| 摘要 |
1498889 Dental burr DENTSPLY INTERNATIONAL INC 3 Sept 1975 [11 Sept 1974] 36367/75 Heading A5R [Also in Division B3] A dental burr 20 comprises a head, fixed to one end of a shank, and having longitudinally extending teeth 28 each with a sharp cutting edge 26, a flat cutting face 24, a relief surface 30 and a groove 22 to receive chips removed from a patients tooth in which the burr operates. The groove 22 is defined along one side by the cutting face 24 which also defines one side of the cutting edge 26 and extends from the edge radially towards the axis of the head, the opposite surface of each edge 26 being defined by the relief surface 30 which is convex in cross section and merges with an adjacent side surface 32 of groove 22 along a rounded ridge 34 substantially midway between successive edges 26. The helix angle of the teeth with respect to the burr axis is 10‹-30‹, preferably 12‹. The root surface of each groove extends radially a distance e ranging between 40% and 60% of the radial length f of the face 24, the dimension f being 20% to 30% of the radius g of the burr cutting head. |
