Preliminary evaluation of tooth coloration potential and wear of full-contour alumina in vitro
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Objective: The objective of this study was: a. to evaluate the effect of color-infusion of alumina at pre-sintered porous stage with different metal salt solutions, at different concentrations; resulting in a variety of shades corresponding to VITA Classical and VITA 3D Master shade guides; b. to assess the wear behavior of alumina against VITA Mark II (VMKII). Methods: Color: thirty four alumina tiles (19x15x3mm) were sliced and made off of In-Ceram 2000 AL-20 blocks (Vident VITA) to be infused with coloring solutions. Six different elements were chosen to form our coloring solutions: rare earths Ce, Er, Nd, and Pr along with Zn in the form of acetate at two different concentrations of 1% and 5% (by weight); and Sn solution in the form of oxide at 15% concentration. Thus, we had eleven solution groups (n=3) and one alumina tile was not color-infused as the control. Color measurement was done with a clinical spectrophotometer (Easyshade Compact, Vident VITA) for shades and CIEL*a*b* parameters. Three measurements were made for each specimen. [Delta]E values relative to the control were compared for 1% and 5% concentrations of each solution. Unpaired student t-test was used for statistical analysis, [alpha]=0.95. Wear: Feldspathic porcelain VITA Mark II pins (Vident VITA) were trephined out of ceramic blocks and cemented on one end of brass rods. Alumina tiles were mounted onto metal plates to form tracks for the pins to slide against them in the wear simulator for 200,000 cycles and at baseline, 1K, 10K, 50K, 100K, 150K, and 200K data-gathering points the following parameters were measured: length (Mark II), weight, surface roughness (alumina), and groove depth (alumina only at baseline and 200K). Results: Mean [Delta]E values were as follows: Ce: 1%: 17.01[plus or minus]0.08, 5%: 24.57[plus or minus]0.15; Er: 1%: 6.29[plus or minus]0.23, 5%: 8.28[plus or minus]0.21; Nd: 1%: 10.54[plus or minus]0.10, 5%: 20.23[plus or minus]0.34; Zn: 1%: 10.05[plus or minus]0.61, 5%: 11.31[plus or minus]0.38; Pr: 1%: 7.71[plus or minus]0.52, 5%: 13.14[plus or minus]0.56; Sn 15%: 8.37[plus or minus]0.39. There were significant differences between [Delta]E values for 1% and 5% concentrations (P[less than]0.05). Mean length loss and weight loss for Mark II specimens almost followed the same continuous trend until around 150K cycles when the trend started to show a marked decrease. Surface roughness values decreased throughout the experiment for alumina until it plateaued at 150K cycles, indicating a highly polished surface (0.023[plus or minus]0.005 Ra, [mu]m). Weight loss values for alumina specimens were marked as zero because they were not detectable by the weight measurement device used in this study. Conclusion: All coloring solutions changed the color of alumina specimens relative to the control into shades corresponding to VITA Classical and 3D Master shades and the results were concentration-dependent; alumina specimens remained almost intact throughout the wear experiment in terms of weight and groove depth, While Mark II specimens exhibited weight and vertical length loss; unpolished alumina caused a higher wear rate of VITA Mark II specimens; but decrease in surface roughness of alumina specimens resulted in decrease in their abrasiveness.
PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact email@example.com.Thesis (MSD) --Boston University, Henry M. Goldman School of Dental Medicine, 2013 (Department of Restorative Sciences and Biomaterials).Includes bibliography: leaves 54-64.
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