Potential of curcumin-mediated photodynamic inactivation to reduce oral colonization

The present study assessed the susceptibility of salivary pathogens to photodynamic inactivation (PDI), mediated by a water-soluble mixture of curcuminoids (CRM) and LED light.

A 10mL sample of unstimulated saliva was collected from volunteers. The inoculum was prepared using 9mL of saline and 1mL of saliva. Inoculum suspensions were divided into 14 groups and treated according to the description below. Groups that received the PDI treatment (light for 1min or 5min and 1.5g/L or 3.0g/L of CRM concentration) were called C1.5L1.8, C1.5L9.0, C3.0L1.8, C3.0L9.0. To evaluate the CRM decontamination alone, the C1.5/1,C1.5/5,C3.0/1 and C3.0/5 groups were assessed. Likewise, light alone was evaluated through the L1.8 and L9.0 groups. Chlorhexidine at 0.12% (CLX) for 1 or 5min was used for the positive control groups (CLX1 and CLX5, respectively); saline was used for 1 or 5min (CTR1, CTR5, respectively) for the negative control groups. After the tests, serial dilutions were performed, and the resulting samples were plated on blood agar in microaerophilic conditions. The number of colony forming units (CFU/mL) was determined and log10-transformed. Data were analyzed using a One-way Analysis of Variance with Welch correction, followed by the Games Howell's test (α=0.05). Log reduction (LR) measure for antimicrobial efficacy was also calculated using data from the CTR5 as untreated samples.

The CHX5 showed the best antimicrobial result, followed by the CLX1. The antimicrobial effect of CRM was more pronounced when associated with light (PDI), but significantly lower than the CLX5 effect. The C3.0L9.0 protocol showed similar results to the CLX1.

The results show that PDI with CRM at the studied concentrations is as effective for oral decontamination in clinical dental care conditions as the CLX at 0.12% for 1min.