| 摘要 |
A dental tool to drill out the root channels of teeth is made of a long needle-like part which is designed integral with the thicker shack for insertion in the dental drill chuck, and consists of thermosetting plastic. The tool end can be designed as twist drill, a file or a nerve needle. The shank has flats on two sides where the flash from the two-part mould is formed. The depth of the flats is at least equal to the height of the flash; in the case of the usual shank diameter of 2 mm it lies between 0.02 and 0.05 mm. Such a tool is simple to manufacture and to sterilise. It requires no machining after moulding. |
