Arch length preservation, and maintenance of the leeway space in the mixed dentition can often provide an adequate space to resolve lower incisor crowding. Yet, the frequency of this occurrence is not known. To obtain this information, lingual arches
were placed in the mandibular arches of 107 consecutive mixed dentition patients with incisor crowding to preserve arch length and make the leeway space available to resolve the crowding. Arch length decreased by only 0.44mm, whereas the intercanine, interpremolar, and intermolar dimensions increased by0.72-2.27mm. There was an adequate space to resolve the crowding in 65 out of 107 patients(60%). If perfect arch length preservation occurred, there would bean adequate space to resolve the crowding in 73 out of 107 patients(68%)
