Comparison of the reliability of ANB Sar and W measurements used in cephalometric diagnostics for the assessment of sagittal discrepancy

Accurate cephalometric assessment is used in orthodontic diagnosis and treatment planning. The aim of this study was to confirm the reliability of Sar and W angle measurements with the results obtained for the ANB angle. The reliability of angular measurements for determining sagittal discrepancy was assessed after determining anthropometric points (N, A, B, S, W, M, G). These formed the ANB, Sar, and W angles, respectively. Cephalometric analyses were performed separately, 7 days apart, by 22 orthodontists. To determine inter-rater reliability, a two-way ANOVA without repeated measures was used, using the ICC(3,1) coefficient. To compare the reliability of the ANB, Sar, and W angles, the Blant-Altman plot, Dahlberg formula, intraclass correlation coefficients (ICC), R2 coefficients, and R&R coefficients were used. Pearson's chi-square test was used to assess the number of individuals classified into each skeletal class. The ICC(3.1) coefficient at a 95% confidence level was 0.941 for the ANB angle, 0.679 for the Sar angle, and 0.688 for the W angle. These results demonstrate excellent measurement reliability for the ANB angle and good reliability for the Sar and W angles. The participating orthodontists measured sagittal discrepancy significantly more accurately using the ANB angle compared to the Sar and W angles. One of the main factors implying poorer reliability of the Sar and W results is operator error. The difficulty in determining the values of the angle tests is related to the determination of new anthropometric points. The obtained results indicate higher reliability of the ANB measurement in assessing sagittal discrepancy in malocclusions. The Sar and W angles can be used to a limited extent, especially in the assessment of extreme cases. Further studies determining the usefulness of the new Sar and W angles in the orthodontic diagnosis of sagittal discrepancy should be correlated with previous measurements, including Wits or Beta angle measurements.