Mechanical strength of dental implants

A series of tests of mechanical strength has been carried out in order to characterise some dental implants. Most specimens tested were of the tapered-joint kind, but for comparison some further tests have been carried out on screw-joined implants. The loads applied were similar to those existing in the typical working conditions of the component; however, in order also to conform to the ISO 14801 normative, loads higher than achieved in working conditions have been applied. The tests of static characterisation have determined the strength of the system, with large deformations preceding rupture. The fatigue tests have led to the determination of the fatigue limit of the dental implant, defined conventionally in these cases as the maximum value under which the system has a life of at least two million of cycles. The fatigue limit is higher than the stress which the teeth endure during a normal process of mastication and it confirms the suitable structural design of the device. Failure analysis has shown that the fatigue crack leading to rupture commonly occurs in the section in which the hexagonal insert in the tapered joint begins.