Clinical Wear Of Antagonists Against Monolithic Zirconia: A Profilometric Approach.

Objectives: To introduce a reliable method for clinical wear evaluation. The used method was applied investigating clinical antagonist wear rates against monolithic zirconia crowns after one year.
Methods: Thirteen patients with natural teeth or fixed prosthodontics as antagonist teeth showing the indication for posterior full crowns were restored with polished monolithic zirconia crowns using the Lava system (Lava Plus, 3M Espe, Germany). Based on this prospective clinical trial, polyurethane replicas (AlphaDie, Schuetz Dental, Germany) were produced from high precision polyvinyl siloxane impressions (Flexitime, Heraeus Kulzer, Germany) of the two respective antagonist teeth. Two replicas of each antagonist were produced, one qualitatively examined under SEM and the other one under a high-resolution non-contact profilometer equipped with a white light sensor (CyberSCAN CT 100, Cyber Technologies, Germany) that ensures a z-resolution of up to 20 nm. At baseline and after twelve month the crown antagonist surfaces were analysed and both surfaces matched in order to receive the volume loss [in mm³] as well as the maximum wear depth [in µm].
Results: The evaluation of the antagonist teeth presented an overall volume loss of 0.23 (+/- 0.24 mm³) and a maximum wear depth of 144.5 µm (+/- 55.5 µm). Antagonist materials were natural enamel, silica based ceramics and composites.
Conclusions: Monolithic zirconia crowns produced acceptable antagonist wear rates after 12 month in vivo. The high scatter in data is due to the various antagonist materials and due to inhomogeneities of the wear profiles.