Can all highly concentrated in-office bleaching gels be used as a single-application?

In vitro evaluation of the effect of different bleaching varnishes: Hydrogen peroxide penetration into the pulp chamber and color change

“…24 However, more acidic gels can have detrimental effects on the enamel surface, 9,12 and enhance the diffusion of HP into the pulp, as previously observed for in-office bleaching gels. 10,23 Regarding the color change, it was expected that the color change would be similar because the bleaching varnishes tested had similar concentrations of HP. However, according to the manufacturer's recommendation, the application time of the bleaching varnish is relatively short, therefore, it was not expected significant differences between 10-and 30-min.…”

“…The resulting solution was measured using a Cary 50 UV–Vis spectrophotometer (Varian). Despite other available methods in the literature, 25 this is the most used to measure the amount of HP inside the pulp chamber 9–11,18,19,22,23,27–29,32,33,41–43 . According to the Beer Law, absorbance directly corresponds to the concentration.…”

“…25 this is the most used to measure the amount of HP inside the pulp chamber. [9][10][11]18,19,22,23,[27][28][29]32,33,[41][42][43] According to the Beer Law, absorbance directly corresponds to the concentration. Therefore, the concentration of HP (μg/mL) was determined by comparing it with the calibration curve previously obtained.…”

“…Different tooth bleaching techniques on vital teeth performed or supervised by the dentist are described in the literature in search of color change 5–8 . Among them, the most established is the in‐office bleaching which uses higher concentrations of hydrogen peroxide (HP) (up to 40%), 9–13 the gel application being performed by the dentist, 14 and the at‐home bleaching, which uses lower concentrations of HP (up to 10%), performed by the patient himself with the application of bleaching gel in custom trays 15 . However, both techniques showed adverse effects and tooth sensitivity induced by bleaching was among the most prevalent 16 …”

“…bleaching which uses higher concentrations of hydrogen peroxide (HP) (up to 40%), [9][10][11][12][13] the gel application being performed by the dentist, 14 and the at-home bleaching, which uses lower concentrations of HP (up to 10%), performed by the patient himself with the application of bleaching gel in custom trays. 15 However, both techniques showed adverse effects and tooth sensitivity induced by bleaching was among the most prevalent.…”