| المؤلفون: |
Cinelli, F1 (AUTHOR), Saratti, CM2 (AUTHOR), Di Bella, E3 (AUTHOR), Mustapha, M4 (AUTHOR), Rossier, I2 (AUTHOR), Caseiro, L2 (AUTHOR), Tempest, RM5 (AUTHOR), Scotti, N5 (AUTHOR), Rocca, GT2 (AUTHOR), Gichetta, L.1 (AUTHOR) |
| مستخلص: |
The aim of this in-vitro study was to assess the two-body wear and to analyze wear behavior of different direct composite materials characterized by different filler load content but homogenous resin matrix composition, filler content size and kind. 144 disc-shaped specimens (5 mm in diameter, 2 mm-thick) were obtained from six different commercially available resin composite materials, characterized by an increasing filler load (% vol): ELS E, 49% vol (Saremco Dental AG, Switzerland); EvoCeram EC, 53-55% vol (Ivoclar, Liechtenstein); Z-250 Z, 60% vol (3 M ESPE, USA); Inspiro I, 65% vol (Edelweiss DR, Switzerland); Grandio G, 71,4% vol (Voco, Germany); and Clearfil Majesty Posterior M, 82% vol (Kuraray Dental, Japan). All specimens were fixed in a dual axis chewing simulator (CS-4.2, SD Mechatronik GmbH, Germany) specimen holder and exposed to the two-body wear test, against stainless steel antagonist (tip radius 2 mm/30° cone) (thermocycles 55°C/50°C, load 80 N/ 1.8 Hz). In each composite group, all the samples were further divided into three subgroups (n=8), according to the aging method, respectively for 150,000 (a), and 300,000 (b) and 600,000 (c) loading cycles. To assess the volume loss, 3D optical profilometric analysis was performed with a XY step sizes of 5 μm (CT 100, Cyber Technologies, Germany). Digital and scanning electron microscopy were used for qualitative analysis. Some samples were sectioned longitudinally to the wear scar to examine the depth trend of the microfractures. The statistical analysis was conducted using a two-way analysis of variance. The normality assumption required for the application of the method was verified using the Kolmogorov and Smirnov normality test (significance level: 0.05) while the homogeneity of variance was verified using the Levene's test. The profilometry analysis highlighted statistically significant differences between groups in terms of volumetric loss (mm3) but there were not always linear with the degree of load content. Microscopic images revealed wear patterns characterized by the presence of sub-superficial microcracking, mostly concentered at the arresting area of the indenter path but not homogeneously distributed in different groups. However, any signs of chemical micro-pitting were detected. The wear resistance caused by two-body wear differed among the restorative materials tested. In addition to the filler load, other factors could be involved in determining the mechanical characteristics of the material. [ABSTRACT FROM AUTHOR] |
