The aim of this study was to determine the prevalence of malocclusion and orthodontic treatment need in 12- to 16-year-old Spanish schoolchildren using the aesthetic component (AC) and Dental Health Component (DHC) of the Index of Orthodontic Treatment Need (IOTN) and to analyse the relationship with gender and age. The study followed the World Health Organization recommendations for oral health surveys. The sample comprised 655 schoolchildren (306 males and 349 females) who had not undergone orthodontic treatment, divided into two groups: 363 12-year-olds and 292 15- to 16-year-olds, out of a representative sample of the school population of the Valencian Community. The IOTN results were analysed with regard to gender using the chi-square test. Orthodontic treatment need, using the DHC, was found in 21.8 per cent of the 12-year-olds and in 17.1 per cent of the 15- to 16-year-olds; and with the AC in 4.4 and 2.4 per cent, respectively. Considering both components together, 23.5 per cent of the population [confidence interval (CI) 95%: 19.2-28.1] of 12-year-olds and 18.5 per cent (CI 95% 14.2-23.4) of 15- to 16-year-olds had a definite treatment need. No gender dependent differences were found. Spanish orthodontic treatment need is similar to that reported in most recent studies in Europe, with approximately one in five to six children with an orthodontic treatment need.

The aim of this study was to establish orthodontic treatment need according to the Dental Aesthetic Index (DAI) and Aesthetic Component (AC) and Dental Health Component (DHC) of the Index of Orthodontic Treatment Need (IOTN) and to determine its association with gender among Saharan schoolchildren. The study was carried out in accordance with World Health Organization (WHO) recommendations for oral health surveys at 12 years of age. The sample comprised 248 Sahrawi children (135 girls and 113 boys) living in refugee camps in Tindouf, Algeria. None of the children had previously received any orthodontic treatment. A chi-square test was used to analyse the IOTN results by gender, and a Student's t-test was employed for the DAI results. The mean DAI was 23.32 with a standard deviation of 6.05, 4 percent with a very severe and 9.2 per cent with severe malocclusion. Orthodontic treatment need was 16.1 and 2.0 percent, respectively, according to grades 4 and 5 of the IOTN DHC, 13.7 percent according to the IOTN AC, and 28.6 percent according to the modified IOTN (IOTN DHC grades 4-5 and/or IOTN AC grades 8-10). There were no statistically significant differences by gender. The orthodontic treatment need of Western Saharan schoolchildren is similar to that reported by many recent studies in European and in Sub-Saharan countries.

The aim of this study was to estimate the diagnostic agreement between assessments of orthodontic treatment need of a child population using the Dental Aesthetic Index (DAI) and the Index of Orthodontic Treatment Need (IOTN). A cross-sectional study of a representative random sample of children aged 12 (n = 475) and 15-16 (n = 398) years was carried out in the Valencia region of Spain. A Student's t-test was used to compare the DAI means by gender and age and a chi-square test to compare the proportions of the population in need of orthodontic treatment. To calculate the agreement between the two indices, intra-class correlation coefficient and Kappa statistics were employed. Of the 12-year-olds, 23.5 percent (n = 121) and of the 15- to 16-year-olds, 26.6 percent (n = 108) were receiving or had previously received orthodontic treatment. The observed agreement between the two indices on the need for treatment among the 12-year-olds (n = 363) was 83.4 percent and Kappa for diagnostic agreement was 0.52 [95 percent confidence interval (CI): 0.42-0.63]. For the 15- to 16-year-olds (n = 292), the figures were 82.5 percent and 0.38 (95 percent CI: 0.24-0.52), respectively. For the total sample (n = 655), the observed agreement was 83 percent and the diagnostic agreement was 0.47 (95 percent CI: 0.39-0.55). For this population, there was only moderate agreement between the two indices. This means that, when one of these indices is used to measure or prioritize orthodontic treatment in a determined population, the individuals selected with an obvious treatment need are going to be different in 17 percent of the cases depending on which index is used, DAI or IOTN. This difference has to be taken in consideration when measuring, recording, or quantifying orthodontic treatment need.

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