Divergent post and tube and screw systems for the short crown preparation.

A one-step divergent sliding post incorporated through a crown casting provides effective auxiliary retention for the short crown preparation, especially when interocclusal distance is minimal. With this procedure, retention is gained from the residual walls of both the extracoronal preparation and the canal preparation even though their respective axes may be divergent. A tube and screw attachment may also be incorporated inside and understructure coping to secure a permanently cemented short crown-and-bridge retainer. Both techniques may be used separately or in combination for maximal retention and, despite the additional complexity and cost, will compensate for the short extracoronal walls of the second molar preparation.