Crooked teeth. Can be done for the same.

If your mouth remains open during daytime and night that means positioning of upper teeth or both upper and lower teeth is outwards than natural position . Now there can be 2 reasons for it 1) the teeth are positioned out but the underlying bone is at correct position 2) underlying bone is positioned outwards as a result of which teeth are automatically out . To treat either of the two problem you need to see an orthodontist , who can do a thorough check up and let you know the required treatment plan In addition to that in some cases where tooth are slightly crooked they can be aligned to normal position using cosmetic procedures , this is for someone who does not wish to undergo orthodontic treatment . But technically speaking no cosmetic treatment can be better and long lasting than orthodontic movement and alignment of teeth given such a young age of the patient

Visit an orthodontist and get Radiographs ( Lat Ceph and OPG)

pls rule out any habit in which you might hold some object between upper and lower teeth