hello and welcome,
the gap between front teeth is due to high frenal attachment.
this condition is known as midline diasthema.
you should visit an orthodontist and get an orthopantamograph.
i advice you to get done frenectomy
,ie,cutting th high frenal attachment.this will prevent the opening up of space again.z-spring along with fixed appliance can correct the spacing.
i would also advice you to put retention appliance.
please stop tongue thrusting/thumb sucking/mouthbreathing habits if you have any.
as we cannot suggest the appliance without clinical examination,get direct consultation.
you can ask your dentist
for habit breaking appliance too if you have any.
do mouth exercises like,water holding in mouth for 1 minute,paper holding in b/w lips,etc.
z-spring or double cantilever spring used for labial movement of incisors and for bringing minor rotations.
get scaling and restorations done if you have any decayed tooth.