Stress And Energy Relieving Effects Of Different Thickness Soft Denture Liner On Mandibular Complete Denture With Low And Flat Alveolar Ridge

Objective: To establish 3D finite element model of edentulous mandible with low and flat alveolar ridge and its mandibular complete denture with different thickness of soft liner materials.To analyze the energy relieving effects of different thicknesses of soft liner materials on the stress distribution of complete denture and its supporting tissues.And to provide theoretical and experimental evidence for relining of edentulous complete denture from the view of energy analysis,provide a new perspective for the biomechanical analysis of dentures.Methods: The 3D finite element models of edentulous mandible and the mandibular complete dentures with different thickness of soft liner material were set up by cone beam computerized tomography(CBCT)scanning method.There were three group models according to different thickness of soft liner material,Group A : Without soft liner material(0mm)under mandibular complete denture base;Group B: 0.5mm soft liner material under mandibular complete denture base;Group C: 1.0mm soft liner material under mandibular complete denture base;200N static and dynamic force were loaded in the vertical direction respectively to simulate the stress distribution of complete dentures and the supporting tissues,and the energy and stress relieving effects of different thickness of soft liner materials were analyzed by energy transferring method.Results: The results showed that the energy analysis was an effective method for the oral biomechanical analysis.Different thickness of soft-lining material had significant influence on the energy transferring rate.While under static loading,1)The energy transmission rates were decreased with the increase of soft liner material thickness,the results of A,B,C groups were 59.53%,49.10% and 37.73% respectively,which meant that the energy transferred to the alveolar ridge was reduced;2)The stress peak values of the alveolar ridge,mucoperiosteum and denture base were all occurred in the molars posterior area.The peak values were gradually decreased with the increase of thickness of the soft liner material.While the dynamic impact loading,1)With the thickness of the liner material increasing,the energy transferring rates of the groups were 44.8%,36.05%,and 27.70% respectively.The energy transferred to the alveolar ridge was reduced,and the loading of alveolar ridge decreased simultaneously and evenly;2)Stress peak values of alveolar ridge,mucoperiosteum and denture base also occurred at the molar area in three groups.The stress values were gradually reduced with the thickening of the soft liner material,which made the stress distribution more evenly.Conclusion: 1)The energy transfer rate decreased with the increase of the thickness of the soft liner material,which means energy relieving capacity increases with the liner material thickness.2)For the complete denture of the low and flat alveolar ridge,the soft liner material have stress and energy relieving effect,the stress peak value of the alveolar ridge is reduced and the stress distribution is more even with increase of the liner thickness.