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

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. Twodimensional 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.

Prevalence of non-carious cervical lesions and cervical dentinary hypersensitivity in undergraduate students

“…In non-carious cervical lesions, there is a loss of tooth structure in the cervical region of the teeth, which can cause damage to aesthetics and hypersensitivity, as reported by Telles et al 2 and Nascimento et al 8 . The dentinal tubules can be exposed as a result of enamel loss by friction, abrasion, erosion or abfraction, generating a short, sharp pain that arises from the exposed dentin in response to stimuli 16 . This fact corroborates the present study, in which, in relation to the aspects that were analyzed, it can be seen that of the students who presented dentinal hypersensitivity, only one did not have a non-carious cervical lesion.…”

“…Furthermore, studies have reported that the position of the occlusal load modifies the intensity of stress concentration in the cervical regions. Loads applied obliquely along the long axis of the tooth can promote an increase in stress in the cervical region and are related to the formation and progression of NCCLs 16 . Also, the presence of traumatic dental occlusion is considered an important factor in the occurrence of these injuries 13 .…”

“…According to Soares et al 4 in their study, 90% of participants who were diagnosed with bruxism reported symptoms of stress. Apparently, stress plays an important role in triggering and maintaining bruxism, which is one of the predisposing factors for the onset of non-carious cervical lesions 2,4,5,16 . Stress related to undergraduate students is explained by Soares et al 4 , due to the irregular sleep pattern and the accumulation of extracurricular activities that can be conflicting, exposing undergraduate students to various stressful situations.…”

“…Probably, the fact that no correlation was found between these injuries with stress and these reported temporomandibular symptoms can be justified due to the average age of 22 years, demonstrating that, in addition to the factors presented, a fatigue component would be necessary in the formation of NCCLs associated with occlusal interferences or any event that alters dental occlusion, because, as they are young people, these factors, even if they exist, did not have enough time to cause wear. These events change the pattern of stress distribution in the cervical region and can lead to a weakening of the continuity between the structures, generating an NCCL 16 . Furthermore, it is argued that an occlusal load that is far from the site of the cervical defect cannot be considered cause of these injuries 8 .…”

Influence of non-carious cervical lesions, bone attachment level, and occlusal load on the stress distribution pattern in maxillary premolars: finite element analysis

“…The buccal load (BL) and palatal load (PL) were applied at 45 degrees to the long axis on buccal and palatal cusps respectively, simulating occlusal interferences (Rees 2002). The models were constrained to the side and base of cortical and trabecular bones to prevent displacement (Zeola et al 2015;Machado et al 2017).…”