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

Abstract

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 (ΔE 00) 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 ΔE 00 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.

Efficacy of products for bleaching and whitening under orthodontic brackets

“…28,29 The in-office and at-home bleaching procedures showed statistically greater color changes and similarity around the bracket area, corroborating with previous studies. 18,19,21,22,25,30 The area under the bracket showed greater color alteration and tooth whiteness, when compared with the area around the bracket, for the non-whitening toothpaste, 2% hydrogen peroxide whitening toothpaste, and at-home bleaching procedure.…”

“…Although previous studies [14][15][16][17][18][19] have evaluated the efficacy of different dental bleaching agents under orthodontic brackets, no study has evaluated the whitening toothpastes. Since many patients wearing orthodontic appliances perceive changes in the shade of their teeth, and whitening toothpaste is an easily accessible product, 12 its efficacy needed to be tested.…”

“…Some whitening toothpastes have included peroxide in their formulations; however, the efficacy of peroxide from toothpaste is questioned regarding the concentration and exposure time during toothbrushing. 13 Previous clinical 14,15 and laboratory [16][17][18][19] studies have shown color alteration under the bracket area using bleaching agents. However, even with the increasing presence of whitening toothpastes on the market, the authors are unaware of a study that has been conducted to test their efficacy on teeth with bonded brackets.…”