Effects of combined use of light irradiation and 35% hydrogen peroxide for dental bleaching on human enamel mineral content.
OBJECTIVE
The objective of this study was to evaluate the effects of the combined use of light irradiation (LIR, halogen light, or LED/diode laser) and 35% hydrogen peroxide (35%HP) on human enamel mineral content.


BACKGROUND
The use of high-intensity light has been indicated for acceleration of the rate of chemical bleaching; however, it is not known whether LIR can promote additional effects on enamel surfaces during the bleaching.


METHODS
One hundred enamel samples were obtained from third molars and randomly divided into 10 groups (n = 10). The control group (CG) remained untreated. Three whitening products were used: Whiteness HP Maxx, Pola Office, and Opalescence Xtra. Bleaching consisted of one session, and the products were applied three times to each specimen for 10 min each. The products were subjected, or not, to LIR during treatment with halogen light or LED/diode laser. The mineral concentration of enamel was determined before and after treatments using an FT-Raman spectroscope (FT-RS), and the amount of calcium lost from the bleached enamel surfaces was quantified with an atomic absorption spectrometer (AAS).


RESULTS
FT-RS results showed a decreased mineral content after all treatments, with the exception of Pola Office when irradiated with LED/diode laser and the CG. The losses of calcium detected for Pola Office and Opalescence Xtra were similar for the three situations (without or with light irradiations), whereas for Whiteness HP Maxx the lowest calcium loss was detected without LIR.


CONCLUSIONS
Most of the bleaching treatments investigated, in combination with LIR or not, can reduce the mineral content of enamel surface. LIR increased the calcium loss for Whiteness HP Maxx; no effects were observed for Pola Office and Opalescence Xtra.
Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
Sandrine Bittencourt
SB
Berger
Vanessa
V
Cavalli
Airton Abrahão
AA
Martin
Luis Eduardo Silva
LE
Soares
Marco Aurelio Zezzi
MA
Arruda
Marcel Luis
ML
Brancalion
Marcelo
M
Giannini
D003743:Dental Enamel / Q000737:chemistry*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D016877:Oxidants / Q000494:pharmacology*; D010789:Phototherapy; D011897:Random Allocation; D013059:Spectrum Analysis, Raman; D014073:Tooth Bleaching / Q000379:methods*
D016877:Oxidants; D006861:Hydrogen Peroxide