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This study evaluated, by mechanical testing, the strength of four-hole grid plates used for mandibular angle fracture fixation. Much has been discussed about the treatment of mandibular fractures with straight or curved plates. However, there are few studies about the use of grid plates. The geometry of such plates provides three-dimensional stability, resistance against torque associated with a low profile. Ninety polyurethane hemimandibles were used as substratum. The hemimandibles were divided into nine groups and fixation of the fractures was performed varying the type and position of plate and type of screw. An intact hemimandible group was used as control. It was possible to observe that plates positioned at the tension zone present the highest load values, both for dislocations of 3 and 5 mm. There was no statistical difference when plates with or without an intermediate bar were tested. The locking screws were more efficient than the non-locking screws when the plates were positioned at the neutral zone. Results allowed us to conclude that grid plates installed at the tension zone presented greater mechanical efficiency. If grid plates are positioned at the neutral zone, they should have an intermediate bar and be fixed with locking screws.

Cephalometric tracing done manually was considered gold standard for the cephalometric analysis in the last decades. The digital radiographs began to be commonly used in order to make that in a digital way. The objective was to define the accuracy of the predictive and final cephalometric tracings performed manually and virtually. The authors selected 20 patients submitted to bimaxillary orthognathic surgery. The data were collected from lateral cephalometric radiographs, in the preoperative and postoperative periods. The interest were: points, angles (Sella-Nasion to A point angle; Sella-Nasion to B point angle; Frankfurt plane to Mandibular plane angle; Frankfurt plane to occlusal plane angle; Upper and lower central incisors long axes angle; Incisor to Mandibular plane angle; Upper incisor axis to Sella-Nasion plane angle) distances (Co-A; Co-Gn). Data were submitted to the Shapiro-Wilk, analysis of variance, and Kruskal-Wallis tests. The measurement differences were compared using a t test. Descriptive statistics were performed in Excel 2013 and SPSS software, P0.05 being considered significant. No statistically significant difference was found between the mean values predictive and postoperative of the angles and distances within the manual and digital groups. When comparing the means of the differences between the predictive values and the final values, only the 1:1 angle presented a statistically significant difference, indicating a greater accuracy of the digital predictive tracing for this measure. In conclusion, both methods for obtaining predictive tracings are accurate, which shows that clinical results can be successfully simulated by the most accessible technique.