Antimicrobial activity of probiotics against oral pathogens around orthodontic mini-implants: an in vitro study

The aim of this in vitro study was to evaluate the antimicrobial effect of five types of non-industrialized and industrialized probiotics on biofilms formed around orthodontic mini-implants. The null hypothesis tested was: there is no difference in the antimicrobial effect between the five types of probiotics tested around orthodontic mini-implants.

For the experiment, 120 mini-implants were immersed for seven days in Staphylococcus aureus solution for biofilm formation, and were subsequently plated in culture medium containing probiotics. The mini-implants were divided into six different groups, according to the probiotic used: G1)Lactobacillus casei; G2)Lactobacillus brevis; G3)Lactobacillus rhamnosus; G4) Lactobacillus from fermented milk Yakult®; G5) Lactobacillus from fermented milk Batavito® and G6) without use of probiotic, as negative control. Qualitative and quantitative analyses of all groups were performed using the CFU (colony forming unit) count.

The study showed that groups G4 and G6 did not present antimicrobial activity, in comparison to groups G1, G2, G3, and G5 (p< 0.05), which demonstrated antimicrobial activity.

The non-commercial probiotic bacteria, Lactobacillus casei and Lactobacillus rhamnosus, as well as commercially available fermented milk Batavito® presented promising results in the reduction of colonization of mini-implants by S. aureus. Therefore, the null hypothesis was rejected.