The study of the influence of a photosensitizer and combined effects of low-intensity laser radiation on the composition of the microflora of the dental plaque

The effect of low-intensity laser radiation (LILR) on the background of a photosensitizer (ethacridine lactate) on selective elimination of pathogenic and conditionally pathogenic microorganisms has been studied. Taking into account antiseptic properties of ethacridine lactate the maximally possible time of influence of ethacridine lactate as a photosensitizer should be set. It has been found that after the influence of rivanol (ethacridine lactate) within 1.5-3 minutes the bactericidal action on microorganisms is observed. The effect of antiseptic in the interval from 30 to 60 seconds was not accompanied with the expressed quantitative change of the microbial population. The second stage of the research was identification of microorganisms sensitivity to various concentrations of the photosensitizer. As a photosensitizer the aqueous solution of ethacridine lactate in the concentrations of 0.1; 0.05; 0.01% was used. The results obtained allow to conclude that the concentration of 0.1% solution of ethacridine lactate increases the sensitivity of microorganisms to the effects of low-intensity laser radiation. During the experiment the combined impact of the antimicrobial activity of 0.1% solution of ethacridine lactate and blue spectrum laser radiation has been determined; it is manifested by decrease in the number of CFU/ml of the total microflora of the dental plaque. The number of CFU is reduced from 14.3 ± 0.12 . 10 3 /ml up to 2.4 ± 0.3 . 10 2 /ml after exposure (Table 1). Comparing the data of the control (the initial number of the colonies grown) and the experiment (the number of the colonies grown after the photoactivated disinfection) we have found that the antibacterial action of photoactivated disinfection depends directly on duration of exposure. Thus, the effectiveness of combined use of a photosensitizer with LILR is 1.2 times higher than that of ethacridine lactate (the exposure time is 60 seconds), and 2.0 times higher than the antimicrobial effect of the laser blue spectrum (the exposure time is 120 seconds).