Assessment of malocclusion in the permanent dentition: reliability of intraoral measurements.

Malocclusion assessment methods are based on registrations and measurements made on study casts, which requires that impressions be taken. In addition to being costly and time consuming, this process can be unpleasant for children and adolescents. Therefore, the aim of this study was to evaluate the reliability of intraoral measurements that compute a malocclusion index score to determine malocclusion severity in permanent dentition. The research was a part of a longitudinal study of 530 3-year-old children. In Slovenia at 14 years of age [mean = 14.8 years, standard deviation (SD) = 0.2], a cohort of 92 children (39 boys and 53 girls) were selected at random in a cross-sectional study. Quantitative registrations of space and occlusal anomalies were performed intraorally as well as on study casts. Kappa (kappa) statistics were used to evaluate agreement between clinical and study cast malocclusion assessment. Systematic bias of measurements was tested using Wilcoxon's signed-rank test. The results showed almost complete agreement between the two measurements for anterior crossbite, anterior open bite (AOB), transverse occlusion of the posterior teeth, and crowding (kappa = 0.81-1); excellent reliability for rotation of incisors and canines, for buccal segment relationship, overjet, and axial inclination of teeth (kappa = 0.61-0.80); and for the remainder of the traits the reliability was moderate: vestibular canine eruption, overbite, and midline deviation (kappa = 0.41-0.60). Intraorally small, but statistically significant (P < 0.05) lower scoring of axial inclination of teeth was identified. Overall classification into severity grades, based on total malocclusion score, showed excellent agreement between the two methods ( kappa = 0.84), without statistically significant bias. Malocclusion assessment, recorded and measured intraorally, is as reliable as assessment on study casts. The proposed method can be used in screening, in epidemiological studies, and in clinical orthodontic assessment.