| 摘要 |
The invention describes an expansion screw made from at least one first metal or from at least one first alloy, for correcting misalignment of teeth, having two bodies that can be varied with respect to their spacing by means of a spindle, which latter comprises an actuator element and, projecting from the latter, one threaded portion or two threaded portions which extend in opposite directions one relative to the other, each of them being rotatably seated in one of the bodies and engaging an inner thread in the body, and having at least one slide guide that is in engagement with the two bodies and acts to guide them along a straight line, while preventing them from twisting one relative to the other as their spacing is being varied. It is provided according to the invention that at least the one threaded portion or, in the case of two threaded portions, at least one of such threaded portions of the spindle is coated with a second metal or with a second alloy that differs in hardness from the at least one first metal or from the at least one first alloy.
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