Whitening Efficacy and Hydrogen Peroxide Penetration based on Tooth Whitening System

Objectives: To evaluate the whitening efficacy and hydrogen peroxide penetration into the pulp cavity using different whitening systems.
Methods: Extracted human premolars (n=100) were prepared to maintain intact labial tooth structure of 2mm thickness and encompass 50µl of acetate buffer. A standardized surface area served as the color reading and whitening area. The specimens were randomly assigned into five groups. NC: Glycerin gel; OPAL: 10% Carbamide peroxide (Opalescence PF, Ultradent Products Inc., USA); KNITE: 16% Carbamide peroxide (KÖR Night, Evolve Technologies, USA); QPRO: 20% hydrogen peroxide varnish (Zoom Quick Pro, Philips Oral Healthcare, USA); KULTRA: 43% hydremide peroxide gel (KÖR Ultra, Evolve Technologies, USA). Application time and frequency followed manufacturer’s recommendations. Instrumental color measurements were performed with a contact-type intraoral spectrophotometer (Vita Easyshade Compact Advance, Vita Zahnfabrik, Germany). Color measurements were taken at baseline (T₁), 1-day post whitening (T₂), and 1-month post whitening (T₃). Throughout the study teeth were stored in artificial saliva at room temperature. Hydrogen peroxide penetration (HPP) levels was measured after the whitening treatment and estimated with leucocrystal violet and horseradish peroxidase. One-way ANOVA with post-hoc Tukey HSD test was performed to compare color change and HPP level (µg/ml) among the experimental groups. Tests of hypotheses were two-sided with an alpha level of 0.05.
Results: There was no significant difference of all baseline color parameters among the five groups (p>0.05). There was a significant difference in ΔE*ab at T₂ and T₃ among the experimental groups with the in-office whitening systems (QPRO and KULTRA) exhibiting higher overall color change compared to the home whitening systems (OPAL and KNITE). Hydrogen peroxide penetration was significantly different among the experimental groups with QPRO showing the least penetration levels (p<0.05).
Conclusions: Overall color change and hydrogen peroxide penetration levels are influenced by many factors not limited to concentration, exposure time and delivery system.