Abstract
Background and aims. There are many edentulous people with severely resorbed residual ridges and non-resilient lining
mucosa that are unable to tolerate occlusal forces during functional and parafunctional movements. Lining the tissue
surface of dentures with a flexible material can theoretically distribute and absorb forces with cushioning effect. The aim of
this study was to evaluate the effect of a soft liner on stress levels in mandibular complete denture and its supporting structures
by finite element analysis.
Materials and methods. A simplified 3-dimensional finite element model of relatively resorbed mandible, mucosa,
denture and a soft liner was prepared. Then the model, with and without soft liner, underwent normal vertical and lateral
occlusal forces. The stresses were analyzed using the ANSYS 12 software.
Results. Using the soft liner increased stress levels up to 18.5% and 30% in the cortical bone and mucosa, respectively,
after vertical load was applied in the incisor region. Application of bilateral vertical load on the molar area increased stress
in cortical bone u to 44% and in the mucosa up to 29%. Unilateral loading in the canine area increased stress level in the
mucosa up to 63.5%. The highest stress was seen at denture base followed by the cortical bone.
Conclusion. Use of soft liners increased stress in denture supporting structures. Higher level of stress concentration was
observed primarily in the denture base followed by the cortical bone.