On the Dental BioTribology: Comparison of Zirconia/Zirconia and Zirconia/Natural Tooth Friction Coefficients by Using a Reciprocating Tribometer

In recent years the interest of tribology applied to dentistry is taking on a large scale due to its rapid expansion and growth. Intensive experimental research conducted on dental tribology allows to develop a more detailed understanding of all the phenomena that take part in the phenomenon of tooth wear. The purpose of this work is to investigate tribological performances in the tooth-to-tooth contact and material-to-natural tooth contact (zirconia vs. zirconia and natural tooth vs. zirconia). The tribological tests were carried out by using a reciprocating tribometer under lubricated conditions (artificial saliva). The normal force in these tests was 20 N, and the duration was of 60 min. The stroke length was 2 mm, according to the range of displacement used in scientific literature. The wear mass loss evaluation was evaluated by using a gravimetric method. A topographic analysis was carried with a 3D non-contact optical profiler in order to characterize the wear mechanisms present in the worn surfaces after each of tribo-tests. The results show that the minimum value of the COF is obtained in the case of Zirconia vs. Zirconia tribo-couple, corresponding to 0.49±0.03. In the case of the tooth-tooth couple this value is 0.52 ±0.03. The results on the wear mass loss show a very low wear rate when coupling in tribological condition natural tooth with a ceramic restoration (a mean value of 0.5 mg was found). This rate is even lower when the contact is between two artificial zirconia teeth.