Evaluation of a Novel Zygomatic-based Cephalometric Angle for Sagittal Skeletal Discrepancy: A Retrospective Study

To evaluate the diagnostic accuracy of a novel zygomatic-based cephalometric parameter, the ZYen angle, for assessing sagittal skeletal discrepancies.

This retrospective cross-sectional study analyzed 369 pretreatment lateral cephalograms of subjects aged 18-25 years, equally distributed into skeletal class I (n = 123), class II (n = 123), and class III (n = 123) groups. Skeletal classification was performed using the A point-nasion-B point angle (ANB) and Wits appraisal. The ZYen angle, defined using points M, Z (zygomatic point), and D, was measured, and its diagnostic performance was assessed using one-way analysis of variance (ANOVA) and receiver operating characteristic (ROC) curve analysis to determine sensitivity, specificity, and area under the curve (AUC).

The ZYen angle showed significant differences among skeletal classes (p < 0.001). Receiver operating characteristic analysis demonstrated excellent discrimination between skeletal class I and class III (AUC = 0.908), with a cut-off value of 29.5° providing balanced sensitivity (78.9%) and specificity (82.9%). In contrast, discrimination between class I and class II was poor (AUC = 0.594), indicating limited diagnostic ability for identifying class II patterns.

The ZYen angle is a reliable sagittal skeletal parameter with high diagnostic accuracy for distinguishing class I from class III relationships but limited utility in differentiating class II malocclusions.

Accurate sagittal skeletal diagnosis is essential for orthodontic treatment planning and prognosis. The ZYen angle utilizes stable zygomatic landmarks and minimizes reliance on cranial base and dental reference points, enhancing diagnostic confidence in class III cases. It may serve as a clinically useful adjunct to conventional cephalometric parameters, particularly in borderline or ambiguous sagittal discrepancies.