Using the appropriate modulus of elasticity of periodontal ligament matters in stress analysis of human first premolar tooth and periodontium structures

Although the modulus of elasticity of the human periodontal ligament (E_PDL) values used in dentistry widely ranged from 0.01 to 175 MPa, the exact E_PDL value has not been determined. This study aimed to verify whether and how E_PDL values affect the stress distribution over the tooth and periodontium structures, and to determine the appropriate E_PDL range. A 3D multi-component human first premolar model was created based on a cone-beam computed tomography dataset. Finite element analysis was performed to analyze stress distribution and deformation of the structures under an average Asian occlusal force with different E_PDL values (0.0689-68.9 MPa). The low E_PDL caused excessive PDL deformation, contributing to a non-uniform stress distribution and localized stress concentration, especially in the cementum, enamel, and dentin. With the low E_PDL value, the stress magnitude was overestimated by 1,195%, potentially leading to erroneous conclusions regarding material failure and tooth movement. The E_PDL value significantly affects the stress magnitude and distribution over the tooth and periodontium. The appropriate E_PDL range of 0.964 ± 0.276 MPa is suggested for human first premolars to ensure accurate and reliable FEA simulations and help avoid misinterpretation of the stress results, which could compromise orthodontic planning and restoration design.