Micro-scale abrasion and sliding wear of zirconium-lithium silicate glass-ceramic and polymer-infiltrated ceramic network used in dentistry

The main aim of the present study was to evaluate the micro-scale abrasion and sliding wear behavior of a zirconium-lithium silicate (ZLS) glass-ceramic and a polymer-infiltrated ceramic network used in dentistry. Samples were assessed on a reciprocating ball-on-plate tribometer at 30 N normal load, 1 Hz and stroke length of 2 mm. The wear sliding tests were carried out against an alumina ball in artificial saliva at 37 °C. Also, micro-scale abrasion tests were performed in the presence of abrasive particles to simulate three-body abrasion conditions. The micro-scale abrasion tests were performed at 60 rpm on 0.8 N normal load for 600 revolutions of a stainless-steel ball in contact with a suspension of hydrated silica particles. After wear tests, the worn surfaces were inspected by scanning electron microscopy (SEM). Abrasion was the main wear mechanism found during the tests. However, the hybrid ceramic revealed an unstable adhesive tribo-layer, associated with a delamination process. The wear volume mean values recorded after the micro-abrasion tests were significantly higher for the polymer infiltrated ceramic network (~1.44 x10^-1 mm³) than those for the ZLS glass-ceramic (~9.89 x10^-2 mm³). Also, the mean values of specific sliding wear rate were higher for the polymer-infiltrated ceramic network (~5.33 x10^-5 mm³/N.m) than those for the ZLS glass-ceramic ZL(~3.17 x10^-5 mm³/N.m). For all test conditions, zirconium-lithium glass-ceramic revealed higher wear resistance and lower friction coefficient when compared to the polymer-infiltrated ceramic network. The findings indicated a less damage of glass-ceramics in comparison to polymer-matrix composites on sliding loading or micro-scale abrasion that can occur during the masticatory process.