In-office Bleaching Activated With Violet LED: Effect on Pulpal and Tooth Temperature and Pulp Viability

Area of Science:

• Biomaterials Science
• Dental Materials
• Biotechnology

Background:

• Tooth whitening procedures often involve hydrogen peroxide (HP), which can pose risks like pulp irritation due to temperature increase.
• Titanium dioxide nanotubes (TiO2) and violet LED (VL) have been explored to enhance bleaching efficacy and potentially mitigate risks.

Purpose of the Study:

• To evaluate the impact of 35% and 7.5% HP, with or without TiO2 and VL, on pulp chamber temperature, HP decomposition, and pulp cell cytotoxicity.
• To determine the safety and efficacy of novel tooth whitening formulations.

Main Methods:

• Eight experimental groups of bovine incisors were subjected to different combinations of HP concentrations (35% and 7.5%), TiO2 (1%), and VL exposure for 30 minutes.
• Temperature changes were monitored using thermocouples in the pulp chamber and on the facial surface.
• HP decomposition was measured using an automatic potentiometric titrator.
• Cytotoxicity was assessed by applying treatment extracts to MDPC-23 odontoblast cells via MTT assay.

Main Results:

• Violet LED (VL) caused a minor temperature increase in the pulp chamber (max 1.9°C), not exceeding critical damage thresholds.
• Higher HP concentration (35%) showed increased decomposition when combined with VL.
• Lower HP concentration (7.5%) demonstrated significantly higher cell viability compared to 35% HP.
• Cell viability was reduced for 7.5% HP when used with VL.

Conclusions:

• The combination of VL and HP, even with TiO2, did not lead to critical pulp temperature increases.
• Lower HP concentrations are safer for pulp cells, with viability decreasing when VL is applied.
• This study suggests that careful formulation and concentration selection are crucial for safe and effective tooth whitening treatments.