Influence of the Light Source and Bleaching Gel on the Efficacy of the Tooth Whitening Process

Objective: To examine the whitening efficacy of three whitening agents in combination with six different photoactivation systems. Background: Bleaching techniques have achieved significant advances using photoactivation with coherent or incoherent radiation sources. Methods: Quick White, Ena White Power, and Opalescence Endo bleaching agents, all containing 35% hydrogen peroxide, were stimulated with halogen lamp, light-emitting diode (LED), low-power diode laser, and neodymium: yttrium-aluminum-garnet (Nd:YAG), second harmonic of Nd:YAG, and Er:YAG lasers. One hundred twenty-six extracted human incisors were treated, and color change, pulpal temperature, and enamel morphological alterations were evaluated. Results: Only the groups that were photoactivated using a diode laser, halogen lamp, and LED showed statistically significant differences (p < 0.005) in color change when compared with the control group (without photoactivation). All whitening protocols were safe with regard to the increase in pulpal temperature. Scanning electron microscopy showed no evidence of effects on the integrity of enamel. Conclusions: The source of irradiation is more relevant than the bleaching agent for efficient tooth whitening. In addition, photoactivation with LED was found to be the best choice: it yielded significant change in color with only a minor increase in pulpal temperature.