| 摘要 |
There is provided set of at least two externally threaded bodies each of which has a cylindrical external surface provided with a screw thread. The screw threads have identical pitches, and the crest diameter or diameters of one or more helices of one of the screw threads is or are larger than the crest diameters of helices of the other screw thread. The externally threaded bodies can constitute screws or taps for use in osteosynthesis. If a screw becomes loose, it is removed and the hole for such screw is tapped with a larger tap prior to insertion of a screw having helices with crest diameters larger than the crest diameters of helices of the removed screw. The core diameters of the screw threads of a set of externally threaded bodies need not be the same.
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