Role of Photofunctionalization in Mitigating Impaired Osseointegration Associated with Type 2 Diabetes in Rats

Purpose: Peri-implant osteogenesis is reported to be impaired in patients with diabetes. The current study tested the hypothesis that ultraviolet (UV) treatment of titanium, or photofunctionalization, is able to mitigate the impaired osseointegration associated with type 2 diabetes. Materials and Methods: Untreated and photofunctionalized titanium implants were placed into the femurs of genetically modified rats with a close phenotypic resemblance to human type 2 diabetes, as characterized by late-onset hyperglycemia and obesity. Implants were photofunctionalized with UV light for 15 minutes immediately before placement. The strength of osseointegration was evaluated using a biomechanical push-in test, and the tissue-implant interface was examined using scanning electron microscopy and energy-dispersive spectroscopy. Results: Photofunctionalization converted implants from hydrophobic to superhydrophilic. Photofunctionalization-induced hemophilicity was also confirmed during surgery. The strength of osseointegration of photofunctionalized implants was significantly greater than that of untreated implants, by 1.8 and 3 times, at weeks 2 and 4 of healing, respectively. Osseointegration of photofunctionalized implants in diabetic animals was even stronger than that of untreated implants placed in normal animals throughout the healing period. Photofunctionalized implants placed in diabetic rats were extensively covered with calcium-and phosphorusrich tissue that masked the titanium signal. Conclusion: Photofunctionalization accelerated and enhanced levels of osseointegration and overcame impaired osseointegration in a rat model of type 2 diabetes. Further prospective studies are warranted to establish the clinical efficacy of photofunctionalization in patients with diabetes.