The impact of photodynamic therapy on the viability of Streptococcus mutans in a planktonic culture.

Objective: This study investigated the effect of photodynamic therapy (PDT) with toluidine blue O (TBO) and a light-emitting diode (LED) on the viability of Streptococcus mutans cells in a planktonic culture.

Background Data: Growth of Streptococcus mutans is the first step in the development of tooth decay. The use of light and dyes promotes cellular death in a noninvasive way, reducing treatment time.

Methods: The LED used in this study had output power of 116 mW, its energy was 21 J, and the fluency was 2.18 J/cm(2). Samples were prepared and divided into five groups: (1) control group (-); (2) control group (+); (3) TBO; (4) LED; and (5) LED + TBO.

Results: One hundred percent of the bacteria were killed following irradiation with LED and TBO. The biofilm that formed on the glass surfaces was analyzed by SEM and colony count.

Conclusions: It was demonstrated that PDT was efficient at killing microorganisms and preventing the formation of biofilms.