braces and jaw surgery may be required. Retreating non-surgically would probably be equally unsuccessful. If your Orthodontist says no, fid out why. A second opinion may be advisable. Consider talking to a different Orthodontist.