Micromotions and combined damages at the dental implant/bone interface

Micromotion and fretting damages at the dental implant/bone interface are neglected for the limitation of check methods, but it is particularly important for the initial success of osseointegration and the life time of dental implant. This review article describes the scientific documentation of micromotion and fretting damages on the dental implant/bone interface. The fretting amplitude is less than 30 µm in vitro and the damage in the interface is acceptable. While in vivo, the micromotion’s effect is the combination of damage in tissue level and the real biological reaction. Tiny movements at the contact area between dental implants and the underlying bone surface can cause wear and tear that threatens the long-term integrity of dental prostheses. This problem of so-called ‘fretting damage’ was long ignored by dentists and dental surgeons. Now, a review by Hai-Yang Yu and colleagues at Sichuan University in Chengdu, China, shows that the micrometer-scale movements at the dental implant–bone interface can actually be subdivided into two types: tangential fretting, which is caused by the direct contact stress of mastication, and radial fretting, which arises from the grinding-like pressure between the two surfaces when they remain in contact. The combination of these stresses leads to small cracks that are a big problem in the replacement of missing teeth by implant-supported prostheses.