[Retention status of crown/bridge constructions]

An apparatus consisting of an acid resistant steel cone and a cap of the same maternal, was used for retention and rotation experiments after cementation of the cap on the cone. The upper diameter of the cone was 6 mm, the lower diameter 7 mm and the height 6 mm. The force of retention, the force necessary for removing the cap from the cone in the direction of removal, was 89,7 +/- 8,3 kp. Forces of rotation, 30 kp applied 100 times continuously, did not reduce the force of retention. Increasing the forces of rotation to 50 kp damage was cuased on the cement, resulting in removal of the cap from the cone after some applications. The possible clinical value of the investigation was discussed.