Measurement of volumetric wear of printed polymer resin and milled polymer infused ceramic network definitive restorative materials.

Statement of problem: Currently there is no regulatory requirement or international standard for the wear resistance of dental materials and therefore no need to test prior to market launch.

Purpose: The purpose of this in vitro study was to evaluate and compare the total volumetric wear characteristics of milled polymer infiltrated ceramic network (MPICN) and printed polymer resin (PPR) as substrates opposing five antagonists, human enamel (EN), lithium disilicate (LD), zirconia (ZR), MPICN, and PPR, and to evaluate and compare the volumetric wear of these same materials as antagonists.

Material and methods: Ten of each antagonist for a total of 50 EN, LD (IPS e.max CAD), ZR (IPS e.max ZirCAD MT), MPICN (Crystal Ultra), and PPR (Crowntec for NextDent) were shaped into spherical heads and were tested against 2 disk-shaped substrates, MPICN (Crystal Ultra) and PPR (Crowntec for NextDent). Specimens were tested in a wear machine with a third-body food substitute and loaded with a force of 20 to 70 N at 1 Hz for 100 000 cycles. The total wear volume was digitally measured by comparing scans before and after cycling. The area of the wear facet of the antagonists was measured in a similar way and used to estimate the total volume loss of the antagonists. Data were analyzed using 2-way and 1-way ANOVA followed by the Tukey multiple comparisons post hoc test (α=.05).

Results: Antagonist type was found to significantly affect the total volume wear of the substrate (P=.022). EN was found to cause significantly more wear in opposing substrates than ZR and PPR. Substrate material did not significantly affect the wear rate of the substrates (P=.345) nor did the interaction between substrate and antagonist type (P=.150). Antagonist wear was significantly affected by antagonist type (P<.001), with ZR showing no visible signs of wear and MPICN showing the most wear overall; substrate type (P=.002), with antagonists opposing MPICN showing more wear than PPR; and their interaction (P=.031).

Conclusions: Differences in the wear resistance of milled polymer infiltrated ceramic network and printed polymer resin definitive restorative materials were found but varied depending on the opposing material. No material showed superior wear resistance across all tests. Overall, printed polymer resins created less wear in opposing antagonists than milled polymer infiltrated ceramic network materials.