Master of Science (M.S.) in Dentistry
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College of Dental Medicine
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Nova Southeastern University
Zainab M. Alsadah. 2017. Effect of Ceramic Thickness on the Final Color of Veneer Restorations. Master's thesis. Nova Southeastern University. Retrieved from NSUWorks, College of Dental Medicine. (97)
Background: The integration of ceramic veneer thickness and substrate color are very challenging factors that dentists and lab technicians should control to achieve a good color match. The reproduction of a natural and homogenous color can be laborious when laminate veneers of 0.4 to 1.2 mm thick are cemented over a dark underlying substrate. Objective: The purpose of this in vitro study was to investigate the association of different ceramic veneer thicknesses cemented on different tooth substrate colors and its influence on final color match of ceramic veneers. Material and methods: Ninety slices IPS e-max CAD (Ivoclar Vivadent, Amherst, NY, USA) ceramic veneers shade A1 were fabricated with three different thicknesses (0.4, 0.7 and 1.0mm). The thickness of 0.4mm corresponds to the minimum thickness that the CAD/CAM milling unit can fabricate for minimally invasive veneers. Additionally, ninety slices were fabricated from light-cured composite resin material shades (A1, A3 and C4) representing the tooth substrate color (stump shade), Filtek Supreme (3M ESPE, St Paul, MN, USA). The ceramic slice was bonded to the composite resin material using light cured neutral shade resin cement (Variolink Esthetic, Ivoclar Vivadent, Amherst, NY, USA). The specimen combinations were divided into 9 groups (n=10/group). Color parameters CIE lightness (L*), chroma (A*), and hue (B*) values were measured using a digital spectrophotometer (Gretag Macbeth Color-Eye® 7000A). Shade A1 was used as control. A 2-way analysis of variance (ANOVA) was used to compare the means and standard deviations between the different color combinations (=0.05), followed by Tukey’s HSD post hoc test for significant interactions. Results: A two-way ANOVA was conducted to examine the effect of stump shade (A1, A3, C4), ceramic thickness (0.4mm, 0.7mm, 1.0mm), and the interaction effect of stump shade by ceramic thickness on Delta E value of 3.3. We tested the model for equal variances using Bartlett’s test and found them to be equal. There was a statistically significant effect of stump shade F (2, 81) = 513.80, p < 0.001, Eta-Squared = 79.1%; ceramic thickness F (2, 81) = 60.35, p < 0.001, Eta-Squared = 9.2%; and the interaction effect of stump shade by ceramic thickness, F (4, 81) = 17.28, p < 0.001, Eta-Squared = 5.8% on Delta E value of 3.3. Conclusion: It can be concluded that, the final color of ceramic veneer is highly affected by the different stump shades and thickness of the ceramic veneer. Also, color mismatch or reflection of the stump shade may occur in thin veneers obtained from CAD/CAM blocks after cementation. Moreover, the ∆E values for thin veneers were higher than the values obtained from thick specimens; referring to the preference of thicker ceramic with lower translucency in terms of clinical relevance.
Ceramic, Color, Cosmetic, Esthetic, Porcelain, Veneers
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