Influence of repositioning guides' color and usage on precision in tooth color measurement with a clinical spectrophotometer.

BACKGROUND: 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.

Effect of gingival barrier brands on operator perception, cervical adaptation, and patient comfort during in-office tooth bleaching: a randomized clinical trial.

BACKGROUND: Light-cured resins are widely used as gingival barriers to protect the gums from highly concentrated peroxides used in tooth bleaching. The impact of barrier brand on clinical outcomes is typically considered negligible. However, there is limited evidence on the effects of different brands on operator experience, barrier adaptation, and patient comfort. OBJECTIVE: This clinical trial assessed the impact of four commercial gingival barrier brands (Opaldam, Topdam, Lysadam, and Maxdam) on operator perception, adaptation quality, and patient comfort. METHODS: Twenty-one undergraduate students placed gingival barriers in a randomized sequence using blinded syringes. Photographs of the barriers were taken from frontal and incisal perspectives. After bleaching procedures, operators rated handling features and safety using Likert scale forms. Two experienced evaluators independently assessed barrier adaptation quality on a scale from 1 (perfect) to 5 (unacceptable). The absolute risk of barrier-induced discomfort was recorded. Data were analyzed using Friedman and Chi-square tests (α = 0.05). RESULTS: Opaldam and Topdam received the highest scores in most handling features, except for removal, which was similar among all brands. No significant difference was observed in barrier adaptation quality between the evaluated brands. Discomforts were mainly reported in the upper dental arch, with Maxdam having the highest absolute risk (35% for this arch and 24% overall). CONCLUSIONS: This study suggests that gingival barrier brands can influence operator perception and patient comfort. Opaldam and Topdam were preferred by operators, but all brands demonstrated comparable adaptation quality. CLINICAL TRIAL REGISTRATION: The study was nested in a randomized clinical trial registered in the Brazilian Clinical Trials Registry under identification number RBR-9gtr9sc.

Effects of enamel moistening and repositioning guide color on tooth whitening outcomes: A clinical trial.

This clinical trial investigated the effects of pre-application enamel moistening on the impact of a 37% carbamide peroxide whitener on tooth color changes and the influence of repositioning guide colors. Forty participants were randomly assigned to in-office tooth bleaching with either moistened enamel (experimental) or dry enamel (control). The whitener was applied for 45 min over two sessions. Tooth color was visually measured or assessed using a spectrophotometer with purple or green silicone guides. Tooth bleaching was assessed using CIE76 (ΔEab ) and CIEDE2000 (ΔE00 ) formulas and by whitening and bleaching index score changes. Moistening the enamel did not significantly affect tooth color. However, the guide color choice only impacted tooth color when measured instrumentally. At baseline, the green guide resulted in statistically significantly whiter teeth than the purple guide. Less pronounced differences in the b* coordinate between baseline and final measurements were found using the green guide. The green guide also produced lower ΔEab values and less change in indexes. In conclusion, moistening the enamel did not significantly impact tooth color changes. However, the repositioning guide color influenced the tooth bleaching measured instrumentally, except for ΔE00 .

Influence of repositioning guides' color and usage on precision in tooth color measurement with a clinical spectrophotometer

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.

The role of interface distance and underlying substrate on the color adjustment potential of single-shade composites.

OBJECTIVE: This study assessed how the distance from the composite interface and the underlying chromatic substrate affect the color adjustment potential (CAP) of two single-shade composites. MATERIALS AND METHODS: Cylinder-shaped specimens were created using Vittra APS Unique (VU), Charisma Diamond One (DO), and a shaded (A3) composite. Some single-shade specimens were surrounded by the A3 composite, forming dual specimens. Color measurements of simple specimens were taken against a gray background using a spectrophotometer. All specimens were positioned at a 45° angle in a viewing booth under illuminant D65, and images were captured with a DSLR camera against gray or A3 backgrounds. Image colors were measured using image processing software and converted to CIELAB coordinates. Color differences (ΔE00 ) between the single-shade composites and the A3 composite were calculated. CAP was determined by comparing data from simple and dual specimens. RESULTS: No clinically significant differences were observed between color measurements obtained from images and the spectrophotometer. CAP was higher for DO compared to VU and increased as the distance from the composite interface decreased and when specimens were positioned against an A3 background. CONCLUSION: The color adjustment potential increased with decreased distance from the composite interface and against a chromatic background. CLINICAL SIGNIFICANCE: Achieving satisfactory color match in restorations using single-shade composites is crucial, and selecting an appropriate underlying substrate is essential. The color adjustment gradually decreases from the restoration margins towards its center.

Color heterogeneity and individual color changes in dentin and enamel bleached in the presence of a metallic orthodontic bracket.

