2017 年 30 巻 4 号 p. 278-286
Purpose : This study was performed to investigate and compare the mechanical influence of attachment types on the implant and mucosal tissue under the posterior part of implant overdentures (IOD) with a combination of mechanical reaction analysis and structural analysis using the finite element method (FEM) .
Methods : Implant overdentures with ball attachments (B-IOD), implant overdentures with locator attachments (L-IOD), and complete dentures (CD) were established in the experiment model. A 50 N load was applied onto the right first molar position of the overdenture, and the bending moment on each implant and the overdenture displacement were measured. Additionally, the FEM model was prepared based on DICOM data of the in vitro model. The interface between the denture base and mucosal tissue was assumed to be a contact interface, not a continuous interface. Displacement data measured by the experiment model analysis were inputted into the FEM model, and the stress distribution in the mucosal tissue under the posterior part of the denture was evaluated.
Results : In the L-IOD, the bending moment in the loaded-side implant was greater than that in the nonloaded side. In the B-IOD, the stress on both the loaded and non-loaded sides was smaller and almost equal. Mucosal stress in the loaded posterior part using B-IOD was the highest among the B-IOD, L-OD, and CD. The mucosal stress in the L-IOD was lower than that in the B-IOD and CD on both the loaded and non-loaded sides.
Conclusion : Stress in the mucosal tissue under the denture base was able to be evaluated using a combination of mechanical reaction analysis and FEM analysis. Differences in the mucosal stress distribution were detected among the CD, B-IOD, and L-IOD. The highest mucosal stress value was shown in the B-IOD.
