I am not sure how fully your crossbite was corrected when you had treatment 6-7 years ago. It may not be possible to get complete correction of a crossbite in the back teeth, if the crossbite has been caused by an underlying skeletal proportion (skeletal crossbite) issue.
We tend to see crossbites originating from jawbone size and proportion in patients with a small upper jaw and/or a large lower jaw. The bony foundations of the teeth are out of proportion, and the body adapts to this by creating a crossbite. Without the crossbite, the back teeth in the affected area would not meet together. For skeletal crossbites, braces cannot reshape the jawbones and jaw surgery is usually required for a definitive solution.
Crossbites may return after braces are removed and if retainers are stopped. Our jawbones continue to grow and remodel throughout our lifetime, and our teeth compensate for this by moving.
Depending on your current age and how long you have had the crossbite, the jawbones may become slanted. The longer the crossbite has been present, the more likely it is that this slanting has become permanent. Some patients with crossbites may also have jaw joint or jaw muscle issues. So this is a good reason to seek assessment and treatment.
Our jawbone growth patterns are determined genetically, and no amount of treatment can change this inherent tendency. Some patients grow in a way that tends to make a crossbite recur.
Our biting and chewing habits also affect the way we bite. One-sided chewing tends to make the chewing muscles on one side of the face stronger and may encourage the lower jaw to deviate to this side.
If this is an issue that is bothering you, I would advise you to get assessed in person. A thorough examination of your bite, your jaw muscles and joints and xrays of your skull are needed to identify the source of the crossbite. Have a frank discussion with your treating dentist about the prognosis for correcting the crossbite.
Hope this helps!
