In-vitro series of experiments on the antibacterial efficacy of a photodynamic system with riboflavin (vitamin B2) and a polychromatic LED light source against the pathogenic oral germ Streptococcus mutans.
Executing Body:
Diagnostics & Research (D&F) Institute for Hygiene, Microbiology and Environmental Medicine, Medical University of Graz
Client: Mana Health Technologies GmbH
1. Aim of the experimental series
The aim of this series of experiments was to investigate the antibacterial effect of the oral photodynamic care system "manadental" by Mana Health Technologies GmbH on the pathogenic oral germ Streptococcus mutans. For comparison, two commercially available conventional mouthwashes were tested for their antibacterial efficacy.
Using the indicator germ Streptococcus mutans as an example, an in-vitro study was conducted to determine the extent to which the method is able to reduce the number of Colony Forming Units (CFU/ml) in the experimental approach.
2. Material and Methods
The pathogenic oral germ Streptococcus mutans was incubated on COL-S agar plates at 37°C, 5% CO2 concentration for 48h before irradiation, then suspended in 0.9% NaCl and adjusted to a defined initial germ count (107 - 108) using OD600 measurement. The germ suspension was mixed with the solutions to be tested (riboflavin rinse, conventional mouthwash 1, conventional mouthwash 2) in the experimental setup.
The LED light source used in the experiment has a polychromatic emission spectrum that contains the wavelength required for the photophysical excitation of riboflavin at the necessary energy level. Irradiation was applied in 5-minute (300 sec.) cycles.
The photodynamic rinse was a water-based solution with a special vitamin B2 (riboflavin) derivative as a photosensitizer. The formulation was designed as a mouthwash and therefore contains not only flavoring agents but also other active ingredients that are synergistically related to the primary photodynamic effect.
After manipulation and incubation with the mouthwashes, the solutions were re-mixed with a pipette, diluted in a 1:10 dilution series up to 107, and plated out. Each experiment was evaluated twice as a technical duplicate. In addition, the photodynamic irradiation was designed as a biological duplicate.
The following experimental approaches were compared:
- Control
- LED irradiation
- Riboflavin rinse
- Riboflavin rinse + LED irradiation
- Conventional mouthwash 1
- Conventional mouthwash 2
3. Results
The results of the experimental approaches can be found in the following table:
Table 1: Results of the in-vitro studies
The results of the experiments show that neither irradiation alone (BK) nor the riboflavin rinse alone (RK) exhibit detectable bactericidal effects compared to the growth control (WK1 and WK2). However, the combination of irradiation and riboflavin rinse (BES I, BES II) develops a strong antibacterial effect within the experiment against Streptococcus mutans (germ reduction of ~5.5 log levels).
The relative difference in effectiveness between the conventional mouthwashes (SP1, SP2) and the photosensitizing irradiated riboflavin rinse (BES I, BES II) within the experimental series is ~3.0 log levels. Since three logarithmic units (3.0 log levels) mean a percentage reduction of 99.9%, it can be assumed that the manadental photodynamic system is 99.9% more effective against S. mutans than the conventional mouthwash solutions tested.
4. Interpretation and Summary
This study thus classifies the antimicrobial efficacy of the tested photodynamic system as significantly more effective than commercially available mouthwashes when incubated according to the manufacturer's instructions within the experimental series (Fig. 1).
Figure 1: Results of the in-vitro studies
literature references
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