A comparison of two types of two implant-retained overdenture attachments on the stresses introduced to the mandibular posterior residual ridge: 3D Finite Element Analysis

The biomechanics of implant-retained overdenture can lead to different resorption patterns in the posterior regions of each arch. Two of the most commonly used attachment systems for these type of prostheses are Bar/clip and Ball with different biomechanical properties. The aim of the present study was to compare two types of implant-retained overdenture attachments on the stresses introduced to the mandibular posterior residual ridge by means of 3D Finite Element Method. This experimental study performed with Ansys software. The basic model was generated from data provided by a CT-scan of edentulous patient. Two root form implants were placed in inter foramen region of the mandible. Models were used in order to simulate two situations: In group A, model represented an edentulous mandible supporting an over denture retained by two-splinted implants connected with Bar/clip system while in group B, model simulated an edentulous mandible supporting an overdenture retained by two solitary implants with Ball attachments. The occlusal load of maxillary complete denture was introduced in two directions for each group: vertical load as in centric occlusion, and oblique load as in working lateral excursion. The amount of stress introduced by over denture using Bar attachment was higher in centric occlusion and working lateral excursion. If the only determining factor for choosing the attachment system was the amount of stress introduced to the mandibular posterior ridge, then the Ball system would be the attachment of choice.