Overlays represent an effective restorative alternative for the rehabilitation of affected dental structures. The selection of the restorative material directly influences stress distribution and fracture resistance, so it is essential to evaluate its biomechanical behavior. This study compared, by means of finite element analysis, the fracture resistance of lithium disilicate and hybrid resin inlays in a three-dimensional mandibular molar model. The maximum deformations and Von Mises stresses were analyzed under an occlusal load of 500 N applied perpendicularly to the occlusal surface, considering a physiological environment with a temperature of 37°C and 95% humidity.

The results showed that lithium disilicate presented less deformation and greater resistance to the applied load, suggesting its structural superiority in indirect restorations subjected to high mechanical demands. In contrast, the hybrid resin showed greater deformation and lower Von Mises stress, indicating greater flexibility and lower structural strength. Statistical analysis confirmed significant differences (p < 0.05) between the three groups evaluated (sound tooth, lithium disilicate and hybrid resin), establishing that material selection influences the stability and stress distribution in the restoration. These findings support the use of lithium disilicate in areas of high functional load, while hybrid resin could be suitable for restorations in areas with lower mechanical demands.