Predictability and Reliability of Different Anterio-Posterior Skeletal Discrepancy Indicators in Different Age Groups - A Cephalometric Study.

Abstract

The lateral cephalometric skeletal discrepancy indicators play a major role in diagnosing and preparing a case for orthognathic surgeries and the dentofacial corrections. The study was aimed to check the reliability and the predictability of different anterio-posterior skeletal discrepancy indicators in different age groups and to derive the most reliable indicator for the orthodontic diagnosis. A cross-sectional study was conducted on a sample of 100 subjects including 29 adolescent (15 males and 14 females) and 71 adult (41 males and 30 females) subjects with the mean age of 19.05 ± 5.78 years. All the subjects had Angle's Class I molar relationship. The lateral cephalograms of the sample were taken under the standard setting and hand tracing of the cephalometric radiographs using a sharp 4H pencil were made on acetate tracing paper. The anterio-posterior cephalometric indicators like β-angle, Wits appraisal (mm), Sella- Nasion plane to Point A and Point B distance (SN-AB mm) and Maxillo-Mandibular plane angle bisector to Point A and Point B distance (MM-AB mm) were measured. Intra-examiner reliability of tracings was evaluated using Intra Class Correlation (ICC) test. Mann Whitney U-test was applied for comparison of parameters between different malocclusion groups. Concurrent validity of various parameters was calculated using Cohen's kappa. A p-value <0.05 was considered statistically significant. The comparison of intra-examiner reliability of tracings in Angle's Class I adolescent group showed, MM-AB to have an almost perfect agreement followed by Wits. Intra-examiner reliability of tracings in Angle's Class I adult group showed moderate agreement for Wits and MM-AB showed almost perfect agreement and all the parameters showed statistically significant ICC. Comparison of parameters between adolescent and adult, Angle's Class I malocclusion group showed significant difference between adolescent and adult group for the Wits and SN-AB parameter. The final outcome of the present study revealed that, the MM-AB is highly reliable in the reproducibility and also highly valid parameter for checking antero-posterior discrepancies and ANB angle was least reliable for diagnosing the antero-posterior skeletal discrepancies.