| 摘要 |
Fixed or removable orthodontics apparatus for the dental and/or skeletal expansion of the maxillary comprising a device including a cylindrical metal tube or the like wherein slides, in the horizontal plane and with a negligible friction, a cylindrical metal shaft having a small diameter. Said tube and shaft have smooth surfaces and are each terminated by a retaining prolongation which may be welded to orthodontics braces sealed to selected rear teeth or embedded in resin or in a thermosettable material used for anchoring onto the selected rear teeth. The device comprised of a tube and a shaft is intended to be surrounded by a coil spring with spaced turns which is initially compressed between the two retaining extremities and which delivers a continuous force causing a lateral displacement of the teeth and/or of the two lateral parts of the maxillary. A self-blocking device, designed in such a way as to define with precision and for each case the amount of displacement which should take place, stops automatically the separation motion of the metal shaft with respect to the metal tube generated by the thrust of the spring, and consequently stops the displacement of the teeth and/or the side portions of the maxillary. |
