Objective: This study has investigated two new cephalometric variables. The Pi angle and Pi linear i. The evaluation of anteroposterior skeletal discrepancy. Design: Retrospective cross-sectional study. Setting: Manipal College of Dental Sciences, Manipal, India Subjects and method: A sample of 155 subjects (mean age 19.7 years) were subdivided into skeletal class I, II and III groups based upon ANB angle. Descriptive data were calculated for each variable and group. Receiver operating characteristics curves were used to examine sensitivity and specificity o. The Pi angle i. The discrimination between different skeletal groups. Correlation coefficients were obtained for each o. The parameters to compar. Their relationship with other parameters i. The class I group. Coefficient of determination, regression coefficient, regression equation and standard error of estimate were also calculated fro. The parameters showing significant correlation wit. The Pi angle. Results: Mean values fo. The Pi angle in skeletal class I, II and III subjects were 3.40 (±2.04), 8.94 (±3.16) and 23.57 (±1.61) degrees, respectively. Fo. The Pi linea. They were 3.40 (±2.20), 8.90 (±3.56) and 23.30 (±2.30) mm for class I, II and III subjects, respectively. Receiver operating characteristic curves showed that a Pi angle greater than 5 degrees had 89% sensitivity and 82% specificity for discriminating a skeletal class II group from class I. A Pi angle of less than 1.3 degrees had 100% sensitivity and 84% specificity in discriminating skeletal class III groups from class I. The overall accuracy for discriminating class II groups from class I wasand for class III from class I, 90%. Thus, a cut-off point between class I and II groups could be considered a Pi angle of approximately 5 degrees and between class I and class III, approximately 1.3 degrees. There were no statistically significant correlations found between Pi angle and ANB (0.07), Beta angle (20.04) and WITS analysis (0.19). The highest level of correlation was obtained fo. The Pi angle and Pi linear (0.96). Conclusion. The anglar and linear components o. The Pi analysis are a suitable method for assessing anteroposterior jaw discrepancy in daily clinical practice.
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