Influence of Printing Orientation on Flexural Strength and Flexural Modulus of Restorative Composites Produced by 3D Printing

Introduction: 3D printing resins have gained popularity in dentistry due to their practicality and reproducibility. However, differences in chemical composition have a direct influence on the mechanical properties of these materials and the various evaluation methods have generated different results which make it difficult to compare their properties. Objective: The aim of this study was to evaluate the influence of the orientation of the impression layers on the mechanical properties (flexural strength and flexural modulus) of biocompatible printed resins. Methods: 100 specimens (n=20) were made from bars measuring 2 x 2 x 25 mm, divided according to the angulation relative to the printing platform (V0, V22.5, V45, V67.5, V90). The bars were designed using Autodesk Meshmixer CAD software and printed on a 3D LCD printer. For the control group, composite resin specimens were made following the same patterns as the printed resins. These bars were subjected to 3-point bending tests on a universal testing machine and flexural strength (FS) and flexural modulus (MF) were evaluated. Results: The mean values of flexural strength and flexural modulus showed no statistically significant differences between the groups. The composite resin control group showed significantly higher mean values in both factors analyzed. Conclusion: It can be concluded that the groups showed minimal differences in the angles studied in both flexural strength and flexural modulus, showing the anisotropic behavior of the restorative material manufactured by 3D printing, suggesting that the choice of any printing angle can determine the applicability according to the characteristics and function of the object to be printed.