Chitosan gel prevents the growth of Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola in mini-implant during orthodontic treatment

We evaluated the effect of chitosan gel on total oral bacteria, Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola, during orthodontic treatment with mini-implants.Thirty subjects with 52 orthodontic mini-implants were divided into three groups: one group was treated with chitosan gel, the other group with chlorhexidine gel, and the control group with placebo. The plaque of the orthodontic peri-mini-implant area was collected before and after gel treatment. The total oral bacteria and red-complex bacteria of P. pingivalis, T. forsythia, and T. denticola were determined with reverse transcription-quantitative PCR.Thirty-four orthodontic mini-implants (65.38%) appeared as healthy and showed no clinical signs of inflammation. The total number of bacteria was reduced after chitosan gel application. The highest decrease in the proportion of P. gingivalis was observed in the chlorhexidine gel application group, which showed a value of 70.86%, whereas the chitosan gel application showed a reduction of only 26.59%, and the control gel application showed the lowest reduction effect of only 2.55%. The difference in the reduction between gel application groups was significant (P < 0.05) for T. denticola and T. forsythia.The gel containing chitosan reduced the levels of total oral bacteria and red-complex bacteria.