Two-body wear performance of dental colored zirconia after different surface treatments

Statement of problem. Colored zirconia is widely used in dental clinical practice; however, data pertaining to its wear resistance after different surface treatments are sparse. Purpose. The purpose of this in vitro study was to evaluate the 2-body wear resistance of dental colored zirconia after different glazing and polishing treatments. Material and methods. Standardized specimens were prepared from dental zirconia (internal and external staining and no staining) and subjected to different surface treatments. The stained zirconia and control ceramics were polished with a Robinson brush and polishing paste or polishing kits, while the nonstained zirconia was airborne-particle abraded and glazed. The specimens were then abraded against steatite antagonists using a pin-on-disk wear tester. The wear depth for the specimens was measured using confocal microscopy. Wear areas on the steatite antagonists were measured by using an optical microscope. Scanning electron microscopy (SEM) was used to evaluate the wear pattern of the zirconia specimens. All data were statistically analyzed with 1-way ANOVA and the Tamhane test for post hoc analysis (alpha=.05). Results. The surfaces polished using the Robinson brush and paste showed no wear. The wear depth of the unglazed surfaces was 42.27 +/- 3.21 similar to 84.15 +/- 2.57 mu m and 87.75 +/- 9.36 and 91.76 +/- 13.58 mu m for the glazed surfaces. The antagonist wear area was 1.79 +/- 0.21 similar to 2.69 +/- 0.34 mm(2) (unglazed) and 3.34 +/- 0.29 similar to 4.51 +/- 0.88 mm(2) (glazed). SEM revealed chipping fractures, and peeling cracks were observed on the glazed zirconia surfaces, indicating a combination of fatigue and abrasive wear. Conclusions. The results of this in vitro study suggest that highly polished zirconia shows the least wear, including antagonist wear. Furthermore, glazed zirconia can be significantly more abrasive than polished zirconia. The wear properties of internally and externally stained zirconia are similar.