LED activation of whitening increased enamel roughness, lasers did not

Light that speeds up whitening does not behave the same way

In-office whitening counts as a minimally invasive procedure, but every change to the enamel surface carries a price: a rougher surface retains plaque and pigment more easily, so the result is lost faster. That is why N. Azimi and colleagues, writing in Lasers in Medical Science, compared what conventional whitening without light, LED activation and four laser systems do to the enamel surface.

Sixty freshly extracted human anterior teeth were selected and randomly assigned to groups of ten samples: no light activation, LED, and KTP, diode, Nd:YAG and CO2 lasers. Roughness was measured on all samples before the procedure and again after whitening. The control group was treated with Opalescence Xtra Boost, the others with JW Power Bleaching gel. The data were analysed with the Kruskal-Wallis test and two-way analysis of variance at a significance threshold of 0.05.

Laser activation is proposed in the literature as the safer alternative, and the measurements pointed that way. The change in roughness was considerably larger with LED activation than without light (P = 0.0236). The laser groups did not differ significantly either from the conventional group or from one another. In the middle third of the crown, LED produced significantly greater roughness than the KTP laser (P = 0.029). The authors conclude that laser activation better preserves the integrity of the enamel surface under these conditions.

Limitations

The investigation is in vitro, with ten samples per group, and the control group was whitened with a different preparation than the others, so the difference in gel remains a possible confounder alongside the difference in light source.

For your practice

• If your protocol uses an LED lamp, expect a larger change in roughness than without activation and reinforce polishing and the post-procedure maintenance instructions.
• The finding concerns the enamel surface, not the success of whitening; the study did not compare the colour change achieved between the groups.
• The middle third of the crown showed the largest difference between LED and the KTP laser, so it is worth a closer look at the follow-up visit.