Overdenture with an Innovative T-OVER on a Single Implant versus the Locator System on One and Two Implants: A Finite Element Analysis

Bone loss resulting from prolonged edentulism often compromises the placement of multiple implants, resulting in alternatives with lower surgical complexity and reduced cost. In this context, overdentures (OVs) retained by a single implant have been proposed as a viable solution, particularly for patients with anatomical or financial limitations, using different types of retention systems. This study evaluated the biomechanical behavior of mandibular OVs through finite element analysis (FEA) under three prosthetic configurations: (i) the innovative T-OVER abutment with a T-PLUG on a single midline implant; (ii) the Locator system on a single midline implant (LA1); and (iii) Locators placed on two interforaminal implants (LA2). The T-OVER system features an abutment with a hyperbolic paraboloid geometry, a segmented tripod structure, and double curvature, allowing force equalization and selective load transmission, based on the principles of optimezed biodynamics for peri-implant tissues (BOPiT). Three loading conditions were simulated using FEA: bilateral posterior, unilateral posterior, and unilateral anterior, with stress and strain values analyzed. The T-OVER model exhibited the lowest stress and strain concentrations under bilateral posterior loading, followed by the LA2 and LA1 models. Under unilateral loading, the LA1 model demonstrated excessive stresses due to its lower rigidity, promoting prosthetic rotation. In the T-OVER model, an almost complete transfer of load to the implant was observed because of its smaller mucosal support area, resulting in higher bone stress. However, its geometry induces a more favorable axial direction of force transmission.