OBJECTIVE: This in-vitro study evaluated the color changes in enamel and dentin bleached in the presence of an orthodontic bracket, as well as the heterogeneity of the color and contribution of each tissue to the color change (CTCC). MATERIALS AND METHODS: Enamel-dentin specimens from extracted bovine teeth were bleached before or after bracket removal or maintained without any treatment (control). The colors of the dentin and enamel were measured individually and after recombining these substrates. The changes in the color (ΔE00 ) and whitening index (ΔWID) were estimated by the color difference between the bleached specimens and those of the control. The CTCC was also calculated by recombining the tissues from different treatments. Images of specimens obtained from a stereomicroscope were used to analyze the color homogeneity within each tissue. RESULTS: The highest values of ΔE00 and ΔWID were observed in the specimens bleached in the absence of a bracket. Bleaching in the presence of a bracket resulted in enamel with a center that was whiter than the periphery. Dentin and enamel presented similar CTCC values. CONCLUSIONS: Tooth bleaching performed in the presence of a metallic bracket resulted in a reduced bleaching effect and increased color heterogeneity within both tissues. CLINICAL SIGNIFICANCE: Tooth bleaching before the orthodontic bracket removal reduces the bleaching effect in both dentin and enamel. Moreover, a heterogeneous color of enamel surface can be observed after tooth bleaching in the presence of a nickel-free metallic orthodontic bracket.

Role of enamel and dentin on color changes after internal bleaching associated or not with external bleaching

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.

Role of enamel and dentin on color changes after internal bleaching associated or not with external bleaching.

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.

Separate contribution of dentin and enamel to color changes caused by staining pigments and dental bleaching.

AIM: This study assessed the changes in color and translucency of dentin and enamel after staining and bleaching procedures as well as the contribution of the tissues to color change (CTCC). MATERIALS AND METHODS: Fifty enamel-dentin specimens were obtained from bovine incisors and grouped into 10 blocks based on the similarity of the baseline color. One specimen in each block was used as the control, and the others were intrinsically (blood) or extrinsically (coffee) stained. One stained specimen for each pigment was bleached with 35% hydrogen peroxide. The enamel was separated from the dentin, and the tooth color and translucency parameter (TP) were measured individually and after recombining these substrates. Changes in color (ΔE00), whitening index (WI), and TP caused by the staining and bleaching procedures were estimated through assessing the color differences compared with the controls. CTCC was also calculated by recombining the enamel and dentin tissues from different treatments. The data were analyzed using the paired t test or the two-way repeated measures ANOVA (α = 0.05). RESULTS: Extrinsic staining procedures produced higher color changes than intrinsic ones, except in dentin. The highest bleaching effect was observed in the dentin of specimens that were extrinsically stained. Similar CTCC values were observed for the dentin and enamel for both the staining and bleaching procedures. Except for the specimens that were treated with intrinsic staining and became more translucent after the bleaching procedure, the other treatments resulted in non-significant TP changes. CONCLUSIONS: Staining the specimens extrinsically resulted in higher color change than staining them intrinsically, and these specimens were more affected by the bleaching procedure. Enamel and dentin demonstrated similar CTCC values.

A simple method to increase the bleaching effectiveness of high-concentrated carbamide peroxide used for in-office bleaching.

This in vitro study aimed to evaluate the effect of two alternative clinical protocols on the tooth bleaching effectiveness of 37% carbamide peroxide. Thirty enamel-dentin blocks from bovine incisors were stained with a coffee solution for 1 week. After color measurement at baseline with a portable spectrophotometer, the blocks were bleached during two 45-min applications of 37% carbamide peroxide with a 2-day interval between bleaching procedures, according to one of the following protocols: 1) Control: placement of bleaching agent over dried enamel; 2) Moist enamel: placement of bleaching agent over enamel previously humidified with a damp gauze for 1 min; 3) Moist cotton pellet: covering the bleaching agent with a moist cotton pellet during the entire bleaching procedure. The tooth color was assessed 2 days after each bleaching procedure. The data of ΔL, Δa, Δb, and ΔE were individually analyzed using ANOVA and Tukey's test (α = 0.05). In general, applying the bleaching agent to the moist enamel resulted in lower Δa and Δb values, and higher ΔL and ΔE values than the control. No difference was observed between the control and the protocol of covering the bleaching agent with a moist cotton pellet. Regardless of the protocol, the second bleaching procedure resulted in a further increase in ΔL and ΔE, and a reduction in Δa. A further decrease in Δb was observed only for the moist enamel protocol. In conclusion, humidifying the enamel with a damp gauze prior to the placement of 37% carbamide peroxide improved the effectiveness of the bleaching.