One of the orthodontist's most important tasks with children is to spot any harmful habits. These can include incorrect tongue position, the tongue pushing against the teeth when swallowing, and breathing through an open mouth. The earlier such a problem is identified and corrected, the more likely it is that the jaws will develop normally without the need to wear appliances. Ideally, harmful habits should be corrected while the child still has baby teeth. The change from baby to permanent teeth involves major changes in the jaws, and if the harmful habit is stopped before this period, the jaws can develop normally.
This answer is for general information. Your own case needs an examination by an orthodontist.