Fretting Failure of Dental Implant–Bone Interface - Dental Biotribology - page 153

Fig. 7.3 The interfaces
of a dental implant system

implant interface during normal functions in vivo [ 11 ], which is often regarded as
fretting from the viewpoint of tribology. Fretting is a small-amplitude oscillatory
movement that occurs between contacting surfaces, which are usually nominally at
rest [ 12 ]. It may result in two kinds of damage for nonliving tissue: wear, with the
associated production of debris, leading to a loss of fi t between contacting surfaces;
and rapid crack nucleation and propagation [ 13 ]. It would drastically reduce the
service life of the components. The implant and the surrounding osseointegrated
bone contact tightly and compose a special friction pair during the process of chew-
ing. Dental implants will bear a great variety of loading modes during normal chew-
ing functions; the loading varies on the directions, magnitudes, frequencies, and
modes (tension, compression, or shear), which will initially cause complex fretting
damage at the bone-implant interface and might fi nally induce implant failure.
Here, in order to simulate the fretting behavior of the dental implant-bone interface,
two main types of fretting modes have been investigated on the cortical bone against
the titanium alloys: tangential and radial fretting, described next.

7.2.1 Tangential Fretting Behavior

Under lubrication by an imitated human physiological solution, we investigated the
fretting behavior of fl at cortical bone against titanium (TA2) and its alloy (TC4) ball
counterpart [ 13 , 14 ]. During testing, variations of frictional force versus the imposed