Photofunctionalized Dental Implants: Role of Hydrophilization and Photocatalysis

Method: Polycrystalline submicron anatase coatings were prepared by pulse magnetron sputtering on machined (MA) and blasted/acid etched (BAE) Ti and functionalized by UV-A at 382 nm (25 mW cm^-2) or by blue light at 405 nm (1050 mW cm^-2; Hoenle, Germany). Changes in hydrophilicity were quantified by contact angle analysis (Kruess, Germany). Initial adhesion and surface coverage by cells were determined by crystal violet staining. Photocatalytic decomposition of protein layers was quantified by a mass-sensitive quartz crystal microbalance system (Q-Sense, Sweden) in real time.

Result: Contact angles <10° were measured below 5 min UV-A or below 60 min blue light irradiation. Pre-adsorbed protein layers were decomposed at a level >75% (UV-A) or >60% (blue light). Under each irradiation regime, contact angle decrease and decomposition rates significantly differed from the Ti reference (p≤0.05). Proliferation of osteoblasts was significantly increased (p≤0.05), resulting in a more than sevenfold increase in cell coverage on the anatase-coated BAE samples after 3-5 days in culture. On MA, anatase coating enhanced initial cell adhesion (90min) of human oral keratinocytes twofold (p≤0.05).

Conclusion: Photofunctionalization by UV irradiation of anatase offers the possibility for chairside hydrophilization of dental implant surfaces. Additionally, photocatalysis provides a possible means to attack biological films in course of therapeutic treatments of e.g. peri-implantatis at the implant/biofilm interface.

Supported by the ITI foundation (Basel, Switzerland)