Analysis of the abfraction lesions formation mechanism by the finite element method.
BACKGROUND
An abfraction lesion is a type of a non-carious cervical lesion (NCCL) that represents a sharp defect on the cervical part of tooth, caused by occlusal biomechanical forces. The largest prevalence of the NCCL is found on the mandibular first premolar. The goal of the study is, by means of a numerical method - the finite element method (FEM), in an appropriate computer program, conduct a stress analysis of the mandibular premolar under various static loads, with a special reference to the biomechanics of cervical tooth region.


METHODS
A three-dimensional model of the mandibular premolar is gained from a µCT x-ray image. By using the FEM, straining of the enamel, dentin, peridontal ligament and alveolar bone under axial and paraxial forces of 200 [N] is analyzed. The following software were used in the analysis: CT images processing-CTAn program and FEM analysis-AnsysWorkbench 14.0.


RESULTS
According to results obtained through the FEM method, the calculated stress is higher with eccentric forces within all tested tooth tissue. The occlusal load leads to a significant stress in the cervical tooth area, especially in the sub-superficial layer of the enamel (over 50 MPa). The measured stress in the peridontal ligament is approximately three times higher under paraxial load with regard to the axial load, while stress calculated in the alveolar bone under paraxial load is almost ten times higher with regard to the axial load. The highest stress values were calculated in the cervical part of the alveoli, where bone resorption is most commonly seen.


CONCLUSIONS
Action of occlusal forces, especially paraxial ones, leads to significant stress in the cervical part of tooth. The stress values in the cervical sub-superficial enamel layer are almost 5 times higher in relation to the superficial enamel, which additionally confirms complexity of biomechanical processes in the creation of abfraction lesions.
Department of Restorative Dentistry and Endodontics, Faculty of Dentistry, University of Sarajevo, Sarajevo, Bosnia and Herzegovina.
Selma
S
Jakupovic
Department of Production Engineering, Faculty of Mechanical Engineering, University of Tuzla, Tuzla, Bosnia and Herzegovina.
Edin
E
Cerjakovic
Department of Production Engineering, Faculty of Mechanical Engineering, University of Tuzla, Tuzla, Bosnia and Herzegovina.
Alan
A
Topcic
Department of Prosthodontics, Faculty of Dentistry, University of Sarajevo, 71000 Sarajevo, Bosnia and Herzegovina.
Muhamed
M
Ajanovic
Department of Restorative Dentistry and Endodontics, Faculty of Dentistry, University of Sarajevo, Sarajevo, Bosnia and Herzegovina.
Alma Konjhodzic-
AK
Prcic
Department of Dental Morphology with Dental Anthropology and Forensics, Faculty of Dentistry, University of Sarajevo, Sarajevo, Bosnia and Hercegovina.
Amra
A
Vukovic
abfraction; finite element method; occlusion; stress