Abstract: Patients with constricted maxillary arches are very common in orthodontic clinics，which need dental arch expansion. Expansion with Hyrax appliance or Hass appliance, surgery assisted maxillary or mandibular expansion, arch wire and auxiliary arch wire expansion are usually used as the solution of the problem. Recently ,mini-implants assisted expansion, magnetic expansion and no-brackets invisible appliance expansion has also been reported. In this article ,the methods above will be summarized and discussed.

Key words: maxillary expansion, dental arch expansion, no-brackets invisible appliance, surgey assisted mandibular expansion