Background: This in vitro study determined the effectiveness of violet-blue light (405 nm) on inhibiting Streptococcus mutans-induced enamel demineralization.
Materials and methods: S. mutans UA159 biofilm was grown on human enamel specimens for 13 h in 5% CO₂ at 37 °C with/without 1% sucrose. Wet biofilm was treated twice daily with violet-blue light for five minutes over five days. A six-hour reincubation was included daily between treatments excluding the final day. Biofilms were harvested and colony forming units (CFU) were quantitated. Lesion depth (L) and mineral loss (∆Z) were quantified using transverse microradiography (TMR). Quantitative light-induced fluorescence Biluminator (QLF-D) was used to determine mean fluorescence loss. Data were analyzed using one-way analysis of variance (ANOVA) to compare differences in means.
Results: The results demonstrated a significant reduction in CFUs between treated and non-treated groups grown with/without 1% sucrose. ∆Z was significantly reduced for specimens exposed to biofilms grown without sucrose with violet-blue light. There was only a trend on reduction of ∆Z with sucrose and with L on both groups. There were no differences in fluorescence-derived parameters between the groups.
Conclusions: Within the limitations of the study, the results indicate that violet-blue light can serve as an adjunct prophylactic treatment for reducing S. mutans biofilm formation and enamel mineral loss.
Keywords: Streptococcus mutans; dental caries; phototherapy; violet-blue light.