ABSTRACT
Abstract Repositioning guides are commonly employed in clinical studies to ensure consistent tooth color measurements. Yet, their influence on measured color remains uncertain. Objective This study evaluated the impact of repositioning guides' color and usage on tooth color measurement using a clinical spectrophotometer. Methodology In total, 18 volunteers participated in this study, in which the color of their upper left central incisor and upper left canine was measured with or without repositioning guides (control). The guides were made from pink, blue, or translucent silicone, as well as an acetate-based bleaching tray. Tooth color was measured in triplicates using a clinical spectrophotometer based on the CIELAB system. The standard deviations of these readings were used to estimate reproducibility, and color differences (ΔE00) between the measurements with guides and the control were calculated. Results Repositioning guides had a minimal effect on L* values and no effect on b* values. The use of pink silicone increased a* values, whereas blue or translucent silicone reduced them. Irrespective of the evaluated tooth, the lowest ΔE00 values were observed for the translucent silicone and bleaching tray. The usage of guides only affected data variability for the L* color coordinate. Conclusion Using repositioning guides can significantly impact the precision of tooth color measurement with a clinical spectrophotometer.
ABSTRACT
Abstract Objective To evaluate the effect of the association between external and internal tooth bleaching on color changes in dentin and enamel, individually or recombined, previously stained with triple antibiotic paste (TAP). Methodology Forty enamel-dentin specimens from bovine incisors were separated into ten blocks according to similarity in their whiteness index (WID). Three specimens within each block were stained by dentin exposure to TAP, and the remaining specimen was used as control to estimate color changes. Specimens were sectioned to separate tissues, and dentin and enamel colors were measured individually and after being recombined. Alterations in color (CIEDE2000 - ΔE00) and translucency parameter (TP) resulting from staining were estimated by color difference between stained and control specimens. The contribution of each tissue to the color change (CTCC) was also calculated. Non-sectioned stained specimens were bleached by applying sodium perborate on dentin, associated or not with 35% hydrogen peroxide on enamel. Color changes caused by bleaching procedures were estimated and data were analyzed using the paired t-test or Two-way repeated measures ANOVA. Results TAP caused more pronounced changes in dentin, but enamel color was also affected. Both protocols presented a similar ΔE00, and dentin showed the greater color change. After exposure to TAP, we observed a reduction in WID; WID values were the same for bleached and control specimens regardless of protocol. We found no significant effect of substrate and bleaching technique on TP. Enamel played a more critical role in color changes caused by either staining or bleaching procedures. Conclusion Enamel color played a greater role on tooth color changes than dentin. External and internal bleaching association did not improve bleaching effect on specimens stained with TAP.