IADR Abstract Archives
Homogeneity of the Micro-mechanical Properties in CAD-CAM Resin-composite Blocks
Objectives: The study aims determining the spatial distribution of various micro-mechanical parameters in high-translucent CAD-CAM resin-composite (HTRC) blocks to verify their homogeneity along center towards peripheral locations.
Methods: Five representative HTRC have been selected (Grandio Blocs, GB, VOCO; Luxacam Composite, LC, DMG; Lava Ultimate, LU, 3M; Shofu Block HC, SB, Shofu; Tetric CAD, TC, Ivoclar Vivadent). Perpendicular and longitudinal sections through the middle of individual HTRC blocks were prepared. The spatial distribution of a battery of micro-mechanical parameters were assessed from depth-sensing indentation tests (Vickers hardness, HV; Martens Hardness, HM; indentation modulus, Y; creep, Cr; elastic and total indentation work, We and Wtot), encompassing up to 8,000 individual indentations. A central region (C) with an area of 3x3mm2 was defined in each specimen. Adjacent 1.5mm thick regions towards periphery were labeled as P1 to P4. Filler size and shape were analysed by scanning electron microscopy.
Results: Cumulated depth-sensing indentation results within one material allow identifying significant differences in the micro-mechanical properties among tested materials (Table 1: Superscripts indicate statistically homogeneous subgroups within a column; Tukey’s HSD test, α=0.05), in strict correlation with materials’ filler content. A multivariate analysis (general linear model) identified a very strong influence of the HTRC on all measured properties (p<0.001; partial eta squared ηP2>0.943), while the most sensitive parameters in identifying differences within the defined regions were Y and We.
Significant higher HV, HM, Y and corresponding lower Cr, We and Wtot were identified in the central compared to the peripheral region in LU, GB, LC and TC. The opposite is valid in SB.
Conclusions: Clinical applications as well as in-vitro study designs should consider slightly inhomogeneity of micro-mechanical properties in HTRC blocks, while the location of the most advantageous regions (central or peripheral) is material dependent.
Methods: Five representative HTRC have been selected (Grandio Blocs, GB, VOCO; Luxacam Composite, LC, DMG; Lava Ultimate, LU, 3M; Shofu Block HC, SB, Shofu; Tetric CAD, TC, Ivoclar Vivadent). Perpendicular and longitudinal sections through the middle of individual HTRC blocks were prepared. The spatial distribution of a battery of micro-mechanical parameters were assessed from depth-sensing indentation tests (Vickers hardness, HV; Martens Hardness, HM; indentation modulus, Y; creep, Cr; elastic and total indentation work, We and Wtot), encompassing up to 8,000 individual indentations. A central region (C) with an area of 3x3mm2 was defined in each specimen. Adjacent 1.5mm thick regions towards periphery were labeled as P1 to P4. Filler size and shape were analysed by scanning electron microscopy.
Results: Cumulated depth-sensing indentation results within one material allow identifying significant differences in the micro-mechanical properties among tested materials (Table 1: Superscripts indicate statistically homogeneous subgroups within a column; Tukey’s HSD test, α=0.05), in strict correlation with materials’ filler content. A multivariate analysis (general linear model) identified a very strong influence of the HTRC on all measured properties (p<0.001; partial eta squared ηP2>0.943), while the most sensitive parameters in identifying differences within the defined regions were Y and We.
Significant higher HV, HM, Y and corresponding lower Cr, We and Wtot were identified in the central compared to the peripheral region in LU, GB, LC and TC. The opposite is valid in SB.
Conclusions: Clinical applications as well as in-vitro study designs should consider slightly inhomogeneity of micro-mechanical properties in HTRC blocks, while the location of the most advantageous regions (central or peripheral) is material dependent.
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