Comparison of preload values of dental implant abutment screws subjected to surface and non-surface treatments

Abutment screws of implants can become loose, and loosening can be prevented using several techniques. One technique involves increasing the preload, whereas another easy technique entails reducing the friction coefficient of the screw by applying surface treatment without changing the screw design or material. The purpose of this study was to compare TiN and TiAlCrN surface treatment with non-surface treatment and assess their effects on the preload. Thirty of dental implant fixture were machined by using Grade 4 titanium and these fixtures were fixed in plastic container. Furthermore, thirty of abutment screws were machined by using Grade 5 titanium alloy and divided into the three groups；Group A （no surface treatment as control）, Group B （surface treated with TiN）, and Group C（surface treated with TiAlCrN）. The fixtures fixed in plastic containers were then fixed on a torque-measuring machine, and the magnitudes of torque, retorque, and untorque were recorded. In the comparisons of preload among Groups A, B, and C, Group C was significantly higher than the values for Groups A （p＜0.01） and Group B （p＜0.05）. These results suggested that surface treatment with TiAlCrN is very useful for abutment screws in clinical practice to reduce the incidence of screw loosening and associated complications.