Intra- and inter-examiner reliability of intraoral malocclusion assessment

Malocclusion assessment methods are based on measurements of study casts, which requires that impressions be taken. In addition to being costly and time consuming, this process can be unpleasant for children. Therefore, the aim of this study was to evaluate intra- and inter-examiner reliability of intraoral score measurements to determine malocclusion severity in the permanent dentition. The research was a part of a longitudinal study from which a cohort of 92 children (39 boys, 53 girls), with a mean age of 14.8 years (standard deviation = 0.18), were randomly selected and classified into severity grades based on total malocclusion score. Subsequently, 12 children were randomly selected for a reliability study to assess intra-examiner reliability of malocclusion trait measurements. Nine subjects gave informed consent to participate in the study. Quantitative registrations of space and occlusal anomalies were performed intraorally by five examiners, on two occasions with a 1-month interval between the two measurements. Intra- and inter-examiner reliability was determined using intraclass correlation coefficients (ICCs). Overall classification into severity grades, based on total malocclusion score, showed almost perfect intra-examiner reliability for all examiners (ICC = 0.97-0.99); inter-examiner ICC was almost perfect (0.97). Near perfect intra-examiner reliability was determined for eight occlusal trait measurements (ICC = 0.89-1.0); substantial reliability for midline deviation (ICC = 0.68), overbite (ICC = 0.78), but large variability for space condition assessment (ICC = 0.42-0.52). Inter-examiner reliability was almost perfect for the eight traits (ICC = 0.81-1.0); substantial reliability for midline deviation (ICC = 0.65), and axial tooth inclination (ICC = 0.75), but large variability for space condition assessment (ICC = 0.13-0.26). Intra- and inter-examiner malocclusion assessment, recorded and measured intraorally to determine malocclusion severity scores in 14-year old children, is reliable. It is therefore proposed as the method of choice to be used not only in epidemiological studies and screening but also in clinical orthodontic assessment.