| 摘要 |
<p>Dental bridge or crown caps are removed by drilling a hole in the crown for inserting the end of a bolt to contact the tooth stub. The bolt is in a metal stabilizing bar member which rests in balanced and aligned position upon the cap structure and is connected thereto as a unit that moves together by means of wire or equivalent flexible means wrapped thereabout and tightened so that the bolt pressure on the tooth stub will apically lift the crown without shear stresses. A porcelain crown is non-destructively removed by exerting an upward force on a noose about the neck of the crown from a balanced bar-body resting on the tooth by means of a screw threaded through the bar-body. Balancing is achieved by connecting the noose to the bar-body with a plurality of special straps spaced about the crow circumference and passed over pegs on which cylindrical bushings of various diameters may be placed for changing the effective lengths of the straps. Special lightweight tooling is made feasible for tightening the noose about the crown and clamping it in place so that hands are freed to thereby effect a simpler more efficient crown removal process.</p> |
