ABSTRACT
The constriction of Maxilla is considered a common disorder in daily clinical practice; which is usually accompanied with narrow nasal cavity. Many techniques are used to expand constricted maxilla; such as slow maxillary expansion and rapid maxillary expansion. The aim of this study is to evaluate changes in nasal cavity width after slow maxillary expansion by using Spring Jet II expander in late mixed dentition; and to compare them with changes caused by rapid maxillary expansion using Hyrax expander. The sample of this study consists of 40 patients with narrow Maxilla [age: 9 - 12.2 y]. The sample is divided in two groups: First group consists of 20 patients treated with Nickel Titanium coil springs [Spring Jet II appliance]. Second group consists of 20 patients treated with rapid maxillary expansion [Hyrax appliance]. Frontal cephalometric X-ray is taken before treatment -T1- and after expansion and retention for three months -T2-. The width of nasal cavity increased in both groups. No significant differences were found between them. It is recommended to use maxillary expansion to relief nasal obstruction and improve nasal respiration in patients who are complaining of maxillary constriction