A study conducted by researchers from São Paulo State University (São Paulo, Brazil) confirms that using low-level red laser light to activate bleaching gel increases the effectiveness of teeth whitening.
To assess the red laser light's effectiveness in activating a bleaching gel and its effect in pulp temperature, researchers used 40 extracted bovine teeth immersed in a solution of coffee 14 days for darkening, with their initial colors recorded by spectrophotometric analysis. Then, the specimens were randomly distributed into two groups of 20: the control group, which did not receive light, and the experimental group, which received light from an appliance fitted with three red light-emitting laser diodes (λ = 660 nm).
A green-colored, 35% H2O2-based bleaching gel was applied to the teeth for 30 minutes and changed three times. After bleaching, the colors were again measured to obtain the L*a*b* values. Color variation was calculated (ΔE) and the data submitted to the non-paired t-test (5%). To assess temperature, 10 human incisors were prepared, in which one thermocouple was placed on the bleaching gel applied on the surface of the teeth and another inside the pulp chamber.
The researchers found a significant difference between the groups (p = 0.016), and the experimental group presented a significantly higher mean variation (7.21 ± 2.76) in comparison with the control group (5.37 ± 1.76). Results showed that there was an increase in pulp temperature, but it was not sufficient to cause damage to the pulp.
"Bleaching gel activation with low-intensity red laser was capable of increasing the effectiveness of bleaching treatment and did not increase pulp temperature to levels deleterious to the pulp," the researchers concluded.
The study is published in the June 15 issue of the Journal of Esthetic and Restorative Dentistry.
Posted by Lee Mather
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