Sensitivity and specificity of SNB and Facial angles in diagnosis of mandibular anteroposterior position in class II patients

There is little information about the diagnostic ability of SNB and Facial angles in class II malocclusion. The aim of this study was to evaluate sensitivity and specificity of SNB and Facial angle in diagnosing anteroposterior position of mandible in patients with skeletal class II malocclusion. Pretreatment cephalograms of 76 patients with skeletal class II malocclusion were assessed in this study. Sensitivity and specificity of SNB and Facial angles were determined using SPSS and ROC (Receiver Operative Characteristics) curves. Sensitivity and specificity of Facial angle were 61 and 70 percent, respectively. The corresponding values for SNB angle were 40 and 86 percent. The highest sensitivity and specificity for SNB and Facial angles related to 75.5 and 79.5 degrees, respectively. The findings showed that in diagnosing mandibular anteroposterior position of class II patients, Facial angle is more sensitive and SNB angle is more specific. Moreover, it is suggested that in cephalometric analysis, patients with Facial and SNB angles less than 79.5 and 75.5 degree respectively, be assumed to have skeletal class II malocclusion.