Patent ID: 7234939

Claim:
A dental instrument having a two-shot molded handle, comprising: a dental instrument shank made of metal having a proximal end and a distal end, the shank having a diameter so as to be at least partially insertable into a root canal of a tooth; a handle formed at or near the proximal end of the dental instrument shank by a two-shot molding process, the handle comprising: a rigid first polymer formed by molding over a portion of the shank at or near the proximal end of the shank; and a flexible second polymer formed by molding over at least a portion of the rigid first polymer in order to form a spaceless interface between the rigid first polymer and the flexible second polymer; and means, disposed on a surface of the dental instrument shank at or near the proximal end, for increasing mechanical interlock between the shank and the rigid first polymer so as to better resist torsional and/or tensional slippage between the shank and the handle during use compared to a dental instrument lacking the means for increasing mechanical interlock, wherein the rigid first polymer helps attach the handle more firmly to the shank compared to the flexible second polymer so as to better resist torsional and/or tensional slippage between the shank and the handle during use compared to a dental instrument in which only the second polymer is formed over the shank.