Prevalence and distribution by gender of occlusal characteristics in a sample of Italian secondary school students: a cross-sectional study

The aim of this study was to describe the prevalence and distribution, by gender, of occlusal traits in a sample of Italian students aged 11-14 years (mean 13 +/- 1 years). Using standardized and validated recording criteria, a single operator measured the overjet, overbite, open bite, anterior and posterior crossbites, crowding, coincidence of the upper and lower midlines, and diastema, in 810 secondary school students (53.6 per cent males). Chi-square, t-test statistics, and odds ratios (ORs) with 95 per cent confidence intervals (CI) were used to investigate the relationship between gender and malocclusion characteristic. Logistic regression was used to further analyse the independent association between gender and each outcome measure. Ninety-three per cent of the subjects showed at least one occlusal trait, with one or two anomalies recorded in 63 per cent of children. The prevalence of occlusal traits ranged from 1.1 (negative overjet) to 54 per cent (upper and lower midlines not coincident). Males were more likely than females to show both an increased overbite and an increased overjet, although the latter result was not confirmed by logistic regression (P = 0.05). Multivariate analysis showed a negative association between overbite and misalignment of the lower incisors and lack of coincidence of the upper and lower midlines, whereas subjects with an increased overbite were more likely to have an increased overjet (all P < 0.01). Further studies are required in order to further clarify these findings and to provide accurate estimates of the orthodontic treatment need in Italian adolescents.