Crown retention and cyclic loading (in vitro)

Cast gold crowns were luted on extracted and prepared human teeth with zinc phosphate cement and subjected to a fatigue test by cyclic loading. The correlation between crown retention and three retention variables was determined by the fatigue test. The results show that the smallest convergence angle tested, 20 degrees, gave better retention than did angles of 40 degrees and 60 degrees, and that surface roughness, surface size, height, and base diameter of the preparations had no influence on crown retention within the parameter sizes tested.