Non-stick properties of thin-film coatings on dental-restorative instruments

The non-stick properties of thin-film coatings on dental-restorative instruments were investigated by static contact-angle measurement using dental filler resin as well as by scanning electron microscopy of the amount of sticking dental restorative material. Furthermore, using a customized dipping measurement set-up, non-stick properties were evaluated by measuring force-by-time when the instrument was pulled out of restorative material. Minor improvements in non-stick properties were obtained with commercial diamond-like carbon and commercial polytetrafluoroethylene-based coatings. Major improvements were obtained with an in-house fabricated superhydrophobic coating prepared by a multistep process consisting of surface microstructuring by etching in hydrogen fluoride (HF): hydrogen peroxide (H₂ O₂ ) (1:1; vol/vol), atomic layer deposition of a 7 nm coating of aluminium oxide and titanium oxide, and a self-assembled monolayer of fluorinated organosilicon. Superhydrophobic coatings provide a possible future solution to prevent unwanted adnerence of composite restorative material to dental instruments.