Assessment of the accuracy of cephalometric prediction tracings in patients subjected to orthognathic surgery in the mandible

Objective: The purpose of this study was to assess the accuracy of cephalometric prediction tracings—performed for orthognathic surgery—by means of the cephalometric analysis of preoperative and seven-day postoperative tracings, in patients subjected to correction of mandibular deformities. Methods: The lateral cephalograms of 17 patients who had been submitted to mandibular orthognathic surgery, three years earlier, were used. Cephalometric tracings were performed in the preoperative and seven-day postoperative periods and the following landmarks were traced: condyle (Co), pogonion (Pog), gonial (Go), menton (Me), B (B) and incisor (I). The analysis was based on the difference obtained by superimposing preoperative, prediction and postoperative tracings. The landmarks were projected onto a Cartesian plane for measuring distances between points in millimeters. The data were statistically analyzed using the paired Student t test (α = 0.05). Results: A statistically significant mean difference was observed between the planned change and the change effectively achieved in the postoperative cephalometric tracings for points Pog (p = 0.014) and I (p = 0.008) on the horizontal axis. No statistically significant difference was found for the aforementioned cephalometric points on the vertical axis (p > 0.05). Conclusions: Cephalometric prediction tracings contributed to the preoperative evaluation of the patients and consequently to treatment optimization. However, they was not entirely reliable in these cases due to a slight underestimation of horizontal skeletal changes. These changes should be considered in planning and postoperative follow-up of patients subjected to orthognathic surgery in the mandible. Abstract