| 摘要 |
An anchoring pin for retention of a dental restoration onto a tooth stub, the pin including an upper retention portion on which a restoration is to be formed, a lower anchoring threaded portion self-threadable in a bore pre-drilled in the tooth stub and a stop collar interconnected between the retention portion and the anchoring portion. A stepped dental drill having two coaxial drill bits of different diameters is provided, which in addition to forming the bore makes a counterbore at the mount of the bore at the exposed excavated surface of the tooth. The counterbore receives the stop collar of the anchoring pin as the latter is driven into the tooth bore thereby preventing bottoming out of the pin so as to avoid concentrated stress at the tip of the pin and also providing distribution of stress as the wider collar abuts the bottom of the counterbore. |
