Over-the-counter (OTC) whitening strips (WS) may be an effective way to enhance and prolong the whitening results of in-office treatments, according to research published on January 23 in the Journal of Dentistry.
In-office whitening with 37.5% hydrogen peroxide (HP) immediately enhanced tooth lightness, but without using strips, the sparkle faded within one month, the authors wrote.
"When analysing the use of 6% HP WS combined with in-office 37.5% HP gel, the present results confirm that combining the two treatments helps maintain the gel's effect on lightness for longer, the chromatic effect being lost after 4 weeks without use of WS," wrote the authors, led by Cristina Gómez-Polo of the University of Salamanca in Spain.
The study included 60 adults who underwent in-office whitening with 37.5% HP gel applied in four cycles. Of these, 30 participants received no further treatment, while the other 30 used 6% HP whitening strips daily for 15 minutes over 15 days, they wrote.
Color measurements were taken at baseline, immediately after in-office treatment, after 15 days of strip use, and four weeks post-treatment. The whitening effects were assessed by analyzing changes in CIELAB color coordinates and determining if these changes exceeded the clinical perceptibility threshold using color difference formulas.
The in-office 37.5% HP treatment significantly increased the lightness coordinate and decreased the red and yellow coordinates, resulting in noticeable color changes in over 80% of participants across all thirds of the tooth.
In the group using WS, the increase in lightness and reductions in red and yellow tones were maintained in the cervical and middle thirds after four weeks, while only the decrease in yellow was preserved in the incisal third, they wrote.
In contrast, the group that did not use WS retained the reductions in red and yellow but lost the lightness increase. Overall, the use of WS helped maintain the lightness achieved by the 37.5% HP treatment over four weeks. All observed color changes were perceptible in over 70% of participants.
The study had limitations. There was limited research concerning the use of OTC products in dentist-planned treatments and specifying tooth areas for color measurement, the authors noted.
"The use of WS for 15 days helps maintain the increase in lightness created by the inoffice 37.5% HP gel treatment for at least 1 month," they concluded.
