Properties of a titanium nitride coating for dental instruments

Adhesion of tooth-coloured restorative materials to the instruments used to place them is a clinical problem. This paper examines the low-stick properties and the durability of a 5 micron coating of titanium nitride on stainless steel when used with two composites (a hybrid and a microfilled) and a glass polyalkenoate (ionomer) cement. Titanium nitride-coated dies were compared to polished stainless steel for adhesion to the unset restorative material before and after a period of wear, and also for properties of surface hardness, contact angle with unfilled resin and frictional coefficient. The results demonstrated that, while the coated instruments were significantly harder and showed a lower coefficient of friction and a higher contact angle with resin, they were slightly 'stickier' than highly polished stainless steel, and this difference persisted even after wear. However, the material is very hard, resistant to damage, and appears to have little potential to discolour the restorative materials with which it is used. It is concluded that a titanium nitride coating confers no additional advantage as regards low-stick properties, over clean, polished stainless steel used for dental instruments.