As consumer demand for rapid, non-invasive cosmetic treatments grows, LED-based tooth bleaching has emerged as a popular in-office and at-home solution. This technology leverages specific light wavelengths - particularly violet (405–410 nm) and blue (450–500 nm) - to either activate peroxide-based gels or, in some protocols, to bleach without any chemicals.

Across multiple clinical and laboratory studies, key insights have emerged regarding how effective and safe these methods are when used alone or in combination with bleaching agents.

A clinical study by Hayward et al. (2012) tested a blue LED system (BriteWhite) combined with 44% carbamide peroxide followed by 14 days of at-home treatment with 35% gel. The primary improvement occurred immediately after the LED session, with only a minor increase in whiteness after the at-home phase. The total color change was modest (∆Eab = 1.8 units), with low tooth and gum sensitivity reported (below mild levels). The LED treatment was mild in concentration and application duration, offering safety but limited brightness results.

In contrast, studies evaluating violet LED systems, like Menezes et al. (2022), found significant color changes without compromising enamel hardness or causing genotoxicity. The violet LED (405–410 nm) showed better performance than blue LEDs, particularly when used without chemical gels. Importantly, violet LED use alone caused no enamel damage and preserved tooth structure, a key concern in whitening treatments.

Further support comes from a 12-month randomized clinical trial by Lopes et al. (2024), which compared violet LED with and without 37% carbamide peroxide. Both protocols produced lasting whitening effects, but the peroxide-enhanced treatment consistently yielded greater color change (∆E > 4). The group using violet LED without gel still saw meaningful results (∆E ~2.66 at 12 months) with lower sensitivity, especially for patients with naturally extrinsic stains.

Together, these findings suggest that while peroxide-enhanced LED treatments offer stronger whitening, gel-free violet LED protocols are promising for patients sensitive to peroxide. Results depend on the baseline tooth color, gel concentration, and LED wavelength, with violet light showing particular promise in balancing safety and performance.