Orthodontic treatment needs of 14-18 year-old female students of Isfahan in 2009-2010 using IOTN index

14-18 year-old female students of Isfahan public schools in 2009-2010 based on Index of Orthodontic Treatment Need (IOTN). In this descriptive study, 370 14-18 year-old female students were selected by random clustering method. The subjects were examined clinically based on two components of IOTN: Dental Health Component (DHC) and Aesthetic Component (AC). Data was analyzed with descriptive statistical methods, including Spearman’s correlation coefficient (α = 0.05). Regarding DHC, 10.8% of samples showed grade 5, 13.5% showed grade 4, 23.8% had grade 3, and 51.8% demonstrated grades 1 and 2. In those showing grade 5, the most common malocclusion was unerupted (i) teeth. The most common malocclusion in grade 4 was contact displasments (d) for more than 4 mm and in grade 3, contact displasment was less than 4 mm and more than 2 mm. The most common malocclusion in grade 2 was contact displasment (d) less than 2 and more than 1 mm. In addition, regarding AC, 98.8% of the subjects were classified as “no need”, 1% as “borderline need” and 0.0% as “definite need” for treatment. No statistically significant differences were noted between AC and DHC (p value = 0.294). It was concluded that 24.3% of 14-18 year-old female students in Isfahan need orthodontic treatment (IOTN grades 4 and 5) and common malocclusions are contact point displacements, unerupted teeth and increased overjet.