With the crossbite you describe, upper jaw expansion is most certainly required to get a stable result. Upper jaw expansion can be accomplished at any age IF the right techniques are used. It has been a long standing myth in orthodontics that expansion of the upper jaw can't be accomplished without surgery past ages 12-14. Slow palatal expansion (SPE) with removable treatment appliances can be accomplished at any age. RPE's (Rapid Palatal Expansion) attached directly to the teeth can dangerously push the roots of the teeth through the supporting bone structures because they push directly on the teeth and push faster than the bone can accommodate. This RPE treatment has been shown to be unstable long term with as much as a 40% relapse rate. That is why expansion past ages 12-14 has received such a bad rap. The key is in the technique and the viable techniques use SPE with expansion pressures being placed directly in the roof of the mouth, right where the expansion is needed.