Combined catalytic strategies applied to in-office tooth bleaching: whitening efficacy, cytotoxicity, and gene expression of human dental pulp cells in a 3D culture model.

Abstract

Objectives: To evaluate the feasibility of using a 3D model with human dental pulp cells (HDPCs) to compare bleaching therapies and assess whether coating enamel with a nanofiber scaffold (NS) and polymeric catalyst primer (PCP), combined with violet LED (LEDv) irradiation, enhances bleaching efficacy (BE) and reduces cytotoxicity (CT).

Materials and methods: After using NS + PCP to cover enamel of enamel/dentin discs adapted to artificial pulp chambers containing 3D culture with HDPCs, a bleaching gel with 35%H₂O₂ was applied and then irradiated with LEDv. The following groups were established (n = 8): NC - no treatment; PC- 35%H₂O₂ for 45 min, and EXP: NS + PCP + 35%H₂O₂ + LEDv for 15 min. The study evaluated BE (ΔE₀₀ and ΔWI_D), CT (alamarBlue), and HDPCs gene modulation (TNF, IL1B, PTGS2, IL8, IL6, PPRAG, HMOX1, DSPP, DMP1, SPP1, BGLAP, and ALPL; RTqPCR).

Results: BE showed no significant difference between PC and EXP (p > 0.05). EXP had lower oxidative stress, higher cell viability, reduced inflammatory marker expression, and increased mineralization marker expression compared to PC (p < 0.05).

Conclusion: The 3D model using HDPCs effectively compared bleaching protocols. Coating enamel with NS + PCP and applying violet LED (LEDv) reduced bleaching time from 45 to 15 min while lowering cytotoxicity compared to conventional in-office treatments.

Clinical relevance: This study shows that a 3D model with human dental pulp cells (HDPCs) effectively compares tooth bleaching protocols. The combination of a nanofiber scaffold with violet LED (LEDv) reduces bleaching time, as well as minimizes cytotoxicity and inflammation, offering a safer alternative to conventional treatments.