Targeted photocatalytic whitening with LED/laser-activated hydrogen peroxide gels containing nitrogen-doped TiO2: A multi-study clinical analysis of efficacy, sensitivity, and energy optimization

Abstract

Objective: This study assessed the clinical efficacy, safety, and energy parameters of 6 % and 15 % hydrogen peroxide (HP) gels containing nitrogen-doped titanium dioxide (N-TiO₂), activated by dual-wavelength light sources.

Materials and methods: A pooled analysis was performed using data from six randomized controlled trials with harmonized protocols. All gels incorporated N-TiO₂ nanoparticles as visible-light-sensitive photocatalysts and were activated using a blue LED (450 ± 10 nm) and an infrared laser (808 ± 10 nm). Standardized dosimetric conditions were maintained (irradiance: 1528-1783 mW/cm²; total energy: 4300-6500 J). Clinical outcomes included spectrophotometric color change (ΔE), shade guide unit change (ΔSGU), and tooth sensitivity measured by visual analog scale (VAS).

Results: Bleaching with 6 % HP + N-TiO₂ consistently achieved ΔE values >5.0, with low sensitivity scores (VAS < 1.0). The 15 % HP formulation showed slightly enhanced whitening (ΔE ≈ 6.5-8.9) with a modest increase in VAS. Long-term follow-up (12-24 months) confirmed sustained color stability and minimal rebound. There was no significant correlation between ΔE and VAS (r = 0.12, p = 0.81), suggesting effective bleaching without increased discomfort.

Conclusions: LED/laser-activated gels containing N-TiO₂ offer effective and regulation-compliant whitening with significantly reduced sensitivity. The bleaching effect is attributed to wavelength-specific photocatalysis rather than heat.

Clinical significance: This study supports the use of light as a selective photochemical activator in peroxide-based bleaching, challenging generalizations that associate light with thermal sensitivity.

Keywords: Dental phototherapy;Tooth sensitivity reduction; Low-concentration hydrogen peroxide; Nitrogen-doped titanium dioxide (TiO₂_N); Photodynamic Therapy; Photodynamic activation; Tooth bleaching;LED/laser-assisted whitening.