3D Finite Element Analysis Of Two Implants Retained Mandible Overdenture Connectted With Different Attachments

ObjectiveThe aim of this study was to analyze the effect of attachment types on thebiomechanical properties of mandibular overdenture, by contructing threetwo-implant retained mandibular overdenture models with three differentattachments, by means of three-dimensional finite element analysis.MethodsThrough the use of CT scanning, Mimics3D reconstruction, Geomagic Studioreconstruction of mandible, NX3D modeling and3D finite element analysissoftware, three edentulous overdenture models retained by two implant weregenerated. They were connected with ball,locator and bar-clasp attachmentrespectively.100N vertical and100N oblique loads were applied on the left firstmolar and100N vertical loads were applied on the lower incisors. Thebiomechanical behaviors of implant, periimplant bone,mucosa and denture basewere recorded.ResultThe result shows that, regardless of what kind of loading conditions and whatkind of attachment, stress concentration phenomenon is found on the neck of theimplant, especially on the contact zone of implant and abutment of attachment. Stressconcentration is occoured on the cortical cancellous bone surrounding the implant.The stress values do not exceed their limits. Compared with oblique loads, the peakstress values of implant and periimplant and denture mobility was lower undervertical loads. As for attachment types, compared with the bar attachment, ball andlocator attachment is more favor of reduce the pressure on the implant and alveolarridge.ConclusionsWith the limitations of this in vitro study, the following conclusions can bedrawn as follows:1.The stress of implant are concentrated in the neck of implant. The stress of supporting organizations are concentrated in the cortical bone around the implant,which may lead to bone absorption and rebuild of this part.2.Stress distribution characteristics of different attachment systems are different.Compared with locator attachment and bar-clasp attachment, ball attachmentoverdenture may cause less stress concentration of implants and periimplant tissue.3.The stress of the implant and periimplant bone tissue are greater when thelateral force is loaded. So compare with vertical force, oblique force may more easilyleads to bone remodeling and bone resorption.