Restor Dent Endod.  2021 Nov;46(4):e47. 10.5395/rde.2021.46.e47.

Laboratory model to evaluate efficacy of an experimental titanium oxide nanofibers bleaching agent

• Tran C
• Choi E
• Watu B
• Oyoyo U
• Perry C
• Kwon SR

• KMID: 2548091
• DOI: http://doi.org/10.5395/rde.2021.46.e47

Abstract

Objectives
This study aimed to use a laboratory model to evaluate the efficacy of an experimental bleaching agent.
Materials and Methods
The model used human extracted molars that were treated and measured for bleaching efficacy. Teeth (n = 50) were distributed into 5 groups: Negative control (NC): immersion in water for 8 hours; Nanofibers (NFs): Experimental titanium dioxide nanofibers with stirring and light activation for 8 hours; Whitestrips (WS): Crest 3D White Glamorous White Whitestrips, 2 applications daily for 30 minutes, 14 days; 1% hydrogen peroxide (HP) standard: 1% hydrogen peroxide for 8 hours; and 30% HP standard: 30% hydrogen peroxide for 8 hours. Instrumental measurements were performed using a spectrophotometer. Results were recorded at baseline, 1-day post-bleaching, and 1-week post-bleaching. Kruskal-Wallis procedure was used to determine differences in color change. Pearson correlation was used to evaluate the relationship between visual and instrumental measurements. Tests of hypotheses were 2-sided with alpha = 0.05.
Results
There was no significant difference in color parameters (L1, a1, b1, and shade guide units [SGU]) at baseline (p > 0.05). There was a significant difference among the groups for overall color change (ΔE^*ab) and change in shade guide units (ΔSGU) at 1-day and 1-week post-bleaching (p < 0.05). The higher the HP concentration, the higher the color change as expressed in ΔSGU and ΔE^*ab. The negative control exceeded the perceptibility threshold of ΔE^* = 1.2 regardless of time point. NFs showed a decrease in chroma, but were not statistically different compared to the negative control.
Conclusions
The laboratory model was successful in screening an experimental bleaching agent.

Keyword

Color; Experimental model; Titanium dioxide; Tooth bleaching

Figure

• 

  Figure 1 Step-by-step protocol of laboratory model for bleaching efficacy. (A) The roots are trimmed 3 mm apical to the cemento-enamel junction. (B) Teeth are mounted on a plastic dish with cyanoacrylate adhesive and further stabilized with acrylic resin on the lingual side. (C) A custom-fabricated jig is fabricated for repeated color measurements. (D) Teeth of groups NC, 1% HP, and 30% HP are immersed in respective solutions for 8 hours while the NFs group is treated in the TiO2 solution with stirring and UV-light activation. The WS group is treated with whitening strips according to manufacturer's recommendations with 2 applications daily for 30 minutes for 14 days. (E) Instrumental color measurements are performed on the middle third of the buccal surface using a contact type intraoral spectrophotometer. A custom fabricated jig is used for repeated measurements on the same area and a wet gauze is placed to prevent dehydration of the remaining teeth.1% HP, 1% hydrogen peroxide for 8 hours; 30% HP, 30% hydrogen peroxide for 8 hours; NC, negative control; NF, experimental titanium dioxide nanofibers with stirring and light activation for 8 hours; WS, Crest 3D White Glamorous White Whitestrips, 2 applications daily for 30 minutes, 14 days.

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  Figure 2 Scatterplot of correlation between visual and instrumental measurements at 1-week post-bleaching.ΔE*3-1, overall color change from 1-week post bleaching relative to baseline; ΔSGU3-1, change in shade guide units from 1-week post bleaching relative to baseline.

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