The decrease in the amount of bone (periodontitis) results in an acceleration of tooth movement caused by the forces generated by the function. This dental migration results in spaces for the front teeth, an increase in the overhang (distance between the maxillary (upper teeth) and mandibular (lower teeth) incisors seen from the side) and the overlap. Despite the fact that the forces are usually horizontal, the conical shape of the roots systematically generates a vertical component, at the origin of a vicious circle. Indeed, this overlay is accentuated leading to a bite of the palate by these same teeth. It is often the presence of this bite that alerts the patient to the need for treatment. Another consequence of this overlay is the increase in mandibular tooth overlap, making dental hygiene maintenance difficult or even impossible.