A comparison of the friction associated with diamond-like carbon (DLC) or titanium nitride (TiN) plating metal brackets

The purpose of the present study was to compare the friction associated with DLC as compared to TiN coating brackets. A total of 270 metal brackets were divided into 3 groups: a blank control group, a DLC-coated group, and a TiN-coated group. Energy-dispersive spectroscopy was used to identify the elemental composition of bracket surfaces. After metal brackets were corroded by an electrochemical device in artificial saliva and mouthwash, static and kinetic friction were evaluated and recorded on an EZ-test machine. A randomized design (two-way) ANOVA was used to test for significant differences. The DLC-coated corrosion group in mouthwash exhibited the highest corrosion potential among all groups (p < 0.0001). Static friction was higher in the mouthwash group for all test samples (p < 0.0001). The kinetic friction of corrosion brackets in mouthwash was statistically different from the no coated and DLC- or TiN-coated groups (p < 0.0001). However, in artificial saliva, corrosion brackets (DLC- or TiN-coated groups) were not statistically different from control (p = 0.241 > 0.05). The DLC-coated groups exhibited lower static and kinetic friction forces than TiN-coated brackets. DLC-coated metal brackets can be applied to reduce metal bracket friction.