Crowding and spacing in the dental arches: Long-term development in treated and untreated subjects

Long-lasting developmental factors seem to result in universally reduced maxillary anterior spacing, orthodontic treatment notwithstanding. Compared with untreated subjects, the long-term development of mandibular anterior crowding was unfavorable in subjects treated without extractions. Compared with untreated subjects, the long-term development of maxillary anterior crowding was favorable when treatment included extraction of the maxillary premolars.