A Experimental Study of Dental Implant Superstructure Loosening

Objective: To investigate the reasons and preventions of the loosening of implant superstructure. Methods: Implant was inserted into a resin model with 300 inclinations. The distance between the inclination surface to the top of implant was 2 mm and it was 10.06mm between the implant-abutment interface to the top of the crown. The fatigue test was measured by the Instron 8511.20 materiel test machine which controlled by computer. 15Kg force was applied to the crown's top at 13 times per second. The fatigue cyclic were recorded by computer when the test was finished. The periotest value(PTV) were measured every 0.2°Á106 cycles and the end of the test. The abutment screw elongation was measured at 72h after the preload applied and the test finished. Results: The average crown's fatigue life was 15.3°Á10 6cycles, and the abutment screw elongation at 72h after preload applied and the test finished were 11.5µm and 76.3µm. The PTV was 9.4 at the test finished. Conclusions: The abutment screw was elonged under the 15 Kg force applied and the crown was mobility.