OBJECTIVES: The purpose of this study was to evaluate, through biomechanical tests, which synthetic material used for the manufacturing of test especimens (ABS plastic, polyamide, and polyurethane) shows a better biomechanical behavior for in vitro simulations of load resistance of a fixation method established to mandibular SSRO [Sagittal Split Ramus Osteotomy]. METHODS: 30 synthetic and standardized replicas of human hemimandibles with SSRO were divided into 3 groups of 10 samples each: Group A - ABS plastic, Group B - Polyamide, and Group C - Polyurethane. These were fixed by three positional bicortical screws (16 mm length, 2.0 mm system), in an inverted "L" pattern, using drilling guides and advancement of 5 mm. Each sample was subjected to a vertical linear load and the load resistance values recorded at 1, 3, 5, 7, and 10mm displacement. The standard deviations and means were compared using analysis of variance (p<0.05) and Tukey's test. RESULTS: It was observed a tendency for lower values in group B than in groups A and C. In displacements of 3 and 5 mm, there was a difference between groups A and C to group B (p<0.05). In displacements of 7 and 10 mm, there was a difference among the 3 groups, the highest values being found in group C and the lowest ones in group B (p<0.05). CONCLUSIONS: Taking into consideration the results achieved and the behavior of each material used as substrate, we can consider that ABS plastic was very flexible and polyurethane very rigid. On the other hand, polyamide samples behaved more likely to the human cortical bone, which can be validated to perform load tests, for SSRO, compared to other tested materials.