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

Thallita Pereira QUEIROZ, Jéssica Lemos GULINELLI, Francisley Ávila SOUZA, Liliane Scheidegger da Silva ZANETTI, Osvaldo MAGRO FILHO, Idelmo Rangel GARCIA JÚNIOR, Eduardo Hochuli VIEIRA

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 (Į = 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.

Keywords: Surgery. Cephalometry. Mandible.

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