Stress distribution of different attachment systems in mandibular implant overdentures: A 3D finite element study

The choice of attachment system in mandibular implant overdentures directly affects stress distribution in the implant-prosthesis-bone complex. Despite the wide use of different systems, their biomechanical performance has not been comprehensively compared, particularly for the recently introduced LOCATOR R-Tx design.

The purpose of this 3-dimensional (3D) finite element analysis FEA study was to compare and assess the biomechanical performance of the LOCATOR R-Tx attachment system with 4 different attachment systems.

A 3D model of an edentulous mandible was generated from computed tomography data and restored with 3 implants placed in the midline and canine regions. 5 attachment systems were digitally modeled, and FEA was performed under unilateral oblique (UO) and unilateral vertical (UV) loading conditions with a 200-N load. von Mises stress values were calculated for the implant and abutment, and maximum principal stress (Pmax) values were recorded for cortical and trabecular bone.

LOCATOR and LOCATOR R-Tx attachments exhibited the lowest von Mises stresses at the implant and abutment interfaces under both loading conditions. Telescopic attachments generated the highest stresses, particularly under oblique loading. Ball attachments produced the lowest cortical and trabecular Pmax values, while bar attachments produced the highest. Oblique loading consistently generated higher stresses than vertical loading, and the stress concentration was greatest at the implant neck.

LOCATOR type attachments, especially LOCATOR R-Tx, demonstrated favorable biomechanical performance by reducing stress transfer and distributing loads more uniformly. These features may lower the risk of implant overload and bone resorption. Within the limitations of this study, LOCATOR R-Tx appears to be the most advantageous option, offering predictable stress distribution in 3 implant mandibular overdentures.