Impact of Bone Grafts Containing Metformin on Implant Surface Hydrophilicity: An In Vitro Study

Background/Objectives: The effect of metformin combined with bone grafting materials and its effect on the hydrophilicity of different implant surfaces has not been investigated. Investigation of the use of metformin as a therapeutic for implant surface treatment may be useful in improving overall implant longevity and success. Methods: Herein, a 1.5% metformin solution was created with crystalline metformin and distilled water. Titanium alloy (machined surface), titanium with sandblasted, large-grit acid-etched surface (Ti-SLA), and zirconia (SDS) surfaces were treated with five different solutions: 0.9% sodium chloride (Group A), bovine cancellous bone graft (Bio-Oss^®)/0.9% sodium chloride solution (Group B), Bio-Oss^® bone graft with metformin/0.9% sodium chloride solution (Group C), algae-based bone graft (AlgOss^®)/0.9% sodium chloride solution (Group D), and AlgOss^® bone graft with metformin/0.9% sodium chloride solution (Group E). Hydrophilicity tests utilizing droplet angle measurements (n = 20 droplets/disk) of each of the solutions were carried out (total N = 600 contact angle measurements). Statistical comparison between treatment groups for each implant surface using ANOVA and Bonferroni correction at p < 0.05 was performed. Results: Analyses revealed a statistically significant improvement in hydrophilicity for group C compared to group B (p < 0.05) in Ti-alloy, but a significant decrease in hydrophilicity for group E compared to group D in Ti-SLA. Zirconia surfaces displayed a decrease in hydrophilicity for all groups compared to group A. Conclusions: Thus, there were varying effects of combined metformin and bone graft on implants.