Influence of non carious cervical lesions depth, loading point application and restoration on stress distribution pattern in lower premolars: a 2D finite element analysis

Abstract

The aim of this study was to analyze the biomechanical behavior of lower premolars regarding the non-carious cervical lesion (NCCL) depth, load type and restoration status, using finite element analysis. Two-dimensional virtual model simulating a healthy lower premolar were created using the CAD software. Based on this image, five models were generated: healthy (H), three types of NCCLs: small lesion (SL - 0.5 mm deep), medium lesion (ML - 1.0 mm), deep lesion (DL - 1.5 mm), and restored lesion (RL). The models were export to a CAE software (ANSYS Finite Element Analysis Software), the areas of all structures were plotted and each model was meshed using a control mesh device. All of the virtual models were subjected to two occlusal load types, (100N each): occlusal load (OL) and buccal load (BL) on buccal cusp. The magnitude and the stress distribution were obtained using the von Mises and maximum principal stress criteria (σ1), in MPa. The quantitative analysis of stress (MPa) was identified at three points of the NCCLs: enamel surface on its upper wall , dentin at the bottom wall and dentin on the lower wall. The results showed a direct relation between sequential removal of cervical structure and higher stress concentration for any groups and for both loads types. For OL the highest value of stress was 8.8 MPa for DL on upper wall of NCCLs.The BL exhibited higher stress values in comparison to the OL for all models.In addtion, the BL was responsible for providing the highest stress accumulation on the bottom wall, 38.2 MPa for DL. The restoration with composite resin was able to restore a stress distribution close to the healthy model, for both load types. In conclusion, the extent of non-carious cervical lesion and loading conditions influenced the stress distribution pattern of lower premolar. The outer load seems to be more critical in affecting the biomechanical behavior of lower premolars, regardless of the lesion size. The restoration of NCCLs with composite resin appears to recover the biomechanical behavior, similar to healthy model.