Two-body wear of various microlayering ceramics on zirconia restorations: An in vitro study

To prevent chipping of zirconia restorations, thinner veneering techniques like microlayering ceramic (µLC) have been used; however, the wear of these materials requires further investigation.

The purpose of this in vitro study was to measure the wear and particle size of µLCs and compare them with veneered and monolithic zirconia and human teeth.

Zirconia crowns (n=12) were microlayered with Ceramotion One Touch 3D (CER), IQ SQIN (IQS), MiYO structure (MIY), and Structure (STR). Veneered zirconia (VEN), monolithic zirconia (MZ), and human teeth (HUM) (n=12) were used as controls. After 60 000, 120 000, and 600 000 masticatory cycles, the 2-body wear of crowns and antagonists (steatite balls) and the particle size of the µLCs was measured. The specimens were qualitatively examined using a light microscope to visualize wear patterns. Data were analyzed using nonparametric statistical methods, including the Spearman and Kendall correlation, Kruskal-Wallis-, Mann-Whitney-U- (α=.05), and ANOVA-type statistics for longitudinal data, with pairwise comparison adjusted by Bonferroni correction (α=.0034).

Material type and number of masticatory cycles affected volumetric loss for crowns and antagonists (P≤.003). MIY showed higher wear than STR (P≤.002), and the remaining µLCs were statistically similar (P≥.088). HUM also fell within the same range of values as CER, STR, IQS, and VEN (P=.191 to.950). HUM showed no wear on antagonists. The wear on MZ could not be quantified. Particle size was determined: MIY

The µLCs and VEN showed measurable wear in contrast with MZ; but VEN demonstrated material loss more similar to that of HUM, reflecting physiological behavior. Increased masticatory cycles led to greater wear, risking exposure of the zirconia substrate.