Mechanical properties of human bone surrounding plateau root form implants retrieved after 0.3–24 years of function

Bone remodeling, along with tissue biomechanics, is critical for the clinical success of endosseous implants. This study evaluated the long‐term evolution of the elastic modulus (GPa) and hardness (GPa) of cortical bone around human retrieved plateau root form implants. Thirty implant‐in‐bone specimens showing no clinical failure were retrieved from patients at different in‐vivo times (0.3 to ∼24 years) due to retreatment needs. After dehydration, specimens were embedded in methacrylate‐based resin, sectioned along the bucco‐lingual long axis and fixed to acrylic plates and nondecalcified processed to slides with ∼50 μm in thickness. Nanoindentation testing was carried out under wet conditions on bone areas within the first three plateaus. Indentations ( n = 120 per implant total) were performed with a maximum load of 300 μ N (loading rate: 60 μ N /s) followed by a holding and unloading time of 10 s and 2 s, respectively. Elastic modulus (E, GPa) and hardness (H, GPa) were computed. Both E and H values presented increased values as time in vivo elapsed (E: r = 0.84; H: r = 0.78). Significantly higher values for E and H were found after 5 years in vivo ( p < 0.001). Maxillary or mandibulary arches or positioning did not affect mechanical properties, nor did implant surface treatment on the long‐term bone biomechanical response (E: p ≥ 0.09; H: p ≥ 0.3). This work suggests that human cortical bone around plateau root form implants presents an increase in elastic modulus and hardness during the first 5 years following implantation and presents stable mechanical properties thereafter.