Discrimination thresholds on the tritan axis were obtained for an extensive group of 66 stimuli: ... more Discrimination thresholds on the tritan axis were obtained for an extensive group of 66 stimuli: in some of the stimuli,S-cone trolands were held constant by keeping the product of theS-cone excitation level and the luminance unchanged, while in others only the luminance was changed to establish variousS-cone troland values. These thresholds depended clearly on theS-cone value of the stimuli, while they remained almost constant against the retinal illumination. Thus, we noted that the excitation of theL−2M channel had practically no influence over the discrimination threshold on the tritan axis, although this independence of ΔS fromL−2M was not so obvious when theS value was high. With our data, we performed different fits, and found that the fit including the termsS,(L−2M) and(L+M) adapted better to our results.
This study deals with the influence of surface roughness on the color of resin composites. Ten re... more This study deals with the influence of surface roughness on the color of resin composites. Ten resin composites (microfilled, hybrid, and microhybrid) were each polished with 500-grit, 1 200-grit, 2 000-grit, and 4 000-grit SiC papers. The roughness parameter (R a) was measured using a Plμ confocal microscope, and field-emission scanning electron microscope (Fe-SEM) images were used to investigate filler morphology. Color was measured using a spectroradiometer and a D65 standard illuminant (geometry diffuse/0° specular component excluded (SCE) mode). Surface roughness decreased with grit number and was not influenced by filler size or size distribution. A significant influence of R a on lightness (L*) was found. Lightness increased with decreases in roughness, except for specimens that underwent polishing procedure 4 (PP4; 500-grit, 1 200-grit, 2 000-grit, and 4 000-grit SiC papers consecutively). Generally, it was found that surface roughness influenced the color of resin composites. The composites that underwent PP1 (500-grit SiC paper) exhibited significant differences in chroma (C*), hue (h°), and lightness (L*) compared to composites that underwent PP3 (500-grit, 1 200-grit, and 2 000-grit SiC papers consecutively) and PP4. Color difference (ΔE*) between the polishing procedures was within acceptability thresholds in dentistry.
Discrimination thresholds on the tritan axis were obtained for an extensive group of 66 stimuli: ... more Discrimination thresholds on the tritan axis were obtained for an extensive group of 66 stimuli: in some of the stimuli,S-cone trolands were held constant by keeping the product of theS-cone excitation level and the luminance unchanged, while in others only the luminance was changed to establish variousS-cone troland values. These thresholds depended clearly on theS-cone value of the stimuli, while they remained almost constant against the retinal illumination. Thus, we noted that the excitation of theL−2M channel had practically no influence over the discrimination threshold on the tritan axis, although this independence of ΔS fromL−2M was not so obvious when theS value was high. With our data, we performed different fits, and found that the fit including the termsS,(L−2M) and(L+M) adapted better to our results.
This study deals with the influence of surface roughness on the color of resin composites. Ten re... more This study deals with the influence of surface roughness on the color of resin composites. Ten resin composites (microfilled, hybrid, and microhybrid) were each polished with 500-grit, 1 200-grit, 2 000-grit, and 4 000-grit SiC papers. The roughness parameter (R a) was measured using a Plμ confocal microscope, and field-emission scanning electron microscope (Fe-SEM) images were used to investigate filler morphology. Color was measured using a spectroradiometer and a D65 standard illuminant (geometry diffuse/0° specular component excluded (SCE) mode). Surface roughness decreased with grit number and was not influenced by filler size or size distribution. A significant influence of R a on lightness (L*) was found. Lightness increased with decreases in roughness, except for specimens that underwent polishing procedure 4 (PP4; 500-grit, 1 200-grit, 2 000-grit, and 4 000-grit SiC papers consecutively). Generally, it was found that surface roughness influenced the color of resin composites. The composites that underwent PP1 (500-grit SiC paper) exhibited significant differences in chroma (C*), hue (h°), and lightness (L*) compared to composites that underwent PP3 (500-grit, 1 200-grit, and 2 000-grit SiC papers consecutively) and PP4. Color difference (ΔE*) between the polishing procedures was within acceptability thresholds in dentistry.
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