In vitro evaluation of halogen light-activated vs chemically activated in-office bleaching systems

Abstract

Objectives. To compare the tooth whitening efficacy, temperature and HP concentration changes induced by halogen light-activated and chemically activated in-office bleaching systems. Materials and methods. Twenty-four extracted premolars were randomly divided into two groups (n = 12): Group BL (35% HP with halogen light activation) and Group OP (38% HP with chemical activation). Tooth color was measured by a spectrophotometer according to the CIE L*a*b* color space system. Temperatures of bleaching gels and pulp chambers during the bleaching process were monitored and recorded by a digital multimeter with K-type thermocouple. HP concentrations were tested before and after treatments by iodometry. ANOVA and paired t-test were used for statistical analyses at the significance of p < 0.05. Results. Tooth whitening resulted in the increase of ΔL* and ΔE and reduction of Δb*. Paired t-tests revealed groups BL had greater ΔE than group OP, however, there was no statistically significant difference in ΔE between them after 3 weeks post-treatment. Maximal temperature rise (ΔT) was found only in group BL, showing the increment of 2.55 and 2.02°C for bleaching gels and pulp chambers, respectively. HP concentrations were higher than baseline values for group OP (p < 0.001) rather than group BL. Conclusions. Halogen light and chemically activated in-office bleaching systems were both effective for tooth whitening, but halogen light activation could improve the immediate whitening effect. In contrast, chemical activation was a more conservative method due to the little temperature rise in pulp chambers.

Key Words::

• activation
• color
• temperature
• tooth bleaching

Acknowledgments

This work was supported by the Natural Science Foundation of China (No. 81071190, No.81070853, No.81100770), the Fundamental Research Funds for the central Universities (No. 41030030, No.2012304020201) and the Self-Research Program for Doctoral Candidates of Wuhan University (No.201130402020003).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

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