Unilateral posterior crossbite with functional shift of the mandible is a common condition. Early correction by expanding upper jaw is the best because it affects how the jaws develop, which may end up with facial asymmetry. A unilateral posterior crossbite with facial asymmetry is difficult to correct with orthodontic treatment alone and orthognathic surgery may be necessary.
Unfortunately our patient in this case is an adult with asymmetric facial appearance. Jaw surgery was rejected because the facial asymmetry didn't bother the patient much.
Clinically, it showed the back teeth on the right hand side of the mouth fit normally with the upper teeth forming a perimiter around the lower teeth and there was a crossbite on the left hand side with the upper teeth fitting inside the perimiter of the lower teeth.
The patient was very happy with the final result - a nice and straight smile! But as a dentist, I was not quite happy with her smile because of the shape of her top front teeth. The proportion of the teeth are not aesthetically perfect - gums cover teeth too much, teeth are too square and gummy smile. Aesthetic crown lengthening was recommended. We will follow up when the case is done.