Bleaching of stained teeth using Cu-coupled TiO₂ nanoparticles using hydrogen peroxide and blue light.

Abstract

Purpose: To evaluate the efficacy of copper-doped titanium dioxide (Cu-TiO₂) nanoparticles (NPs) in bleaching the stained teeth when subjected to hydrogen peroxide (H₂O₂) and blue light irradiation.

Methods: Cu-TiO₂ NPs were synthesized by mixing TiO₂ and Cu, followed by calcination. Their light absorbance was measured. Photocatalytic reactions were evaluated using methylene blue (MB), 3,3',5,5'-tetramethylbenzidine (TMB), and terephthalic acid (TA) assays. Color changes in stained teeth were monitored under various conditions, including the presence or absence of 3% H₂O₂ and light irradiation. Additionally, the cytotoxicity of Cu-TiO₂ NPs on normal oral cells (periodontal ligament fibroblast: PDLF) was evaluated.

Results: Unlike pristine TiO₂, Cu-TiO₂ exhibited a slightly increased absorbance in the 600-800 nm range due to the incorporated Cu. Cu-TiO₂ demonstrated high MB degradation and a marginal increase in peak intensity at 650 nm upon combined H₂O₂ and light irradiation. The TA assay showed a gradual increase in peak fluorescence intensity near 425 nm with increasing light exposure. Stained teeth treated concurrently with Cu-TiO₂ NPs, 3% H₂O₂, and laser irradiation exhibited significantly superior color changes. Importantly, the tested Cu-TiO₂ NPs displayed negligible toxicity to PDLF at concentrations up to 500 ppm.

Clinical significance: Cu-TiO₂ NPs, when utilized with 3% H₂O₂ and blue laser, offer enhanced bleaching efficacy through photoinduced radical generation compared to 15% H₂O₂ alone, while maintaining negligible damage to normal oral cells at concentrations of 500 ppm or higher.