JS sagittal dysplasia – a new frontier for true assessment of antero-posterior relationship of jaws

Objective: There are several methods to determine anteroposterior dysplasia but the reliability of the landmarks used have always been questioned as misleading factors may provide false results. Thus the objective of this article is to develop a new composite method, using stable landmarks, to assess the antero-posterior sagittal dysplasia. Material and methods: Lateral cephalograms of 1500 patientswere selected for study. Out of these based on exclusion and inclusion criteria,42 patients with class I , 42 patients with class II and 41 patients with class III were selected.10 angles were designed to evaluate the antero-posterior dysplasia and the values for each parameter was measured for each patient. The values were measured independently by two investigators. Cephalometric measurements were done by a trained orthodontist with more than 92% intra-rating agreement. Results: A new JS sagittal dysplasia indicator based on relatively stable landmarks, utilizing the S1-post surface of ramus, S2-mandibular plane angle and MNG angle can be used to evaluate the sagittal dysplasia. Conclusion: Patients with the JS sagittal dysplasia indicator values of 15.59 indicates Class I malocclusion, 7.99 indicates Class II malocclusion and -8.50 indicates Class III malocclusion. This new indicator can be used as an adjunct with various other parameters in evaluating the antero-posterior jaw relationship.