Whitening toothpaste containing activated charcoal, blue covarine, hydrogen peroxide or microbeads: which one is the most effective?

Abstract The efficacy of whitening toothpastes is questionable and controversial. Clinicians, patients and researchers have expressed concern with whitening toothpastes due to the risk of wearing the dental structure and the potential for disappointment if the advertised cosmetic results are not achieved. Objective: This study compared the whitening performance of toothpastes with different whitening technologies after initial and continued use. Material and Methods: Ninety bovine incisors were stained using a concentrated solution of black tea. They were randomly distributed into 6 groups, according to the toothpaste whitening technology: activated charcoal (B&W), blue covarine (WAD), hydrogen peroxide (LWA), microbeads (Oral B 3D White Perfection – 3DW) and optimized abrasives (XW4D). They were compared to a traditional toothpaste without a whitening agent (TA – control). Specimens underwent a brushing machine with controlled pressure, time and temperature. A calibrated examiner measured the color using a VITA-Classical scale before the first brushing cycle (T0), after the first brushing cycle (TI), and after a brushing cycle that simulates continuous use (TCU). Whitening performance was evaluated by the difference of shades (ΔSGU) between T0–TI and T0–TCU timepoints, using the Kruskal-Wallis and Dunn's non-parametric test. The Wilcoxon test was used to evaluate the cumulative effect (α=0.05). Results: Statistically significant differences were observed between toothpastes in both TI and TCU (p<0.05). The time of use also had a significant effect (p<0.05). Conclusion: Only WAD and 3DW showed whitening performance after the first use (TI). The greatest whitening performance after continuous use was obtained by WAD, followed by LWA and 3DW. The use of conventional toothpaste (TA) promotes no tooth whitening. Clinical relevance: Microbead abrasives (3DW) and blue covarine (WAD) were the active technology tested that presented the best global tooth whitening performance.


Introduction
Despite unparalleled results, tooth whitening with concentrated peroxides results in high rates of side effects and serious biological risks. 1,2 These side effects have led to increasingly restrictive regulations concerning the use of whitening products containing high concentrations of peroxide and even questions regarding the use of the procedure at all. 3,4 Alternatively, aesthetic improvements can also be achieved with whitening toothpastes. 5 These toothpastes offer the same therapeutic benefits (anticaries and anti-gingivitis) of conventional toothpastes with added whitening activity from abrasives, adsorbent particles, peroxides, enzymes or optical effect agents. 6,7 Whitening toothpaste with formulations containing hydrated silica, calcium carbonate, dicalcium phosphate dihydrate, calcium pyrophosphate, alumina, perlite or sodium bicarbonate mechanically remove pigmented biofilms and chromophores on the surface of the dental enamel. In addition, the daily use of these abrasives modifies the enamel surface, reducing the adhesion of dental biofilms and chromophores, reducing tooth pigmentation and altering its coloration. 7,8 Whitening toothpastes containing oxidants or enzymes chemically modify pigments adhered to the teeth, reducing the intensity and appearance of discoloration. 6,7 Optical modifying toothpastes contain pigments such as blue covarine, which act to shift the apparent color of teeth by depositing a thin, semitransparent film of bluish pigment on the dental surface. This film instantly modifies the interaction of incident light resulting in teeth that appear whiter and brighter. 6,7,9,10 Recently, activated charcoal/carbon has attracted interest because it acts in a high surface area and consequently has the capacity of adsorbing pigments, chromophores and stains responsible for the color change of teeth. The establishment of tooth whitening performance of each of these technologies will contribute to a better understanding of the advantages and limitations of each whitening toothpaste tested. Furthermore, it will provide both patients and dental professionals the ability to critically select a product that is the best fit for them, based on scientific results and without the After staining, all specimens had a Vita A4 shade.
These were stored for 7 days in artificial saliva. After this period, the initial color was recorded before toothpaste application (T0).

Discussion
This study showed a variety of technologies used in whitening toothpastes and found different whitening efficacies compared to the control and between the different groups. The null hypothesis was rejected because statistically significant differences were observed between and within groups. One class of whitening toothpastes relies on mechanical or abrasive activity to remove biofilms and chromophores adhered to the dental enamel surface, improving the aesthetics by restoring the natural dental color. 8,17 In addition, the continued use of more abrasive toothpastes can increase brightness and reflectance of the enamel, resulting in a more pleasing appearance of whiter and brighter teeth. 17 However, the possible early and excessive wear of dental enamel is a matter of concern, especially when whitening toothpastes   or digital photographs analyzed in Adobe Photoshop, 9,32 while studies that did not prove the whitening effect The whitening effect of activated charcoal is based on its high capacity to adsorb and retain chromophores in the oral cavity. Activated charcoal is highly porous and has an extremely high surface area, 11 resulting in effective and progressive cleaning of the dentition.

Conclusion
The results of this in vitro study demonstrated that all whitening toothpastes were effective for whitening teeth when compared to a toothpaste without added whitening agents (TA). The best whitening performance was obtained with microbeads (3DW), followed by hydrogen peroxide (LWA) and blue covarine (WAD). Continuous use enhances the whitening performance of all whitening toothpastes.
The low initial performance of the control toothpaste (TA) did not improve.