| 摘要 |
<p>The tooth-crown stump preparation instrument has a round symmetrical grinder part and a coaxial spindle. The part is a hollow one (1), open at the end furthest from the spindle (3), and whose surfaces forming the inner periphery are at least partly covered with a grinding agent (5), while its outer surfaces (7) are free of the latter. One or more sight holes are formed in the body periphery, allowing observation of the tooth surface being machined as the body is rotating. The part can be of truncated cone section, e.g., coiled spring with a cone angle of at least 1 deg., and axially adjacent areas of it can have different cone angles.</p> |
