Biomechanical consequences of progressive marginal bone loss around oral implants: a finite element stress analysis

The purpose of this study was to explore the biomechanical effects of progressive marginal bone loss in the peri-implant bone. Finite element model of a Ø 4.1 x 10 mm Straumann dental implant and a solid abutment was constructed as predefined eight-layers around the implant neck. The implant-abutment complex was embedded in a cylindrical bone model to analyze bone biomechanics regardless of anatomical influences. Angular and circular progressive marginal bone loss was simulated by sequential removal of each layer, resulting crater-like defects and a total of ten finite element models for analysis. Each model was subjected to a vertical and oblique static load of 100 N in separate load cases. Principal stress minimum and maximum, displacement, and equivalent of elastic strain outcomes were compared. Under vertical loading, principal stresses minimum and maximum decreased remarkably as with the increase in bone resorption. Under oblique load simulations, decrease in principal stress maximum and minimum was evident. With progressive bone loss and under oblique load simulations, displacement and equivalent of elastic strain increased considerably in trabecular bone contacting the implant neck. The presence of cortical bone contacting a load-carrying implant, even in a bone defect, improves the biomechanical performance of implants in comparison with only trabecular bone support as a sequel of progressive marginal bone loss.