The progressive wear and abrasiveness of novel graded glass/zirconia materials relative to their dental ceramic counterparts.

Objective: To investigate the wear behavior of novel graded glass/zirconia materials and their abrasiveness to the antagonist relative to homogeneous zirconias (polished or glazed) and a glass-ceramic.

Methods: Graded glass/zirconia specimens were prepared by sintering with concurrent glass-infiltration of pre-sintered zirconia (3Y-TZP) with a polished or as-machined surface. Monolithic zirconia samples were sintered and their surfaces were polished or glazed (as-machined). Glass-ceramic samples were obtained and the surface polished. All specimens were subjected to chewing simulations with a steatite antagonist (r = 3 mm) and a cyclic load of 50 N. Quantitative measurements of wear and roughness were performed on ceramics and antagonists for prescribed number of cycles. Damage sustained in ceramics and antagonists was analyzed by SEM.

Results: The polished zirconia presented little to no variation in wear depth (2 μm) and roughness (0.06 μm). Graded and glazed zirconia experienced a rapid increase in wear depth while the superficial glass layer was present (until 1000 cycles), but showed little variations afterwards - at 450k cycles ∼15 μm for graded and 78 μm for glazed zirconia. The glass-ceramic presented the greatest wear depth (463 μm) and roughness (1.48 μm). Polished zirconia, polished graded zirconia and glazed zirconia yielded significantly lower volumetric wear (∼3 mm) of the antagonist than as-machined graded zirconia and glass-ceramic (∼5 mm).

Significance: Polished graded zirconia and polished zirconia presented little wear and roughness, as well as yielded reduced antagonist wear. Glassy materials are both more susceptible to wear and more abrasive to the antagonist relative to zirconia.