Contrast ratio and masking ability of pressed veneers as a function of their thickness and resin cement variables
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Abstract
Objectives: The restoration of discolored teeth using ceramic veneers is an accepted conservative treatment modality. However, due to the translucency and limited thickness of the ceramic veneers, their color could be affected by the underlying cement and the shade of the substrate. This study aims to evaluate the effect of both the thickness of the pressed ceramic and the cement used on the optical properties of the veneers.
Materials and Methods: The experiment was conducted in two parts. In the first part, disk-shaped samples of IPS e.max Press Low Translucency shade 81 were fabricated in two thicknesses: 0.Smm(n=18) and 0.8mm(n=18). A spectrophotometer, ColorIS (Xrite, USA), was used to measure the contrast ratio (CR), the translucency parameter (TP), and the color differences of the samples when placed over an A4 and 81 backgrounds (LiE [S(A4 backing), S(Bl backing)]). In the second part of the experiment, six resin cement shades in two systems were applied to the original e.max samples and pressed against a glass slab. The samples were cured then separated from the glass. The six cements used where RelyX Veneer cement (Shades: White Opaque, 80.5, and A1) and Choice 2 Veneer cement (Shades: Milky Bright, A1, and 81). Groups were again tested for CR, TP, and color change over two backgrounds A4 and B1. T-test, OneĀ way ANOVA and Tukey, as well as paired t-test were used to analyze the data.
Results: Independent t-test results suggest that the two groups of thicknesses of e.max (0.5mm and 0.8mm) were significantly different in all three parameters tested (P[less than]0.01). For the e.max with cement groups, AN OVA and Tukey's post-hoc tests were performed to study the effect of varying the cement brand and shade. The results suggest that the groups of different cements used with 0.5mm e.max were significantly different. However, when using 0.8mm e.max, there were no significant differences between the cements (P[less than]0.05). All 0.8 mm e.max groups exhibited significantly higher opacity and masking ability values than 0.5mm e.max groups except for 0.5mm e.max with RelyX WO and Choice 2 MB. The paired t-test of samples with and without cement suggests that RelyX veneer WO and Choice2 veneer cements significantly improved opacity and masking ability of 0.5mm e.max. However, the remaining 4 cements used in conjunction with 0.5mm e.max and all cements tested with 0.8mm e.max did not exhibit any significant difference. The three parameters tested were strongly correlated with Pearson correlation values above 0.9.
Conclusions: Varying the thickness and the cement shade significantly affected opacity and masking ability. For 0.8mm e.max, none of the cements tested contributed to opacity and masking ability. Two cements (RelyX Veneer WO and Choice 2 MB) increased the opacity and masking ability of 0.5mm e.max comparable to 0.8mm e.max values. None of the groups tested achieved full masking.
Description
Thesis (MSD) --Boston University, Goldman School of Dental Medicine, 2009 (Department of Restorative Sciences and Biomaterials).
Includes bibliographic references: leaves 52-55.
Includes bibliographic references: leaves 52-55.
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This work is being made available in OpenBU by permission of its author, and is available for research purposes only. All rights are reserved to the author.