732,213. Dental drills. AKTIEBOLAGET DENTATUS. Oct. 14, 1953 [Oct. 22, 1952], No. 28305/53. Class 81 (2). A dental drill is provided with an annular projection located between the cutting portion of the drill and the fastening portion, to serve as a distinguishing or identifying characteristic, the annular projection having a diameter which is large compared with that of the drill shank and being close to the fastening portion of the drill. The projection 3 may be integral with the shank 1 of a drill or secured to it by shrinking or other means and also serves to prevent saliva or chips from entering the handpiece into which the drill is fitted. A ring 4 is provided with teeth 5 in number equal to an integral factor of the number of cutting edges of the drill. It is passed over the cutting portion of the drill on to the shank into which the teeth 5 bite firmly. An alternative form of the invention (not shown) comprises a conical annular member which is passed over the cutting edges of the drill and is then flattened so that it forms an annular disc perpendicular to the shank and so that the inner edge enters an annular-groove in the shank.
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