Immediate versus conventional loading of implant-supported maxillary overdentures: A finite element stress analysis

Purpose: To compare biomechanical outcomes of immediately and conventionally loaded bar-retained implant-supported maxillary overdentures using finite element stress analysis. Materials and Methods: Finite element models were created to replicate the spatial positioning of four 4.1- × 12-mm implants in the completely edentulous maxillae of four cadavers to support bar-retained overdentures with 7-mm distalextension cantilevers. To simulate the bone-implant interface of immediately loaded implants, a contact situation was defined at the interface; conventional loading was simulated by "bonding" the implants to the surrounding bone. The prostheses were loaded with 100 N in the projected molar regions bilaterally, and strain magnitudes were measured at the buccal aspect of bone. Results: The amplitude of axial and lateral strains, the overall strain magnitudes, and the strain magnitudes around anterior and posterior implants in the immediate loading group were comparable to those seen in the conventional loading group, suggesting that the loading regimens created similar stress/strain fields (P > .05). Conclusions: Conventional and immediate loading of maxillary implants supporting bar-retained overdentures resulted in similar bone strains.