Low temperature growth of thin film coatings for the surface modification of dental prostheses

In this work we present some results about the low temperature, plasma-assisted growth of silicon–oxygen amorphous thin film alloys (a-SiOx) on different types of dental materials used for the fabrication of dental prostheses. The a-SiOx films were grown at substrate temperatures lower than 70 °C by a PECVD deposition system using silane (SiH4) and nitrous oxide (N2O) as precursor gases. The chemical bonding structure of the films was investigated by Fourier transform infra-red spectroscopy (FTIR), while the morphological characteristics of the dental materials were analyzed before and after the coating deposition by means of high-resolution mechanical profilometry. The surface energy of dental materials was estimated before and after the coating process by contact angle measurements, revealing that the coating produced a considerable change of surface energy in all the tested samples, evidenced by a contact angle reduction from more than 90° to less than 10°. Some tests were also performed to estimate the effect of the coating on the bacterial adhesion properties, revealing that the a-SiOx coatings show some effectiveness in reducing the bacterial adhesion on the dental materials surface.