Principles of connection in combined prosthesis
con ancoraggio rigido
The anchorage system between fixed and removable parts of combined prostheses must be made up of:
- THE ATTACHMENT, that has RETENTIVE functions which is to say that it HAS TO OPPOSE THE VERTICAL DETACHMENT FORCES (for instance during the mastication). This device must be positioned with a PARALLELOMETER.with the support of
- THE MILLING, made by a MILLING MACHINE, that has to supply the vertical, transversal and horizontal stabilization of the COMBINED PROSTHESIS thanks to its constituent elements:
- one cervical and/or occlusal shoulder with support functions, that oppose the vertical forces;
- one guidance groove with embrace and balancing functions of the transversal forces;
- one milled arm that takes part in the retention and oppose the horizontal forces.
Once confirmed the retentive force of the attachment, the milled arm must not have any play in the crown; the only possible movement between crown and milled arm, once reached the stroke limit, must be the vertical insertion one. In this way the only function of the attachment will be the retentive one, that is in fact the only one it must have.
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