Effect of toothbrushing on the color of extrinsically stained monolithic zirconia :
Nouh, Hesham Mohamed
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Intro: Typical zirconium oxide-based materials are starkly white with minimal translucency, making it esthetically unpleasing when used for a full contour restoration. The opaque white zirconia has been largely controlled by color staining of cores and layering porcelains. Studies have analyzed the effects of tooth brushing on surface stains. However, the current study examines the effects of brushing on extrinsically stained and glazed zirconia. Objective: The aim of this study is to evaluate the outcome of toothbrushing on extrinsically stained monolithic zirconia using two different zirconia brands and to evaluate the protective functions that glazing may provide. Materials: Two brands of monolithic zirconia were used in this study, Vita InCeram YZ and Sirona inCoris TZI. Zirconia are sectioned into tiles (15.5mmx19mmx4mm) and stained using a spray technique with Vita Akzent spray stain and glaze or Zirlux Characterization and Staining kit. Effects of glaze were studied by glazing only half of stained specimens. A mechanical toothbrushing simulator replicated abrasion occurring from clinical tooth brushing using Colgate Extra Clean toothbrush and Sensodyne Extra-Whitening toothpaste. A set number of brushing cycles, 20,000, 40,000, and 60,000 cycles, representing 2, 4, and 6 years of toothbrushing were simulated on each specimen, representing 2, 4, 6 years of brushing. Results were calculated from reflective color measurements by spectrophotometer after. Results: Data include [Delta]E*stain and [Delta]E*abrasion, which correspond to the change in color caused by simulated brushing. inCoris zirconia stained with Zirlux FC stain kit, without glaze showed significant differences between the baseline [Delta]E and 20K, 40K, and 60K brush simulation cycles (p[less than] 0.05). inCeram zirconia stained with the Zirlux FC stain kit exhibited a significant difference between glazed and unglazed groups (p[less than]0.05). [Delta]E*abrasion showed significant differences between glazed and unglazed specimens of the inCoris zirconia stained with Vita Akzent after 40K and 60K brushing cycles (p[less than]0.05). Significant differences were also seen between glazed and unglazed inCeram zirconia stained with Vita Akzent after 60K brushing cycles (p[less than]0.05). Conclusion: Results show that glazing is an essential step when staining monolithic zirconia to protect from abrasion caused by toothbrushing with a moderately abrasive toothbrush. This study is clinically relevant showing that glazing increases the longevity of the stains for the best esthetic outcome.
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, Goldman School of Dental Medicine, 2015 (Department of Restorative Sciences and Biomaterials).Includes bibliography: leaves 63-67.
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