Class 1 - Crossbite
There is a size relationship between the upper and lower jaws where the upper is so wide that the upper teeth over-lap, and this allows for proper incising among the front teeth and milling among the posterior teeth. If this is compromised, there probably won’t be enough space.
Very often, crowding is the result of inadequate width of the jaw(s). In this case, the upper is too narrow; and there is a “cross-bite” on the right side (arrow). The upper teeth are crossed over onto the inside of the lower.
Maxillary Expansion is the treatment of choice. It causes the upper jaw to grow to a larger width, and there is more room for the teeth. It is not uncommon for a space (diastema) to develop between the two front teeth. In fact, that is indicative of a successful expansion.
5 months later, the one tooth discrepancy has been resolved, and no braces were necessary!