Effect of whitening pens on hydrogen peroxide permeability in the pulp chamber, color change and surface morphology

Objective: To evaluate hydrogen peroxide (HP) permeability into the pulp chamber, color change, and surface morphology promoted by different whitening pens. Material and methods: Fifty premolars were divided into five groups (n = 10): untreated control; Colgate Optic White Express Whitening Pen (OE-C), Colgate Optic White Overnight Whitening Pen (OW-C), Equate Teeth Whitening Kit (TK-E) and Zimba Teeth Whitening Pen (TW-Z), applied daily for 15 minutes over ten days. HP permeability (mu g/mL) was measured using UV-VIS spectroscopy, and color change (Delta Eab, Delta E00, and WID) by a digital spectrophotometer at baseline (T0), after one (T1), five (T5) and ten days (T10). Initial HP concentration (%), pH and surface morphology were determined through titration, pH meter, and scanning electron microscopy, respectively. Statistical analysis included one-way and two-way ANOVA with Tukey's and Dunnett's tests (alpha = 0.05). Results: OE-C and OW-C exhibited higher pH, lower HP concentrations, reduced HP penetration (p < 0.05), and a similar surface morphology pattern compared to TK-E and TW-Z. Bleaching efficacy showed no significant differences among the whitening pens (p > 0.05). For Delta Eab and Delta E00, OE-C and OW-C showed similar color changes across all time points, whereas the TK-E and TW-Z exhibited greater changes from T0 to T5 and T0 to T10 (p < 0.05). WID values significantly increased at T5 and T10 across all groups (p < 0.05). Conclusions: Whitening pens vary in pH, initial hydrogen peroxide concentration, and hydrogen peroxide penetration; however, these differences do not significantly impact their surface morphology and bleaching effect. Clinical significance: The use of whitening pens appears promising for achieving effective teeth bleaching after five days of application. However, the detection of hydrogen peroxide within the pulp chamber may increase the risk of tooth sensitivity.