Abstract: An instrument for the treatment of interdental surfaces is disclosed. The instrument is adapted for attachment to a bored, reciprocable holder of a driven dental tool which includes a fluid supply conduit in communication with the tool holder. The dental instrument has a flexible blade (3) having at least one diamond abrasive surface (4) bonded thereto. The instrument also has a pair of mutually opposed, bowed ears (2a) attached to the blade adapted for biased insertion into the bored holder so as to secure retention within the holder. The pair of mutually opposed bowed ears also defines a channel therebetween for fluid communication from the holder fluid supply conduit to the abrasive surface.