Sol-gel dip-coated TiO₂ nanofilms reduce heat production in titanium alloy implants produced by microwave diathermy

Objective: To verify that the TiO₂ nanofilm dip-coated by sol-gel can reduce titanium alloy implants (TAI)'s heat production after microwave diathermy (MD).Methods: The effect of 40 W and 60 W MD on the titanium alloy substrate coated with TiO₂ nanofilm (Experimental Group) and the titanium alloy substrate without film (Control Group) were analyzed in vitro and in vivo. Changes in the skeletal muscle around the implant were evaluated in ex vivo by histology.Results: After 20 min of MD, in vitro the temperature rise of the titanium substrate was less in the Experimental Group than in the Control Group (40 W: 1.4 °C vs. 2.6 °C, p < .01, 60 W: 2.5 °C vs. 3.7 °C, p < .01) and in vivo, the temperature rise of the muscle tissue adjacent to TAI was lower in the Experimental Group than in the Control Group (40 W: 3.29 °C vs. 4.8 °C, p < .01, 60 W: 4.16 °C vs. 6.52 °C, p < .01). Skeletal muscle thermal injury can be found in the Control Group but not in the Experimental Group.Conclusion: Sol-gel dip-coated TiO₂ nanofilm can reduce the heat production of TAIs under single 40～60 W and continuous 40 W MD and protect the muscle tissue adjacent to the implants against thermal injury caused by irradiation.