Background: Dental sensitivity is a common secondary effect related to vital tooth whitening (VTW) treatment and it's associated with the concentrations and time of application of the bleaching agents. The aim of this research was to evaluate the relationship of dental sensitivity and the combinations of different concentrations of peroxides [hydrogen peroxide (HP) 10%/HP 40%] in order to define a tooth whitening protocol that is effective, while minimizing the discomfort experienced by patients.Methods: A cross-sectional retrospective study was carried out based on secondary de-identified data of 27 patients collected from a previous VTW clinical trial. The days of dental sensitivity and levels of sensitivity were measured. Descriptive statistics and the Pearson correlation coefficient were calculated. A level of significance P<0.05 was established. Results:The mean values obtained for the variables "day of dental sensitivity" and "levels of sensitivity" were 1.0741 (SD =0.91676) and 0.8148 (SD =0.62247), respectively. The Pearson correlation (r) obtained was 0.766, 95% CI: 0.55, 0.89, P=0.01. Conclusions:The findings indicate that dental sensitivity when occurs during or after VTW with HP 10% and HP 40% tends to be mild and does not last more than a day. The clinical implications and recommendations indicate that clinicians can safely use the treatment and that patients must be informed that dental sensitivity due to VTW may occur.