Estimation of the prevalence of malocclusion on the basis of nationwide oral health examinations of pre-adolescent and adolescent students during 2012-2017

Objective: To investigate the prevalence of malocclusion with respect to grade, sex, and year among Korean pre-adolescent and adolescent students during 2012-2017. Methods: A total of 165,996 students (first grade [E1, 6-7 years of age], fourth grade [E4, 9-10 years], seventh grade [M1, 12-13 years], and tenth grade [H1, 15-16 years]) were selected by stratified sampling method and underwent the nationwide oral health examination performed by the Ministry of Education, Republic of Korea. The malocclusion assessments based on dentists' judgments were "no malocclusion," "needs orthodontic treatment (N-OTx)," and "under orthodontic treatment (U-OTx)." The sum of N-OTx and U-OTx cases was determined as the number of students with malocclusion. After analyzing the prevalence of malocclusion according to grade, sex, and year-by-year differences, Pearson correlation analyses and two-way analyses of variance were performed. Results: The prevalence of malocclusion was 18.7%, which increased with the grades (E1 [8.3%] < E4 [15.8%) < M1 [22.9%] < H1 [25.3%), p < 0.001). However, there was no significant difference in the prevalence of malocclusion in each grade group for the period (p > 0.05) without significant correlation (El, rho= 0.129; E4, rho = -0.495; Ml, rho = 0.406; HI, rho = -0.383; all p > 0.05). The prevalence of malocclusion within each grade group over the six-year period was more prominent in the female (p < 0.0001). Conclusions: Further studies are necessary to modify the malocclusion assessment method to account for specific types of malocclusion in pre-adolescent and adolescent students.