Effect of elastic soft liner on stress distribution in mabibular complete denture and its supporting structures

Abstract

There are many edentulous people with severe resorbed residual ridge and non-resilient lining mucosa that are unable to tolerate occlusal forces during functional and parafunctional movements. In such condition, lining the tissue surface of denture prosthesis with a flexible material can distribute and absorb forces with cushioning effect,theoretically. Evaluation of stress distribution within denture supportive tissues is not possible by in-vivo studies but there are little and conflicting information about the stress distribution within the mandibular complete denture supportive structures with and without soft liner by finite element analysis. Aim: the purpose of this study was to evaluate the effect of soft liner on stress level in mabibular complete denture and its supporting structures by finite element analysis. Methods and materials: A simplified 3 dimensional finite element model of relatively resorbed mandible, mucosa, denture and soft liner was prepared. Then the model, with and without soft liner, was undertook normal vertical and lateral occlusal forces. The amount of stresses were analyzed using the ANSYS 12 software. Results: Using the soft liner, 18/5% and 30% ncreased stress level was seen in cortical bone and mucosa after vertical load applied in incisors region, respectively. Application of bilateral vertical load on molar area increased stress in cortical bone to 44% and in mucosa to 29%. Unilateral loading in canine area increased stress level in mucosa to 63/5%. Conclusions: Use of soft liners increased stress in denture supportive structures. Higher level of stress concentration was observed primarily in the denture base followed by the cortical bone.