Effect of violet LED light on in-office bleaching protocols: a randomized controlled clinical trial

Abstract

Colorimetric evaluation was performed using a spectrophotometer (ΔE, ΔL, Δa, Δb) and a visual shade guide (ΔSGU). Calcium (Ca)/phosphorous (P) ratio was quantified in the enamel microbiopsies. Measurements were performed at baseline (T 0), after bleaching (T B) and in the 14-day follow-up (T 14). At each bleaching session, a visual scale determined the absolute risk (AR) and intensity of tooth sensitivity (TS). Data were evaluated by one-way (ΔE, Δa, ΔL, Δb), two-way repeated measures ANOVA (Ca/P ratio), and Tukey post-hoc tests. ΔSGU and TS were evaluated by Kruskal-Wallis and Mann-Whitney, and AR by Chi-Squared tests (a=5%). Results: LED produced the lowest ΔE (p<0.05), but LED/HP promoted greater ΔE, ΔSGU and Δb (T 14) than HP (p<0.05). No differences were observed in ΔE and ΔSGU for LED/CP and HP groups (p>0.05). ΔL and Δa were not influenced by LED activation. After bleaching, LED/CP exhibited greater Δb than CP (p>0.05), but no differences were found between these groups at T 14 (p>0.05). LED treatment promoted the lowest risk of TS (16%), while HP promoted the highest (94.4%) (p<0.05). No statistical differences of risk of TS were found for CP (44%), LED/CP (61%) and LED/HP (88%) groups (p>0.05). No differences were found in enamel Ca/P ratio among treatments, regardless of evaluation times. Conclusions: Violet LED alone produced the lowest bleaching effect, but enhanced HP bleaching results. Patients treated with LED/CP reached the same efficacy of HP, with reduced risk and intensity of tooth sensitivity and none of the bleaching protocols adversely affected enamel mineral content.

Effect of light and heat on bleaching action of hydrogen peroxide

“…On the other hand, a clinical study evidenced a low capacity of violet light to promote a bleaching effect compared to 40% hydrogen peroxide (Kury et al, 2020). However, increased bleaching potential was found associating carbamide and hydrogen peroxide and LED (Kury et al 2020), corroborating our results. In our study, groups CL and CA were similar when another heat source was used.…”

“…It is speculated that the short wavelength of violet light (405 nm) may present a photolytic effect, breaking same absorption spectrum pigments on enamel surface (Alshammery, 2019). On the other hand, a clinical study evidenced a low capacity of violet light to promote a bleaching effect compared to 40% hydrogen peroxide (Kury et al, 2020). However, increased bleaching potential was found associating carbamide and hydrogen peroxide and LED (Kury et al 2020), corroborating our results.…”

“…Recently, violet LEDs associated with bleaching gel improved bleaching effect of hydrogen peroxide without affecting mineral structures of enamel (Kury et al, 2020). It is speculated that the short wavelength of violet light (405 nm) may present a photolytic effect, breaking same absorption spectrum pigments on enamel surface (Alshammery, 2019).…”

Effects of activated charcoal powder combined with toothpastes on enamel color change and surface properties

“…25 In vivo evidence demonstrated that enamel properties are preserved after whitening with peroxide gels in the presence of human saliva and adhered pellicle. 26 Therefore, evidence-based research indicates that CP treatment is an effective and safe option for patients seeking dental whitening. 1 Because charcoal powder requires the act of brushing, this could mislead patients not to brush teeth with fluoridecontaining toothpastes.…”

“…In vivo evidence demonstrated that enamel properties are preserved after whitening with peroxide gels in the presence of human saliva and adhered pellicle 26 . Therefore, evidence‐based research indicates that CP treatment is an effective and safe option for patients seeking dental whitening 1 .…”